Fix postProcessors having value semantics when unset

Currently, if postProcessors was empty, it would be set to a new
pointer value. But that would only apply for the current Configurable,
so if you passed a Configurable by value to a function and then
that function added a postProcessor, the caller wouldn't see that.

Configurable properties in general have a confusing mix of pointer
and value semantics (thanks go...), this fixes one part of it but in
followup cls I'll try to make it consistent.

Bug: 362579941
Test: m nothing --no-skip-soong-tests
Change-Id: Ib33497768be3af45233cf1a682adffb28ee64bfd

Android.bp

@@ -133,6 +133,7 @@ bootstrap_go_package {
     ],
     testSrcs: [
         "proptools/clone_test.go",
+        "proptools/configurable_test.go",
         "proptools/escape_test.go",
         "proptools/extend_test.go",
         "proptools/filter_test.go",

bpfmt/bpfmt.go

@@ -66,7 +66,7 @@ func processReader(filename string, in io.Reader, out io.Writer) error {
 
 	r := bytes.NewBuffer(src)
 
-	file, errs := parser.Parse(filename, r, parser.NewScope(nil))
+	file, errs := parser.Parse(filename, r)
 	if len(errs) > 0 {
 		for _, err := range errs {
 			fmt.Fprintln(os.Stderr, err)

bpmodify/bpmodify.go

@@ -85,7 +85,7 @@ func processFile(filename string, in io.Reader, out io.Writer) error {
 		return err
 	}
 	r := bytes.NewBuffer(src)
-	file, errs := parser.Parse(filename, r, parser.NewScope(nil))
+	file, errs := parser.Parse(filename, r)
 	if len(errs) > 0 {
 		for _, err := range errs {
 			fmt.Fprintln(os.Stderr, err)
@@ -131,11 +131,13 @@ func findModules(file *parser.File) (modified bool, errs []error) {
 	for _, def := range file.Defs {
 		if module, ok := def.(*parser.Module); ok {
 			for _, prop := range module.Properties {
-				if prop.Name == "name" && prop.Value.Type() == parser.StringType && targetedModule(prop.Value.Eval().(*parser.String).Value) {
-					for _, p := range targetedProperties.properties {
-						m, newErrs := processModuleProperty(module, prop.Name, file, p)
-						errs = append(errs, newErrs...)
-						modified = modified || m
+				if prop.Name == "name" {
+					if stringValue, ok := prop.Value.(*parser.String); ok && targetedModule(stringValue.Value) {
+						for _, p := range targetedProperties.properties {
+							m, newErrs := processModuleProperty(module, prop.Name, file, p)
+							errs = append(errs, newErrs...)
+							modified = modified || m
+						}
 					}
 				}
 			}
@@ -194,7 +196,7 @@ func getOrCreateRecursiveProperty(module *parser.Module, name string, prefixes [
 	m := &module.Map
 	for i, prefix := range prefixes {
 		if prop, found := m.GetProperty(prefix); found {
-			if mm, ok := prop.Value.Eval().(*parser.Map); ok {
+			if mm, ok := prop.Value.(*parser.Map); ok {
 				m = mm
 			} else {
 				// We've found a property in the AST and such property is not of type
@@ -236,9 +238,9 @@ func processParameter(value parser.Expression, paramName, moduleName string,
 	}
 
 	if (*replaceProperty).size() != 0 {
-		if list, ok := value.Eval().(*parser.List); ok {
+		if list, ok := value.(*parser.List); ok {
 			return parser.ReplaceStringsInList(list, (*replaceProperty).oldNameToNewName), nil
-		} else if str, ok := value.Eval().(*parser.String); ok {
+		} else if str, ok := value.(*parser.String); ok {
 			oldVal := str.Value
 			replacementValue := (*replaceProperty).oldNameToNewName[oldVal]
 			if replacementValue != "" {

context.go

@@ -1221,9 +1221,9 @@ func (c *Context) parseOne(rootDir, filename string, reader io.Reader,
 		return nil, nil, []error{err}
 	}
 
-	scope.Remove("subdirs")
-	scope.Remove("optional_subdirs")
-	scope.Remove("build")
+	scope.DontInherit("subdirs")
+	scope.DontInherit("optional_subdirs")
+	scope.DontInherit("build")
 	file, errs = parser.ParseAndEval(filename, reader, scope)
 	if len(errs) > 0 {
 		for i, err := range errs {
@@ -1357,10 +1357,10 @@ func (c *Context) findSubdirBlueprints(dir string, subdirs []string, subdirsPos
 }
 
 func getLocalStringListFromScope(scope *parser.Scope, v string) ([]string, scanner.Position, error) {
-	if assignment, local := scope.Get(v); assignment == nil || !local {
+	if assignment := scope.GetLocal(v); assignment == nil {
 		return nil, scanner.Position{}, nil
 	} else {
-		switch value := assignment.Value.Eval().(type) {
+		switch value := assignment.Value.(type) {
 		case *parser.List:
 			ret := make([]string, 0, len(value.Values))
 
@@ -1386,24 +1386,6 @@ func getLocalStringListFromScope(scope *parser.Scope, v string) ([]string, scann
 	}
 }
 
-func getStringFromScope(scope *parser.Scope, v string) (string, scanner.Position, error) {
-	if assignment, _ := scope.Get(v); assignment == nil {
-		return "", scanner.Position{}, nil
-	} else {
-		switch value := assignment.Value.Eval().(type) {
-		case *parser.String:
-			return value.Value, assignment.EqualsPos, nil
-		case *parser.Bool, *parser.List:
-			return "", scanner.Position{}, &BlueprintError{
-				Err: fmt.Errorf("%q must be a string", v),
-				Pos: assignment.EqualsPos,
-			}
-		default:
-			panic(fmt.Errorf("unknown value type: %d", assignment.Value.Type()))
-		}
-	}
-}
-
 // Clones a build logic module by calling the factory method for its module type, and then cloning
 // property values.  Any values stored in the module object that are not stored in properties
 // structs will be lost.

module_ctx.go

@@ -1392,8 +1392,7 @@ func runAndRemoveLoadHooks(ctx *Context, config interface{}, module *moduleInfo,
 //
 // The filename is only used for reporting errors.
 func CheckBlueprintSyntax(moduleFactories map[string]ModuleFactory, filename string, contents string) []error {
-	scope := parser.NewScope(nil)
-	file, errs := parser.Parse(filename, strings.NewReader(contents), scope)
+	file, errs := parser.Parse(filename, strings.NewReader(contents))
 	if len(errs) != 0 {
 		return errs
 	}

parser/ast.go

@@ -16,6 +16,7 @@ package parser
 
 import (
 	"fmt"
+	"os"
 	"strings"
 	"text/scanner"
 )
@@ -40,14 +41,13 @@ type Assignment struct {
 	Name       string
 	NamePos    scanner.Position
 	Value      Expression
-	OrigValue  Expression
 	EqualsPos  scanner.Position
 	Assigner   string
 	Referenced bool
 }
 
 func (a *Assignment) String() string {
-	return fmt.Sprintf("%s@%s %s %s (%s) %t", a.Name, a.EqualsPos, a.Assigner, a.Value, a.OrigValue, a.Referenced)
+	return fmt.Sprintf("%s@%s %s %s %t", a.Name, a.EqualsPos, a.Assigner, a.Value, a.Referenced)
 }
 
 func (a *Assignment) Pos() scanner.Position { return a.NamePos }
@@ -131,6 +131,10 @@ func (p *Property) String() string {
 func (p *Property) Pos() scanner.Position { return p.NamePos }
 func (p *Property) End() scanner.Position { return p.Value.End() }
 
+func (p *Property) MarkReferencedVariables(scope *Scope) {
+	p.Value.MarkReferencedVariables(scope)
+}
+
 // An Expression is a Value in a Property or Assignment.  It can be a literal (String or Bool), a
 // Map, a List, an Operator that combines two expressions of the same type, or a Variable that
 // references and Assignment.
@@ -139,11 +143,24 @@ type Expression interface {
 	// Copy returns a copy of the Expression that will not affect the original if mutated
 	Copy() Expression
 	String() string
-	// Type returns the underlying Type enum of the Expression if it were to be evaluated
+	// Type returns the underlying Type enum of the Expression if it were to be evaluated, if it's known.
+	// It's possible that the type isn't known, such as when a select statement with a late-bound variable
+	// is used. For that reason, Type() is mostly for use in error messages, not to make logic decisions
+	// off of.
 	Type() Type
-	// Eval returns an expression that is fully evaluated to a simple type (List, Map, String, or
-	// Bool).  It will return the same object for every call to Eval().
-	Eval() Expression
+	// Eval returns an expression that is fully evaluated to a simple type (List, Map, String,
+	// Bool, or Select).  It will return the origional expression if possible, or allocate a
+	// new one if modifications were necessary.
+	Eval(scope *Scope) (Expression, error)
+	// PrintfInto will substitute any %s's in string literals in the AST with the provided
+	// value. It will modify the AST in-place. This is used to implement soong config value
+	// variables, but should be removed when those have switched to selects.
+	PrintfInto(value string) error
+	// MarkReferencedVariables marks the variables in the given scope referenced if there
+	// is a matching variable reference in this expression. This happens naturally during
+	// Eval as well, but for selects, we need to mark variables as referenced without
+	// actually evaluating the expression yet.
+	MarkReferencedVariables(scope *Scope)
 }
 
 // ExpressionsAreSame tells whether the two values are the same Expression.
@@ -157,9 +174,6 @@ func ExpressionsAreSame(a Expression, b Expression) (equal bool, err error) {
 // TODO(jeffrygaston) once positions are removed from Expression structs,
 // remove this function and have callers use reflect.DeepEqual(a, b)
 func hackyExpressionsAreSame(a Expression, b Expression) (equal bool, err error) {
-	if a.Type() != b.Type() {
-		return false, nil
-	}
 	left, err := hackyFingerprint(a)
 	if err != nil {
 		return false, nil
@@ -173,7 +187,7 @@ func hackyExpressionsAreSame(a Expression, b Expression) (equal bool, err error)
 }
 
 func hackyFingerprint(expression Expression) (fingerprint []byte, err error) {
-	assignment := &Assignment{"a", noPos, expression, expression, noPos, "=", false}
+	assignment := &Assignment{"a", noPos, expression, noPos, "=", false}
 	module := &File{}
 	module.Defs = append(module.Defs, assignment)
 	p := newPrinter(module)
@@ -183,17 +197,19 @@ func hackyFingerprint(expression Expression) (fingerprint []byte, err error) {
 type Type int
 
 const (
-	BoolType Type = iota + 1
+	UnknownType Type = iota
+	BoolType
 	StringType
 	Int64Type
 	ListType
 	MapType
-	NotEvaluatedType
 	UnsetType
 )
 
 func (t Type) String() string {
 	switch t {
+	case UnknownType:
+		return "unknown"
 	case BoolType:
 		return "bool"
 	case StringType:
@@ -204,12 +220,10 @@ func (t Type) String() string {
 		return "list"
 	case MapType:
 		return "map"
-	case NotEvaluatedType:
-		return "notevaluated"
 	case UnsetType:
 		return "unset"
 	default:
-		panic(fmt.Errorf("Unknown type %d", t))
+		panic(fmt.Sprintf("Unknown type %d", t))
 	}
 }
 
@@ -217,7 +231,6 @@ type Operator struct {
 	Args        [2]Expression
 	Operator    rune
 	OperatorPos scanner.Position
-	Value       Expression
 }
 
 func (x *Operator) Copy() Expression {
@@ -227,26 +240,142 @@ func (x *Operator) Copy() Expression {
 	return &ret
 }
 
-func (x *Operator) Eval() Expression {
-	return x.Value.Eval()
+func (x *Operator) Type() Type {
+	t1 := x.Args[0].Type()
+	t2 := x.Args[1].Type()
+	if t1 == UnknownType {
+		return t2
+	}
+	if t2 == UnknownType {
+		return t1
+	}
+	if t1 != t2 {
+		return UnknownType
+	}
+	return t1
 }
 
-func (x *Operator) Type() Type {
-	return x.Args[0].Type()
+func (x *Operator) Eval(scope *Scope) (Expression, error) {
+	return evaluateOperator(scope, x.Operator, x.Args[0], x.Args[1])
+}
+
+func evaluateOperator(scope *Scope, operator rune, left, right Expression) (Expression, error) {
+	if operator != '+' {
+		return nil, fmt.Errorf("unknown operator %c", operator)
+	}
+	l, err := left.Eval(scope)
+	if err != nil {
+		return nil, err
+	}
+	r, err := right.Eval(scope)
+	if err != nil {
+		return nil, err
+	}
+
+	if _, ok := l.(*Select); !ok {
+		if _, ok := r.(*Select); ok {
+			// Promote l to a select so we can add r to it
+			l = &Select{
+				Cases: []*SelectCase{{
+					Value: l,
+				}},
+			}
+		}
+	}
+
+	l = l.Copy()
+
+	switch v := l.(type) {
+	case *String:
+		if _, ok := r.(*String); !ok {
+			fmt.Fprintf(os.Stderr, "not ok")
+		}
+		v.Value += r.(*String).Value
+	case *Int64:
+		v.Value += r.(*Int64).Value
+		v.Token = ""
+	case *List:
+		v.Values = append(v.Values, r.(*List).Values...)
+	case *Map:
+		var err error
+		v.Properties, err = addMaps(scope, v.Properties, r.(*Map).Properties)
+		if err != nil {
+			return nil, err
+		}
+	case *Select:
+		v.Append = r
+	default:
+		return nil, fmt.Errorf("operator %c not supported on %v", operator, v)
+	}
+
+	return l, nil
+}
+
+func addMaps(scope *Scope, map1, map2 []*Property) ([]*Property, error) {
+	ret := make([]*Property, 0, len(map1))
+
+	inMap1 := make(map[string]*Property)
+	inMap2 := make(map[string]*Property)
+	inBoth := make(map[string]*Property)
+
+	for _, prop1 := range map1 {
+		inMap1[prop1.Name] = prop1
+	}
+
+	for _, prop2 := range map2 {
+		inMap2[prop2.Name] = prop2
+		if _, ok := inMap1[prop2.Name]; ok {
+			inBoth[prop2.Name] = prop2
+		}
+	}
+
+	for _, prop1 := range map1 {
+		if prop2, ok := inBoth[prop1.Name]; ok {
+			var err error
+			newProp := *prop1
+			newProp.Value, err = evaluateOperator(scope, '+', prop1.Value, prop2.Value)
+			if err != nil {
+				return nil, err
+			}
+			ret = append(ret, &newProp)
+		} else {
+			ret = append(ret, prop1)
+		}
+	}
+
+	for _, prop2 := range map2 {
+		if _, ok := inBoth[prop2.Name]; !ok {
+			ret = append(ret, prop2)
+		}
+	}
+
+	return ret, nil
+}
+
+func (x *Operator) PrintfInto(value string) error {
+	if err := x.Args[0].PrintfInto(value); err != nil {
+		return err
+	}
+	return x.Args[1].PrintfInto(value)
+}
+
+func (x *Operator) MarkReferencedVariables(scope *Scope) {
+	x.Args[0].MarkReferencedVariables(scope)
+	x.Args[1].MarkReferencedVariables(scope)
 }
 
 func (x *Operator) Pos() scanner.Position { return x.Args[0].Pos() }
 func (x *Operator) End() scanner.Position { return x.Args[1].End() }
 
 func (x *Operator) String() string {
-	return fmt.Sprintf("(%s %c %s = %s)@%s", x.Args[0].String(), x.Operator, x.Args[1].String(),
-		x.Value, x.OperatorPos)
+	return fmt.Sprintf("(%s %c %s)@%s", x.Args[0].String(), x.Operator, x.Args[1].String(),
+		x.OperatorPos)
 }
 
 type Variable struct {
 	Name    string
 	NamePos scanner.Position
-	Value   Expression
+	Type_   Type
 }
 
 func (x *Variable) Pos() scanner.Position { return x.NamePos }
@@ -257,15 +386,33 @@ func (x *Variable) Copy() Expression {
 	return &ret
 }
 
-func (x *Variable) Eval() Expression {
-	return x.Value.Eval()
+func (x *Variable) Eval(scope *Scope) (Expression, error) {
+	if assignment := scope.Get(x.Name); assignment != nil {
+		assignment.Referenced = true
+		return assignment.Value, nil
+	}
+	return nil, fmt.Errorf("undefined variable %s", x.Name)
+}
+
+func (x *Variable) PrintfInto(value string) error {
+	return nil
+}
+
+func (x *Variable) MarkReferencedVariables(scope *Scope) {
+	if assignment := scope.Get(x.Name); assignment != nil {
+		assignment.Referenced = true
+	}
 }
 
 func (x *Variable) String() string {
-	return x.Name + " = " + x.Value.String()
+	return x.Name
 }
 
-func (x *Variable) Type() Type { return x.Value.Type() }
+func (x *Variable) Type() Type {
+	// Variables do not normally have a type associated with them, this is only
+	// filled out in the androidmk tool
+	return x.Type_
+}
 
 type Map struct {
 	LBracePos  scanner.Position
@@ -285,8 +432,36 @@ func (x *Map) Copy() Expression {
 	return &ret
 }
 
-func (x *Map) Eval() Expression {
-	return x
+func (x *Map) Eval(scope *Scope) (Expression, error) {
+	newProps := make([]*Property, len(x.Properties))
+	for i, prop := range x.Properties {
+		newVal, err := prop.Value.Eval(scope)
+		if err != nil {
+			return nil, err
+		}
+		newProps[i] = &Property{
+			Name:     prop.Name,
+			NamePos:  prop.NamePos,
+			ColonPos: prop.ColonPos,
+			Value:    newVal,
+		}
+	}
+	return &Map{
+		LBracePos:  x.LBracePos,
+		RBracePos:  x.RBracePos,
+		Properties: newProps,
+	}, nil
+}
+
+func (x *Map) PrintfInto(value string) error {
+	// We should never reach this because selects cannot hold maps
+	panic("printfinto() is unsupported on maps")
+}
+
+func (x *Map) MarkReferencedVariables(scope *Scope) {
+	for _, prop := range x.Properties {
+		prop.MarkReferencedVariables(scope)
+	}
 }
 
 func (x *Map) String() string {
@@ -379,8 +554,35 @@ func (x *List) Copy() Expression {
 	return &ret
 }
 
-func (x *List) Eval() Expression {
-	return x
+func (x *List) Eval(scope *Scope) (Expression, error) {
+	newValues := make([]Expression, len(x.Values))
+	for i, val := range x.Values {
+		newVal, err := val.Eval(scope)
+		if err != nil {
+			return nil, err
+		}
+		newValues[i] = newVal
+	}
+	return &List{
+		LBracePos: x.LBracePos,
+		RBracePos: x.RBracePos,
+		Values:    newValues,
+	}, nil
+}
+
+func (x *List) PrintfInto(value string) error {
+	for _, val := range x.Values {
+		if err := val.PrintfInto(value); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (x *List) MarkReferencedVariables(scope *Scope) {
+	for _, val := range x.Values {
+		val.MarkReferencedVariables(scope)
+	}
 }
 
 func (x *List) String() string {
@@ -407,8 +609,29 @@ func (x *String) Copy() Expression {
 	return &ret
 }
 
-func (x *String) Eval() Expression {
-	return x
+func (x *String) Eval(scope *Scope) (Expression, error) {
+	return x, nil
+}
+
+func (x *String) PrintfInto(value string) error {
+	count := strings.Count(x.Value, "%")
+	if count == 0 {
+		return nil
+	}
+
+	if count > 1 {
+		return fmt.Errorf("list/value variable properties only support a single '%%'")
+	}
+
+	if !strings.Contains(x.Value, "%s") {
+		return fmt.Errorf("unsupported %% in value variable property")
+	}
+
+	x.Value = fmt.Sprintf(x.Value, value)
+	return nil
+}
+
+func (x *String) MarkReferencedVariables(scope *Scope) {
 }
 
 func (x *String) String() string {
@@ -433,8 +656,15 @@ func (x *Int64) Copy() Expression {
 	return &ret
 }
 
-func (x *Int64) Eval() Expression {
-	return x
+func (x *Int64) Eval(scope *Scope) (Expression, error) {
+	return x, nil
+}
+
+func (x *Int64) PrintfInto(value string) error {
+	return nil
+}
+
+func (x *Int64) MarkReferencedVariables(scope *Scope) {
 }
 
 func (x *Int64) String() string {
@@ -459,8 +689,15 @@ func (x *Bool) Copy() Expression {
 	return &ret
 }
 
-func (x *Bool) Eval() Expression {
-	return x
+func (x *Bool) Eval(scope *Scope) (Expression, error) {
+	return x, nil
+}
+
+func (x *Bool) PrintfInto(value string) error {
+	return nil
+}
+
+func (x *Bool) MarkReferencedVariables(scope *Scope) {
 }
 
 func (x *Bool) String() string {
@@ -542,29 +779,6 @@ func (c Comment) Text() string {
 	return string(buf)
 }
 
-type NotEvaluated struct {
-	Position scanner.Position
-}
-
-func (n NotEvaluated) Copy() Expression {
-	return NotEvaluated{Position: n.Position}
-}
-
-func (n NotEvaluated) String() string {
-	return "Not Evaluated"
-}
-
-func (n NotEvaluated) Type() Type {
-	return NotEvaluatedType
-}
-
-func (n NotEvaluated) Eval() Expression {
-	return NotEvaluated{Position: n.Position}
-}
-
-func (n NotEvaluated) Pos() scanner.Position { return n.Position }
-func (n NotEvaluated) End() scanner.Position { return n.Position }
-
 func endPos(pos scanner.Position, n int) scanner.Position {
 	pos.Offset += n
 	pos.Column += n
@@ -609,13 +823,13 @@ func (c *ConfigurableCondition) String() string {
 }
 
 type Select struct {
-	KeywordPos     scanner.Position // the keyword "select"
-	Conditions     []ConfigurableCondition
-	LBracePos      scanner.Position
-	RBracePos      scanner.Position
-	Cases          []*SelectCase // the case statements
-	Append         Expression
-	ExpressionType Type
+	Scope      *Scope           // scope used to evaluate the body of the select later on
+	KeywordPos scanner.Position // the keyword "select"
+	Conditions []ConfigurableCondition
+	LBracePos  scanner.Position
+	RBracePos  scanner.Position
+	Cases      []*SelectCase // the case statements
+	Append     Expression
 }
 
 func (s *Select) Pos() scanner.Position { return s.KeywordPos }
@@ -633,8 +847,24 @@ func (s *Select) Copy() Expression {
 	return &ret
 }
 
-func (s *Select) Eval() Expression {
-	return s
+func (s *Select) Eval(scope *Scope) (Expression, error) {
+	s.Scope = scope
+	s.MarkReferencedVariables(scope)
+	return s, nil
+}
+
+func (x *Select) PrintfInto(value string) error {
+	// PrintfInto will be handled at the Configurable object level
+	panic("Cannot call PrintfInto on a select expression")
+}
+
+func (x *Select) MarkReferencedVariables(scope *Scope) {
+	for _, c := range x.Cases {
+		c.MarkReferencedVariables(scope)
+	}
+	if x.Append != nil {
+		x.Append.MarkReferencedVariables(scope)
+	}
 }
 
 func (s *Select) String() string {
@@ -642,18 +872,35 @@ func (s *Select) String() string {
 }
 
 func (s *Select) Type() Type {
-	if s.ExpressionType == UnsetType && s.Append != nil {
-		return s.Append.Type()
+	if len(s.Cases) == 0 {
+		return UnsetType
 	}
-	return s.ExpressionType
+	return UnknownType
+}
+
+type SelectPattern struct {
+	Value   Expression
+	Binding Variable
+}
+
+func (c *SelectPattern) Pos() scanner.Position { return c.Value.Pos() }
+func (c *SelectPattern) End() scanner.Position {
+	if c.Binding.NamePos.IsValid() {
+		return c.Binding.End()
+	}
+	return c.Value.End()
 }
 
 type SelectCase struct {
-	Patterns []Expression
+	Patterns []SelectPattern
 	ColonPos scanner.Position
 	Value    Expression
 }
 
+func (x *SelectCase) MarkReferencedVariables(scope *Scope) {
+	x.Value.MarkReferencedVariables(scope)
+}
+
 func (c *SelectCase) Copy() *SelectCase {
 	ret := *c
 	ret.Value = c.Value.Copy()
@@ -681,21 +928,28 @@ type UnsetProperty struct {
 	Position scanner.Position
 }
 
-func (n UnsetProperty) Copy() Expression {
-	return UnsetProperty{Position: n.Position}
+func (n *UnsetProperty) Copy() Expression {
+	return &UnsetProperty{Position: n.Position}
 }
 
-func (n UnsetProperty) String() string {
+func (n *UnsetProperty) String() string {
 	return "unset"
 }
 
-func (n UnsetProperty) Type() Type {
+func (n *UnsetProperty) Type() Type {
 	return UnsetType
 }
 
-func (n UnsetProperty) Eval() Expression {
-	return UnsetProperty{Position: n.Position}
+func (n *UnsetProperty) Eval(scope *Scope) (Expression, error) {
+	return n, nil
 }
 
-func (n UnsetProperty) Pos() scanner.Position { return n.Position }
-func (n UnsetProperty) End() scanner.Position { return n.Position }
+func (x *UnsetProperty) PrintfInto(value string) error {
+	return nil
+}
+
+func (x *UnsetProperty) MarkReferencedVariables(scope *Scope) {
+}
+
+func (n *UnsetProperty) Pos() scanner.Position { return n.Position }
+func (n *UnsetProperty) End() scanner.Position { return n.Position }

parser/modify.go

@@ -23,13 +23,11 @@ import (
 
 func AddStringToList(list *List, s string) (modified bool) {
 	for _, v := range list.Values {
-		if v.Type() != StringType {
-			panic(fmt.Errorf("expected string in list, got %s", v.Type()))
-		}
-
 		if sv, ok := v.(*String); ok && sv.Value == s {
 			// string already exists
 			return false
+		} else if !ok {
+			panic(fmt.Errorf("expected string in list, got %s", v.Type()))
 		}
 	}
 
@@ -43,13 +41,11 @@ func AddStringToList(list *List, s string) (modified bool) {
 
 func RemoveStringFromList(list *List, s string) (modified bool) {
 	for i, v := range list.Values {
-		if v.Type() != StringType {
-			panic(fmt.Errorf("expected string in list, got %s", v.Type()))
-		}
-
 		if sv, ok := v.(*String); ok && sv.Value == s {
 			list.Values = append(list.Values[:i], list.Values[i+1:]...)
 			return true
+		} else if !ok {
+			panic(fmt.Errorf("expected string in list, got %s", v.Type()))
 		}
 	}
 
@@ -59,9 +55,6 @@ func RemoveStringFromList(list *List, s string) (modified bool) {
 func ReplaceStringsInList(list *List, replacements map[string]string) (replaced bool) {
 	modified := false
 	for i, v := range list.Values {
-		if v.Type() != StringType {
-			panic(fmt.Errorf("expected string in list, got %s", v.Type()))
-		}
 		if sv, ok := v.(*String); ok && replacements[sv.Value] != "" {
 			pos := list.Values[i].Pos()
 			list.Values[i] = &String{
@@ -69,6 +62,8 @@ func ReplaceStringsInList(list *List, replacements map[string]string) (replaced
 				Value:      replacements[sv.Value],
 			}
 			modified = true
+		} else if !ok {
+			panic(fmt.Errorf("expected string in list, got %s", v.Type()))
 		}
 	}
 	return modified

parser/parser.go

@@ -29,6 +29,7 @@ var errTooManyErrors = errors.New("too many errors")
 const maxErrors = 1
 
 const default_select_branch_name = "__soong_conditions_default__"
+const any_select_branch_name = "__soong_conditions_any__"
 
 type ParseError struct {
 	Err error
@@ -45,22 +46,6 @@ type File struct {
 	Comments []*CommentGroup
 }
 
-func (f *File) Pos() scanner.Position {
-	return scanner.Position{
-		Filename: f.Name,
-		Line:     1,
-		Column:   1,
-		Offset:   0,
-	}
-}
-
-func (f *File) End() scanner.Position {
-	if len(f.Defs) > 0 {
-		return f.Defs[len(f.Defs)-1].End()
-	}
-	return noPos
-}
-
 func parse(p *parser) (file *File, errs []error) {
 	defer func() {
 		if r := recover(); r != nil {
@@ -87,22 +72,54 @@ func parse(p *parser) (file *File, errs []error) {
 }
 
 func ParseAndEval(filename string, r io.Reader, scope *Scope) (file *File, errs []error) {
-	p := newParser(r, scope)
-	p.eval = true
-	p.scanner.Filename = filename
+	file, errs = Parse(filename, r)
+	if len(errs) > 0 {
+		return nil, errs
+	}
 
-	return parse(p)
+	// evaluate all module properties
+	var newDefs []Definition
+	for _, def := range file.Defs {
+		switch d := def.(type) {
+		case *Module:
+			for _, prop := range d.Map.Properties {
+				newval, err := prop.Value.Eval(scope)
+				if err != nil {
+					return nil, []error{err}
+				}
+				switch newval.(type) {
+				case *String, *Bool, *Int64, *Select, *Map, *List:
+					// ok
+				default:
+					panic(fmt.Sprintf("Evaled but got %#v\n", newval))
+				}
+				prop.Value = newval
+			}
+			newDefs = append(newDefs, d)
+		case *Assignment:
+			if err := scope.HandleAssignment(d); err != nil {
+				return nil, []error{err}
+			}
+		}
+	}
+
+	// This is not strictly necessary, but removing the assignments from
+	// the result makes it clearer that this is an evaluated file.
+	// We could also consider adding a "EvaluatedFile" type to return.
+	file.Defs = newDefs
+
+	return file, nil
 }
 
-func Parse(filename string, r io.Reader, scope *Scope) (file *File, errs []error) {
-	p := newParser(r, scope)
+func Parse(filename string, r io.Reader) (file *File, errs []error) {
+	p := newParser(r)
 	p.scanner.Filename = filename
 
 	return parse(p)
 }
 
 func ParseExpression(r io.Reader) (value Expression, errs []error) {
-	p := newParser(r, NewScope(nil))
+	p := newParser(r)
 	p.next()
 	value = p.parseExpression()
 	p.accept(scanner.EOF)
@@ -114,14 +131,11 @@ type parser struct {
 	scanner  scanner.Scanner
 	tok      rune
 	errors   []error
-	scope    *Scope
 	comments []*CommentGroup
-	eval     bool
 }
 
-func newParser(r io.Reader, scope *Scope) *parser {
+func newParser(r io.Reader) *parser {
 	p := &parser{}
-	p.scope = scope
 	p.scanner.Init(r)
 	p.scanner.Error = func(sc *scanner.Scanner, msg string) {
 		p.errorf(msg)
@@ -234,34 +248,9 @@ func (p *parser) parseAssignment(name string, namePos scanner.Position,
 	assignment.Name = name
 	assignment.NamePos = namePos
 	assignment.Value = value
-	assignment.OrigValue = value
 	assignment.EqualsPos = pos
 	assignment.Assigner = assigner
 
-	if p.scope != nil {
-		if assigner == "+=" {
-			if old, local := p.scope.Get(assignment.Name); old == nil {
-				p.errorf("modified non-existent variable %q with +=", assignment.Name)
-			} else if !local {
-				p.errorf("modified non-local variable %q with +=", assignment.Name)
-			} else if old.Referenced {
-				p.errorf("modified variable %q with += after referencing", assignment.Name)
-			} else {
-				val, err := p.evaluateOperator(old.Value, assignment.Value, '+', assignment.EqualsPos)
-				if err != nil {
-					p.error(err)
-				} else {
-					old.Value = val
-				}
-			}
-		} else {
-			err := p.scope.Add(assignment)
-			if err != nil {
-				p.error(err)
-			}
-		}
-	}
-
 	return
 }
 
@@ -297,13 +286,7 @@ func (p *parser) parseModule(typ string, typPos scanner.Position) *Module {
 
 func (p *parser) parsePropertyList(isModule, compat bool) (properties []*Property) {
 	for p.tok == scanner.Ident {
-		property := p.parseProperty(isModule, compat)
-
-		// If a property is set to an empty select or a select where all branches are "unset",
-		// skip emitting the property entirely.
-		if property.Value.Type() != UnsetType {
-			properties = append(properties, property)
-		}
+		properties = append(properties, p.parseProperty(isModule, compat))
 
 		if p.tok != ',' {
 			// There was no comma, so the list is done.
@@ -363,115 +346,6 @@ func (p *parser) parseExpression() (value Expression) {
 	}
 }
 
-func (p *parser) evaluateOperator(value1, value2 Expression, operator rune,
-	pos scanner.Position) (Expression, error) {
-
-	if value1.Type() == UnsetType {
-		return value2, nil
-	}
-	if value2.Type() == UnsetType {
-		return value1, nil
-	}
-
-	value := value1
-
-	if p.eval {
-		e1 := value1.Eval()
-		e2 := value2.Eval()
-		if e1.Type() != e2.Type() {
-			return nil, fmt.Errorf("mismatched type in operator %c: %s != %s", operator,
-				e1.Type(), e2.Type())
-		}
-
-		if _, ok := e1.(*Select); !ok {
-			if _, ok := e2.(*Select); ok {
-				// Promote e1 to a select so we can add e2 to it
-				e1 = &Select{
-					Cases: []*SelectCase{{
-						Value: e1,
-					}},
-					ExpressionType: e1.Type(),
-				}
-			}
-		}
-
-		value = e1.Copy()
-
-		switch operator {
-		case '+':
-			switch v := value.(type) {
-			case *String:
-				v.Value += e2.(*String).Value
-			case *Int64:
-				v.Value += e2.(*Int64).Value
-				v.Token = ""
-			case *List:
-				v.Values = append(v.Values, e2.(*List).Values...)
-			case *Map:
-				var err error
-				v.Properties, err = p.addMaps(v.Properties, e2.(*Map).Properties, pos)
-				if err != nil {
-					return nil, err
-				}
-			case *Select:
-				v.Append = e2
-			default:
-				return nil, fmt.Errorf("operator %c not supported on type %s", operator, v.Type())
-			}
-		default:
-			panic("unknown operator " + string(operator))
-		}
-	}
-
-	return &Operator{
-		Args:        [2]Expression{value1, value2},
-		Operator:    operator,
-		OperatorPos: pos,
-		Value:       value,
-	}, nil
-}
-
-func (p *parser) addMaps(map1, map2 []*Property, pos scanner.Position) ([]*Property, error) {
-	ret := make([]*Property, 0, len(map1))
-
-	inMap1 := make(map[string]*Property)
-	inMap2 := make(map[string]*Property)
-	inBoth := make(map[string]*Property)
-
-	for _, prop1 := range map1 {
-		inMap1[prop1.Name] = prop1
-	}
-
-	for _, prop2 := range map2 {
-		inMap2[prop2.Name] = prop2
-		if _, ok := inMap1[prop2.Name]; ok {
-			inBoth[prop2.Name] = prop2
-		}
-	}
-
-	for _, prop1 := range map1 {
-		if prop2, ok := inBoth[prop1.Name]; ok {
-			var err error
-			newProp := *prop1
-			newProp.Value, err = p.evaluateOperator(prop1.Value, prop2.Value, '+', pos)
-			if err != nil {
-				return nil, err
-			}
-			ret = append(ret, &newProp)
-		} else {
-			ret = append(ret, prop1)
-		}
-	}
-
-	for _, prop2 := range map2 {
-		if _, ok := inBoth[prop2.Name]; !ok {
-			ret = append(ret, prop2)
-		}
-	}
-
-	return ret, nil
-}
-
 func (p *parser) parseOperator(value1 Expression) Expression {
 	operator := p.tok
 	pos := p.scanner.Position
@@ -479,14 +353,11 @@ func (p *parser) parseOperator(value1 Expression) Expression {
 
 	value2 := p.parseExpression()
 
-	value, err := p.evaluateOperator(value1, value2, operator, pos)
-	if err != nil {
-		p.error(err)
-		return nil
+	return &Operator{
+		Args:        [2]Expression{value1, value2},
+		Operator:    operator,
+		OperatorPos: pos,
 	}
-
-	return value
-
 }
 
 func (p *parser) parseValue() (value Expression) {
@@ -535,22 +406,9 @@ func (p *parser) parseVariable() Expression {
 	var value Expression
 
 	text := p.scanner.TokenText()
-	if p.eval {
-		if assignment, local := p.scope.Get(text); assignment == nil {
-			p.errorf("variable %q is not set", text)
-		} else {
-			if local {
-				assignment.Referenced = true
-			}
-			value = assignment.Value
-		}
-	} else {
-		value = &NotEvaluated{}
-	}
 	value = &Variable{
 		Name:    text,
 		NamePos: p.scanner.Position,
-		Value:   value,
 	}
 
 	p.accept(scanner.Ident)
@@ -645,44 +503,72 @@ func (p *parser) parseSelect() Expression {
 		return nil
 	}
 
-	parseOnePattern := func() Expression {
+	maybeParseBinding := func() (Variable, bool) {
+		if p.scanner.TokenText() != "@" {
+			return Variable{}, false
+		}
+		p.next()
+		value := Variable{
+			Name:    p.scanner.TokenText(),
+			NamePos: p.scanner.Position,
+		}
+		p.accept(scanner.Ident)
+		return value, true
+	}
+
+	parseOnePattern := func() SelectPattern {
+		var result SelectPattern
 		switch p.tok {
 		case scanner.Ident:
 			switch p.scanner.TokenText() {
-			case "default":
+			case "any":
+				result.Value = &String{
+					LiteralPos: p.scanner.Position,
+					Value:      any_select_branch_name,
+				}
 				p.next()
-				return &String{
+				if binding, exists := maybeParseBinding(); exists {
+					result.Binding = binding
+				}
+				return result
+			case "default":
+				result.Value = &String{
 					LiteralPos: p.scanner.Position,
 					Value:      default_select_branch_name,
 				}
-			case "true":
 				p.next()
-				return &Bool{
+				return result
+			case "true":
+				result.Value = &Bool{
 					LiteralPos: p.scanner.Position,
 					Value:      true,
 				}
-			case "false":
 				p.next()
-				return &Bool{
+				return result
+			case "false":
+				result.Value = &Bool{
 					LiteralPos: p.scanner.Position,
 					Value:      false,
 				}
+				p.next()
+				return result
 			default:
-				p.errorf("Expted a string, true, false, or default, got %s", p.scanner.TokenText())
+				p.errorf("Expected a string, true, false, or default, got %s", p.scanner.TokenText())
 			}
 		case scanner.String:
 			if s := p.parseStringValue(); s != nil {
 				if strings.HasPrefix(s.Value, "__soong") {
-					p.errorf("select branch conditions starting with __soong are reserved for internal use")
-					return nil
+					p.errorf("select branch patterns starting with __soong are reserved for internal use")
+					return result
 				}
-				return s
+				result.Value = s
+				return result
 			}
 			fallthrough
 		default:
-			p.errorf("Expted a string, true, false, or default, got %s", p.scanner.TokenText())
+			p.errorf("Expected a string, true, false, or default, got %s", p.scanner.TokenText())
 		}
-		return nil
+		return result
 	}
 
 	hasNonUnsetValue := false
@@ -694,11 +580,7 @@ func (p *parser) parseSelect() Expression {
 				return nil
 			}
 			for i := 0; i < len(conditions); i++ {
-				if p := parseOnePattern(); p != nil {
-					c.Patterns = append(c.Patterns, p)
-				} else {
-					return nil
-				}
+				c.Patterns = append(c.Patterns, parseOnePattern())
 				if i < len(conditions)-1 {
 					if !p.accept(',') {
 						return nil
@@ -712,18 +594,14 @@ func (p *parser) parseSelect() Expression {
 				return nil
 			}
 		} else {
-			if p := parseOnePattern(); p != nil {
-				c.Patterns = append(c.Patterns, p)
-			} else {
-				return nil
-			}
+			c.Patterns = append(c.Patterns, parseOnePattern())
 		}
 		c.ColonPos = p.scanner.Position
 		if !p.accept(':') {
 			return nil
 		}
 		if p.tok == scanner.Ident && p.scanner.TokenText() == "unset" {
-			c.Value = UnsetProperty{Position: p.scanner.Position}
+			c.Value = &UnsetProperty{Position: p.scanner.Position}
 			p.accept(scanner.Ident)
 		} else {
 			hasNonUnsetValue = true
@@ -742,16 +620,17 @@ func (p *parser) parseSelect() Expression {
 		return nil
 	}
 
-	patternsEqual := func(a, b Expression) bool {
-		switch a2 := a.(type) {
+	patternsEqual := func(a, b SelectPattern) bool {
+		// We can ignore the bindings, they don't affect which pattern is matched
+		switch a2 := a.Value.(type) {
 		case *String:
-			if b2, ok := b.(*String); ok {
+			if b2, ok := b.Value.(*String); ok {
 				return a2.Value == b2.Value
 			} else {
 				return false
 			}
 		case *Bool:
-			if b2, ok := b.(*Bool); ok {
+			if b2, ok := b.Value.(*Bool); ok {
 				return a2.Value == b2.Value
 			} else {
 				return false
@@ -762,7 +641,7 @@ func (p *parser) parseSelect() Expression {
 		}
 	}
 
-	patternListsEqual := func(a, b []Expression) bool {
+	patternListsEqual := func(a, b []SelectPattern) bool {
 		if len(a) != len(b) {
 			return false
 		}
@@ -775,18 +654,29 @@ func (p *parser) parseSelect() Expression {
 	}
 
 	for i, c := range result.Cases {
-		// Check for duplicates
+		// Check for duplicate patterns across different branches
 		for _, d := range result.Cases[i+1:] {
 			if patternListsEqual(c.Patterns, d.Patterns) {
 				p.errorf("Found duplicate select patterns: %v", c.Patterns)
 				return nil
 			}
 		}
+		// check for duplicate bindings within this branch
+		for i := range c.Patterns {
+			if c.Patterns[i].Binding.Name != "" {
+				for j := i + 1; j < len(c.Patterns); j++ {
+					if c.Patterns[i].Binding.Name == c.Patterns[j].Binding.Name {
+						p.errorf("Found duplicate select pattern binding: %s", c.Patterns[i].Binding.Name)
+						return nil
+					}
+				}
+			}
+		}
 		// Check that the only all-default cases is the last one
 		if i < len(result.Cases)-1 {
 			isAllDefault := true
 			for _, x := range c.Patterns {
-				if x2, ok := x.(*String); !ok || x2.Value != default_select_branch_name {
+				if x2, ok := x.Value.(*String); !ok || x2.Value != default_select_branch_name {
 					isAllDefault = false
 					break
 				}
@@ -798,21 +688,6 @@ func (p *parser) parseSelect() Expression {
 		}
 	}
 
-	ty := UnsetType
-	for _, c := range result.Cases {
-		otherTy := c.Value.Type()
-		// Any other type can override UnsetType
-		if ty == UnsetType {
-			ty = otherTy
-		}
-		if otherTy != UnsetType && otherTy != ty {
-			p.errorf("Found select statement with differing types %q and %q in its cases", ty.String(), otherTy.String())
-			return nil
-		}
-	}
-
-	result.ExpressionType = ty
-
 	result.RBracePos = p.scanner.Position
 	if !p.accept('}') {
 		return nil
@@ -913,79 +788,107 @@ func (p *parser) parseMapValue() *Map {
 }
 
 type Scope struct {
-	vars          map[string]*Assignment
-	inheritedVars map[string]*Assignment
+	vars              map[string]*Assignment
+	preventInheriting map[string]bool
+	parentScope       *Scope
 }
 
 func NewScope(s *Scope) *Scope {
-	newScope := &Scope{
-		vars:          make(map[string]*Assignment),
-		inheritedVars: make(map[string]*Assignment),
+	return &Scope{
+		vars:              make(map[string]*Assignment),
+		preventInheriting: make(map[string]bool),
+		parentScope:       s,
 	}
-
-	if s != nil {
-		for k, v := range s.vars {
-			newScope.inheritedVars[k] = v
-		}
-		for k, v := range s.inheritedVars {
-			newScope.inheritedVars[k] = v
-		}
-	}
-
-	return newScope
 }
 
-func (s *Scope) Add(assignment *Assignment) error {
-	if old, ok := s.vars[assignment.Name]; ok {
-		return fmt.Errorf("variable already set, previous assignment: %s", old)
+func (s *Scope) HandleAssignment(assignment *Assignment) error {
+	switch assignment.Assigner {
+	case "+=":
+		if !s.preventInheriting[assignment.Name] && s.parentScope.Get(assignment.Name) != nil {
+			return fmt.Errorf("modified non-local variable %q with +=", assignment.Name)
+		}
+		if old, ok := s.vars[assignment.Name]; !ok {
+			return fmt.Errorf("modified non-existent variable %q with +=", assignment.Name)
+		} else if old.Referenced {
+			return fmt.Errorf("modified variable %q with += after referencing", assignment.Name)
+		} else {
+			newValue, err := evaluateOperator(s, '+', old.Value, assignment.Value)
+			if err != nil {
+				return err
+			}
+			old.Value = newValue
+		}
+	case "=":
+		if old, ok := s.vars[assignment.Name]; ok {
+			return fmt.Errorf("variable already set, previous assignment: %s", old)
+		}
+
+		if old := s.parentScope.Get(assignment.Name); old != nil && !s.preventInheriting[assignment.Name] {
+			return fmt.Errorf("variable already set in inherited scope, previous assignment: %s", old)
+		}
+
+		if newValue, err := assignment.Value.Eval(s); err != nil {
+			return err
+		} else {
+			assignment.Value = newValue
+		}
+		s.vars[assignment.Name] = assignment
+	default:
+		return fmt.Errorf("Unknown assigner '%s'", assignment.Assigner)
 	}
-
-	if old, ok := s.inheritedVars[assignment.Name]; ok {
-		return fmt.Errorf("variable already set in inherited scope, previous assignment: %s", old)
-	}
-
-	s.vars[assignment.Name] = assignment
-
 	return nil
 }
 
-func (s *Scope) Remove(name string) {
-	delete(s.vars, name)
-	delete(s.inheritedVars, name)
+func (s *Scope) Get(name string) *Assignment {
+	if s == nil {
+		return nil
+	}
+	if a, ok := s.vars[name]; ok {
+		return a
+	}
+	if s.preventInheriting[name] {
+		return nil
+	}
+	return s.parentScope.Get(name)
 }
 
-func (s *Scope) Get(name string) (*Assignment, bool) {
+func (s *Scope) GetLocal(name string) *Assignment {
+	if s == nil {
+		return nil
+	}
 	if a, ok := s.vars[name]; ok {
-		return a, true
+		return a
 	}
+	return nil
+}
 
-	if a, ok := s.inheritedVars[name]; ok {
-		return a, false
-	}
-
-	return nil, false
+// DontInherit prevents this scope from inheriting the given variable from its
+// parent scope.
+func (s *Scope) DontInherit(name string) {
+	s.preventInheriting[name] = true
 }
 
 func (s *Scope) String() string {
-	vars := []string{}
+	var sb strings.Builder
+	s.stringInner(&sb)
+	return sb.String()
+}
 
-	for k := range s.vars {
-		vars = append(vars, k)
+func (s *Scope) stringInner(sb *strings.Builder) {
+	if s == nil {
+		return
 	}
-	for k := range s.inheritedVars {
+	vars := make([]string, 0, len(s.vars))
+	for k := range s.vars {
 		vars = append(vars, k)
 	}
 
 	sort.Strings(vars)
 
-	ret := []string{}
 	for _, v := range vars {
-		if assignment, ok := s.vars[v]; ok {
-			ret = append(ret, assignment.String())
-		} else {
-			ret = append(ret, s.inheritedVars[v].String())
-		}
+		sb.WriteString(s.vars[v].String())
+		sb.WriteRune('\n')
 	}
 
-	return strings.Join(ret, "\n")
+	s.parentScope.stringInner(sb)
 }

parser/parser_test.go

@@ -565,12 +565,7 @@ var validParseTestCases = []struct {
 					LiteralPos: mkpos(9, 2, 9),
 					Value:      "stuff",
 				},
-				OrigValue: &String{
-					LiteralPos: mkpos(9, 2, 9),
-					Value:      "stuff",
-				},
-				Assigner:   "=",
-				Referenced: true,
+				Assigner: "=",
 			},
 			&Assignment{
 				Name:      "bar",
@@ -579,21 +574,8 @@ var validParseTestCases = []struct {
 				Value: &Variable{
 					Name:    "foo",
 					NamePos: mkpos(25, 3, 9),
-					Value: &String{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      "stuff",
-					},
 				},
-				OrigValue: &Variable{
-					Name:    "foo",
-					NamePos: mkpos(25, 3, 9),
-					Value: &String{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      "stuff",
-					},
-				},
-				Assigner:   "=",
-				Referenced: true,
+				Assigner: "=",
 			},
 			&Assignment{
 				Name:      "baz",
@@ -602,155 +584,26 @@ var validParseTestCases = []struct {
 				Value: &Operator{
 					OperatorPos: mkpos(41, 4, 13),
 					Operator:    '+',
-					Value: &String{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      "stuffstuff",
-					},
 					Args: [2]Expression{
 						&Variable{
 							Name:    "foo",
 							NamePos: mkpos(37, 4, 9),
-							Value: &String{
-								LiteralPos: mkpos(9, 2, 9),
-								Value:      "stuff",
-							},
 						},
 						&Variable{
 							Name:    "bar",
 							NamePos: mkpos(43, 4, 15),
-							Value: &Variable{
-								Name:    "foo",
-								NamePos: mkpos(25, 3, 9),
-								Value: &String{
-									LiteralPos: mkpos(9, 2, 9),
-									Value:      "stuff",
-								},
-							},
 						},
 					},
 				},
-				OrigValue: &Operator{
-					OperatorPos: mkpos(41, 4, 13),
-					Operator:    '+',
-					Value: &String{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      "stuffstuff",
-					},
-					Args: [2]Expression{
-						&Variable{
-							Name:    "foo",
-							NamePos: mkpos(37, 4, 9),
-							Value: &String{
-								LiteralPos: mkpos(9, 2, 9),
-								Value:      "stuff",
-							},
-						},
-						&Variable{
-							Name:    "bar",
-							NamePos: mkpos(43, 4, 15),
-							Value: &Variable{
-								Name:    "foo",
-								NamePos: mkpos(25, 3, 9),
-								Value: &String{
-									LiteralPos: mkpos(9, 2, 9),
-									Value:      "stuff",
-								},
-							},
-						},
-					},
-				},
-				Assigner:   "=",
-				Referenced: true,
+				Assigner: "=",
 			},
 			&Assignment{
 				Name:      "boo",
 				NamePos:   mkpos(49, 5, 3),
 				EqualsPos: mkpos(53, 5, 7),
-				Value: &Operator{
-					Args: [2]Expression{
-						&Variable{
-							Name:    "baz",
-							NamePos: mkpos(55, 5, 9),
-							Value: &Operator{
-								OperatorPos: mkpos(41, 4, 13),
-								Operator:    '+',
-								Value: &String{
-									LiteralPos: mkpos(9, 2, 9),
-									Value:      "stuffstuff",
-								},
-								Args: [2]Expression{
-									&Variable{
-										Name:    "foo",
-										NamePos: mkpos(37, 4, 9),
-										Value: &String{
-											LiteralPos: mkpos(9, 2, 9),
-											Value:      "stuff",
-										},
-									},
-									&Variable{
-										Name:    "bar",
-										NamePos: mkpos(43, 4, 15),
-										Value: &Variable{
-											Name:    "foo",
-											NamePos: mkpos(25, 3, 9),
-											Value: &String{
-												LiteralPos: mkpos(9, 2, 9),
-												Value:      "stuff",
-											},
-										},
-									},
-								},
-							},
-						},
-						&Variable{
-							Name:    "foo",
-							NamePos: mkpos(68, 6, 10),
-							Value: &String{
-								LiteralPos: mkpos(9, 2, 9),
-								Value:      "stuff",
-							},
-						},
-					},
-					OperatorPos: mkpos(66, 6, 8),
-					Operator:    '+',
-					Value: &String{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      "stuffstuffstuff",
-					},
-				},
-				OrigValue: &Variable{
+				Value: &Variable{
 					Name:    "baz",
 					NamePos: mkpos(55, 5, 9),
-					Value: &Operator{
-						OperatorPos: mkpos(41, 4, 13),
-						Operator:    '+',
-						Value: &String{
-							LiteralPos: mkpos(9, 2, 9),
-							Value:      "stuffstuff",
-						},
-						Args: [2]Expression{
-							&Variable{
-								Name:    "foo",
-								NamePos: mkpos(37, 4, 9),
-								Value: &String{
-									LiteralPos: mkpos(9, 2, 9),
-									Value:      "stuff",
-								},
-							},
-							&Variable{
-								Name:    "bar",
-								NamePos: mkpos(43, 4, 15),
-								Value: &Variable{
-									Name:    "foo",
-									NamePos: mkpos(25, 3, 9),
-									Value: &String{
-										LiteralPos: mkpos(9, 2, 9),
-										Value:      "stuff",
-									},
-								},
-							},
-						},
-					},
 				},
 				Assigner: "=",
 			},
@@ -761,18 +614,6 @@ var validParseTestCases = []struct {
 				Value: &Variable{
 					Name:    "foo",
 					NamePos: mkpos(68, 6, 10),
-					Value: &String{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      "stuff",
-					},
-				},
-				OrigValue: &Variable{
-					Name:    "foo",
-					NamePos: mkpos(68, 6, 10),
-					Value: &String{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      "stuff",
-					},
 				},
 				Assigner: "+=",
 			},
@@ -791,10 +632,6 @@ var validParseTestCases = []struct {
 				Value: &Operator{
 					OperatorPos: mkpos(12, 2, 12),
 					Operator:    '+',
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      -3,
-					},
 					Args: [2]Expression{
 						&Int64{
 							LiteralPos: mkpos(9, 2, 9),
@@ -804,10 +641,6 @@ var validParseTestCases = []struct {
 						&Operator{
 							OperatorPos: mkpos(17, 2, 17),
 							Operator:    '+',
-							Value: &Int64{
-								LiteralPos: mkpos(14, 2, 14),
-								Value:      1,
-							},
 							Args: [2]Expression{
 								&Int64{
 									LiteralPos: mkpos(14, 2, 14),
@@ -823,43 +656,7 @@ var validParseTestCases = []struct {
 						},
 					},
 				},
-				OrigValue: &Operator{
-					OperatorPos: mkpos(12, 2, 12),
-					Operator:    '+',
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      -3,
-					},
-					Args: [2]Expression{
-						&Int64{
-							LiteralPos: mkpos(9, 2, 9),
-							Value:      -4,
-							Token:      "-4",
-						},
-						&Operator{
-							OperatorPos: mkpos(17, 2, 17),
-							Operator:    '+',
-							Value: &Int64{
-								LiteralPos: mkpos(14, 2, 14),
-								Value:      1,
-							},
-							Args: [2]Expression{
-								&Int64{
-									LiteralPos: mkpos(14, 2, 14),
-									Value:      -5,
-									Token:      "-5",
-								},
-								&Int64{
-									LiteralPos: mkpos(19, 2, 19),
-									Value:      6,
-									Token:      "6",
-								},
-							},
-						},
-					},
-				},
-				Assigner:   "=",
-				Referenced: false,
+				Assigner: "=",
 			},
 		},
 		nil,
@@ -882,13 +679,7 @@ var validParseTestCases = []struct {
 					Value:      1000000,
 					Token:      "1000000",
 				},
-				OrigValue: &Int64{
-					LiteralPos: mkpos(9, 2, 9),
-					Value:      1000000,
-					Token:      "1000000",
-				},
-				Assigner:   "=",
-				Referenced: true,
+				Assigner: "=",
 			},
 			&Assignment{
 				Name:      "bar",
@@ -897,23 +688,8 @@ var validParseTestCases = []struct {
 				Value: &Variable{
 					Name:    "foo",
 					NamePos: mkpos(25, 3, 9),
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      1000000,
-						Token:      "1000000",
-					},
 				},
-				OrigValue: &Variable{
-					Name:    "foo",
-					NamePos: mkpos(25, 3, 9),
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      1000000,
-						Token:      "1000000",
-					},
-				},
-				Assigner:   "=",
-				Referenced: true,
+				Assigner: "=",
 			},
 			&Assignment{
 				Name:      "baz",
@@ -922,164 +698,26 @@ var validParseTestCases = []struct {
 				Value: &Operator{
 					OperatorPos: mkpos(41, 4, 13),
 					Operator:    '+',
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      2000000,
-					},
 					Args: [2]Expression{
 						&Variable{
 							Name:    "foo",
 							NamePos: mkpos(37, 4, 9),
-							Value: &Int64{
-								LiteralPos: mkpos(9, 2, 9),
-								Value:      1000000,
-								Token:      "1000000",
-							},
 						},
 						&Variable{
 							Name:    "bar",
 							NamePos: mkpos(43, 4, 15),
-							Value: &Variable{
-								Name:    "foo",
-								NamePos: mkpos(25, 3, 9),
-								Value: &Int64{
-									LiteralPos: mkpos(9, 2, 9),
-									Value:      1000000,
-									Token:      "1000000",
-								},
-							},
 						},
 					},
 				},
-				OrigValue: &Operator{
-					OperatorPos: mkpos(41, 4, 13),
-					Operator:    '+',
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      2000000,
-					},
-					Args: [2]Expression{
-						&Variable{
-							Name:    "foo",
-							NamePos: mkpos(37, 4, 9),
-							Value: &Int64{
-								LiteralPos: mkpos(9, 2, 9),
-								Value:      1000000,
-								Token:      "1000000",
-							},
-						},
-						&Variable{
-							Name:    "bar",
-							NamePos: mkpos(43, 4, 15),
-							Value: &Variable{
-								Name:    "foo",
-								NamePos: mkpos(25, 3, 9),
-								Value: &Int64{
-									LiteralPos: mkpos(9, 2, 9),
-									Value:      1000000,
-									Token:      "1000000",
-								},
-							},
-						},
-					},
-				},
-				Assigner:   "=",
-				Referenced: true,
+				Assigner: "=",
 			},
 			&Assignment{
 				Name:      "boo",
 				NamePos:   mkpos(49, 5, 3),
 				EqualsPos: mkpos(53, 5, 7),
-				Value: &Operator{
-					Args: [2]Expression{
-						&Variable{
-							Name:    "baz",
-							NamePos: mkpos(55, 5, 9),
-							Value: &Operator{
-								OperatorPos: mkpos(41, 4, 13),
-								Operator:    '+',
-								Value: &Int64{
-									LiteralPos: mkpos(9, 2, 9),
-									Value:      2000000,
-								},
-								Args: [2]Expression{
-									&Variable{
-										Name:    "foo",
-										NamePos: mkpos(37, 4, 9),
-										Value: &Int64{
-											LiteralPos: mkpos(9, 2, 9),
-											Value:      1000000,
-											Token:      "1000000",
-										},
-									},
-									&Variable{
-										Name:    "bar",
-										NamePos: mkpos(43, 4, 15),
-										Value: &Variable{
-											Name:    "foo",
-											NamePos: mkpos(25, 3, 9),
-											Value: &Int64{
-												LiteralPos: mkpos(9, 2, 9),
-												Value:      1000000,
-												Token:      "1000000",
-											},
-										},
-									},
-								},
-							},
-						},
-						&Variable{
-							Name:    "foo",
-							NamePos: mkpos(68, 6, 10),
-							Value: &Int64{
-								LiteralPos: mkpos(9, 2, 9),
-								Value:      1000000,
-								Token:      "1000000",
-							},
-						},
-					},
-					OperatorPos: mkpos(66, 6, 8),
-					Operator:    '+',
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      3000000,
-					},
-				},
-				OrigValue: &Variable{
+				Value: &Variable{
 					Name:    "baz",
 					NamePos: mkpos(55, 5, 9),
-					Value: &Operator{
-						OperatorPos: mkpos(41, 4, 13),
-						Operator:    '+',
-						Value: &Int64{
-							LiteralPos: mkpos(9, 2, 9),
-							Value:      2000000,
-						},
-						Args: [2]Expression{
-							&Variable{
-								Name:    "foo",
-								NamePos: mkpos(37, 4, 9),
-								Value: &Int64{
-									LiteralPos: mkpos(9, 2, 9),
-									Value:      1000000,
-									Token:      "1000000",
-								},
-							},
-							&Variable{
-								Name:    "bar",
-								NamePos: mkpos(43, 4, 15),
-								Value: &Variable{
-									Name:    "foo",
-									NamePos: mkpos(25, 3, 9),
-									Value: &Int64{
-										LiteralPos: mkpos(9, 2, 9),
-										Value:      1000000,
-										Token:      "1000000",
-									},
-								},
-							},
-						},
-					},
 				},
 				Assigner: "=",
 			},
@@ -1090,20 +728,6 @@ var validParseTestCases = []struct {
 				Value: &Variable{
 					Name:    "foo",
 					NamePos: mkpos(68, 6, 10),
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      1000000,
-						Token:      "1000000",
-					},
-				},
-				OrigValue: &Variable{
-					Name:    "foo",
-					NamePos: mkpos(68, 6, 10),
-					Value: &Int64{
-						LiteralPos: mkpos(9, 2, 9),
-						Value:      1000000,
-						Token:      "1000000",
-					},
 				},
 				Assigner: "+=",
 			},
@@ -1171,7 +795,7 @@ func TestParseValidInput(t *testing.T) {
 	for i, testCase := range validParseTestCases {
 		t.Run(strconv.Itoa(i), func(t *testing.T) {
 			r := bytes.NewBufferString(testCase.input)
-			file, errs := ParseAndEval("", r, NewScope(nil))
+			file, errs := Parse("", r)
 			if len(errs) != 0 {
 				t.Errorf("test case: %s", testCase.input)
 				t.Errorf("unexpected errors:")
@@ -1236,6 +860,17 @@ func TestParserError(t *testing.T) {
 			`,
 			err: "Duplicate select condition found: arch()",
 		},
+		{
+			name: "select with duplicate binding",
+			input: `
+			m {
+				foo: select((arch(), os()), {
+					(any @ bar, any @ bar): true,
+				}),
+			}
+			`,
+			err: "Found duplicate select pattern binding: bar",
+		},
 		// TODO: test more parser errors
 	}
 
@@ -1284,7 +919,7 @@ func TestParserEndPos(t *testing.T) {
 
 	r := bytes.NewBufferString(in)
 
-	file, errs := ParseAndEval("", r, NewScope(nil))
+	file, errs := Parse("", r)
 	if len(errs) != 0 {
 		t.Errorf("unexpected errors:")
 		for _, err := range errs {
@@ -1318,9 +953,8 @@ func TestParserEndPos(t *testing.T) {
 
 func TestParserNotEvaluated(t *testing.T) {
 	// When parsing without evaluation, create variables correctly
-	scope := NewScope(nil)
 	input := "FOO=abc\n"
-	_, errs := Parse("", bytes.NewBufferString(input), scope)
+	file, errs := Parse("", bytes.NewBufferString(input))
 	if errs != nil {
 		t.Errorf("unexpected errors:")
 		for _, err := range errs {
@@ -1328,11 +962,11 @@ func TestParserNotEvaluated(t *testing.T) {
 		}
 		t.FailNow()
 	}
-	assignment, found := scope.Get("FOO")
-	if !found {
+	assignment, ok := file.Defs[0].(*Assignment)
+	if !ok || assignment.Name != "FOO" {
 		t.Fatalf("Expected to find FOO after parsing %s", input)
 	}
-	if s := assignment.String(); strings.Contains(s, "PANIC") {
-		t.Errorf("Attempt to print FOO returned %s", s)
+	if assignment.Value.String() != "abc" {
+		t.Errorf("Attempt to print FOO returned %s", assignment.Value.String())
 	}
 }

parser/printer.go

@@ -99,7 +99,7 @@ func (p *printer) printAssignment(assignment *Assignment) {
 	p.requestSpace()
 	p.printToken(assignment.Assigner, assignment.EqualsPos)
 	p.requestSpace()
-	p.printExpression(assignment.OrigValue)
+	p.printExpression(assignment.Value)
 	p.requestNewline()
 }
 
@@ -134,7 +134,7 @@ func (p *printer) printExpression(value Expression) {
 	case *Select:
 		p.printSelect(v)
 	default:
-		panic(fmt.Errorf("bad property type: %s", value.Type()))
+		panic(fmt.Errorf("bad property type: %v", value))
 	}
 }
 
@@ -143,7 +143,7 @@ func (p *printer) printSelect(s *Select) {
 		return
 	}
 	if len(s.Cases) == 1 && len(s.Cases[0].Patterns) == 1 {
-		if str, ok := s.Cases[0].Patterns[0].(*String); ok && str.Value == default_select_branch_name {
+		if str, ok := s.Cases[0].Patterns[0].Value.(*String); ok && str.Value == default_select_branch_name {
 			p.printExpression(s.Cases[0].Value)
 			p.pos = s.RBracePos
 			return
@@ -196,22 +196,7 @@ func (p *printer) printSelect(s *Select) {
 			p.printToken("(", p.pos)
 		}
 		for i, pat := range c.Patterns {
-			switch pat := pat.(type) {
-			case *String:
-				if pat.Value != default_select_branch_name {
-					p.printToken(strconv.Quote(pat.Value), pat.LiteralPos)
-				} else {
-					p.printToken("default", pat.LiteralPos)
-				}
-			case *Bool:
-				s := "false"
-				if pat.Value {
-					s = "true"
-				}
-				p.printToken(s, pat.LiteralPos)
-			default:
-				panic("Unhandled case")
-			}
+			p.printSelectPattern(pat)
 			if i < len(c.Patterns)-1 {
 				p.printToken(",", p.pos)
 				p.requestSpace()
@@ -222,7 +207,7 @@ func (p *printer) printSelect(s *Select) {
 		}
 		p.printToken(":", c.ColonPos)
 		p.requestSpace()
-		if unset, ok := c.Value.(UnsetProperty); ok {
+		if unset, ok := c.Value.(*UnsetProperty); ok {
 			p.printToken(unset.String(), unset.Pos())
 		} else {
 			p.printExpression(c.Value)
@@ -240,6 +225,33 @@ func (p *printer) printSelect(s *Select) {
 	}
 }
 
+func (p *printer) printSelectPattern(pat SelectPattern) {
+	switch pat := pat.Value.(type) {
+	case *String:
+		if pat.Value == default_select_branch_name {
+			p.printToken("default", pat.LiteralPos)
+		} else if pat.Value == any_select_branch_name {
+			p.printToken("any", pat.LiteralPos)
+		} else {
+			p.printToken(strconv.Quote(pat.Value), pat.LiteralPos)
+		}
+	case *Bool:
+		s := "false"
+		if pat.Value {
+			s = "true"
+		}
+		p.printToken(s, pat.LiteralPos)
+	default:
+		panic("Unhandled case")
+	}
+	if pat.Binding.Name != "" {
+		p.requestSpace()
+		p.printToken("@", pat.Binding.Pos())
+		p.requestSpace()
+		p.printExpression(&pat.Binding)
+	}
+}
+
 func (p *printer) printList(list []Expression, pos, endPos scanner.Position) {
 	p.requestSpace()
 	p.printToken("[", pos)

parser/printer_test.go

@@ -733,6 +733,26 @@ foo {
         default: [],
     }),
 }
+`,
+	},
+	{
+		name: "Select with bindings",
+		input: `
+foo {
+    stuff: select(arch(), {
+        "x86": "a",
+        any
+          @ baz: "b" + baz,
+    }),
+}
+`,
+		output: `
+foo {
+    stuff: select(arch(), {
+        "x86": "a",
+        any @ baz: "b" + baz,
+    }),
+}
 `,
 	},
 }
@@ -744,7 +764,7 @@ func TestPrinter(t *testing.T) {
 			expected := testCase.output[1:]
 
 			r := bytes.NewBufferString(in)
-			file, errs := Parse("", r, NewScope(nil))
+			file, errs := Parse("", r)
 			if len(errs) != 0 {
 				t.Errorf("test case: %s", in)
 				t.Errorf("unexpected errors:")

parser/sort.go

@@ -282,8 +282,8 @@ func isListOfPrimitives(values []Expression) bool {
 	if len(values) == 0 {
 		return true
 	}
-	switch values[0].Type() {
-	case BoolType, StringType, Int64Type:
+	switch values[0].(type) {
+	case *Bool, *String, *Int64:
 		return true
 	default:
 		return false

proptools/configurable.go

@@ -21,6 +21,7 @@ import (
 	"strings"
 
 	"github.com/google/blueprint/optional"
+	"github.com/google/blueprint/parser"
 )
 
 // ConfigurableOptional is the same as ShallowOptional, but we use this separate
@@ -150,6 +151,17 @@ type ConfigurableValue struct {
 	boolValue   bool
 }
 
+func (c *ConfigurableValue) toExpression() parser.Expression {
+	switch c.typ {
+	case configurableValueTypeBool:
+		return &parser.Bool{Value: c.boolValue}
+	case configurableValueTypeString:
+		return &parser.String{Value: c.stringValue}
+	default:
+		panic(fmt.Sprintf("Unhandled configurableValueType: %s", c.typ.String()))
+	}
+}
+
 func (c *ConfigurableValue) String() string {
 	switch c.typ {
 	case configurableValueTypeString:
@@ -193,6 +205,7 @@ const (
 	configurablePatternTypeString configurablePatternType = iota
 	configurablePatternTypeBool
 	configurablePatternTypeDefault
+	configurablePatternTypeAny
 )
 
 func (v *configurablePatternType) String() string {
@@ -203,6 +216,8 @@ func (v *configurablePatternType) String() string {
 		return "bool"
 	case configurablePatternTypeDefault:
 		return "default"
+	case configurablePatternTypeAny:
+		return "any"
 	default:
 		panic("unimplemented")
 	}
@@ -222,6 +237,7 @@ type ConfigurablePattern struct {
 	typ         configurablePatternType
 	stringValue string
 	boolValue   bool
+	binding     string
 }
 
 func NewStringConfigurablePattern(s string) ConfigurablePattern {
@@ -251,6 +267,9 @@ func (p *ConfigurablePattern) matchesValue(v ConfigurableValue) bool {
 	if v.typ == configurableValueTypeUndefined {
 		return false
 	}
+	if p.typ == configurablePatternTypeAny {
+		return true
+	}
 	if p.typ != v.typ.patternType() {
 		return false
 	}
@@ -271,6 +290,9 @@ func (p *ConfigurablePattern) matchesValueType(v ConfigurableValue) bool {
 	if v.typ == configurableValueTypeUndefined {
 		return true
 	}
+	if p.typ == configurablePatternTypeAny {
+		return true
+	}
 	return p.typ == v.typ.patternType()
 }
 
@@ -282,27 +304,46 @@ func (p *ConfigurablePattern) matchesValueType(v ConfigurableValue) bool {
 // different configurable properties.
 type ConfigurableCase[T ConfigurableElements] struct {
 	patterns []ConfigurablePattern
-	value    *T
+	value    parser.Expression
 }
 
 type configurableCaseReflection interface {
-	initialize(patterns []ConfigurablePattern, value interface{})
+	initialize(patterns []ConfigurablePattern, value parser.Expression)
 }
 
 var _ configurableCaseReflection = &ConfigurableCase[string]{}
 
 func NewConfigurableCase[T ConfigurableElements](patterns []ConfigurablePattern, value *T) ConfigurableCase[T] {
+	var valueExpr parser.Expression
+	if value == nil {
+		valueExpr = &parser.UnsetProperty{}
+	} else {
+		switch v := any(value).(type) {
+		case *string:
+			valueExpr = &parser.String{Value: *v}
+		case *bool:
+			valueExpr = &parser.Bool{Value: *v}
+		case *[]string:
+			innerValues := make([]parser.Expression, 0, len(*v))
+			for _, x := range *v {
+				innerValues = append(innerValues, &parser.String{Value: x})
+			}
+			valueExpr = &parser.List{Values: innerValues}
+		default:
+			panic(fmt.Sprintf("should be unreachable due to the ConfigurableElements restriction: %#v", value))
+		}
+	}
 	// Clone the values so they can't be modified from soong
 	patterns = slices.Clone(patterns)
 	return ConfigurableCase[T]{
 		patterns: patterns,
-		value:    copyConfiguredValuePtr(value),
+		value:    valueExpr,
 	}
 }
 
-func (c *ConfigurableCase[T]) initialize(patterns []ConfigurablePattern, value interface{}) {
+func (c *ConfigurableCase[T]) initialize(patterns []ConfigurablePattern, value parser.Expression) {
 	c.patterns = patterns
-	c.value = value.(*T)
+	c.value = value
 }
 
 // for the given T, return the reflect.type of configurableCase[T]
@@ -371,6 +412,22 @@ type Configurable[T ConfigurableElements] struct {
 	marker       configurableMarker
 	propertyName string
 	inner        *configurableInner[T]
+	// See Configurable.evaluate for a description of the postProcessor algorithm and
+	// why this is a 2d list
+	postProcessors *[][]postProcessor[T]
+}
+
+type postProcessor[T ConfigurableElements] struct {
+	f func(T) T
+	// start and end represent the range of configurableInners
+	// that this postprocessor is applied to. When appending two configurables
+	// together, the start and end values will stay the same for the left
+	// configurable's postprocessors, but the rights will be rebased by the
+	// number of configurableInners in the left configurable. This way
+	// the postProcessors still only apply to the configurableInners they
+	// origionally applied to before the appending.
+	start int
+	end   int
 }
 
 type configurableInner[T ConfigurableElements] struct {
@@ -384,6 +441,7 @@ type configurableInner[T ConfigurableElements] struct {
 type singleConfigurable[T ConfigurableElements] struct {
 	conditions []ConfigurableCondition
 	cases      []ConfigurableCase[T]
+	scope      *parser.Scope
 }
 
 // Ignore the warning about the unused marker variable, it's used via reflection
@@ -398,6 +456,7 @@ func NewConfigurable[T ConfigurableElements](conditions []ConfigurableCondition,
 	// Clone the slices so they can't be modified from soong
 	conditions = slices.Clone(conditions)
 	cases = slices.Clone(cases)
+	var zeroPostProcessors [][]postProcessor[T]
 	return Configurable[T]{
 		inner: &configurableInner[T]{
 			single: singleConfigurable[T]{
@@ -405,35 +464,81 @@ func NewConfigurable[T ConfigurableElements](conditions []ConfigurableCondition,
 				cases:      cases,
 			},
 		},
+		postProcessors: &zeroPostProcessors,
 	}
 }
 
+func newConfigurableWithPropertyName[T ConfigurableElements](propertyName string, conditions []ConfigurableCondition, cases []ConfigurableCase[T], addScope bool) Configurable[T] {
+	result := NewConfigurable(conditions, cases)
+	result.propertyName = propertyName
+	if addScope {
+		for curr := result.inner; curr != nil; curr = curr.next {
+			curr.single.scope = parser.NewScope(nil)
+		}
+	}
+	return result
+}
+
 func (c *Configurable[T]) AppendSimpleValue(value T) {
 	value = copyConfiguredValue(value)
 	// This may be a property that was never initialized from a bp file
 	if c.inner == nil {
-		c.inner = &configurableInner[T]{
-			single: singleConfigurable[T]{
-				cases: []ConfigurableCase[T]{{
-					value: &value,
-				}},
-			},
-		}
+		c.initialize(nil, "", nil, []ConfigurableCase[T]{{
+			value: configuredValueToExpression(value),
+		}})
 		return
 	}
 	c.inner.appendSimpleValue(value)
 }
 
+// AddPostProcessor adds a function that will modify the result of
+// Get() when Get() is called. It operates on all the current contents
+// of the Configurable property, but if other values are appended to
+// the Configurable property afterwards, the postProcessor will not run
+// on them. This can be useful to essentially modify a configurable
+// property without evaluating it.
+func (c *Configurable[T]) AddPostProcessor(p func(T) T) {
+	// Add the new postProcessor on top of the tallest stack of postProcessors.
+	// See Configurable.evaluate for more details on the postProcessors algorithm
+	// and data structure.
+	num_links := c.inner.numLinks()
+	if c.postProcessors == nil {
+		var nilCases []ConfigurableCase[T]
+		c.initialize(nil, "", nil, nilCases)
+	}
+	if len(*c.postProcessors) == 0 {
+		*c.postProcessors = [][]postProcessor[T]{{{
+			f:     p,
+			start: 0,
+			end:   num_links,
+		}}}
+	} else {
+		deepestI := 0
+		deepestDepth := 0
+		for i := 0; i < len(*c.postProcessors); i++ {
+			if len((*c.postProcessors)[i]) > deepestDepth {
+				deepestDepth = len((*c.postProcessors)[i])
+				deepestI = i
+			}
+		}
+		(*c.postProcessors)[deepestI] = append((*c.postProcessors)[deepestI], postProcessor[T]{
+			f:     p,
+			start: 0,
+			end:   num_links,
+		})
+	}
+}
+
 // Get returns the final value for the configurable property.
 // A configurable property may be unset, in which case Get will return nil.
 func (c *Configurable[T]) Get(evaluator ConfigurableEvaluator) ConfigurableOptional[T] {
-	result := c.inner.evaluate(c.propertyName, evaluator)
+	result := c.evaluate(c.propertyName, evaluator)
 	return configuredValuePtrToOptional(result)
 }
 
 // GetOrDefault is the same as Get, but will return the provided default value if the property was unset.
 func (c *Configurable[T]) GetOrDefault(evaluator ConfigurableEvaluator, defaultValue T) T {
-	result := c.inner.evaluate(c.propertyName, evaluator)
+	result := c.evaluate(c.propertyName, evaluator)
 	if result != nil {
 		// Copy the result so that it can't be changed from soong
 		return copyConfiguredValue(*result)
@@ -441,6 +546,127 @@ func (c *Configurable[T]) GetOrDefault(evaluator ConfigurableEvaluator, defaultV
 	return defaultValue
 }
 
+type valueAndIndices[T ConfigurableElements] struct {
+	value   *T
+	replace bool
+	// Similar to start/end in postProcessor, these represent the origional
+	// range or configurableInners that this merged group represents. It's needed
+	// in order to apply recursive postProcessors to only the relevant
+	// configurableInners, even after those configurableInners have been merged
+	// in order to apply an earlier postProcessor.
+	start int
+	end   int
+}
+
+func (c *Configurable[T]) evaluate(propertyName string, evaluator ConfigurableEvaluator) *T {
+	if c.inner == nil {
+		return nil
+	}
+
+	if len(*c.postProcessors) == 0 {
+		// Use a simpler algorithm if there are no postprocessors
+		return c.inner.evaluate(propertyName, evaluator)
+	}
+
+	// The basic idea around evaluating with postprocessors is that each individual
+	// node in the chain (each configurableInner) is first evaluated, and then when
+	// a postprocessor operates on a certain range, that range is merged before passing
+	// it to the postprocessor. We want postProcessors to only accept a final merged
+	// value instead of a linked list, but at the same time, only operate over a portion
+	// of the list. If more configurables are appended onto this one, their values won't
+	// be operated on by the existing postProcessors, but they may have their own
+	// postprocessors.
+	//
+	// _____________________
+	// |         __________|
+	// ______    |    _____|        ___
+	// |    |         |    |        | |
+	// a -> b -> c -> d -> e -> f -> g
+	//
+	// In this diagram, the letters along the bottom is the chain of configurableInners.
+	// The brackets on top represent postprocessors, where higher brackets are processed
+	// after lower ones.
+	//
+	// To evaluate this example, first we evaluate the raw values for all nodes a->g.
+	// Then we merge nodes a/b and d/e and apply the postprocessors to their merged values,
+	// and also to g. Those merged and postprocessed nodes are then reinserted into the
+	// list, and we move on to doing the higher level postprocessors (starting with the c->e one)
+	// in the same way. When all postprocessors are done, a final merge is done on anything
+	// leftover.
+	//
+	// The Configurable.postProcessors field is a 2d array to represent this hierarchy.
+	// The outer index moves right on this graph, the inner index goes up.
+	// When adding a new postProcessor, it will always be the last postProcessor to run
+	// until another is added or another configurable is appended. So in AddPostProcessor(),
+	// we add it to the tallest existing stack.
+
+	var currentValues []valueAndIndices[T]
+	for curr, i := c.inner, 0; curr != nil; curr, i = curr.next, i+1 {
+		value := curr.single.evaluateNonTransitive(propertyName, evaluator)
+		currentValues = append(currentValues, valueAndIndices[T]{
+			value:   value,
+			replace: curr.replace,
+			start:   i,
+			end:     i + 1,
+		})
+	}
+
+	if c.postProcessors == nil || len(*c.postProcessors) == 0 {
+		return mergeValues(currentValues).value
+	}
+
+	foundPostProcessor := true
+	for depth := 0; foundPostProcessor; depth++ {
+		foundPostProcessor = false
+		var newValues []valueAndIndices[T]
+		i := 0
+		for _, postProcessorGroup := range *c.postProcessors {
+			if len(postProcessorGroup) > depth {
+				foundPostProcessor = true
+				postProcessor := postProcessorGroup[depth]
+				startI := 0
+				endI := 0
+				for currentValues[startI].start < postProcessor.start {
+					startI++
+				}
+				for currentValues[endI].end < postProcessor.end {
+					endI++
+				}
+				endI++
+				newValues = append(newValues, currentValues[i:startI]...)
+				merged := mergeValues(currentValues[startI:endI])
+				if merged.value != nil {
+					processed := postProcessor.f(*merged.value)
+					merged.value = &processed
+				}
+				newValues = append(newValues, merged)
+				i = endI
+			}
+		}
+		newValues = append(newValues, currentValues[i:]...)
+		currentValues = newValues
+	}
+
+	return mergeValues(currentValues).value
+}
+
+func mergeValues[T ConfigurableElements](values []valueAndIndices[T]) valueAndIndices[T] {
+	if len(values) < 0 {
+		panic("Expected at least 1 value in mergeValues")
+	}
+	result := values[0]
+	for i := 1; i < len(values); i++ {
+		if result.replace {
+			result.value = replaceConfiguredValues(result.value, values[i].value)
+		} else {
+			result.value = appendConfiguredValues(result.value, values[i].value)
+		}
+		result.end = values[i].end
+		result.replace = values[i].replace
+	}
+	return result
+}
+
 func (c *configurableInner[T]) evaluate(propertyName string, evaluator ConfigurableEvaluator) *T {
 	if c == nil {
 		return nil
@@ -472,7 +698,12 @@ func (c *singleConfigurable[T]) evaluateNonTransitive(propertyName string, evalu
 		if len(c.cases) == 0 {
 			return nil
 		} else if len(c.cases) == 1 {
-			return c.cases[0].value
+			if result, err := expressionToConfiguredValue[T](c.cases[0].value, c.scope); err != nil {
+				evaluator.PropertyErrorf(propertyName, "%s", err.Error())
+				return nil
+			} else {
+				return result
+			}
 		} else {
 			evaluator.PropertyErrorf(propertyName, "Expected 0 or 1 branches in an unconfigured select, found %d", len(c.cases))
 			return nil
@@ -499,7 +730,13 @@ func (c *singleConfigurable[T]) evaluateNonTransitive(propertyName string, evalu
 			}
 		}
 		if allMatch && !foundMatch {
-			result = case_.value
+			newScope := createScopeWithBindings(c.scope, case_.patterns, values)
+			if r, err := expressionToConfiguredValue[T](case_.value, newScope); err != nil {
+				evaluator.PropertyErrorf(propertyName, "%s", err.Error())
+				return nil
+			} else {
+				result = r
+			}
 			foundMatch = true
 		}
 	}
@@ -511,6 +748,27 @@ func (c *singleConfigurable[T]) evaluateNonTransitive(propertyName string, evalu
 	return nil
 }
 
+func createScopeWithBindings(parent *parser.Scope, patterns []ConfigurablePattern, values []ConfigurableValue) *parser.Scope {
+	result := parent
+	for i, pattern := range patterns {
+		if pattern.binding != "" {
+			if result == parent {
+				result = parser.NewScope(parent)
+			}
+			err := result.HandleAssignment(&parser.Assignment{
+				Name:     pattern.binding,
+				Value:    values[i].toExpression(),
+				Assigner: "=",
+			})
+			if err != nil {
+				// This shouldn't happen due to earlier validity checks
+				panic(err.Error())
+			}
+		}
+	}
+	return result
+}
+
 func appendConfiguredValues[T ConfigurableElements](a, b *T) *T {
 	if a == nil && b == nil {
 		return nil
@@ -579,20 +837,27 @@ type configurableReflection interface {
 // Same as configurableReflection, but since initialize needs to take a pointer
 // to a Configurable, it was broken out into a separate interface.
 type configurablePtrReflection interface {
-	initialize(propertyName string, conditions []ConfigurableCondition, cases any)
+	initialize(scope *parser.Scope, propertyName string, conditions []ConfigurableCondition, cases any)
 }
 
 var _ configurableReflection = Configurable[string]{}
 var _ configurablePtrReflection = &Configurable[string]{}
 
-func (c *Configurable[T]) initialize(propertyName string, conditions []ConfigurableCondition, cases any) {
+func (c *Configurable[T]) initialize(scope *parser.Scope, propertyName string, conditions []ConfigurableCondition, cases any) {
 	c.propertyName = propertyName
 	c.inner = &configurableInner[T]{
 		single: singleConfigurable[T]{
 			conditions: conditions,
 			cases:      cases.([]ConfigurableCase[T]),
+			scope:      scope,
 		},
 	}
+	var postProcessors [][]postProcessor[T]
+	c.postProcessors = &postProcessors
+}
+
+func (c *Configurable[T]) Append(other Configurable[T]) {
+	c.setAppend(other, false, false)
 }
 
 func (c Configurable[T]) setAppend(append any, replace bool, prepend bool) {
@@ -600,12 +865,37 @@ func (c Configurable[T]) setAppend(append any, replace bool, prepend bool) {
 	if a.inner.isEmpty() {
 		return
 	}
+
+	if prepend {
+		newBase := a.inner.numLinks()
+		*c.postProcessors = appendPostprocessors(*a.postProcessors, *c.postProcessors, newBase)
+	} else {
+		newBase := c.inner.numLinks()
+		*c.postProcessors = appendPostprocessors(*c.postProcessors, *a.postProcessors, newBase)
+	}
+
 	c.inner.setAppend(a.inner, replace, prepend)
 	if c.inner == c.inner.next {
 		panic("pointer loop")
 	}
 }
 
+func appendPostprocessors[T ConfigurableElements](a, b [][]postProcessor[T], newBase int) [][]postProcessor[T] {
+	var result [][]postProcessor[T]
+	for i := 0; i < len(a); i++ {
+		result = append(result, slices.Clone(a[i]))
+	}
+	for i := 0; i < len(b); i++ {
+		n := slices.Clone(b[i])
+		for j := 0; j < len(n); j++ {
+			n[j].start += newBase
+			n[j].end += newBase
+		}
+		result = append(result, n)
+	}
+	return result
+}
+
 func (c *configurableInner[T]) setAppend(append *configurableInner[T], replace bool, prepend bool) {
 	if c.isEmpty() {
 		*c = *append.clone()
@@ -644,13 +934,21 @@ func (c *configurableInner[T]) setAppend(append *configurableInner[T], replace b
 	}
 }
 
+func (c *configurableInner[T]) numLinks() int {
+	result := 0
+	for curr := c; curr != nil; curr = curr.next {
+		result++
+	}
+	return result
+}
+
 func (c *configurableInner[T]) appendSimpleValue(value T) {
 	if c.next == nil {
 		c.replace = false
 		c.next = &configurableInner[T]{
 			single: singleConfigurable[T]{
 				cases: []ConfigurableCase[T]{{
-					value: &value,
+					value: configuredValueToExpression(value),
 				}},
 			},
 		}
@@ -678,46 +976,28 @@ func (c *singleConfigurable[T]) printfInto(value string) error {
 		if c.value == nil {
 			continue
 		}
-		switch v := any(c.value).(type) {
-		case *string:
-			if err := printfIntoString(v, value); err != nil {
-				return err
-			}
-		case *[]string:
-			for i := range *v {
-				if err := printfIntoString(&((*v)[i]), value); err != nil {
-					return err
-				}
-			}
+		if err := c.value.PrintfInto(value); err != nil {
+			return err
 		}
 	}
 	return nil
 }
 
-func printfIntoString(s *string, configValue string) error {
-	count := strings.Count(*s, "%")
-	if count == 0 {
-		return nil
+func (c Configurable[T]) clone() any {
+	var newPostProcessors *[][]postProcessor[T]
+	if c.postProcessors != nil {
+		x := appendPostprocessors(*c.postProcessors, nil, 0)
+		newPostProcessors = &x
 	}
-
-	if count > 1 {
-		return fmt.Errorf("list/value variable properties only support a single '%%'")
+	return Configurable[T]{
+		propertyName:   c.propertyName,
+		inner:          c.inner.clone(),
+		postProcessors: newPostProcessors,
 	}
-
-	if !strings.Contains(*s, "%s") {
-		return fmt.Errorf("unsupported %% in value variable property")
-	}
-
-	*s = fmt.Sprintf(*s, configValue)
-
-	return nil
 }
 
-func (c Configurable[T]) clone() any {
-	return Configurable[T]{
-		propertyName: c.propertyName,
-		inner:        c.inner.clone(),
-	}
+func (c Configurable[T]) Clone() Configurable[T] {
+	return c.clone().(Configurable[T])
 }
 
 func (c *configurableInner[T]) clone() *configurableInner[T] {
@@ -755,6 +1035,9 @@ func (c *singleConfigurable[T]) isEmpty() bool {
 		return false
 	}
 	if len(c.cases) == 1 && c.cases[0].value != nil {
+		if _, ok := c.cases[0].value.(*parser.UnsetProperty); ok {
+			return true
+		}
 		return false
 	}
 	return true
@@ -774,7 +1057,7 @@ func (c *singleConfigurable[T]) alwaysHasValue() bool {
 		return false
 	}
 	for _, c := range c.cases {
-		if c.value == nil {
+		if _, isUnset := c.value.(*parser.UnsetProperty); isUnset || c.value == nil {
 			return false
 		}
 	}
@@ -785,17 +1068,84 @@ func (c Configurable[T]) configuredType() reflect.Type {
 	return reflect.TypeOf((*T)(nil)).Elem()
 }
 
-func copyConfiguredValuePtr[T ConfigurableElements](t *T) *T {
-	if t == nil {
-		return nil
+func expressionToConfiguredValue[T ConfigurableElements](expr parser.Expression, scope *parser.Scope) (*T, error) {
+	expr, err := expr.Eval(scope)
+	if err != nil {
+		return nil, err
 	}
-	switch t2 := any(*t).(type) {
-	case []string:
-		result := any(slices.Clone(t2)).(T)
-		return &result
+	switch e := expr.(type) {
+	case *parser.UnsetProperty:
+		return nil, nil
+	case *parser.String:
+		if result, ok := any(&e.Value).(*T); ok {
+			return result, nil
+		} else {
+			return nil, fmt.Errorf("can't assign string value to %s property", configuredTypeToString[T]())
+		}
+	case *parser.Bool:
+		if result, ok := any(&e.Value).(*T); ok {
+			return result, nil
+		} else {
+			return nil, fmt.Errorf("can't assign bool value to %s property", configuredTypeToString[T]())
+		}
+	case *parser.List:
+		result := make([]string, 0, len(e.Values))
+		for _, x := range e.Values {
+			if y, ok := x.(*parser.String); ok {
+				result = append(result, y.Value)
+			} else {
+				return nil, fmt.Errorf("expected list of strings but found list of %s", x.Type())
+			}
+		}
+		if result, ok := any(&result).(*T); ok {
+			return result, nil
+		} else {
+			return nil, fmt.Errorf("can't assign list of strings to list of %s property", configuredTypeToString[T]())
+		}
 	default:
-		x := *t
-		return &x
+		// If the expression was not evaluated beforehand we could hit this error even when the types match,
+		// but that's an internal logic error.
+		return nil, fmt.Errorf("expected %s but found %s (%#v)", configuredTypeToString[T](), expr.Type().String(), expr)
+	}
+}
+
+func configuredValueToExpression[T ConfigurableElements](value T) parser.Expression {
+	switch v := any(value).(type) {
+	case string:
+		return &parser.String{Value: v}
+	case bool:
+		return &parser.Bool{Value: v}
+	case []string:
+		values := make([]parser.Expression, 0, len(v))
+		for _, x := range v {
+			values = append(values, &parser.String{Value: x})
+		}
+		return &parser.List{Values: values}
+	default:
+		panic("unhandled type in configuredValueToExpression")
+	}
+}
+
+func configuredTypeToString[T ConfigurableElements]() string {
+	var zero T
+	switch any(zero).(type) {
+	case string:
+		return "string"
+	case bool:
+		return "bool"
+	case []string:
+		return "list of strings"
+	default:
+		panic("should be unreachable")
+	}
+}
+
+func copyConfiguredValue[T ConfigurableElements](t T) T {
+	switch t2 := any(t).(type) {
+	case []string:
+		return any(slices.Clone(t2)).(T)
+	default:
+		return t
 	}
 }
 
@@ -812,18 +1162,75 @@ func configuredValuePtrToOptional[T ConfigurableElements](t *T) ConfigurableOpti
 	}
 }
 
-func copyConfiguredValue[T ConfigurableElements](t T) T {
-	switch t2 := any(t).(type) {
-	case []string:
-		return any(slices.Clone(t2)).(T)
-	default:
-		return t
-	}
-}
-
 // PrintfIntoConfigurable replaces %s occurrences in strings in Configurable properties
 // with the provided string value. It's intention is to support soong config value variables
 // on Configurable properties.
 func PrintfIntoConfigurable(c any, value string) error {
 	return c.(configurableReflection).printfInto(value)
 }
+
+func promoteValueToConfigurable(origional reflect.Value) reflect.Value {
+	var expr parser.Expression
+	var kind reflect.Kind
+	if origional.Kind() == reflect.Pointer && origional.IsNil() {
+		expr = &parser.UnsetProperty{}
+		kind = origional.Type().Elem().Kind()
+	} else {
+		if origional.Kind() == reflect.Pointer {
+			origional = origional.Elem()
+		}
+		kind = origional.Kind()
+		switch kind {
+		case reflect.String:
+			expr = &parser.String{Value: origional.String()}
+		case reflect.Bool:
+			expr = &parser.Bool{Value: origional.Bool()}
+		case reflect.Slice:
+			strList := origional.Interface().([]string)
+			exprList := make([]parser.Expression, 0, len(strList))
+			for _, x := range strList {
+				exprList = append(exprList, &parser.String{Value: x})
+			}
+			expr = &parser.List{Values: exprList}
+		default:
+			panic("can only convert string/bool/[]string to configurable")
+		}
+	}
+	switch kind {
+	case reflect.String:
+		return reflect.ValueOf(Configurable[string]{
+			inner: &configurableInner[string]{
+				single: singleConfigurable[string]{
+					cases: []ConfigurableCase[string]{{
+						value: expr,
+					}},
+				},
+			},
+			postProcessors: &[][]postProcessor[string]{},
+		})
+	case reflect.Bool:
+		return reflect.ValueOf(Configurable[bool]{
+			inner: &configurableInner[bool]{
+				single: singleConfigurable[bool]{
+					cases: []ConfigurableCase[bool]{{
+						value: expr,
+					}},
+				},
+			},
+			postProcessors: &[][]postProcessor[bool]{},
+		})
+	case reflect.Slice:
+		return reflect.ValueOf(Configurable[[]string]{
+			inner: &configurableInner[[]string]{
+				single: singleConfigurable[[]string]{
+					cases: []ConfigurableCase[[]string]{{
+						value: expr,
+					}},
+				},
+			},
+			postProcessors: &[][]postProcessor[[]string]{},
+		})
+	default:
+		panic(fmt.Sprintf("Can't convert %s property to a configurable", origional.Kind().String()))
+	}
+}

proptools/configurable_test.go

@@ -0,0 +1,95 @@
+package proptools
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+)
+
+func TestPostProcessor(t *testing.T) {
+	// Same as the ascii art example in Configurable.evaluate()
+	prop := NewConfigurable[[]string](nil, nil)
+	prop.AppendSimpleValue([]string{"a"})
+	prop.AppendSimpleValue([]string{"b"})
+	prop.AddPostProcessor(addToElements("1"))
+
+	prop2 := NewConfigurable[[]string](nil, nil)
+	prop2.AppendSimpleValue([]string{"c"})
+
+	prop3 := NewConfigurable[[]string](nil, nil)
+	prop3.AppendSimpleValue([]string{"d"})
+	prop3.AppendSimpleValue([]string{"e"})
+	prop3.AddPostProcessor(addToElements("2"))
+
+	prop4 := NewConfigurable[[]string](nil, nil)
+	prop4.AppendSimpleValue([]string{"f"})
+
+	prop5 := NewConfigurable[[]string](nil, nil)
+	prop5.AppendSimpleValue([]string{"g"})
+	prop5.AddPostProcessor(addToElements("3"))
+
+	prop2.Append(prop3)
+	prop2.AddPostProcessor(addToElements("z"))
+
+	prop.Append(prop2)
+	prop.AddPostProcessor(addToElements("y"))
+	prop.Append(prop4)
+	prop.Append(prop5)
+
+	expected := []string{"a1y", "b1y", "czy", "d2zy", "e2zy", "f", "g3"}
+	x := prop.Get(&configurableEvalutorForTesting{})
+	if !reflect.DeepEqual(x.Get(), expected) {
+		t.Fatalf("Expected %v, got %v", expected, x.Get())
+	}
+}
+
+func TestPostProcessorWhenPassedToHelperFunction(t *testing.T) {
+	prop := NewConfigurable[[]string](nil, nil)
+	prop.AppendSimpleValue([]string{"a"})
+	prop.AppendSimpleValue([]string{"b"})
+
+	helper := func(p Configurable[[]string]) {
+		p.AddPostProcessor(addToElements("1"))
+	}
+
+	helper(prop)
+
+	expected := []string{"a1", "b1"}
+	x := prop.Get(&configurableEvalutorForTesting{})
+	if !reflect.DeepEqual(x.Get(), expected) {
+		t.Fatalf("Expected %v, got %v", expected, x.Get())
+	}
+}
+
+func addToElements(s string) func([]string) []string {
+	return func(arr []string) []string {
+		for i := range arr {
+			arr[i] = arr[i] + s
+		}
+		return arr
+	}
+}
+
+type configurableEvalutorForTesting struct {
+	vars map[string]string
+}
+
+func (e *configurableEvalutorForTesting) EvaluateConfiguration(condition ConfigurableCondition, property string) ConfigurableValue {
+	if condition.functionName != "f" {
+		panic("Expected functionName to be f")
+	}
+	if len(condition.args) != 1 {
+		panic("Expected exactly 1 arg")
+	}
+	val, ok := e.vars[condition.args[0]]
+	if ok {
+		return ConfigurableValueString(val)
+	}
+	return ConfigurableValueUndefined()
+}
+
+func (e *configurableEvalutorForTesting) PropertyErrorf(property, fmtString string, args ...interface{}) {
+	panic(fmt.Sprintf(fmtString, args...))
+}
+
+var _ ConfigurableEvaluator = (*configurableEvalutorForTesting)(nil)

proptools/extend.go

@@ -473,33 +473,7 @@ func ExtendBasicType(dstFieldValue, srcFieldValue reflect.Value, order Order) {
 	// structs when they want to change the default values of properties.
 	srcFieldType := srcFieldValue.Type()
 	if isConfigurable(dstFieldValue.Type()) && !isConfigurable(srcFieldType) {
-		var value reflect.Value
-		if srcFieldType.Kind() == reflect.Pointer {
-			srcFieldType = srcFieldType.Elem()
-			if srcFieldValue.IsNil() {
-				value = srcFieldValue
-			} else {
-				// Copy the pointer
-				value = reflect.New(srcFieldType)
-				value.Elem().Set(srcFieldValue.Elem())
-			}
-		} else {
-			value = reflect.New(srcFieldType)
-			value.Elem().Set(srcFieldValue)
-		}
-		caseType := configurableCaseType(srcFieldType)
-		case_ := reflect.New(caseType)
-		case_.Interface().(configurableCaseReflection).initialize(nil, value.Interface())
-		cases := reflect.MakeSlice(reflect.SliceOf(caseType), 0, 1)
-		cases = reflect.Append(cases, case_.Elem())
-		ct, err := configurableType(srcFieldType)
-		if err != nil {
-			// Should be unreachable due to earlier checks
-			panic(err.Error())
-		}
-		temp := reflect.New(ct)
-		temp.Interface().(configurablePtrReflection).initialize("", nil, cases.Interface())
-		srcFieldValue = temp.Elem()
+		srcFieldValue = promoteValueToConfigurable(srcFieldValue)
 	}
 
 	switch srcFieldValue.Kind() {

proptools/extend_test.go

@@ -20,6 +20,8 @@ import (
 	"reflect"
 	"strings"
 	"testing"
+
+	"github.com/google/blueprint/parser"
 )
 
 type appendPropertyTestCase struct {
@@ -1257,172 +1259,166 @@ func appendPropertiesTestCases() []appendPropertyTestCase {
 		{
 			name: "Append configurable",
 			dst: &struct{ S Configurable[[]string] }{
-				S: Configurable[[]string]{
-					inner: &configurableInner[[]string]{
-						single: singleConfigurable[[]string]{
-							conditions: []ConfigurableCondition{{
-								functionName: "soong_config_variable",
-								args: []string{
-									"my_namespace",
-									"foo",
-								},
-							}},
-							cases: []ConfigurableCase[[]string]{{
-								patterns: []ConfigurablePattern{{
-									typ:         configurablePatternTypeString,
-									stringValue: "a",
-								}},
-								value: &[]string{"1", "2"},
-							}},
-						},
+				S: NewConfigurable[[]string]([]ConfigurableCondition{{
+					functionName: "soong_config_variable",
+					args: []string{
+						"my_namespace",
+						"foo",
 					},
-				},
+				}},
+					[]ConfigurableCase[[]string]{{
+						patterns: []ConfigurablePattern{{
+							typ:         configurablePatternTypeString,
+							stringValue: "a",
+						}},
+						value: &parser.List{Values: []parser.Expression{
+							&parser.String{Value: "1"},
+							&parser.String{Value: "2"},
+						}},
+					}},
+				),
 			},
 			src: &struct{ S Configurable[[]string] }{
-				S: Configurable[[]string]{
-					inner: &configurableInner[[]string]{
-						single: singleConfigurable[[]string]{
-							conditions: []ConfigurableCondition{{
-								functionName: "release_variable",
-								args: []string{
-									"bar",
-								},
-							}},
-							cases: []ConfigurableCase[[]string]{{
-								patterns: []ConfigurablePattern{{
-									typ:         configurablePatternTypeString,
-									stringValue: "b",
-								}},
-								value: &[]string{"3", "4"},
-							}},
-						},
+				S: NewConfigurable([]ConfigurableCondition{{
+					functionName: "release_variable",
+					args: []string{
+						"bar",
 					},
-				},
+				}},
+					[]ConfigurableCase[[]string]{{
+						patterns: []ConfigurablePattern{{
+							typ:         configurablePatternTypeString,
+							stringValue: "b",
+						}},
+						value: &parser.List{Values: []parser.Expression{
+							&parser.String{Value: "3"},
+							&parser.String{Value: "4"},
+						}},
+					}},
+				),
 			},
 			out: &struct{ S Configurable[[]string] }{
-				S: Configurable[[]string]{
-					inner: &configurableInner[[]string]{
-						single: singleConfigurable[[]string]{
-							conditions: []ConfigurableCondition{{
-								functionName: "soong_config_variable",
-								args: []string{
-									"my_namespace",
-									"foo",
-								},
-							}},
-							cases: []ConfigurableCase[[]string]{{
-								patterns: []ConfigurablePattern{{
-									typ:         configurablePatternTypeString,
-									stringValue: "a",
-								}},
-								value: &[]string{"1", "2"},
-							}},
+				S: func() Configurable[[]string] {
+					result := NewConfigurable([]ConfigurableCondition{{
+						functionName: "soong_config_variable",
+						args: []string{
+							"my_namespace",
+							"foo",
 						},
-						next: &configurableInner[[]string]{
-							single: singleConfigurable[[]string]{
-								conditions: []ConfigurableCondition{{
-									functionName: "release_variable",
-									args: []string{
-										"bar",
-									},
-								}},
-								cases: []ConfigurableCase[[]string]{{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "b",
-									}},
-									value: &[]string{"3", "4"},
-								}},
-							},
+					}},
+						[]ConfigurableCase[[]string]{{
+							patterns: []ConfigurablePattern{{
+								typ:         configurablePatternTypeString,
+								stringValue: "a",
+							}},
+							value: &parser.List{Values: []parser.Expression{
+								&parser.String{Value: "1"},
+								&parser.String{Value: "2"},
+							}},
+						}},
+					)
+					result.Append(NewConfigurable([]ConfigurableCondition{{
+						functionName: "release_variable",
+						args: []string{
+							"bar",
 						},
-					},
-				},
+					}},
+						[]ConfigurableCase[[]string]{{
+							patterns: []ConfigurablePattern{{
+								typ:         configurablePatternTypeString,
+								stringValue: "b",
+							}},
+							value: &parser.List{Values: []parser.Expression{
+								&parser.String{Value: "3"},
+								&parser.String{Value: "4"},
+							}},
+						}}))
+					return result
+				}(),
 			},
 		},
 		{
 			name:  "Prepend configurable",
 			order: Prepend,
 			dst: &struct{ S Configurable[[]string] }{
-				S: Configurable[[]string]{
-					inner: &configurableInner[[]string]{
-						single: singleConfigurable[[]string]{
-							conditions: []ConfigurableCondition{{
-								functionName: "soong_config_variable",
-								args: []string{
-									"my_namespace",
-									"foo",
-								},
-							}},
-							cases: []ConfigurableCase[[]string]{{
-								patterns: []ConfigurablePattern{{
-									typ:         configurablePatternTypeString,
-									stringValue: "a",
-								}},
-								value: &[]string{"1", "2"},
-							}},
-						},
+				S: NewConfigurable([]ConfigurableCondition{{
+					functionName: "soong_config_variable",
+					args: []string{
+						"my_namespace",
+						"foo",
 					},
-				},
+				}},
+					[]ConfigurableCase[[]string]{{
+						patterns: []ConfigurablePattern{{
+							typ:         configurablePatternTypeString,
+							stringValue: "a",
+						}},
+						value: &parser.List{Values: []parser.Expression{
+							&parser.String{Value: "1"},
+							&parser.String{Value: "2"},
+						}},
+					}},
+				),
 			},
 			src: &struct{ S Configurable[[]string] }{
-				S: Configurable[[]string]{
-					inner: &configurableInner[[]string]{
-						single: singleConfigurable[[]string]{
-							conditions: []ConfigurableCondition{{
-								functionName: "release_variable",
-								args: []string{
-									"bar",
-								},
-							}},
-							cases: []ConfigurableCase[[]string]{{
-								patterns: []ConfigurablePattern{{
-									typ:         configurablePatternTypeString,
-									stringValue: "b",
-								}},
-								value: &[]string{"3", "4"},
-							}},
-						},
+				S: NewConfigurable([]ConfigurableCondition{{
+					functionName: "release_variable",
+					args: []string{
+						"bar",
 					},
-				},
+				}},
+					[]ConfigurableCase[[]string]{{
+						patterns: []ConfigurablePattern{{
+							typ:         configurablePatternTypeString,
+							stringValue: "b",
+						}},
+						value: &parser.List{Values: []parser.Expression{
+							&parser.String{Value: "3"},
+							&parser.String{Value: "4"},
+						}},
+					}},
+				),
 			},
 			out: &struct{ S Configurable[[]string] }{
-				S: Configurable[[]string]{
-					inner: &configurableInner[[]string]{
-						single: singleConfigurable[[]string]{
-							conditions: []ConfigurableCondition{{
-								functionName: "release_variable",
-								args: []string{
-									"bar",
-								},
-							}},
-							cases: []ConfigurableCase[[]string]{{
-								patterns: []ConfigurablePattern{{
-									typ:         configurablePatternTypeString,
-									stringValue: "b",
-								}},
-								value: &[]string{"3", "4"},
-							}},
-						},
-						next: &configurableInner[[]string]{
-							single: singleConfigurable[[]string]{
-								conditions: []ConfigurableCondition{{
-									functionName: "soong_config_variable",
-									args: []string{
-										"my_namespace",
-										"foo",
-									},
-								}},
-								cases: []ConfigurableCase[[]string]{{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "a",
-									}},
-									value: &[]string{"1", "2"},
-								}},
+				S: func() Configurable[[]string] {
+					result := NewConfigurable(
+						[]ConfigurableCondition{{
+							functionName: "release_variable",
+							args: []string{
+								"bar",
 							},
-						},
-					},
-				},
+						}},
+						[]ConfigurableCase[[]string]{{
+							patterns: []ConfigurablePattern{{
+								typ:         configurablePatternTypeString,
+								stringValue: "b",
+							}},
+							value: &parser.List{Values: []parser.Expression{
+								&parser.String{Value: "3"},
+								&parser.String{Value: "4"},
+							}},
+						}},
+					)
+					result.Append(NewConfigurable(
+						[]ConfigurableCondition{{
+							functionName: "soong_config_variable",
+							args: []string{
+								"my_namespace",
+								"foo",
+							},
+						}},
+						[]ConfigurableCase[[]string]{{
+							patterns: []ConfigurablePattern{{
+								typ:         configurablePatternTypeString,
+								stringValue: "a",
+							}},
+							value: &parser.List{Values: []parser.Expression{
+								&parser.String{Value: "1"},
+								&parser.String{Value: "2"},
+							}},
+						}}))
+					return result
+				}(),
 			},
 		},
 	}
@@ -1892,31 +1888,24 @@ func appendMatchingPropertiesTestCases() []appendMatchingPropertiesTestCase {
 			order: Append,
 			dst: []interface{}{
 				&struct{ S Configurable[bool] }{
-					S: Configurable[bool]{
-						inner: &configurableInner[bool]{
-							single: singleConfigurable[bool]{
-								conditions: []ConfigurableCondition{{
-									functionName: "soong_config_variable",
-									args: []string{
-										"my_namespace",
-										"foo",
-									},
-								}},
-								cases: []ConfigurableCase[bool]{{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "a",
-									}},
-									value: BoolPtr(true),
-								}, {
-									patterns: []ConfigurablePattern{{
-										typ: configurablePatternTypeDefault,
-									}},
-									value: BoolPtr(false),
-								}},
-							},
+					S: NewConfigurable[bool]([]ConfigurableCondition{{
+						functionName: "soong_config_variable",
+						args: []string{
+							"my_namespace",
+							"foo",
 						},
-					},
+					}}, []ConfigurableCase[bool]{{
+						patterns: []ConfigurablePattern{{
+							typ:         configurablePatternTypeString,
+							stringValue: "a",
+						}},
+						value: &parser.Bool{Value: true},
+					}, {
+						patterns: []ConfigurablePattern{{
+							typ: configurablePatternTypeDefault,
+						}},
+						value: &parser.Bool{Value: false},
+					}}),
 				},
 			},
 			src: &struct{ S *bool }{
@@ -1924,38 +1913,30 @@ func appendMatchingPropertiesTestCases() []appendMatchingPropertiesTestCase {
 			},
 			out: []interface{}{
 				&struct{ S Configurable[bool] }{
-					S: Configurable[bool]{
-						inner: &configurableInner[bool]{
-							single: singleConfigurable[bool]{
-								conditions: []ConfigurableCondition{{
-									functionName: "soong_config_variable",
-									args: []string{
-										"my_namespace",
-										"foo",
-									},
-								}},
-								cases: []ConfigurableCase[bool]{{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "a",
-									}},
-									value: BoolPtr(true),
-								}, {
-									patterns: []ConfigurablePattern{{
-										typ: configurablePatternTypeDefault,
-									}},
-									value: BoolPtr(false),
-								}},
+					S: func() Configurable[bool] {
+						result := NewConfigurable[bool]([]ConfigurableCondition{{
+							functionName: "soong_config_variable",
+							args: []string{
+								"my_namespace",
+								"foo",
 							},
-							next: &configurableInner[bool]{
-								single: singleConfigurable[bool]{
-									cases: []ConfigurableCase[bool]{{
-										value: BoolPtr(true),
-									}},
-								},
-							},
-						},
-					},
+						}},
+							[]ConfigurableCase[bool]{{
+								patterns: []ConfigurablePattern{{
+									typ:         configurablePatternTypeString,
+									stringValue: "a",
+								}},
+								value: &parser.Bool{Value: true},
+							}, {
+								patterns: []ConfigurablePattern{{
+									typ: configurablePatternTypeDefault,
+								}},
+								value: &parser.Bool{Value: false},
+							}},
+						)
+						result.AppendSimpleValue(true)
+						return result
+					}(),
 				},
 			},
 		},
@@ -1964,31 +1945,26 @@ func appendMatchingPropertiesTestCases() []appendMatchingPropertiesTestCase {
 			order: Append,
 			dst: []interface{}{
 				&struct{ S Configurable[bool] }{
-					S: Configurable[bool]{
-						inner: &configurableInner[bool]{
-							single: singleConfigurable[bool]{
-								conditions: []ConfigurableCondition{{
-									functionName: "soong_config_variable",
-									args: []string{
-										"my_namespace",
-										"foo",
-									},
-								}},
-								cases: []ConfigurableCase[bool]{{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "a",
-									}},
-									value: BoolPtr(true),
-								}, {
-									patterns: []ConfigurablePattern{{
-										typ: configurablePatternTypeDefault,
-									}},
-									value: BoolPtr(false),
-								}},
-							},
+					S: NewConfigurable[bool]([]ConfigurableCondition{{
+						functionName: "soong_config_variable",
+						args: []string{
+							"my_namespace",
+							"foo",
 						},
-					},
+					}},
+						[]ConfigurableCase[bool]{{
+							patterns: []ConfigurablePattern{{
+								typ:         configurablePatternTypeString,
+								stringValue: "a",
+							}},
+							value: &parser.Bool{Value: true},
+						}, {
+							patterns: []ConfigurablePattern{{
+								typ: configurablePatternTypeDefault,
+							}},
+							value: &parser.Bool{Value: false},
+						}},
+					),
 				},
 			},
 			src: &struct{ S bool }{
@@ -1996,38 +1972,31 @@ func appendMatchingPropertiesTestCases() []appendMatchingPropertiesTestCase {
 			},
 			out: []interface{}{
 				&struct{ S Configurable[bool] }{
-					S: Configurable[bool]{
-						inner: &configurableInner[bool]{
-							single: singleConfigurable[bool]{
-								conditions: []ConfigurableCondition{{
-									functionName: "soong_config_variable",
-									args: []string{
-										"my_namespace",
-										"foo",
-									},
-								}},
-								cases: []ConfigurableCase[bool]{{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "a",
-									}},
-									value: BoolPtr(true),
-								}, {
-									patterns: []ConfigurablePattern{{
-										typ: configurablePatternTypeDefault,
-									}},
-									value: BoolPtr(false),
-								}},
-							},
-							next: &configurableInner[bool]{
-								single: singleConfigurable[bool]{
-									cases: []ConfigurableCase[bool]{{
-										value: BoolPtr(true),
-									}},
+					S: func() Configurable[bool] {
+						result := NewConfigurable[bool](
+							[]ConfigurableCondition{{
+								functionName: "soong_config_variable",
+								args: []string{
+									"my_namespace",
+									"foo",
 								},
-							},
-						},
-					},
+							}},
+							[]ConfigurableCase[bool]{{
+								patterns: []ConfigurablePattern{{
+									typ:         configurablePatternTypeString,
+									stringValue: "a",
+								}},
+								value: &parser.Bool{Value: true},
+							}, {
+								patterns: []ConfigurablePattern{{
+									typ: configurablePatternTypeDefault,
+								}},
+								value: &parser.Bool{Value: false},
+							}},
+						)
+						result.AppendSimpleValue(true)
+						return result
+					}(),
 				},
 			},
 		},

proptools/unpack.go

@@ -158,7 +158,7 @@ func (ctx *unpackContext) buildPropertyMap(prefix string, properties []*parser.P
 		}
 
 		ctx.propertyMap[name] = &packedProperty{property, false}
-		switch propValue := property.Value.Eval().(type) {
+		switch propValue := property.Value.(type) {
 		case *parser.Map:
 			ctx.buildPropertyMap(name, propValue.Properties)
 		case *parser.List:
@@ -313,7 +313,7 @@ func (ctx *unpackContext) unpackToStruct(namePrefix string, structValue reflect.
 				return
 			}
 		} else if isStruct(fieldValue.Type()) {
-			if property.Value.Eval().Type() != parser.MapType {
+			if property.Value.Type() != parser.MapType {
 				ctx.addError(&UnpackError{
 					fmt.Errorf("can't assign %s value to map property %q",
 						property.Value.Type(), property.Name),
@@ -354,15 +354,17 @@ func (ctx *unpackContext) unpackToConfigurable(propertyName string, property *pa
 			})
 			return reflect.New(configurableType), false
 		}
+		var postProcessors [][]postProcessor[string]
 		result := Configurable[string]{
 			propertyName: property.Name,
 			inner: &configurableInner[string]{
 				single: singleConfigurable[string]{
 					cases: []ConfigurableCase[string]{{
-						value: &v.Value,
+						value: v,
 					}},
 				},
 			},
+			postProcessors: &postProcessors,
 		}
 		return reflect.ValueOf(&result), true
 	case *parser.Bool:
@@ -374,15 +376,17 @@ func (ctx *unpackContext) unpackToConfigurable(propertyName string, property *pa
 			})
 			return reflect.New(configurableType), false
 		}
+		var postProcessors [][]postProcessor[bool]
 		result := Configurable[bool]{
 			propertyName: property.Name,
 			inner: &configurableInner[bool]{
 				single: singleConfigurable[bool]{
 					cases: []ConfigurableCase[bool]{{
-						value: &v.Value,
+						value: v,
 					}},
 				},
 			},
+			postProcessors: &postProcessors,
 		}
 		return reflect.ValueOf(&result), true
 	case *parser.List:
@@ -411,26 +415,22 @@ func (ctx *unpackContext) unpackToConfigurable(propertyName string, property *pa
 					value[i] = exprUnpacked.Interface().(string)
 				}
 			}
+			var postProcessors [][]postProcessor[[]string]
 			result := Configurable[[]string]{
 				propertyName: property.Name,
 				inner: &configurableInner[[]string]{
 					single: singleConfigurable[[]string]{
 						cases: []ConfigurableCase[[]string]{{
-							value: &value,
+							value: v,
 						}},
 					},
 				},
+				postProcessors: &postProcessors,
 			}
 			return reflect.ValueOf(&result), true
 		default:
 			panic("This should be unreachable because ConfigurableElements only accepts slices of strings")
 		}
-	case *parser.Operator:
-		property.Value = v.Value.Eval()
-		return ctx.unpackToConfigurable(propertyName, property, configurableType, configuredType)
-	case *parser.Variable:
-		property.Value = v.Value.Eval()
-		return ctx.unpackToConfigurable(propertyName, property, configurableType, configuredType)
 	case *parser.Select:
 		resultPtr := reflect.New(configurableType)
 		result := resultPtr.Elem()
@@ -448,19 +448,15 @@ func (ctx *unpackContext) unpackToConfigurable(propertyName string, property *pa
 
 		configurableCaseType := configurableCaseType(configuredType)
 		cases := reflect.MakeSlice(reflect.SliceOf(configurableCaseType), 0, len(v.Cases))
-		for i, c := range v.Cases {
-			p := &parser.Property{
-				Name:    property.Name + "[" + strconv.Itoa(i) + "]",
-				NamePos: c.ColonPos,
-				Value:   c.Value,
-			}
-
+		for _, c := range v.Cases {
 			patterns := make([]ConfigurablePattern, len(c.Patterns))
 			for i, pat := range c.Patterns {
-				switch pat := pat.(type) {
+				switch pat := pat.Value.(type) {
 				case *parser.String:
 					if pat.Value == "__soong_conditions_default__" {
 						patterns[i].typ = configurablePatternTypeDefault
+					} else if pat.Value == "__soong_conditions_any__" {
+						patterns[i].typ = configurablePatternTypeAny
 					} else {
 						patterns[i].typ = configurablePatternTypeString
 						patterns[i].stringValue = pat.Value
@@ -471,42 +467,15 @@ func (ctx *unpackContext) unpackToConfigurable(propertyName string, property *pa
 				default:
 					panic("unimplemented")
 				}
-			}
-
-			var value reflect.Value
-			// Map the "unset" keyword to a nil pointer in the cases map
-			if _, ok := c.Value.(parser.UnsetProperty); ok {
-				value = reflect.Zero(reflect.PointerTo(configuredType))
-			} else {
-				var err error
-				switch configuredType.Kind() {
-				case reflect.String, reflect.Bool:
-					value, err = propertyToValue(reflect.PointerTo(configuredType), p)
-					if err != nil {
-						ctx.addError(&UnpackError{
-							err,
-							c.Value.Pos(),
-						})
-						return reflect.New(configurableType), false
-					}
-				case reflect.Slice:
-					if configuredType.Elem().Kind() != reflect.String {
-						panic("This should be unreachable because ConfigurableElements only accepts slices of strings")
-					}
-					value, ok = ctx.unpackToSlice(p.Name, p, reflect.PointerTo(configuredType))
-					if !ok {
-						return reflect.New(configurableType), false
-					}
-				default:
-					panic("This should be unreachable because ConfigurableElements only accepts strings, boools, or slices of strings")
-				}
+				patterns[i].binding = pat.Binding.Name
 			}
 
 			case_ := reflect.New(configurableCaseType)
-			case_.Interface().(configurableCaseReflection).initialize(patterns, value.Interface())
+			case_.Interface().(configurableCaseReflection).initialize(patterns, c.Value)
 			cases = reflect.Append(cases, case_.Elem())
 		}
 		resultPtr.Interface().(configurablePtrReflection).initialize(
+			v.Scope,
 			property.Name,
 			conditions,
 			cases.Interface(),
@@ -537,7 +506,7 @@ func (ctx *unpackContext) unpackToConfigurable(propertyName string, property *pa
 // If the given property is a select, returns an error saying that you can't assign a select to
 // a non-configurable property. Otherwise returns nil.
 func selectOnNonConfigurablePropertyError(property *parser.Property) error {
-	if _, ok := property.Value.Eval().(*parser.Select); !ok {
+	if _, ok := property.Value.(*parser.Select); !ok {
 		return nil
 	}
 
@@ -570,7 +539,7 @@ func (ctx *unpackContext) unpackToSlice(
 // does.
 func (ctx *unpackContext) unpackToSliceInner(
 	sliceName string, property *parser.Property, sliceType reflect.Type) (reflect.Value, bool) {
-	propValueAsList, ok := property.Value.Eval().(*parser.List)
+	propValueAsList, ok := property.Value.(*parser.List)
 	if !ok {
 		if err := selectOnNonConfigurablePropertyError(property); err != nil {
 			ctx.addError(err)
@@ -590,33 +559,24 @@ func (ctx *unpackContext) unpackToSliceInner(
 	}
 
 	// The function to construct an item value depends on the type of list elements.
-	var getItemFunc func(*parser.Property, reflect.Type) (reflect.Value, bool)
-	switch exprs[0].Type() {
-	case parser.BoolType, parser.StringType, parser.Int64Type:
-		getItemFunc = func(property *parser.Property, t reflect.Type) (reflect.Value, bool) {
+	getItemFunc := func(property *parser.Property, t reflect.Type) (reflect.Value, bool) {
+		switch property.Value.(type) {
+		case *parser.Bool, *parser.String, *parser.Int64:
 			value, err := propertyToValue(t, property)
 			if err != nil {
 				ctx.addError(err)
 				return value, false
 			}
 			return value, true
-		}
-	case parser.ListType:
-		getItemFunc = func(property *parser.Property, t reflect.Type) (reflect.Value, bool) {
+		case *parser.List:
 			return ctx.unpackToSlice(property.Name, property, t)
-		}
-	case parser.MapType:
-		getItemFunc = func(property *parser.Property, t reflect.Type) (reflect.Value, bool) {
+		case *parser.Map:
 			itemValue := reflect.New(t).Elem()
 			ctx.unpackToStruct(property.Name, itemValue)
 			return itemValue, true
+		default:
+			panic(fmt.Errorf("bizarre property expression type: %v, %#v", property.Value.Type(), property.Value))
 		}
-	case parser.NotEvaluatedType:
-		getItemFunc = func(property *parser.Property, t reflect.Type) (reflect.Value, bool) {
-			return reflect.New(t), false
-		}
-	default:
-		panic(fmt.Errorf("bizarre property expression type: %v", exprs[0].Type()))
 	}
 
 	itemProperty := &parser.Property{NamePos: property.NamePos, ColonPos: property.ColonPos}
@@ -657,7 +617,7 @@ func propertyToValue(typ reflect.Type, property *parser.Property) (reflect.Value
 
 	switch kind := baseType.Kind(); kind {
 	case reflect.Bool:
-		b, ok := property.Value.Eval().(*parser.Bool)
+		b, ok := property.Value.(*parser.Bool)
 		if !ok {
 			if err := selectOnNonConfigurablePropertyError(property); err != nil {
 				return value, err
@@ -672,7 +632,7 @@ func propertyToValue(typ reflect.Type, property *parser.Property) (reflect.Value
 		value = reflect.ValueOf(b.Value)
 
 	case reflect.Int64:
-		b, ok := property.Value.Eval().(*parser.Int64)
+		b, ok := property.Value.(*parser.Int64)
 		if !ok {
 			return value, &UnpackError{
 				fmt.Errorf("can't assign %s value to int64 property %q",
@@ -683,7 +643,7 @@ func propertyToValue(typ reflect.Type, property *parser.Property) (reflect.Value
 		value = reflect.ValueOf(b.Value)
 
 	case reflect.String:
-		s, ok := property.Value.Eval().(*parser.String)
+		s, ok := property.Value.(*parser.String)
 		if !ok {
 			if err := selectOnNonConfigurablePropertyError(property); err != nil {
 				return value, err

proptools/unpack_test.go

@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"reflect"
 	"testing"
+	"text/scanner"
 
 	"github.com/google/blueprint/parser"
 )
@@ -732,16 +733,21 @@ var validUnpackTestCases = []struct {
 			&struct {
 				Foo Configurable[string]
 			}{
-				Foo: Configurable[string]{
-					propertyName: "foo",
-					inner: &configurableInner[string]{
-						single: singleConfigurable[string]{
-							cases: []ConfigurableCase[string]{{
-								value: StringPtr("bar"),
-							}},
+				Foo: newConfigurableWithPropertyName(
+					"foo",
+					nil,
+					[]ConfigurableCase[string]{{
+						value: &parser.String{
+							LiteralPos: scanner.Position{
+								Offset: 17,
+								Line:   3,
+								Column: 10,
+							},
+							Value: "bar",
 						},
-					},
-				},
+					}},
+					false,
+				),
 			},
 		},
 	},
@@ -756,16 +762,22 @@ var validUnpackTestCases = []struct {
 			&struct {
 				Foo Configurable[bool]
 			}{
-				Foo: Configurable[bool]{
-					propertyName: "foo",
-					inner: &configurableInner[bool]{
-						single: singleConfigurable[bool]{
-							cases: []ConfigurableCase[bool]{{
-								value: BoolPtr(true),
-							}},
+				Foo: newConfigurableWithPropertyName(
+					"foo",
+					nil,
+					[]ConfigurableCase[bool]{{
+						value: &parser.Bool{
+							LiteralPos: scanner.Position{
+								Offset: 17,
+								Line:   3,
+								Column: 10,
+							},
+							Value: true,
+							Token: "true",
 						},
-					},
-				},
+					}},
+					false,
+				),
 			},
 		},
 	},
@@ -780,16 +792,43 @@ var validUnpackTestCases = []struct {
 			&struct {
 				Foo Configurable[[]string]
 			}{
-				Foo: Configurable[[]string]{
-					propertyName: "foo",
-					inner: &configurableInner[[]string]{
-						single: singleConfigurable[[]string]{
-							cases: []ConfigurableCase[[]string]{{
-								value: &[]string{"a", "b"},
-							}},
+				Foo: newConfigurableWithPropertyName(
+					"foo",
+					nil,
+					[]ConfigurableCase[[]string]{{
+						value: &parser.List{
+							LBracePos: scanner.Position{
+								Offset: 17,
+								Line:   3,
+								Column: 10,
+							},
+							RBracePos: scanner.Position{
+								Offset: 26,
+								Line:   3,
+								Column: 19,
+							},
+							Values: []parser.Expression{
+								&parser.String{
+									LiteralPos: scanner.Position{
+										Offset: 18,
+										Line:   3,
+										Column: 11,
+									},
+									Value: "a",
+								},
+								&parser.String{
+									LiteralPos: scanner.Position{
+										Offset: 23,
+										Line:   3,
+										Column: 16,
+									},
+									Value: "b",
+								},
+							},
 						},
-					},
-				},
+					}},
+					false,
+				),
 			},
 		},
 	},
@@ -808,42 +847,60 @@ var validUnpackTestCases = []struct {
 			&struct {
 				Foo Configurable[string]
 			}{
-				Foo: Configurable[string]{
-					propertyName: "foo",
-					inner: &configurableInner[string]{
-						single: singleConfigurable[string]{
-							conditions: []ConfigurableCondition{{
-								functionName: "soong_config_variable",
-								args: []string{
-									"my_namespace",
-									"my_variable",
-								},
+				Foo: newConfigurableWithPropertyName(
+					"foo",
+					[]ConfigurableCondition{{
+						functionName: "soong_config_variable",
+						args: []string{
+							"my_namespace",
+							"my_variable",
+						},
+					}},
+					[]ConfigurableCase[string]{
+						{
+							patterns: []ConfigurablePattern{{
+								typ:         configurablePatternTypeString,
+								stringValue: "a",
 							}},
-							cases: []ConfigurableCase[string]{
-								{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "a",
-									}},
-									value: StringPtr("a2"),
+							value: &parser.String{
+								LiteralPos: scanner.Position{
+									Offset: 90,
+									Line:   4,
+									Column: 11,
 								},
-								{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "b",
-									}},
-									value: StringPtr("b2"),
+								Value: "a2",
+							},
+						},
+						{
+							patterns: []ConfigurablePattern{{
+								typ:         configurablePatternTypeString,
+								stringValue: "b",
+							}},
+							value: &parser.String{
+								LiteralPos: scanner.Position{
+									Offset: 106,
+									Line:   5,
+									Column: 11,
 								},
-								{
-									patterns: []ConfigurablePattern{{
-										typ: configurablePatternTypeDefault,
-									}},
-									value: StringPtr("c2"),
+								Value: "b2",
+							},
+						},
+						{
+							patterns: []ConfigurablePattern{{
+								typ: configurablePatternTypeDefault,
+							}},
+							value: &parser.String{
+								LiteralPos: scanner.Position{
+									Offset: 126,
+									Line:   6,
+									Column: 15,
 								},
+								Value: "c2",
 							},
 						},
 					},
-				},
+					true,
+				),
 			},
 		},
 	},
@@ -866,75 +923,117 @@ var validUnpackTestCases = []struct {
 			&struct {
 				Foo Configurable[string]
 			}{
-				Foo: Configurable[string]{
-					propertyName: "foo",
-					inner: &configurableInner[string]{
-						single: singleConfigurable[string]{
-							conditions: []ConfigurableCondition{{
-								functionName: "soong_config_variable",
-								args: []string{
-									"my_namespace",
-									"my_variable",
-								},
-							}},
-							cases: []ConfigurableCase[string]{
-								{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "a",
-									}},
-									value: StringPtr("a2"),
-								},
-								{
-									patterns: []ConfigurablePattern{{
-										typ:         configurablePatternTypeString,
-										stringValue: "b",
-									}},
-									value: StringPtr("b2"),
-								},
-								{
-									patterns: []ConfigurablePattern{{
-										typ: configurablePatternTypeDefault,
-									}},
-									value: StringPtr("c2"),
-								},
+				Foo: func() Configurable[string] {
+					result := newConfigurableWithPropertyName(
+						"foo",
+						[]ConfigurableCondition{{
+							functionName: "soong_config_variable",
+							args: []string{
+								"my_namespace",
+								"my_variable",
 							},
-						},
-						next: &configurableInner[string]{
-							single: singleConfigurable[string]{
-								conditions: []ConfigurableCondition{{
-									functionName: "soong_config_variable",
-									args: []string{
-										"my_namespace",
-										"my_2nd_variable",
-									},
+						}},
+						[]ConfigurableCase[string]{
+							{
+								patterns: []ConfigurablePattern{{
+									typ:         configurablePatternTypeString,
+									stringValue: "a",
 								}},
-								cases: []ConfigurableCase[string]{
-									{
-										patterns: []ConfigurablePattern{{
-											typ:         configurablePatternTypeString,
-											stringValue: "d",
-										}},
-										value: StringPtr("d2"),
+								value: &parser.String{
+									LiteralPos: scanner.Position{
+										Offset: 90,
+										Line:   4,
+										Column: 11,
 									},
-									{
-										patterns: []ConfigurablePattern{{
-											typ:         configurablePatternTypeString,
-											stringValue: "e",
-										}},
-										value: StringPtr("e2"),
+									Value: "a2",
+								},
+							},
+							{
+								patterns: []ConfigurablePattern{{
+									typ:         configurablePatternTypeString,
+									stringValue: "b",
+								}},
+								value: &parser.String{
+									LiteralPos: scanner.Position{
+										Offset: 106,
+										Line:   5,
+										Column: 11,
 									},
-									{
-										patterns: []ConfigurablePattern{{
-											typ: configurablePatternTypeDefault,
-										}},
-										value: StringPtr("f2"),
+									Value: "b2",
+								},
+							},
+							{
+								patterns: []ConfigurablePattern{{
+									typ: configurablePatternTypeDefault,
+								}},
+								value: &parser.String{
+									LiteralPos: scanner.Position{
+										Offset: 126,
+										Line:   6,
+										Column: 15,
 									},
+									Value: "c2",
 								},
 							},
 						},
-					},
-				},
+						true,
+					)
+					result.Append(newConfigurableWithPropertyName(
+						"",
+						[]ConfigurableCondition{{
+							functionName: "soong_config_variable",
+							args: []string{
+								"my_namespace",
+								"my_2nd_variable",
+							},
+						}},
+						[]ConfigurableCase[string]{
+							{
+								patterns: []ConfigurablePattern{{
+									typ:         configurablePatternTypeString,
+									stringValue: "d",
+								}},
+								value: &parser.String{
+									LiteralPos: scanner.Position{
+										Offset: 218,
+										Line:   8,
+										Column: 11,
+									},
+									Value: "d2",
+								},
+							},
+							{
+								patterns: []ConfigurablePattern{{
+									typ:         configurablePatternTypeString,
+									stringValue: "e",
+								}},
+								value: &parser.String{
+									LiteralPos: scanner.Position{
+										Offset: 234,
+										Line:   9,
+										Column: 11,
+									},
+									Value: "e2",
+								},
+							},
+							{
+								patterns: []ConfigurablePattern{{
+									typ: configurablePatternTypeDefault,
+								}},
+								value: &parser.String{
+									LiteralPos: scanner.Position{
+										Offset: 254,
+										Line:   10,
+										Column: 15,
+									},
+									Value: "f2",
+								},
+							},
+						},
+						true,
+					))
+					return result
+				}(),
 			},
 		},
 	},
@@ -953,26 +1052,37 @@ var validUnpackTestCases = []struct {
 				Foo Configurable[string]
 				Bar Configurable[bool]
 			}{
-				Foo: Configurable[string]{
-					propertyName: "foo",
-					inner: &configurableInner[string]{
-						single: singleConfigurable[string]{
-							cases: []ConfigurableCase[string]{{
-								value: StringPtr("asdf"),
-							}},
+				Foo: newConfigurableWithPropertyName(
+					"foo",
+					nil,
+					[]ConfigurableCase[string]{{
+						value: &parser.String{
+							LiteralPos: scanner.Position{
+								Offset: 25,
+								Line:   2,
+								Column: 25,
+							},
+							Value: "asdf",
 						},
-					},
-				},
-				Bar: Configurable[bool]{
-					propertyName: "bar",
-					inner: &configurableInner[bool]{
-						single: singleConfigurable[bool]{
-							cases: []ConfigurableCase[bool]{{
-								value: BoolPtr(true),
-							}},
+					}},
+					false,
+				),
+				Bar: newConfigurableWithPropertyName(
+					"bar",
+					nil,
+					[]ConfigurableCase[bool]{{
+						value: &parser.Bool{
+							LiteralPos: scanner.Position{
+								Offset: 54,
+								Line:   3,
+								Column: 23,
+							},
+							Value: true,
+							Token: "true",
 						},
-					},
-				},
+					}},
+					false,
+				),
 			},
 		},
 	},