Add Validations support to Blueprint

The Android fork of Ninja supports "validations", a node that is
added to the top level of the build graph whenever another node
is in the build graph.  Add support in Blueprint to specify them
on build statements and write them to the ninja.

Test: ninja_writer_test.go
Change-Id: I87cd1281dbd2ed113cc26a265c50d20c65118c91

live_tracker.go

@@ -68,6 +68,11 @@ func (l *liveTracker) AddBuildDefDeps(def *buildDef) error {
 		return err
 	}
 
+	err = l.addNinjaStringListDeps(def.Validations)
+	if err != nil {
+		return err
+	}
+
 	for _, value := range def.Variables {
 		err = l.addNinjaStringDeps(value)
 		if err != nil {

ninja_defs.go

@@ -87,6 +87,7 @@ type BuildParams struct {
 	Inputs          []string          // The list of explicit input dependencies.
 	Implicits       []string          // The list of implicit input dependencies.
 	OrderOnly       []string          // The list of order-only dependencies.
+	Validations     []string          // The list of validations to run when this rule runs.
 	Args            map[string]string // The variable/value pairs to set.
 	Optional        bool              // Skip outputting a default statement
 }
@@ -257,6 +258,7 @@ type buildDef struct {
 	Inputs          []ninjaString
 	Implicits       []ninjaString
 	OrderOnly       []ninjaString
+	Validations     []ninjaString
 	Args            map[Variable]ninjaString
 	Variables       map[string]ninjaString
 	Optional        bool
@@ -314,6 +316,11 @@ func parseBuildParams(scope scope, params *BuildParams) (*buildDef,
 		return nil, fmt.Errorf("error parsing OrderOnly param: %s", err)
 	}
 
+	b.Validations, err = parseNinjaStrings(scope, params.Validations)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing Validations param: %s", err)
+	}
+
 	b.Optional = params.Optional
 
 	if params.Depfile != "" {
@@ -373,6 +380,7 @@ func (b *buildDef) WriteTo(nw *ninjaWriter, pkgNames map[*packageContext]string)
 		explicitDeps  = valueList(b.Inputs, pkgNames, inputEscaper)
 		implicitDeps  = valueList(b.Implicits, pkgNames, inputEscaper)
 		orderOnlyDeps = valueList(b.OrderOnly, pkgNames, inputEscaper)
+		validations   = valueList(b.Validations, pkgNames, inputEscaper)
 	)
 
 	if b.RuleDef != nil {
@@ -380,7 +388,7 @@ func (b *buildDef) WriteTo(nw *ninjaWriter, pkgNames map[*packageContext]string)
 		orderOnlyDeps = append(valueList(b.RuleDef.CommandOrderOnly, pkgNames, inputEscaper), orderOnlyDeps...)
 	}
 
-	err := nw.Build(comment, rule, outputs, implicitOuts, explicitDeps, implicitDeps, orderOnlyDeps)
+	err := nw.Build(comment, rule, outputs, implicitOuts, explicitDeps, implicitDeps, orderOnlyDeps, validations)
 	if err != nil {
 		return err
 	}

ninja_writer.go

@@ -104,7 +104,7 @@ func (n *ninjaWriter) Rule(name string) error {
 }
 
 func (n *ninjaWriter) Build(comment string, rule string, outputs, implicitOuts,
-	explicitDeps, implicitDeps, orderOnlyDeps []string) error {
+	explicitDeps, implicitDeps, orderOnlyDeps, validations []string) error {
 
 	n.justDidBlankLine = false
 
@@ -161,6 +161,14 @@ func (n *ninjaWriter) Build(comment string, rule string, outputs, implicitOuts,
 		}
 	}
 
+	if len(validations) > 0 {
+		wrapper.WriteStringWithSpace("|@")
+
+		for _, dep := range validations {
+			wrapper.WriteStringWithSpace(dep)
+		}
+	}
+
 	return wrapper.Flush()
 }
 

ninja_writer_test.go

@@ -50,9 +50,9 @@ var ninjaWriterTestCases = []struct {
 	{
 		input: func(w *ninjaWriter) {
 			ck(w.Build("foo comment", "foo", []string{"o1", "o2"}, []string{"io1", "io2"},
-				[]string{"e1", "e2"}, []string{"i1", "i2"}, []string{"oo1", "oo2"}))
+				[]string{"e1", "e2"}, []string{"i1", "i2"}, []string{"oo1", "oo2"}, []string{"v1", "v2"}))
 		},
-		output: "# foo comment\nbuild o1 o2 | io1 io2: foo e1 e2 | i1 i2 || oo1 oo2\n",
+		output: "# foo comment\nbuild o1 o2 | io1 io2: foo e1 e2 | i1 i2 || oo1 oo2 |@ v1 v2\n",
 	},
 	{
 		input: func(w *ninjaWriter) {
@@ -94,7 +94,7 @@ var ninjaWriterTestCases = []struct {
 			ck(w.ScopedAssign("command", "echo out: $out in: $in _arg: $_arg"))
 			ck(w.ScopedAssign("pool", "p"))
 			ck(w.BlankLine())
-			ck(w.Build("r comment", "r", []string{"foo.o"}, nil, []string{"foo.in"}, nil, nil))
+			ck(w.Build("r comment", "r", []string{"foo.o"}, nil, []string{"foo.in"}, nil, nil, nil))
 			ck(w.ScopedAssign("_arg", "arg value"))
 		},
 		output: `pool p