platform_build_soong/mk2rbc/expr.go
Cole Faust fc43868a5f Remove starlarkExpr.Eval()
It was only used to substitute variable references to
predefined variables with the predefined value, which
is an easy condition to directly parse into instead
of having a separate evalutation pass.

Bug: 201700692
Test: go test
Change-Id: I543d20a1d6435bfabd9faa90ffb09af3084ed28c
2021-12-16 13:20:22 -08:00

786 lines
18 KiB
Go

// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package mk2rbc
import (
"fmt"
"strings"
)
// Represents an expression in the Starlark code. An expression has a type.
type starlarkExpr interface {
starlarkNode
typ() starlarkType
// Emit the code to copy the expression, otherwise we will end up
// with source and target pointing to the same list.
emitListVarCopy(gctx *generationContext)
// Return the expression, calling the transformer func for
// every expression in the tree. If the transformer func returns non-nil,
// its result is used in place of the expression it was called with in the
// resulting expression. The resulting starlarkExpr will contain as many
// of the same objects from the original expression as possible.
transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr
}
func maybeString(expr starlarkExpr) (string, bool) {
if x, ok := expr.(*stringLiteralExpr); ok {
return x.literal, true
}
return "", false
}
type stringLiteralExpr struct {
literal string
}
func (s *stringLiteralExpr) emit(gctx *generationContext) {
gctx.writef("%q", s.literal)
}
func (_ *stringLiteralExpr) typ() starlarkType {
return starlarkTypeString
}
func (s *stringLiteralExpr) emitListVarCopy(gctx *generationContext) {
s.emit(gctx)
}
func (s *stringLiteralExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
if replacement := transformer(s); replacement != nil {
return replacement
} else {
return s
}
}
// Integer literal
type intLiteralExpr struct {
literal int
}
func (s *intLiteralExpr) emit(gctx *generationContext) {
gctx.writef("%d", s.literal)
}
func (_ *intLiteralExpr) typ() starlarkType {
return starlarkTypeInt
}
func (s *intLiteralExpr) emitListVarCopy(gctx *generationContext) {
s.emit(gctx)
}
func (s *intLiteralExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
if replacement := transformer(s); replacement != nil {
return replacement
} else {
return s
}
}
// Boolean literal
type boolLiteralExpr struct {
literal bool
}
func (b *boolLiteralExpr) emit(gctx *generationContext) {
if b.literal {
gctx.write("True")
} else {
gctx.write("False")
}
}
func (_ *boolLiteralExpr) typ() starlarkType {
return starlarkTypeBool
}
func (b *boolLiteralExpr) emitListVarCopy(gctx *generationContext) {
b.emit(gctx)
}
func (b *boolLiteralExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
if replacement := transformer(b); replacement != nil {
return replacement
} else {
return b
}
}
// interpolateExpr represents Starlark's interpolation operator <string> % list
// we break <string> into a list of chunks, i.e., "first%second%third" % (X, Y)
// will have chunks = ["first", "second", "third"] and args = [X, Y]
type interpolateExpr struct {
chunks []string // string chunks, separated by '%'
args []starlarkExpr
}
func NewInterpolateExpr(parts []starlarkExpr) starlarkExpr {
result := &interpolateExpr{}
needString := true
for _, part := range parts {
if needString {
if strLit, ok := part.(*stringLiteralExpr); ok {
result.chunks = append(result.chunks, strLit.literal)
} else {
result.chunks = append(result.chunks, "")
}
needString = false
} else {
if strLit, ok := part.(*stringLiteralExpr); ok {
result.chunks[len(result.chunks)-1] += strLit.literal
} else {
result.args = append(result.args, part)
needString = true
}
}
}
if len(result.chunks) == len(result.args) {
result.chunks = append(result.chunks, "")
}
if len(result.args) == 0 {
return &stringLiteralExpr{literal: strings.Join(result.chunks, "")}
}
return result
}
func (xi *interpolateExpr) emit(gctx *generationContext) {
if len(xi.chunks) != len(xi.args)+1 {
panic(fmt.Errorf("malformed interpolateExpr: #chunks(%d) != #args(%d)+1",
len(xi.chunks), len(xi.args)))
}
// Generate format as join of chunks, but first escape '%' in them
format := strings.ReplaceAll(xi.chunks[0], "%", "%%")
for _, chunk := range xi.chunks[1:] {
format += "%s" + strings.ReplaceAll(chunk, "%", "%%")
}
gctx.writef("%q %% ", format)
emitArg := func(arg starlarkExpr) {
if arg.typ() == starlarkTypeList {
gctx.write(`" ".join(`)
arg.emit(gctx)
gctx.write(`)`)
} else {
arg.emit(gctx)
}
}
if len(xi.args) == 1 {
emitArg(xi.args[0])
} else {
sep := "("
for _, arg := range xi.args {
gctx.write(sep)
emitArg(arg)
sep = ", "
}
gctx.write(")")
}
}
func (_ *interpolateExpr) typ() starlarkType {
return starlarkTypeString
}
func (xi *interpolateExpr) emitListVarCopy(gctx *generationContext) {
xi.emit(gctx)
}
func (xi *interpolateExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
argsCopy := make([]starlarkExpr, len(xi.args))
for i, arg := range xi.args {
argsCopy[i] = arg.transform(transformer)
}
xi.args = argsCopy
if replacement := transformer(xi); replacement != nil {
return replacement
} else {
return xi
}
}
type variableRefExpr struct {
ref variable
isDefined bool
}
func NewVariableRefExpr(ref variable, isDefined bool) starlarkExpr {
if predefined, ok := ref.(*predefinedVariable); ok {
return predefined.value
}
return &variableRefExpr{ref, isDefined}
}
func (v *variableRefExpr) emit(gctx *generationContext) {
v.ref.emitGet(gctx, v.isDefined)
}
func (v *variableRefExpr) typ() starlarkType {
return v.ref.valueType()
}
func (v *variableRefExpr) emitListVarCopy(gctx *generationContext) {
v.emit(gctx)
if v.typ() == starlarkTypeList {
gctx.write("[:]") // this will copy the list
}
}
func (v *variableRefExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
if replacement := transformer(v); replacement != nil {
return replacement
} else {
return v
}
}
type toStringExpr struct {
expr starlarkExpr
}
func (s *toStringExpr) emit(ctx *generationContext) {
switch s.expr.typ() {
case starlarkTypeString, starlarkTypeUnknown:
// Assume unknown types are strings already.
s.expr.emit(ctx)
case starlarkTypeList:
ctx.write(`" ".join(`)
s.expr.emit(ctx)
ctx.write(")")
case starlarkTypeInt:
ctx.write(`("%d" % (`)
s.expr.emit(ctx)
ctx.write("))")
case starlarkTypeBool:
ctx.write(`("true" if (`)
s.expr.emit(ctx)
ctx.write(`) else "")`)
case starlarkTypeVoid:
ctx.write(`""`)
default:
panic("Unknown starlark type!")
}
}
func (s *toStringExpr) typ() starlarkType {
return starlarkTypeString
}
func (s *toStringExpr) emitListVarCopy(gctx *generationContext) {
s.emit(gctx)
}
func (s *toStringExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
s.expr = s.expr.transform(transformer)
if replacement := transformer(s); replacement != nil {
return replacement
} else {
return s
}
}
type notExpr struct {
expr starlarkExpr
}
func (n *notExpr) emit(ctx *generationContext) {
ctx.write("not ")
n.expr.emit(ctx)
}
func (_ *notExpr) typ() starlarkType {
return starlarkTypeBool
}
func (n *notExpr) emitListVarCopy(gctx *generationContext) {
n.emit(gctx)
}
func (n *notExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
n.expr = n.expr.transform(transformer)
if replacement := transformer(n); replacement != nil {
return replacement
} else {
return n
}
}
type eqExpr struct {
left, right starlarkExpr
isEq bool // if false, it's !=
}
func (eq *eqExpr) emit(gctx *generationContext) {
var stringOperand string
var otherOperand starlarkExpr
if s, ok := maybeString(eq.left); ok {
stringOperand = s
otherOperand = eq.right
} else if s, ok := maybeString(eq.right); ok {
stringOperand = s
otherOperand = eq.left
}
// If we've identified one of the operands as being a string literal, check
// for some special cases we can do to simplify the resulting expression.
if otherOperand != nil {
if stringOperand == "" {
if eq.isEq {
gctx.write("not ")
}
otherOperand.emit(gctx)
return
}
if stringOperand == "true" && otherOperand.typ() == starlarkTypeBool {
if !eq.isEq {
gctx.write("not ")
}
otherOperand.emit(gctx)
return
}
}
if eq.left.typ() != eq.right.typ() {
eq.left = &toStringExpr{expr: eq.left}
eq.right = &toStringExpr{expr: eq.right}
}
// General case
eq.left.emit(gctx)
if eq.isEq {
gctx.write(" == ")
} else {
gctx.write(" != ")
}
eq.right.emit(gctx)
}
func (_ *eqExpr) typ() starlarkType {
return starlarkTypeBool
}
func (eq *eqExpr) emitListVarCopy(gctx *generationContext) {
eq.emit(gctx)
}
func (eq *eqExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
eq.left = eq.left.transform(transformer)
eq.right = eq.right.transform(transformer)
if replacement := transformer(eq); replacement != nil {
return replacement
} else {
return eq
}
}
// variableDefinedExpr corresponds to Make's ifdef VAR
type variableDefinedExpr struct {
v variable
}
func (v *variableDefinedExpr) emit(gctx *generationContext) {
if v.v != nil {
v.v.emitDefined(gctx)
return
}
gctx.writef("%s(%q)", cfnWarning, "TODO(VAR)")
}
func (_ *variableDefinedExpr) typ() starlarkType {
return starlarkTypeBool
}
func (v *variableDefinedExpr) emitListVarCopy(gctx *generationContext) {
v.emit(gctx)
}
func (v *variableDefinedExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
// TODO: VariableDefinedExpr isn't really an expression?
return v
}
type listExpr struct {
items []starlarkExpr
}
func (l *listExpr) emit(gctx *generationContext) {
if !gctx.inAssignment || len(l.items) < 2 {
gctx.write("[")
sep := ""
for _, item := range l.items {
gctx.write(sep)
item.emit(gctx)
sep = ", "
}
gctx.write("]")
return
}
gctx.write("[")
gctx.indentLevel += 2
for _, item := range l.items {
gctx.newLine()
item.emit(gctx)
gctx.write(",")
}
gctx.indentLevel -= 2
gctx.newLine()
gctx.write("]")
}
func (_ *listExpr) typ() starlarkType {
return starlarkTypeList
}
func (l *listExpr) emitListVarCopy(gctx *generationContext) {
l.emit(gctx)
}
func (l *listExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
itemsCopy := make([]starlarkExpr, len(l.items))
for i, item := range l.items {
itemsCopy[i] = item.transform(transformer)
}
l.items = itemsCopy
if replacement := transformer(l); replacement != nil {
return replacement
} else {
return l
}
}
func newStringListExpr(items []string) *listExpr {
v := listExpr{}
for _, item := range items {
v.items = append(v.items, &stringLiteralExpr{item})
}
return &v
}
// concatExpr generates expr1 + expr2 + ... + exprN in Starlark.
type concatExpr struct {
items []starlarkExpr
}
func (c *concatExpr) emit(gctx *generationContext) {
if len(c.items) == 1 {
c.items[0].emit(gctx)
return
}
if !gctx.inAssignment {
c.items[0].emit(gctx)
for _, item := range c.items[1:] {
gctx.write(" + ")
item.emit(gctx)
}
return
}
gctx.write("(")
c.items[0].emit(gctx)
gctx.indentLevel += 2
for _, item := range c.items[1:] {
gctx.write(" +")
gctx.newLine()
item.emit(gctx)
}
gctx.write(")")
gctx.indentLevel -= 2
}
func (_ *concatExpr) typ() starlarkType {
return starlarkTypeList
}
func (c *concatExpr) emitListVarCopy(gctx *generationContext) {
c.emit(gctx)
}
func (c *concatExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
itemsCopy := make([]starlarkExpr, len(c.items))
for i, item := range c.items {
itemsCopy[i] = item.transform(transformer)
}
c.items = itemsCopy
if replacement := transformer(c); replacement != nil {
return replacement
} else {
return c
}
}
// inExpr generates <expr> [not] in <list>
type inExpr struct {
expr starlarkExpr
list starlarkExpr
isNot bool
}
func (i *inExpr) emit(gctx *generationContext) {
i.expr.emit(gctx)
if i.isNot {
gctx.write(" not in ")
} else {
gctx.write(" in ")
}
i.list.emit(gctx)
}
func (_ *inExpr) typ() starlarkType {
return starlarkTypeBool
}
func (i *inExpr) emitListVarCopy(gctx *generationContext) {
i.emit(gctx)
}
func (i *inExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
i.expr = i.expr.transform(transformer)
i.list = i.list.transform(transformer)
if replacement := transformer(i); replacement != nil {
return replacement
} else {
return i
}
}
type indexExpr struct {
array starlarkExpr
index starlarkExpr
}
func (ix *indexExpr) emit(gctx *generationContext) {
ix.array.emit(gctx)
gctx.write("[")
ix.index.emit(gctx)
gctx.write("]")
}
func (ix *indexExpr) typ() starlarkType {
return starlarkTypeString
}
func (ix *indexExpr) emitListVarCopy(gctx *generationContext) {
ix.emit(gctx)
}
func (ix *indexExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
ix.array = ix.array.transform(transformer)
ix.index = ix.index.transform(transformer)
if replacement := transformer(ix); replacement != nil {
return replacement
} else {
return ix
}
}
type callExpr struct {
object starlarkExpr // nil if static call
name string
args []starlarkExpr
returnType starlarkType
}
func (cx *callExpr) emit(gctx *generationContext) {
sep := ""
if cx.object != nil {
gctx.write("(")
cx.object.emit(gctx)
gctx.write(")")
gctx.write(".", cx.name, "(")
} else {
kf, found := knownFunctions[cx.name]
if !found {
panic(fmt.Errorf("callExpr with unknown function %q", cx.name))
}
if kf.runtimeName[0] == '!' {
panic(fmt.Errorf("callExpr for %q should not be there", cx.name))
}
gctx.write(kf.runtimeName, "(")
if kf.hiddenArg == hiddenArgGlobal {
gctx.write("g")
sep = ", "
} else if kf.hiddenArg == hiddenArgConfig {
gctx.write("cfg")
sep = ", "
}
}
for _, arg := range cx.args {
gctx.write(sep)
arg.emit(gctx)
sep = ", "
}
gctx.write(")")
}
func (cx *callExpr) typ() starlarkType {
return cx.returnType
}
func (cx *callExpr) emitListVarCopy(gctx *generationContext) {
cx.emit(gctx)
}
func (cx *callExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
if cx.object != nil {
cx.object = cx.object.transform(transformer)
}
argsCopy := make([]starlarkExpr, len(cx.args))
for i, arg := range cx.args {
argsCopy[i] = arg.transform(transformer)
}
if replacement := transformer(cx); replacement != nil {
return replacement
} else {
return cx
}
}
type ifExpr struct {
condition starlarkExpr
ifTrue starlarkExpr
ifFalse starlarkExpr
}
func (i *ifExpr) emit(gctx *generationContext) {
gctx.write("(")
i.ifTrue.emit(gctx)
gctx.write(" if ")
i.condition.emit(gctx)
gctx.write(" else ")
i.ifFalse.emit(gctx)
gctx.write(")")
}
func (i *ifExpr) typ() starlarkType {
tType := i.ifTrue.typ()
fType := i.ifFalse.typ()
if tType != fType && tType != starlarkTypeUnknown && fType != starlarkTypeUnknown {
panic("Conflicting types in if expression")
}
if tType != starlarkTypeUnknown {
return tType
} else {
return fType
}
}
func (i *ifExpr) emitListVarCopy(gctx *generationContext) {
i.emit(gctx)
}
func (i *ifExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
i.condition = i.condition.transform(transformer)
i.ifTrue = i.ifTrue.transform(transformer)
i.ifFalse = i.ifFalse.transform(transformer)
if replacement := transformer(i); replacement != nil {
return replacement
} else {
return i
}
}
type identifierExpr struct {
name string
}
func (i *identifierExpr) emit(gctx *generationContext) {
gctx.write(i.name)
}
func (i *identifierExpr) typ() starlarkType {
return starlarkTypeUnknown
}
func (i *identifierExpr) emitListVarCopy(gctx *generationContext) {
i.emit(gctx)
}
func (i *identifierExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
if replacement := transformer(i); replacement != nil {
return replacement
} else {
return i
}
}
type foreachExpr struct {
varName string
list starlarkExpr
action starlarkExpr
}
func (f *foreachExpr) emit(gctx *generationContext) {
gctx.write("[")
f.action.emit(gctx)
gctx.write(" for " + f.varName + " in ")
f.list.emit(gctx)
gctx.write("]")
}
func (f *foreachExpr) typ() starlarkType {
return starlarkTypeList
}
func (f *foreachExpr) emitListVarCopy(gctx *generationContext) {
f.emit(gctx)
}
func (f *foreachExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
f.list = f.list.transform(transformer)
f.action = f.action.transform(transformer)
if replacement := transformer(f); replacement != nil {
return replacement
} else {
return f
}
}
type badExpr struct {
errorLocation ErrorLocation
message string
}
func (b *badExpr) emit(gctx *generationContext) {
gctx.emitConversionError(b.errorLocation, b.message)
}
func (_ *badExpr) typ() starlarkType {
return starlarkTypeUnknown
}
func (_ *badExpr) emitListVarCopy(_ *generationContext) {
panic("implement me")
}
func (b *badExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
if replacement := transformer(b); replacement != nil {
return replacement
} else {
return b
}
}
func maybeConvertToStringList(expr starlarkExpr) starlarkExpr {
if xString, ok := expr.(*stringLiteralExpr); ok {
return newStringListExpr(strings.Fields(xString.literal))
}
return expr
}
func isEmptyString(expr starlarkExpr) bool {
x, ok := expr.(*stringLiteralExpr)
return ok && x.literal == ""
}