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// 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
}
}
type globalsExpr struct {
}
func (g *globalsExpr) emit(gctx *generationContext) {
gctx.write("g")
}
func (g *globalsExpr) typ() starlarkType {
return starlarkTypeUnknown
}
func (g *globalsExpr) emitListVarCopy(gctx *generationContext) {
g.emit(gctx)
}
func (g *globalsExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
if replacement := transformer(g); replacement != nil {
return replacement
} else {
return g
}
}
// 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 {
for i := range xi.args {
xi.args[i] = xi.args[i].transform(transformer)
}
if replacement := transformer(xi); replacement != nil {
return replacement
} else {
return xi
}
}
type variableRefExpr struct {
ref variable
}
func NewVariableRefExpr(ref variable) starlarkExpr {
if predefined, ok := ref.(*predefinedVariable); ok {
return predefined.value
}
return &variableRefExpr{ref}
}
func (v *variableRefExpr) emit(gctx *generationContext) {
v.ref.emitGet(gctx)
}
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) {
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
}
}
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) {
if cx.object != nil {
gctx.write("(")
cx.object.emit(gctx)
gctx.write(")")
gctx.write(".", cx.name, "(")
} else {
gctx.write(cx.name, "(")
}
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)
}
for i := range cx.args {
cx.args[i] = cx.args[i].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 binaryOpExpr struct {
left, right starlarkExpr
op string
returnType starlarkType
}
func (b *binaryOpExpr) emit(gctx *generationContext) {
b.left.emit(gctx)
gctx.write(" " + b.op + " ")
b.right.emit(gctx)
}
func (b *binaryOpExpr) typ() starlarkType {
return b.returnType
}
func (b *binaryOpExpr) emitListVarCopy(gctx *generationContext) {
b.emit(gctx)
}
func (b *binaryOpExpr) transform(transformer func(expr starlarkExpr) starlarkExpr) starlarkExpr {
b.left = b.left.transform(transformer)
b.right = b.right.transform(transformer)
if replacement := transformer(b); replacement != nil {
return replacement
} else {
return b
}
}
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 (b *badExpr) emitListVarCopy(gctx *generationContext) {
b.emit(gctx)
}
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 == ""
}
func negateExpr(expr starlarkExpr) starlarkExpr {
switch typedExpr := expr.(type) {
case *notExpr:
return typedExpr.expr
case *inExpr:
typedExpr.isNot = !typedExpr.isNot
return typedExpr
case *eqExpr:
typedExpr.isEq = !typedExpr.isEq
return typedExpr
case *binaryOpExpr:
switch typedExpr.op {
case ">":
typedExpr.op = "<="
return typedExpr
case "<":
typedExpr.op = ">="
return typedExpr
case ">=":
typedExpr.op = "<"
return typedExpr
case "<=":
typedExpr.op = ">"
return typedExpr
default:
return &notExpr{expr: expr}
}
default:
return &notExpr{expr: expr}
}
}