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- // Copyright 2017 Google Inc. All rights reserved.
- //
- // 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 parser
- import (
- "strings"
- )
- type Scope interface {
- Get(name string) string
- Set(name, value string)
- Call(name string, args []string) string
- SetFunc(name string, f func([]string) string)
- }
- type scope struct {
- variables map[string]string
- functions map[string]func([]string) string
- parent Scope
- }
- func (s *scope) Get(name string) string {
- if val, ok := s.variables[name]; ok {
- return val
- } else if s.parent != nil {
- return s.parent.Get(name)
- } else if val, ok := builtinScope[name]; ok {
- return val
- } else {
- return "<'" + name + "' unset>"
- }
- }
- func (s *scope) Set(name, value string) {
- s.variables[name] = value
- }
- func (s *scope) Call(name string, args []string) string {
- if f, ok := s.functions[name]; ok {
- return f(args)
- }
- return "<func:'" + name + "' unset>"
- }
- func (s *scope) SetFunc(name string, f func([]string) string) {
- s.functions[name] = f
- }
- func NewScope(parent Scope) Scope {
- return &scope{
- variables: make(map[string]string),
- functions: make(map[string]func([]string) string),
- parent: parent,
- }
- }
- var builtinScope map[string]string
- func init() {
- builtinScope := make(map[string]string)
- builtinScope["__builtin_dollar"] = "$"
- }
- func (v Variable) EvalFunction(scope Scope) (string, bool) {
- f := v.Name.SplitN(" \t", 2)
- if len(f) > 1 && f[0].Const() {
- fname := f[0].Value(nil)
- if isFunctionName(fname) {
- args := f[1].Split(",")
- argVals := make([]string, len(args))
- for i, a := range args {
- argVals[i] = a.Value(scope)
- }
- if fname == "call" {
- return scope.Call(argVals[0], argVals[1:]), true
- } else {
- return "__builtin_func:" + fname + " " + strings.Join(argVals, " "), true
- }
- }
- }
- return "", false
- }
- func (v Variable) Value(scope Scope) string {
- if ret, ok := v.EvalFunction(scope); ok {
- return ret
- }
- if scope == nil {
- panic("Cannot take the value of a variable in a nil scope")
- }
- return scope.Get(v.Name.Value(scope))
- }
- func toVariable(ms *MakeString) (Variable, bool) {
- if len(ms.Variables) == 1 && ms.Strings[0] == "" && ms.Strings[1] == "" {
- return ms.Variables[0], true
- }
- return Variable{}, false
- }
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