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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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