118 lines
2.8 KiB
Go
118 lines
2.8 KiB
Go
// Copyright 2017 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package parser
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import (
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"strings"
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)
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type Scope interface {
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Get(name string) string
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Set(name, value string)
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Call(name string, args []string) []string
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SetFunc(name string, f func([]string) []string)
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}
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type scope struct {
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variables map[string]string
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functions map[string]func([]string) []string
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parent Scope
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}
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func (s *scope) Get(name string) string {
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if val, ok := s.variables[name]; ok {
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return val
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} else if s.parent != nil {
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return s.parent.Get(name)
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} else if val, ok := builtinScope[name]; ok {
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return val
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} else {
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return "<'" + name + "' unset>"
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}
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}
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func (s *scope) Set(name, value string) {
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s.variables[name] = value
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}
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func (s *scope) Call(name string, args []string) []string {
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if f, ok := s.functions[name]; ok {
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return f(args)
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}
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return []string{"<func:'" + name + "' unset>"}
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}
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func (s *scope) SetFunc(name string, f func([]string) []string) {
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s.functions[name] = f
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}
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func NewScope(parent Scope) Scope {
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return &scope{
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variables: make(map[string]string),
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functions: make(map[string]func([]string) []string),
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parent: parent,
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}
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}
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var builtinScope map[string]string
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func init() {
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builtinScope := make(map[string]string)
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builtinScope[builtinDollar] = "$"
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}
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func (v Variable) EvalFunction(scope Scope) ([]string, bool) {
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f := v.Name.SplitN(" \t", 2)
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if len(f) > 1 && f[0].Const() {
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fname := f[0].Value(nil)
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if isFunctionName(fname) {
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args := f[1].Split(",")
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argVals := make([]string, len(args))
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for i, a := range args {
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argVals[i] = a.Value(scope)
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}
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if fname == "call" {
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return scope.Call(argVals[0], argVals[1:]), true
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} else {
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return []string{"__builtin_func:" + fname + " " + strings.Join(argVals, " ")}, true
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}
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}
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}
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return []string{""}, false
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}
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func (v Variable) Value(scope Scope) string {
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if ret, ok := v.EvalFunction(scope); ok {
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if len(ret) > 1 {
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panic("Expected a single value, but instead got a list")
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}
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return ret[0]
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}
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if scope == nil {
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panic("Cannot take the value of a variable in a nil scope")
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}
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return scope.Get(v.Name.Value(scope))
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}
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func toVariable(ms *MakeString) (Variable, bool) {
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if len(ms.Variables) == 1 && ms.Strings[0] == "" && ms.Strings[1] == "" {
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return ms.Variables[0], true
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}
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return Variable{}, false
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}
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