github.com/westcoastroms/westcoastroms-build@v0.0.0-20190928114312-2350e5a73030/build/soong/androidmk/parser/scope.go (about)

     1  // Copyright 2017 Google Inc. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package parser
    16  
    17  import (
    18  	"strings"
    19  )
    20  
    21  type Scope interface {
    22  	Get(name string) string
    23  	Set(name, value string)
    24  	Call(name string, args []string) string
    25  	SetFunc(name string, f func([]string) string)
    26  }
    27  
    28  type scope struct {
    29  	variables map[string]string
    30  	functions map[string]func([]string) string
    31  	parent    Scope
    32  }
    33  
    34  func (s *scope) Get(name string) string {
    35  	if val, ok := s.variables[name]; ok {
    36  		return val
    37  	} else if s.parent != nil {
    38  		return s.parent.Get(name)
    39  	} else if val, ok := builtinScope[name]; ok {
    40  		return val
    41  	} else {
    42  		return "<'" + name + "' unset>"
    43  	}
    44  }
    45  
    46  func (s *scope) Set(name, value string) {
    47  	s.variables[name] = value
    48  }
    49  
    50  func (s *scope) Call(name string, args []string) string {
    51  	if f, ok := s.functions[name]; ok {
    52  		return f(args)
    53  	}
    54  
    55  	return "<func:'" + name + "' unset>"
    56  }
    57  
    58  func (s *scope) SetFunc(name string, f func([]string) string) {
    59  	s.functions[name] = f
    60  }
    61  
    62  func NewScope(parent Scope) Scope {
    63  	return &scope{
    64  		variables: make(map[string]string),
    65  		functions: make(map[string]func([]string) string),
    66  		parent:    parent,
    67  	}
    68  }
    69  
    70  var builtinScope map[string]string
    71  
    72  func init() {
    73  	builtinScope := make(map[string]string)
    74  	builtinScope["__builtin_dollar"] = "$"
    75  }
    76  
    77  func (v Variable) EvalFunction(scope Scope) (string, bool) {
    78  	f := v.Name.SplitN(" \t", 2)
    79  	if len(f) > 1 && f[0].Const() {
    80  		fname := f[0].Value(nil)
    81  		if isFunctionName(fname) {
    82  			args := f[1].Split(",")
    83  			argVals := make([]string, len(args))
    84  			for i, a := range args {
    85  				argVals[i] = a.Value(scope)
    86  			}
    87  
    88  			if fname == "call" {
    89  				return scope.Call(argVals[0], argVals[1:]), true
    90  			} else {
    91  				return "__builtin_func:" + fname + " " + strings.Join(argVals, " "), true
    92  			}
    93  		}
    94  	}
    95  
    96  	return "", false
    97  }
    98  
    99  func (v Variable) Value(scope Scope) string {
   100  	if ret, ok := v.EvalFunction(scope); ok {
   101  		return ret
   102  	}
   103  	if scope == nil {
   104  		panic("Cannot take the value of a variable in a nil scope")
   105  	}
   106  	return scope.Get(v.Name.Value(scope))
   107  }
   108  
   109  func toVariable(ms *MakeString) (Variable, bool) {
   110  	if len(ms.Variables) == 1 && ms.Strings[0] == "" && ms.Strings[1] == "" {
   111  		return ms.Variables[0], true
   112  	}
   113  	return Variable{}, false
   114  }