xref: /third_party/ninja/src/eval_env.h (revision 695b41ee) 
1// Copyright 2011 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#ifndef NINJA_EVAL_ENV_H_
16#define NINJA_EVAL_ENV_H_
17
18#include <map>
19#include <string>
20#include <vector>
21
22#include "string_piece.h"
23
24struct Rule;
25
26/// An interface for a scope for variable (e.g. "$foo") lookups.
27struct Env {
28  virtual ~Env() {}
29  virtual std::string LookupVariable(const std::string& var) = 0;
30};
31
32/// A tokenized string that contains variable references.
33/// Can be evaluated relative to an Env.
34struct EvalString {
35  /// @return The evaluated string with variable expanded using value found in
36  ///         environment @a env.
37  std::string Evaluate(Env* env) const;
38
39  /// @return The string with variables not expanded.
40  std::string Unparse() const;
41
42  void Clear() { parsed_.clear(); }
43  bool empty() const { return parsed_.empty(); }
44
45  void AddText(StringPiece text);
46  void AddSpecial(StringPiece text);
47
48  /// Construct a human-readable representation of the parsed state,
49  /// for use in tests.
50  std::string Serialize() const;
51
52private:
53  enum TokenType { RAW, SPECIAL };
54  typedef std::vector<std::pair<std::string, TokenType> > TokenList;
55  TokenList parsed_;
56};
57
58/// An invocable build command and associated metadata (description, etc.).
59struct Rule {
60  explicit Rule(const std::string& name) : name_(name) {}
61
62  const std::string& name() const { return name_; }
63
64  void AddBinding(const std::string& key, const EvalString& val);
65
66  static bool IsReservedBinding(const std::string& var);
67
68  const EvalString* GetBinding(const std::string& key) const;
69
70 private:
71  // Allow the parsers to reach into this object and fill out its fields.
72  friend struct ManifestParser;
73
74  std::string name_;
75  typedef std::map<std::string, EvalString> Bindings;
76  Bindings bindings_;
77};
78
79/// An Env which contains a mapping of variables to values
80/// as well as a pointer to a parent scope.
81struct BindingEnv : public Env {
82  BindingEnv() : parent_(NULL) {}
83  explicit BindingEnv(BindingEnv* parent) : parent_(parent) {}
84
85  virtual ~BindingEnv() {}
86  virtual std::string LookupVariable(const std::string& var);
87
88  void AddRule(const Rule* rule);
89  const Rule* LookupRule(const std::string& rule_name);
90  const Rule* LookupRuleCurrentScope(const std::string& rule_name);
91  const std::map<std::string, const Rule*>& GetRules() const;
92
93  void AddBinding(const std::string& key, const std::string& val);
94
95  /// This is tricky.  Edges want lookup scope to go in this order:
96  /// 1) value set on edge itself (edge_->env_)
97  /// 2) value set on rule, with expansion in the edge's scope
98  /// 3) value set on enclosing scope of edge (edge_->env_->parent_)
99  /// This function takes as parameters the necessary info to do (2).
100  std::string LookupWithFallback(const std::string& var, const EvalString* eval,
101                                 Env* env);
102
103private:
104  std::map<std::string, std::string> bindings_;
105  std::map<std::string, const Rule*> rules_;
106  BindingEnv* parent_;
107};
108
109#endif  // NINJA_EVAL_ENV_H_
110