src/eval_env.h


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// Copyright 2011 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.

#ifndef NINJA_EVAL_ENV_H_
#define NINJA_EVAL_ENV_H_

#include <map>
#include <string>
#include <vector>
using namespace std;

// A scope for variable lookups.
struct Env {
  virtual string LookupVariable(const string& var) = 0;
};

// A standard scope, which contains a mapping of variables to values
// as well as a pointer to a parent scope.
struct BindingEnv : public Env {
  BindingEnv() : parent_(NULL) {}
  virtual string LookupVariable(const string& var);
  void AddBinding(const string& key, const string& val);

  map<string, string> bindings_;
  Env* parent_;
};

// A tokenized string that contains variable references.
// Can be evaluated relative to an Env.
struct EvalString {
  bool Parse(const string& input, string* err);
  string Evaluate(Env* env) const;

  const string& unparsed() const { return unparsed_; }
  const bool empty() const { return unparsed_.empty(); }

  string unparsed_;
  enum TokenType { RAW, SPECIAL };
  typedef vector<pair<string, TokenType> > TokenList;
  TokenList parsed_;
};

#endif  // NINJA_EVAL_ENV_H_