github.com/maruel/nin@v0.0.0-20220112143044-f35891e3ce7e/src/eval_env.h (about)

     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  
    24  struct Rule;
    25  
    26  /// An interface for a scope for variable (e.g. "$foo") lookups.
    27  struct 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.
    34  struct 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  
    52  private:
    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.).
    59  struct 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.
    81  struct 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  
   103  private:
   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_