ceph/src/boost/boost/wave/util/cpp_ifblock.hpp

   1 /*=============================================================================
   2     Boost.Wave: A Standard compliant C++ preprocessor library
   3
   4     http://www.boost.org/
   5
   6     Copyright (c) 2001-2012 Hartmut Kaiser. Distributed under the Boost
   7     Software License, Version 1.0. (See accompanying file
   8     LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9 =============================================================================*/
  10
  11 #if !defined(CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED)
  12 #define CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED
  13
  14 #include <stack>
  15 #include <boost/wave/wave_config.hpp>
  16
  17 // this must occur after all of the includes and before any code appears
  18 #ifdef BOOST_HAS_ABI_HEADERS
  19 #include BOOST_ABI_PREFIX
  20 #endif
  21
  22 ///////////////////////////////////////////////////////////////////////////////
  23 namespace boost {
  24 namespace wave {
  25 namespace util {
  26
  27 ///////////////////////////////////////////////////////////////////////////////
  28 // the class if_blocks handles recursive conditional compilation contexts
  29 class if_block
  30 {
  31 public:
  32     if_block() :
  33         status(true), some_part_status(true),
  34         enclosing_status(true), is_in_else(false)
  35     {
  36     }
  37     if_block(bool status_, bool enclosing_status_) :
  38         status(status_),
  39         some_part_status(status_),
  40         enclosing_status(enclosing_status_),
  41         is_in_else(false)
  42     {
  43     }
  44
  45     void set_status(bool status_)
  46     {
  47         status = status_;
  48         if (status_)
  49             some_part_status = true;
  50     }
  51     bool get_status() const { return status; }
  52     bool get_some_part_status() const { return some_part_status; }
  53     bool get_enclosing_status() const { return enclosing_status; }
  54     bool get_in_else() const { return is_in_else; }
  55     void set_in_else() { is_in_else = true; }
  56
  57 private:
  58    bool status;             // Current block is true
  59    bool some_part_status;   // One of the preceding or current #if/#elif was true
  60    bool enclosing_status;   // Enclosing #if block is true
  61    bool is_in_else;         // Inside the #else part
  62 };
  63
  64 ///////////////////////////////////////////////////////////////////////////////
  65 // stack of conditional compilation contexts
  66 class if_block_stack
  67 :   private std::stack<if_block>
  68 {
  69 public:
  70     typedef std::stack<if_block>::size_type size_type;
  71
  72     void enter_if_block(bool new_status)
  73     {
  74     // If enclosing block is false, then this block is also false
  75         bool enclosing_status = get_status();
  76         this->push (value_type (new_status && enclosing_status, enclosing_status));
  77     }
  78     bool enter_elif_block(bool new_status)
  79     {
  80         if (!is_inside_ifpart())
  81             return false;       // #elif without matching #if
  82
  83         if (get_enclosing_status()) {
  84             if (get_status()) {
  85             // entered a (false) #elif block from a true block
  86                 this->top().set_status(false);
  87             }
  88             else if (new_status && !this->top().get_some_part_status()) {
  89             // Entered true #elif block and no previous block was true
  90                 this->top().set_status(new_status);
  91             }
  92         }
  93         return true;
  94     }
  95     bool enter_else_block()
  96     {
  97         if (!is_inside_ifpart())
  98             return false;       // #else without matching #if
  99
 100         if (get_enclosing_status()) {
 101             if (!this->top().get_some_part_status()) {
 102             // Entered (true) #else block and no previous block was true
 103                 this->top().set_status(true);
 104             }
 105             else if (get_status()) {
 106             // Entered (false) #else block from true block
 107                 this->top().set_status(false);
 108             }
 109
 110         // Set else flag
 111             this->top().set_in_else();
 112         }
 113         return true;
 114     }
 115     bool exit_if_block()
 116     {
 117         if (0 == this->size())
 118             return false;   // #endif without matching #if
 119
 120         this->pop();
 121         return true;
 122     }
 123
 124 // return, whether the top (innermost) condition is true or false
 125     bool get_status() const
 126     {
 127         return 0 == this->size() || this->top().get_status();
 128     }
 129     bool get_some_part_status() const
 130     {
 131         return 0 == this->size() || this->top().get_some_part_status();
 132     }
 133     bool get_enclosing_status() const
 134     {
 135         return 0 == this->size() || this->top().get_enclosing_status();
 136     }
 137
 138     size_type get_if_block_depth() const { return this->size(); }
 139
 140 protected:
 141     bool is_inside_ifpart() const
 142     {
 143         return 0 != this->size() && !this->top().get_in_else();
 144     }
 145     bool is_inside_elsepart() const
 146     {
 147         return 0 != this->size() && this->top().get_in_else();
 148     }
 149 };
 150
 151 ///////////////////////////////////////////////////////////////////////////////
 152 }   // namespace util
 153 }   // namespace wave
 154 }   // namespace boost
 155
 156 // the suffix header occurs after all of the code
 157 #ifdef BOOST_HAS_ABI_HEADERS
 158 #include BOOST_ABI_SUFFIX
 159 #endif
 160
 161 #endif // !defined(CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED)