Chris@16: /*=============================================================================
Chris@16:     Boost.Wave: A Standard compliant C++ preprocessor library
Chris@16: 
Chris@16:     http://www.boost.org/
Chris@16: 
Chris@16:     Copyright (c) 2001-2012 Hartmut Kaiser. Distributed under the Boost
Chris@16:     Software License, Version 1.0. (See accompanying file
Chris@16:     LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: =============================================================================*/
Chris@16: 
Chris@16: #if !defined(CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED)
Chris@16: #define CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED
Chris@16: 
Chris@16: #include <stack>
Chris@16: #include <boost/wave/wave_config.hpp>
Chris@16: 
Chris@16: // this must occur after all of the includes and before any code appears
Chris@16: #ifdef BOOST_HAS_ABI_HEADERS
Chris@16: #include BOOST_ABI_PREFIX
Chris@16: #endif
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: namespace boost {
Chris@16: namespace wave {
Chris@16: namespace util {
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // the class if_blocks handles recursive conditional compilation contexts
Chris@16: class if_block
Chris@16: {
Chris@16: public:
Chris@16:     if_block() :
Chris@16:         status(true), some_part_status(true), 
Chris@16:         enclosing_status(true), is_in_else(false)
Chris@16:     {
Chris@16:     }
Chris@16:     if_block(bool status_, bool enclosing_status_) : 
Chris@16:         status(status_), 
Chris@16:         some_part_status(status_),
Chris@16:         enclosing_status(enclosing_status_),
Chris@16:         is_in_else(false)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     void set_status(bool status_) 
Chris@16:     { 
Chris@16:         status = status_; 
Chris@16:         if (status_) 
Chris@16:             some_part_status = true; 
Chris@16:     }
Chris@16:     bool get_status() const { return status; }
Chris@16:     bool get_some_part_status() const { return some_part_status; }
Chris@16:     bool get_enclosing_status() const { return enclosing_status; }
Chris@16:     bool get_in_else() const { return is_in_else; }
Chris@16:     void set_in_else() { is_in_else = true; }
Chris@16: 
Chris@16: private:
Chris@16:    bool status;             // Current block is true
Chris@16:    bool some_part_status;   // One of the preceding or current #if/#elif was true
Chris@16:    bool enclosing_status;   // Enclosing #if block is true
Chris@16:    bool is_in_else;         // Inside the #else part
Chris@16: };
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // stack of conditional compilation contexts
Chris@16: class if_block_stack 
Chris@16: :   private std::stack<if_block> 
Chris@16: {
Chris@16: public:
Chris@16:     typedef std::stack<if_block>::size_type size_type;
Chris@16: 
Chris@16:     void enter_if_block(bool new_status)
Chris@16:     {
Chris@16:     // If enclosing block is false, then this block is also false
Chris@16:         bool enclosing_status = get_status();
Chris@16:         this->push (value_type (new_status && enclosing_status, enclosing_status));
Chris@16:     }
Chris@16:     bool enter_elif_block(bool new_status)
Chris@16:     {
Chris@16:         if (!is_inside_ifpart())
Chris@16:             return false;       // #elif without matching #if
Chris@16: 
Chris@16:         if (get_enclosing_status()) {
Chris@16:             if (get_status()) {
Chris@16:             // entered a (false) #elif block from a true block
Chris@16:                 this->top().set_status(false);
Chris@16:             } 
Chris@16:             else if (new_status && !this->top().get_some_part_status()) {
Chris@16:             // Entered true #elif block and no previous block was true
Chris@16:                 this->top().set_status(new_status);
Chris@16:             }
Chris@16:         }
Chris@16:         return true;
Chris@16:     }
Chris@16:     bool enter_else_block()
Chris@16:     {
Chris@16:         if (!is_inside_ifpart())
Chris@16:             return false;       // #else without matching #if
Chris@16: 
Chris@16:         if (get_enclosing_status()) {
Chris@16:             if (!this->top().get_some_part_status()) {
Chris@16:             // Entered (true) #else block and no previous block was true
Chris@16:                 this->top().set_status(true);
Chris@16:             } 
Chris@16:             else if (get_status()) {
Chris@16:             // Entered (false) #else block from true block
Chris@16:                 this->top().set_status(false);
Chris@16:             }
Chris@16: 
Chris@16:         // Set else flag
Chris@16:             this->top().set_in_else();
Chris@16:         }
Chris@16:         return true;
Chris@16:     }
Chris@16:     bool exit_if_block()
Chris@16:     {
Chris@16:         if (0 == this->size())
Chris@16:             return false;   // #endif without matching #if
Chris@16: 
Chris@16:         this->pop();
Chris@16:         return true;
Chris@16:     }
Chris@16: 
Chris@16: // return, whether the top (innermost) condition is true or false
Chris@16:     bool get_status() const
Chris@16:     { 
Chris@16:         return 0 == this->size() || this->top().get_status(); 
Chris@16:     }
Chris@16:     bool get_some_part_status() const
Chris@16:     { 
Chris@16:         return 0 == this->size() || this->top().get_some_part_status(); 
Chris@16:     }
Chris@16:     bool get_enclosing_status() const
Chris@16:     {
Chris@16:         return 0 == this->size() || this->top().get_enclosing_status();
Chris@16:     }
Chris@16: 
Chris@16:     size_type get_if_block_depth() const { return this->size(); }
Chris@16: 
Chris@16: protected:
Chris@16:     bool is_inside_ifpart() const
Chris@16:     {
Chris@16:         return 0 != this->size() && !this->top().get_in_else();
Chris@16:     }
Chris@16:     bool is_inside_elsepart() const
Chris@16:     {
Chris@16:         return 0 != this->size() && this->top().get_in_else();
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: }   // namespace util
Chris@16: }   // namespace wave
Chris@16: }   // namespace boost
Chris@16: 
Chris@16: // the suffix header occurs after all of the code
Chris@16: #ifdef BOOST_HAS_ABI_HEADERS
Chris@16: #include BOOST_ABI_SUFFIX
Chris@16: #endif
Chris@16: 
Chris@16: #endif // !defined(CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED)