| /*============================================================================= |
| Boost.Wave: A Standard compliant C++ preprocessor library |
| |
| http://www.boost.org/ |
| |
| Copyright (c) 2001-2010 Hartmut Kaiser. Distributed under the Boost |
| Software License, Version 1.0. (See accompanying file |
| LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| =============================================================================*/ |
| |
| #if !defined(CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED) |
| #define CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED |
| |
| #include <stack> |
| #include <boost/wave/wave_config.hpp> |
| |
| // this must occur after all of the includes and before any code appears |
| #ifdef BOOST_HAS_ABI_HEADERS |
| #include BOOST_ABI_PREFIX |
| #endif |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| namespace boost { |
| namespace wave { |
| namespace util { |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // the class if_blocks handles recursive conditional compilation contexts |
| class if_block |
| { |
| public: |
| if_block() : |
| status(true), some_part_status(true), |
| enclosing_status(true), is_in_else(false) |
| { |
| } |
| if_block(bool status_, bool enclosing_status_) : |
| status(status_), |
| some_part_status(status_), |
| enclosing_status(enclosing_status_), |
| is_in_else(false) |
| { |
| } |
| |
| void set_status(bool status_) |
| { |
| status = status_; |
| if (status_) |
| some_part_status = true; |
| } |
| bool get_status() const { return status; } |
| bool get_some_part_status() const { return some_part_status; } |
| bool get_enclosing_status() const { return enclosing_status; } |
| bool get_in_else() const { return is_in_else; } |
| void set_in_else() { is_in_else = true; } |
| |
| private: |
| bool status; // Current block is true |
| bool some_part_status; // One of the preceding or current #if/#elif was true |
| bool enclosing_status; // Enclosing #if block is true |
| bool is_in_else; // Inside the #else part |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // stack of conditional compilation contexts |
| class if_block_stack |
| : private std::stack<if_block> |
| { |
| public: |
| typedef std::stack<if_block>::size_type size_type; |
| |
| void enter_if_block(bool new_status) |
| { |
| // If enclosing block is false, then this block is also false |
| bool enclosing_status = get_status(); |
| this->push (value_type (new_status && enclosing_status, enclosing_status)); |
| } |
| bool enter_elif_block(bool new_status) |
| { |
| if (!is_inside_ifpart()) |
| return false; // #elif without matching #if |
| |
| if (get_enclosing_status()) { |
| if (get_status()) { |
| // entered a (false) #elif block from a true block |
| this->top().set_status(false); |
| } |
| else if (new_status && !this->top().get_some_part_status()) { |
| // Entered true #elif block and no previous block was true |
| this->top().set_status(new_status); |
| } |
| } |
| return true; |
| } |
| bool enter_else_block() |
| { |
| if (!is_inside_ifpart()) |
| return false; // #else without matching #if |
| |
| if (get_enclosing_status()) { |
| if (!this->top().get_some_part_status()) { |
| // Entered (true) #else block and no previous block was true |
| this->top().set_status(true); |
| } |
| else if (get_status()) { |
| // Entered (false) #else block from true block |
| this->top().set_status(false); |
| } |
| |
| // Set else flag |
| this->top().set_in_else(); |
| } |
| return true; |
| } |
| bool exit_if_block() |
| { |
| if (0 == this->size()) |
| return false; // #endif without matching #if |
| |
| this->pop(); |
| return true; |
| } |
| |
| // return, whether the top (innermost) condition is true or false |
| bool get_status() const |
| { |
| return 0 == this->size() || this->top().get_status(); |
| } |
| bool get_some_part_status() const |
| { |
| return 0 == this->size() || this->top().get_some_part_status(); |
| } |
| bool get_enclosing_status() const |
| { |
| return 0 == this->size() || this->top().get_enclosing_status(); |
| } |
| |
| size_type get_if_block_depth() const { return this->size(); } |
| |
| protected: |
| bool is_inside_ifpart() const |
| { |
| return 0 != this->size() && !this->top().get_in_else(); |
| } |
| bool is_inside_elsepart() const |
| { |
| return 0 != this->size() && this->top().get_in_else(); |
| } |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| } // namespace util |
| } // namespace wave |
| } // namespace boost |
| |
| // the suffix header occurs after all of the code |
| #ifdef BOOST_HAS_ABI_HEADERS |
| #include BOOST_ABI_SUFFIX |
| #endif |
| |
| #endif // !defined(CPP_IFBLOCK_HPP_D4676B36_00C5_41F4_BC9F_9CBBAE3B8006_INCLUDED) |