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/*=============================================================================
Boost.Wave: A Standard compliant C++ preprocessor library
http://www.boost.org/
Copyright (c) 2001-2011 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)
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