forked from boostorg/logic
Initial checkin of tribool library
[SVN r23452]
This commit is contained in:
Douglas Gregor
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460
include/boost/logic/tribool.hpp
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include/boost/logic/tribool.hpp
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// Three-state boolean logic library
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||||
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||||
// Copyright Doug Gregor 2002-2004. Use, modification and
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// distribution is subject to the Boost Software License, Version
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// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// For more information, see http://www.boost.org
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#ifndef BOOST_LOGIC_TRIBOOL_HPP
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#define BOOST_LOGIC_TRIBOOL_HPP
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#include <boost/logic/tribool_fwd.hpp>
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#include <boost/config.hpp>
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#include <boost/detail/workaround.hpp>
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#if BOOST_WORKAROUND(_MSC_VER, >= 1200)
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# pragma once
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#endif
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namespace boost { namespace logic {
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||||
|
||||
/// INTERNAL ONLY
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||||
namespace detail {
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||||
/**
|
||||
* INTERNAL ONLY
|
||||
*
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||||
* \brief A type used only to uniquely identify the 'indeterminate'
|
||||
* function/keyword.
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||||
*/
|
||||
struct indeterminate_t
|
||||
{
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#if BOOST_WORKAROUND(__BORLANDC__, < 0x0600)
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char dummy_; // BCB would use 8 bytes by default
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#endif
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};
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||||
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||||
} // end namespace detail
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||||
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||||
/**
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||||
* INTERNAL ONLY
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||||
* The type of the 'indeterminate' keyword. This has the same type as the
|
||||
* function 'indeterminate' so that we can recognize when the keyword is
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* used.
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*/
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||||
typedef bool (*indeterminate_keyword_t)(tribool, detail::indeterminate_t);
|
||||
|
||||
/**
|
||||
* \brief Keyword and test function for the indeterminate tribool value
|
||||
*
|
||||
* The \c indeterminate function has a dual role. It's first role is
|
||||
* as a unary function that tells whether the tribool value is in the
|
||||
* "indeterminate" state. It's second role is as a keyword
|
||||
* representing the indeterminate (just like "true" and "false"
|
||||
* represent the true and false states). If you do not like the name
|
||||
* "indeterminate", and would prefer to use a different name, see the
|
||||
* macro \c BOOST_TRIBOOL_THIRD_STATE.
|
||||
*
|
||||
* \returns <tt>x.value == tribool::indeterminate_value</tt>
|
||||
* \throws nothrow
|
||||
*/
|
||||
inline bool
|
||||
indeterminate(tribool x,
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detail::indeterminate_t dummy = detail::indeterminate_t());
|
||||
|
||||
/**
|
||||
* \brief A 3-state boolean type.
|
||||
*
|
||||
* 3-state boolean values are either true, false, or
|
||||
* indeterminate.
|
||||
*/
|
||||
class tribool
|
||||
{
|
||||
private:
|
||||
/// INTERNAL ONLY
|
||||
struct dummy {
|
||||
void nonnull() {};
|
||||
};
|
||||
|
||||
typedef void (dummy::*safe_bool)();
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||||
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||||
public:
|
||||
/**
|
||||
* Construct a new 3-state boolean value with the value 'false'.
|
||||
*
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||||
* \throws nothrow
|
||||
*/
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tribool() : value(false_value) {}
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||||
|
||||
/**
|
||||
* Construct a new 3-state boolean value with the given boolean
|
||||
* value, which may be \c true or \c false.
|
||||
*
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||||
* \throws nothrow
|
||||
*/
|
||||
tribool(bool value) : value(value? true_value : false_value) {}
|
||||
|
||||
/**
|
||||
* Construct a new 3-state boolean value with an indeterminate value.
|
||||
*
|
||||
* \throws nothrow
|
||||
*/
|
||||
tribool(indeterminate_keyword_t) : value(indeterminate_value) {}
|
||||
|
||||
/**
|
||||
* Use a 3-state boolean in a boolean context. Will evaluate true in a
|
||||
* boolean context only when the 3-state boolean is definitely true.
|
||||
*
|
||||
* \returns true if the 3-state boolean is true, false otherwise
|
||||
* \throws nothrow
|
||||
*/
|
||||
operator safe_bool() const
|
||||
{
|
||||
return value == true_value? &dummy::nonnull : 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* The actual stored value in this 3-state boolean, which may be false, true,
|
||||
* or indeterminate.
|
||||
*/
|
||||
enum { false_value, true_value, indeterminate_value } value;
|
||||
};
|
||||
|
||||
// Check if the given tribool has an indeterminate value. Also doubles as a
|
||||
// keyword for the 'indeterminate' value
|
||||
inline bool indeterminate(tribool x, detail::indeterminate_t)
|
||||
{
|
||||
return x.value == tribool::indeterminate_value;
|
||||
}
|
||||
|
||||
/** @defgroup logical Logical operations
|
||||
*/
|
||||
//@{
|
||||
/**
|
||||
* \brief Computes the logical negation of a tribool
|
||||
*
|
||||
* \returns the logical negation of the tribool, according to the
|
||||
* table:
|
||||
* <table border=1>
|
||||
* <tr>
|
||||
* <th><center><code>!</code></center></th>
|
||||
* <th/>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>false</center></th>
|
||||
* <td><center>true</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>true</center></th>
|
||||
* <td><center>false</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* </table>
|
||||
* \throws nothrow
|
||||
*/
|
||||
inline tribool operator!(tribool x)
|
||||
{
|
||||
return x.value == tribool::false_value? tribool(true)
|
||||
:x.value == tribool::true_value? tribool(false)
|
||||
:tribool(indeterminate);
|
||||
}
|
||||
|
||||
/**
|
||||
* \brief Computes the logical conjuction of two tribools
|
||||
*
|
||||
* \returns the result of logically ANDing the two tribool values,
|
||||
* according to the following table:
|
||||
* <table border=1>
|
||||
* <tr>
|
||||
* <th><center><code>&&</code></center></th>
|
||||
* <th><center>false</center></th>
|
||||
* <th><center>true</center></th>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>false</center></th>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>false</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>true</center></th>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* </table>
|
||||
* \throws nothrow
|
||||
*/
|
||||
inline tribool operator&&(tribool x, tribool y)
|
||||
{
|
||||
if (static_cast<bool>(!x) || static_cast<bool>(!y))
|
||||
return false;
|
||||
else if (static_cast<bool>(x) && static_cast<bool>(y))
|
||||
return true;
|
||||
else
|
||||
return indeterminate;
|
||||
}
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator&&(tribool x, bool y)
|
||||
{ return y? x : tribool(false); }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator&&(bool x, tribool y)
|
||||
{ return x? y : tribool(false); }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator&&(indeterminate_keyword_t, tribool x)
|
||||
{ return !x? tribool(false) : tribool(indeterminate); }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator&&(tribool x, indeterminate_keyword_t)
|
||||
{ return !x? tribool(false) : tribool(indeterminate); }
|
||||
|
||||
/**
|
||||
* \brief Computes the logical disjunction of two tribools
|
||||
*
|
||||
* \returns the result of logically ORing the two tribool values,
|
||||
* according to the following table:
|
||||
* <table border=1>
|
||||
* <tr>
|
||||
* <th><center><code>||</code></center></th>
|
||||
* <th><center>false</center></th>
|
||||
* <th><center>true</center></th>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>false</center></th>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>true</center></th>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>true</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* </table>
|
||||
* \throws nothrow
|
||||
*/
|
||||
inline tribool operator||(tribool x, tribool y)
|
||||
{
|
||||
if (static_cast<bool>(!x) && static_cast<bool>(!y))
|
||||
return false;
|
||||
else if (static_cast<bool>(x) || static_cast<bool>(y))
|
||||
return true;
|
||||
else
|
||||
return indeterminate;
|
||||
}
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator||(tribool x, bool y)
|
||||
{ return y? tribool(true) : x; }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator||(bool x, tribool y)
|
||||
{ return x? tribool(true) : y; }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator||(indeterminate_keyword_t, tribool x)
|
||||
{ return x? tribool(true) : tribool(indeterminate); }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator||(tribool x, indeterminate_keyword_t)
|
||||
{ return x? tribool(true) : tribool(indeterminate); }
|
||||
//@}
|
||||
|
||||
/**
|
||||
* \brief Compare tribools for equality
|
||||
*
|
||||
* \returns the result of comparing two tribool values, according to
|
||||
* the following table:
|
||||
* <table border=1>
|
||||
* <tr>
|
||||
* <th><center><code>==</code></center></th>
|
||||
* <th><center>false</center></th>
|
||||
* <th><center>true</center></th>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>false</center></th>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>true</center></th>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* </table>
|
||||
* \throws nothrow
|
||||
*/
|
||||
inline tribool operator==(tribool x, tribool y)
|
||||
{
|
||||
if (indeterminate(x) || indeterminate(y))
|
||||
return indeterminate;
|
||||
else
|
||||
return x && y || !x && !y;
|
||||
}
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator==(tribool x, bool y) { return x == tribool(y); }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator==(bool x, tribool y) { return tribool(x) == y; }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator==(indeterminate_keyword_t, tribool x)
|
||||
{ return tribool(indeterminate) == x; }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator==(tribool x, indeterminate_keyword_t)
|
||||
{ return tribool(indeterminate) == x; }
|
||||
|
||||
/**
|
||||
* \brief Compare tribools for inequality
|
||||
*
|
||||
* \returns the result of comparing two tribool values for inequality,
|
||||
* according to the following table:
|
||||
* <table border=1>
|
||||
* <tr>
|
||||
* <th><center><code>!=</code></center></th>
|
||||
* <th><center>false</center></th>
|
||||
* <th><center>true</center></th>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>false</center></th>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>true</center></th>
|
||||
* <td><center>true</center></td>
|
||||
* <td><center>false</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* <tr>
|
||||
* <th><center>indeterminate</center></th>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* <td><center>indeterminate</center></td>
|
||||
* </tr>
|
||||
* </table>
|
||||
* \throws nothrow
|
||||
*/
|
||||
inline tribool operator!=(tribool x, tribool y)
|
||||
{
|
||||
if (indeterminate(x) || indeterminate(y))
|
||||
return indeterminate;
|
||||
else
|
||||
return !(x && y || !x && !y);
|
||||
}
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator!=(tribool x, bool y) { return x != tribool(y); }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator!=(bool x, tribool y) { return tribool(x) != y; }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator!=(indeterminate_keyword_t, tribool x)
|
||||
{ return tribool(indeterminate) != x; }
|
||||
|
||||
/**
|
||||
* \overload
|
||||
*/
|
||||
inline tribool operator!=(tribool x, indeterminate_keyword_t)
|
||||
{ return x != tribool(indeterminate); }
|
||||
|
||||
} } // end namespace boost::logic
|
||||
|
||||
// Pull tribool and indeterminate into namespace "boost"
|
||||
namespace boost {
|
||||
using logic::tribool;
|
||||
using logic::indeterminate;
|
||||
}
|
||||
|
||||
/**
|
||||
* \brief Declare a new name for the third state of a tribool
|
||||
*
|
||||
* Use this macro to declare a new name for the third state of a
|
||||
* tribool. This state can have any number of new names (in addition
|
||||
* to \c indeterminate), all of which will be equivalent. The new name will be
|
||||
* placed in the namespace in which the macro is expanded.
|
||||
*
|
||||
* Example:
|
||||
* BOOST_TRIBOOL_THIRD_STATE(true_or_false)
|
||||
*
|
||||
* tribool x(true_or_false);
|
||||
* // potentially set x
|
||||
* if (true_or_false(x)) {
|
||||
* // don't know what x is
|
||||
* }
|
||||
*/
|
||||
#define BOOST_TRIBOOL_THIRD_STATE(Name) \
|
||||
inline bool \
|
||||
Name(boost::logic::tribool x, \
|
||||
boost::logic::detail::indeterminate_t dummy = \
|
||||
boost::logic::detail::indeterminate_t()) \
|
||||
{ return x.value == boost::logic::tribool::indeterminate_value; }
|
||||
|
||||
#endif // BOOST_LOGIC_TRIBOOL_HPP
|
||||
|
||||
15
include/boost/logic/tribool_fwd.hpp
Normal file
15
include/boost/logic/tribool_fwd.hpp
Normal file
@ -0,0 +1,15 @@
|
||||
// Three-state boolean logic library
|
||||
|
||||
// Copyright Doug Gregor 2002-2004. Use, modification and
|
||||
// distribution is subject to 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)
|
||||
|
||||
|
||||
// For more information, see http://www.boost.org
|
||||
#ifndef BOOST_LOGIC_TRIBOOL_FWD_HPP
|
||||
#define BOOST_LOGIC_TRIBOOL_FWD_HPP
|
||||
|
||||
namespace boost { namespace logic { class tribool; } }
|
||||
|
||||
#endif // BOOST_LOGIC_TRIBOOL_FWD_HPP
|
||||
327
include/boost/logic/tribool_io.hpp
Normal file
327
include/boost/logic/tribool_io.hpp
Normal file
@ -0,0 +1,327 @@
|
||||
// Three-state boolean logic library
|
||||
|
||||
// Copyright Doug Gregor 2002-2003. Use, modification and
|
||||
// distribution is subject to 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)
|
||||
#ifndef BOOST_LOGIC_TRIBOOL_IO_HPP
|
||||
#define BOOST_LOGIC_TRIBOOL_IO_HPP
|
||||
|
||||
#include <boost/logic/tribool.hpp>
|
||||
#include <boost/detail/workaround.hpp>
|
||||
#include <boost/noncopyable.hpp>
|
||||
|
||||
#if BOOST_WORKAROUND(_MSC_VER, >= 1200)
|
||||
# pragma once
|
||||
#endif
|
||||
|
||||
#ifndef BOOST_NO_STD_LOCALE
|
||||
# include <locale>
|
||||
#endif
|
||||
|
||||
#include <string>
|
||||
#include <iostream>
|
||||
|
||||
namespace boost { namespace logic {
|
||||
|
||||
#ifdef BOOST_NO_STD_LOCALE
|
||||
|
||||
/**
|
||||
* \brief Returns a string containing the default name for the \c
|
||||
* false value of a tribool with the given character type T.
|
||||
*
|
||||
* This function only exists when the C++ standard library
|
||||
* implementation does not support locales.
|
||||
*/
|
||||
template<typename T> std::basic_string<T> default_false_name();
|
||||
|
||||
/**
|
||||
* \brief Returns the character string "false".
|
||||
*
|
||||
* This function only exists when the C++ standard library
|
||||
* implementation does not support locales.
|
||||
*/
|
||||
template<>
|
||||
inline std::basic_string<char> default_false_name<char>()
|
||||
{ return "false"; }
|
||||
|
||||
# ifndef BOOST_NO_WCHAR_T
|
||||
/**
|
||||
* \brief Returns the wide character string L"false".
|
||||
*
|
||||
* This function only exists when the C++ standard library
|
||||
* implementation does not support locales.
|
||||
*/
|
||||
template<>
|
||||
inline std::basic_string<wchar_t> default_false_name<wchar_t>()
|
||||
{ return L"false"; }
|
||||
# endif
|
||||
|
||||
/**
|
||||
* \brief Returns a string containing the default name for the \c true
|
||||
* value of a tribool with the given character type T.
|
||||
*
|
||||
* This function only exists when the C++ standard library
|
||||
* implementation does not support locales.
|
||||
*/
|
||||
template<typename T> std::basic_string<T> default_true_name();
|
||||
|
||||
/**
|
||||
* \brief Returns the character string "true".
|
||||
*
|
||||
* This function only exists when the C++ standard library
|
||||
* implementation does not support locales.
|
||||
*/
|
||||
template<>
|
||||
inline std::basic_string<char> default_true_name<char>()
|
||||
{ return "true"; }
|
||||
|
||||
# ifndef BOOST_NO_WCHAR_T
|
||||
/**
|
||||
* \brief Returns the wide character string L"true".
|
||||
*
|
||||
* This function only exists * when the C++ standard library
|
||||
* implementation does not support * locales.
|
||||
*/
|
||||
template<>
|
||||
inline std::basic_string<wchar_t> default_true_name<wchar_t>()
|
||||
{ return L"true"; }
|
||||
# endif
|
||||
#endif
|
||||
|
||||
/**
|
||||
* \brief Returns a string containing the default name for the indeterminate
|
||||
* value of a tribool with the given character type T.
|
||||
*
|
||||
* This routine is used by the input and output streaming operators
|
||||
* for tribool when there is no locale support or the stream's locale
|
||||
* does not contain the indeterminate_name facet.
|
||||
*/
|
||||
template<typename T> std::basic_string<T> get_default_indeterminate_name();
|
||||
|
||||
/// Returns the character string "indeterminate".
|
||||
template<>
|
||||
inline std::basic_string<char> get_default_indeterminate_name<char>()
|
||||
{ return "indeterminate"; }
|
||||
|
||||
#if BOOST_WORKAROUND(BOOST_MSVC, <= 1200)
|
||||
// VC++ 6.0 chokes on the specialization below, so we're stuck without
|
||||
// wchar_t support. What a pain.
|
||||
#else
|
||||
# ifndef BOOST_NO_WCHAR_T
|
||||
/// Returns the wide character string L"indeterminate".
|
||||
template<>
|
||||
inline std::basic_string<wchar_t> get_default_indeterminate_name<wchar_t>()
|
||||
{ return L"indeterminate"; }
|
||||
# endif
|
||||
#endif
|
||||
|
||||
// http://www.cantrip.org/locale.html
|
||||
|
||||
#ifndef BOOST_NO_STD_LOCALE
|
||||
/**
|
||||
* \brief A locale facet specifying the name of the indeterminate
|
||||
* value of a tribool.
|
||||
*
|
||||
* The facet is used to perform I/O on tribool values when \c
|
||||
* std::boolalpha has been specified. This class template is only
|
||||
* available if the C++ standard library implementation supports
|
||||
* locales.
|
||||
*/
|
||||
template<typename CharT>
|
||||
class indeterminate_name : public std::locale::facet, boost::noncopyable
|
||||
{
|
||||
public:
|
||||
typedef CharT char_type;
|
||||
typedef std::basic_string<CharT> string_type;
|
||||
|
||||
/// Construct the facet with the default name
|
||||
indeterminate_name() : name_(get_default_indeterminate_name<CharT>()) {}
|
||||
|
||||
/// Construct the facet with the given name for the indeterminate value
|
||||
explicit indeterminate_name(const string_type& name) : name_(name) {}
|
||||
|
||||
/// Returns the name for the indeterminate value
|
||||
string_type name() const { return name_; }
|
||||
|
||||
/// Uniquily identifies this facet with the locale.
|
||||
static std::locale::id id;
|
||||
|
||||
private:
|
||||
string_type name_;
|
||||
};
|
||||
|
||||
template<typename CharT> std::locale::id indeterminate_name<CharT>::id;
|
||||
#endif
|
||||
|
||||
/**
|
||||
* \brief Writes the value of a tribool to a stream.
|
||||
*
|
||||
* When the value of @p x is either \c true or \c false, this routine
|
||||
* is semantically equivalent to:
|
||||
* \code out << static_cast<bool>(x); \endcode
|
||||
*
|
||||
* When @p x has an indeterminate value, it outputs either the integer
|
||||
* value 2 (if <tt>(out.flags() & std::ios_base::boolalpha) == 0</tt>)
|
||||
* or the name of the indeterminate value. The name of the
|
||||
* indeterminate value comes from the indeterminate_name facet (if it
|
||||
* is defined in the output stream's locale), or from the
|
||||
* get_default_indeterminate_name function (if it is not defined in the
|
||||
* locale or if the C++ standard library implementation does not
|
||||
* support locales).
|
||||
*
|
||||
* \returns @p out
|
||||
*/
|
||||
template<typename CharT, typename Traits>
|
||||
inline std::basic_ostream<CharT, Traits>&
|
||||
operator<<(std::basic_ostream<CharT, Traits>& out, tribool x)
|
||||
{
|
||||
if (!indeterminate(x)) {
|
||||
out << static_cast<bool>(x);
|
||||
} else {
|
||||
typename std::basic_ostream<CharT, Traits>::sentry cerberus(out);
|
||||
if (cerberus) {
|
||||
if (out.flags() & std::ios_base::boolalpha) {
|
||||
#ifndef BOOST_NO_STD_LOCALE
|
||||
if (BOOST_HAS_FACET(indeterminate_name<CharT>, out.getloc())) {
|
||||
const indeterminate_name<CharT>& facet =
|
||||
BOOST_USE_FACET(indeterminate_name<CharT>, out.getloc());
|
||||
out << facet.name();
|
||||
} else {
|
||||
out << get_default_indeterminate_name<CharT>();
|
||||
}
|
||||
#else
|
||||
out << get_default_indeterminate_name<CharT>();
|
||||
#endif
|
||||
}
|
||||
else
|
||||
out << 2;
|
||||
}
|
||||
}
|
||||
return out;
|
||||
}
|
||||
|
||||
/**
|
||||
* \brief Reads a tribool value from a stream.
|
||||
*
|
||||
* When <tt>(out.flags() & std::ios_base::boolalpha) == 0</tt>, this
|
||||
* function reads a \c long value from the input stream @p in and
|
||||
* converts that value to a tribool. If that value is 0, @p x becomes
|
||||
* \c false; if it is 1, @p x becomes \c true; if it is 2, @p becomes
|
||||
* \c indetermine; otherwise, the operation fails (and the fail bit is
|
||||
* set on the input stream @p in).
|
||||
*
|
||||
* When <tt>(out.flags() & std::ios_base::boolalpha) != 0</tt>, this
|
||||
* function first determines the names of the false, true, and
|
||||
* indeterminate values. The false and true names are extracted from
|
||||
* the \c std::numpunct facet of the input stream's locale (if the C++
|
||||
* standard library implementation supports locales), or from the \c
|
||||
* default_false_name and \c default_true_name functions (if there is
|
||||
* no locale support). The indeterminate name is extracted from the
|
||||
* appropriate \c indeterminate_name facet (if it is available in the
|
||||
* input stream's locale), or from the \c get_default_indeterminate_name
|
||||
* function (if the C++ standard library implementation does not
|
||||
* support locales, or the \c indeterminate_name facet is not
|
||||
* specified for this locale object). The input is then matched to
|
||||
* each of these names, and the tribool @p x is assigned the value
|
||||
* corresponding to the longest name that matched. If no name is
|
||||
* matched or all names are empty, the operation fails (and the fail
|
||||
* bit is set on the input stream @p in).
|
||||
*
|
||||
* \returns @p in
|
||||
*/
|
||||
template<typename CharT, typename Traits>
|
||||
inline std::basic_istream<CharT, Traits>&
|
||||
operator>>(std::basic_istream<CharT, Traits>& in, tribool& x)
|
||||
{
|
||||
if (in.flags() & std::ios_base::boolalpha) {
|
||||
typename std::basic_istream<CharT, Traits>::sentry cerberus(in);
|
||||
if (cerberus) {
|
||||
typedef std::basic_string<CharT> string_type;
|
||||
|
||||
#ifndef BOOST_NO_STD_LOCALE
|
||||
const std::numpunct<CharT>& numpunct_facet =
|
||||
BOOST_USE_FACET(std::numpunct<CharT>, in.getloc());
|
||||
|
||||
string_type falsename = numpunct_facet.falsename();
|
||||
string_type truename = numpunct_facet.truename();
|
||||
|
||||
string_type othername;
|
||||
if (BOOST_HAS_FACET(indeterminate_name<CharT>, in.getloc())) {
|
||||
othername =
|
||||
BOOST_USE_FACET(indeterminate_name<CharT>, in.getloc()).name();
|
||||
} else {
|
||||
othername = get_default_indeterminate_name<CharT>();
|
||||
}
|
||||
#else
|
||||
string_type falsename = default_false_name<CharT>();
|
||||
string_type truename = default_true_name<CharT>();
|
||||
string_type othername = get_default_indeterminate_name<CharT>();
|
||||
#endif
|
||||
|
||||
typename string_type::size_type pos = 0;
|
||||
bool falsename_ok = true, truename_ok = true, othername_ok = true;
|
||||
|
||||
// Modeled after the code from Library DR 17
|
||||
while (falsename_ok && pos < falsename.size()
|
||||
|| truename_ok && pos < truename.size()
|
||||
|| othername_ok && pos < othername.size()) {
|
||||
typename Traits::int_type c = in.get();
|
||||
if (c == Traits::eof())
|
||||
return in;
|
||||
|
||||
bool matched = false;
|
||||
if (falsename_ok && pos < falsename.size()) {
|
||||
if (Traits::eq(Traits::to_char_type(c), falsename[pos]))
|
||||
matched = true;
|
||||
else
|
||||
falsename_ok = false;
|
||||
}
|
||||
|
||||
if (truename_ok && pos < truename.size()) {
|
||||
if (Traits::eq(Traits::to_char_type(c), truename[pos]))
|
||||
matched = true;
|
||||
else
|
||||
truename_ok = false;
|
||||
}
|
||||
|
||||
if (othername_ok && pos < othername.size()) {
|
||||
if (Traits::eq(Traits::to_char_type(c), othername[pos]))
|
||||
matched = true;
|
||||
else
|
||||
othername_ok = false;
|
||||
}
|
||||
|
||||
if (matched) { ++pos; }
|
||||
if (pos > falsename.size()) falsename_ok = false;
|
||||
if (pos > truename.size()) truename_ok = false;
|
||||
if (pos > othername.size()) othername_ok = false;
|
||||
}
|
||||
|
||||
if (pos == 0)
|
||||
in.setstate(std::ios_base::failbit);
|
||||
else {
|
||||
if (falsename_ok) x = false;
|
||||
else if (truename_ok) x = true;
|
||||
else if (othername_ok) x = indeterminate;
|
||||
else in.setstate(std::ios_base::failbit);
|
||||
}
|
||||
}
|
||||
} else {
|
||||
long value;
|
||||
if (in >> value) {
|
||||
switch (value) {
|
||||
case 0: x = false; break;
|
||||
case 1: x = true; break;
|
||||
case 2: x = indeterminate; break;
|
||||
default: in.setstate(std::ios_base::failbit); break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return in;
|
||||
}
|
||||
|
||||
} } // end namespace boost::logic
|
||||
|
||||
#endif // BOOST_LOGIC_TRIBOOL_IO_HPP
|
||||
Reference in New Issue
Block a user