comparison DEPENDENCIES/generic/include/boost/logic/tribool.hpp @ 16:2665513ce2d3

Add boost headers

+// Three-state boolean logic library
+
+// Copyright Douglas 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_HPP
+#define BOOST_LOGIC_TRIBOOL_HPP
+
+#include <boost/logic/tribool_fwd.hpp>
+#include <boost/config.hpp>
+#include <boost/detail/workaround.hpp>
+
+#if BOOST_WORKAROUND(_MSC_VER, >= 1200)
+#  pragma once
+#endif
+
+namespace boost { namespace logic {
+
+/// INTERNAL ONLY
+namespace detail {
+/**
+ * INTERNAL ONLY
+ *
+ * \brief A type used only to uniquely identify the 'indeterminate'
+ * function/keyword.
+ */
+struct indeterminate_t
+{
+#if BOOST_WORKAROUND(__BORLANDC__, < 0x0600)
+  char dummy_; // BCB would use 8 bytes by default
+#endif
+};
+
+} // end namespace detail
+
+/**
+ * INTERNAL ONLY
+ * The type of the 'indeterminate' keyword. This has the same type as the
+ * function 'indeterminate' so that we can recognize when the keyword is
+ * used.
+ */
+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,
+              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)();
+
+public:
+  /**
+   * Construct a new 3-state boolean value with the value 'false'.
+   *
+   * \throws nothrow
+   */
+  tribool() : value(false_value) {}
+
+  /**
+   * Construct a new 3-state boolean value with the given boolean
+   * value, which may be \c true or \c false.
+   *
+   * \throws nothrow
+   */
+  tribool(bool initial_value) : value(initial_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 value_t { 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>&amp;&amp;</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 =                            \
+       boost::logic::detail::indeterminate_t())                         \
+{ return x.value == boost::logic::tribool::indeterminate_value; }
+
+#endif // BOOST_LOGIC_TRIBOOL_HPP
+