Merge pull request #2 from apolukhin/develop

C++11 updates for tribool: added noexcepts and constexprs, fixed warnings

Tested on Linux with gcc-4.9.1.

doc/Jamfile.v2

@@ -1,3 +1,13 @@
+# Tribool library
+
+# Copyright (C) 2002-2003 Douglas Gregor
+
+# 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/
+
 project boost-sandbox/utility/doc ;
 import boostbook ;
 import doxygen ;

doc/tribool.boostbook

@@ -138,6 +138,18 @@ if (<functionname>indeterminate</functionname>(x)) {
 else {
   // report success or failure of x
 }</programlisting>
+
+  <para> All the logical operators and methods of <code><classname>tribool</classname></code> are marked
+  as <code>constexpr</code> in C++11. It means that <code><classname>tribool</classname></code> can
+  be used in compile time expressions:</para>
+
+  <programlisting>constexpr <classname>tribool</classname> x = (tribool(true) || tribool(indeterminate));
+<functionname>static_assert</functionname>(x, "Must be true!");
+</programlisting>
+
+  <note>Some compilers may have troubles with evaluating <code>tribool::operator safe_bool()</code> at compile time.</note>
+
+
 </section>
   
   <section>

include/boost/logic/tribool.hpp

@@ -14,7 +14,7 @@
 #include <boost/config.hpp>
 #include <boost/detail/workaround.hpp>
 
-#if defined(_MSC_VER)
+#ifdef BOOST_HAS_PRAGMA_ONCE
 #  pragma once
 #endif
 
@@ -59,9 +59,9 @@ typedef bool (*indeterminate_keyword_t)(tribool, detail::indeterminate_t);
  * \returns <tt>x.value == tribool::indeterminate_value</tt>
  * \throws nothrow
  */
-inline bool
+BOOST_CONSTEXPR inline bool
 indeterminate(tribool x,
-              detail::indeterminate_t dummy = detail::indeterminate_t());
+              detail::indeterminate_t dummy = detail::indeterminate_t()) BOOST_NOEXCEPT;
 
 /**
  * \brief A 3-state boolean type.
@@ -85,7 +85,7 @@ public:
    *
    * \throws nothrow
    */
-  tribool() : value(false_value) {}
+  BOOST_CONSTEXPR tribool() BOOST_NOEXCEPT : value(false_value) {}
 
   /**
    * Construct a new 3-state boolean value with the given boolean
@@ -93,14 +93,14 @@ public:
    *
    * \throws nothrow
    */
-  tribool(bool initial_value) : value(initial_value? true_value : false_value) {}
+  BOOST_CONSTEXPR tribool(bool initial_value) BOOST_NOEXCEPT : 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) {}
+  BOOST_CONSTEXPR tribool(indeterminate_keyword_t) BOOST_NOEXCEPT : value(indeterminate_value) {}
 
   /**
    * Use a 3-state boolean in a boolean context. Will evaluate true in a
@@ -109,7 +109,7 @@ public:
    * \returns true if the 3-state boolean is true, false otherwise
    * \throws nothrow
    */
-  operator safe_bool() const
+  BOOST_CONSTEXPR operator safe_bool() const BOOST_NOEXCEPT
   {
     return value == true_value? &dummy::nonnull : 0;
   }
@@ -123,7 +123,7 @@ public:
 
 // 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)
+BOOST_CONSTEXPR inline bool indeterminate(tribool x, detail::indeterminate_t) BOOST_NOEXCEPT
 {
   return x.value == tribool::indeterminate_value;
 }
@@ -156,7 +156,7 @@ inline bool indeterminate(tribool x, detail::indeterminate_t)
  *  </table>
  * \throws nothrow
  */
-inline tribool operator!(tribool x)
+BOOST_CONSTEXPR inline tribool operator!(tribool x) BOOST_NOEXCEPT
 {
   return x.value == tribool::false_value? tribool(true)
         :x.value == tribool::true_value? tribool(false)
@@ -196,38 +196,36 @@ inline tribool operator!(tribool x)
  *       </table>
  * \throws nothrow
  */
-inline tribool operator&&(tribool x, tribool y)
+BOOST_CONSTEXPR inline tribool operator&&(tribool x, tribool y) BOOST_NOEXCEPT
 {
-  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;
+  return (static_cast<bool>(!x) || static_cast<bool>(!y))
+    ? tribool(false)
+    : ((static_cast<bool>(x) && static_cast<bool>(y)) ? tribool(true) : indeterminate)
+  ;
 }
 
 /**
  * \overload
  */
-inline tribool operator&&(tribool x, bool y)
+BOOST_CONSTEXPR inline tribool operator&&(tribool x, bool y) BOOST_NOEXCEPT
 { return y? x : tribool(false); }
 
 /**
  * \overload
  */
-inline tribool operator&&(bool x, tribool y)
+BOOST_CONSTEXPR inline tribool operator&&(bool x, tribool y) BOOST_NOEXCEPT
 { return x? y : tribool(false); }
 
 /**
  * \overload
  */
-inline tribool operator&&(indeterminate_keyword_t, tribool x)
+BOOST_CONSTEXPR inline tribool operator&&(indeterminate_keyword_t, tribool x) BOOST_NOEXCEPT
 { return !x? tribool(false) : tribool(indeterminate); }
 
 /**
  * \overload
  */
-inline tribool operator&&(tribool x, indeterminate_keyword_t)
+BOOST_CONSTEXPR inline tribool operator&&(tribool x, indeterminate_keyword_t) BOOST_NOEXCEPT
 { return !x? tribool(false) : tribool(indeterminate); }
 
 /**
@@ -263,38 +261,36 @@ inline tribool operator&&(tribool x, indeterminate_keyword_t)
  *       </table>
  *  \throws nothrow
  */
-inline tribool operator||(tribool x, tribool y)
+BOOST_CONSTEXPR inline tribool operator||(tribool x, tribool y) BOOST_NOEXCEPT
 {
-  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;
+  return (static_cast<bool>(!x) && static_cast<bool>(!y))
+    ? tribool(false)
+    : ((static_cast<bool>(x) || static_cast<bool>(y)) ? tribool(true) : tribool(indeterminate))
+  ;
 }
 
 /**
  * \overload
  */
-inline tribool operator||(tribool x, bool y)
+BOOST_CONSTEXPR inline tribool operator||(tribool x, bool y) BOOST_NOEXCEPT
 { return y? tribool(true) : x; }
 
 /**
  * \overload
  */
-inline tribool operator||(bool x, tribool y)
+BOOST_CONSTEXPR inline tribool operator||(bool x, tribool y) BOOST_NOEXCEPT
 { return x? tribool(true) : y; }
 
 /**
  * \overload
  */
-inline tribool operator||(indeterminate_keyword_t, tribool x)
+BOOST_CONSTEXPR inline tribool operator||(indeterminate_keyword_t, tribool x) BOOST_NOEXCEPT
 { return x? tribool(true) : tribool(indeterminate); }
 
 /**
  * \overload
  */
-inline tribool operator||(tribool x, indeterminate_keyword_t)
+BOOST_CONSTEXPR inline tribool operator||(tribool x, indeterminate_keyword_t) BOOST_NOEXCEPT
 { return x? tribool(true) : tribool(indeterminate); }
 //@}
 
@@ -331,34 +327,34 @@ inline tribool operator||(tribool x, indeterminate_keyword_t)
  *      </table>
  * \throws nothrow
  */
-inline tribool operator==(tribool x, tribool y)
+BOOST_CONSTEXPR inline tribool operator==(tribool x, tribool y) BOOST_NOEXCEPT
 {
-  if (indeterminate(x) || indeterminate(y))
-    return indeterminate;
-  else
-    return (x && y) || (!x && !y);
+  return (indeterminate(x) || indeterminate(y))
+    ? indeterminate
+    : ((x && y) || (!x && !y))
+  ;
 }
 
 /**
  * \overload
  */
-inline tribool operator==(tribool x, bool y) { return x == tribool(y); }
+BOOST_CONSTEXPR inline tribool operator==(tribool x, bool y) BOOST_NOEXCEPT { return x == tribool(y); }
 
 /**
  * \overload
  */
-inline tribool operator==(bool x, tribool y) { return tribool(x) == y; }
+BOOST_CONSTEXPR inline tribool operator==(bool x, tribool y) BOOST_NOEXCEPT { return tribool(x) == y; }
 
 /**
  * \overload
  */
-inline tribool operator==(indeterminate_keyword_t, tribool x)
+BOOST_CONSTEXPR inline tribool operator==(indeterminate_keyword_t, tribool x) BOOST_NOEXCEPT
 { return tribool(indeterminate) == x; }
 
 /**
  * \overload
  */
-inline tribool operator==(tribool x, indeterminate_keyword_t)
+BOOST_CONSTEXPR inline tribool operator==(tribool x, indeterminate_keyword_t) BOOST_NOEXCEPT
 { return tribool(indeterminate) == x; }
 
 /**
@@ -394,34 +390,34 @@ inline tribool operator==(tribool x, indeterminate_keyword_t)
  *       </table>
  * \throws nothrow
  */
-inline tribool operator!=(tribool x, tribool y)
+BOOST_CONSTEXPR inline tribool operator!=(tribool x, tribool y) BOOST_NOEXCEPT
 {
-  if (indeterminate(x) || indeterminate(y))
-    return indeterminate;
-  else
-    return !((x && y) || (!x && !y));
+  return (indeterminate(x) || indeterminate(y))
+    ? indeterminate
+    : !((x && y) || (!x && !y))
+  ;
 }
 
 /**
  * \overload
  */
-inline tribool operator!=(tribool x, bool y) { return x != tribool(y); }
+BOOST_CONSTEXPR inline tribool operator!=(tribool x, bool y) BOOST_NOEXCEPT { return x != tribool(y); }
 
 /**
  * \overload
  */
-inline tribool operator!=(bool x, tribool y) { return tribool(x) != y; }
+BOOST_CONSTEXPR inline tribool operator!=(bool x, tribool y) BOOST_NOEXCEPT { return tribool(x) != y; }
 
 /**
  * \overload
  */
-inline tribool operator!=(indeterminate_keyword_t, tribool x)
+BOOST_CONSTEXPR inline tribool operator!=(indeterminate_keyword_t, tribool x) BOOST_NOEXCEPT
 { return tribool(indeterminate) != x; }
 
 /**
  * \overload
  */
-inline tribool operator!=(tribool x, indeterminate_keyword_t)
+BOOST_CONSTEXPR inline tribool operator!=(tribool x, indeterminate_keyword_t) BOOST_NOEXCEPT
 { return x != tribool(indeterminate); }
 
 } } // end namespace boost::logic

include/boost/logic/tribool_io.hpp

@@ -279,9 +279,9 @@ operator>>(std::basic_istream<CharT, Traits>& in, tribool& x)
       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()) {
+      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;

test/tribool_test.cpp

@@ -114,6 +114,26 @@ int test_main(int, char*[])
     BOOST_CHECK(false);
   }
 
+#ifndef BOOST_NO_CXX11_CONSTEXPR
+  constexpr bool res_ors = indeterminate(false || tribool(false) || false || indeterminate); // true
+  BOOST_CHECK(res_ors);
+  char array_ors[res_ors ? 2 : 3];
+  BOOST_CHECK(sizeof(array_ors) / sizeof(char) == 2);
+
+  constexpr bool res_ands = !indeterminate(!(true && tribool(true) && true && indeterminate)); // false
+  BOOST_CHECK(!res_ands);
+  char array_ands[res_ands ? 2 : 3];
+  BOOST_CHECK(sizeof(array_ands) / sizeof(char) == 3);
+
+  // We avoid checking the tribool::operator safe_bool(),
+  // because GCC-4.8 fails to evaluate it at compile-time.
+  // Clang compiles well.
+  //
+  // constexpr bool res_safe_bool = tribool(true); // false
+  // constexpr tribool xxx = (tribool(true) || tribool(indeterminate));
+  // static_assert(xxx, "Must be true!");
+#endif
+
   std::cout << "no errors detected\n";
   return 0;
 }