Added to trunk

[SVN r70067]
2011-03-17 16:41:04 +00:00
parent 3362ca85e6
commit d4983b7afe
53 changed files with 5652 additions and 0 deletions
@@ -0,0 +1,170 @@
+// Copyright David Abrahams 2009. 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)
+
+#include <iostream>
+
+#ifdef NO_MOVE
+# undef BOOST_COPY_ASSIGN_REF
+# define BOOST_COPY_ASSIGN_REF(X) X const&
+# undef BOOST_COPYABLE_AND_MOVABLE
+# define BOOST_COPYABLE_AND_MOVABLE(X)
+# define MOVE(x) (x)
+#else
+#include <boost/move/move.hpp>
+# define MOVE(x) boost::move(x)
+#endif
+
+struct X
+{
+    X() : id(instances++)
+    {
+        std::cout << "X" << id << ": construct\n";
+    }
+    
+    X(X const& rhs) : id(instances++)
+    {
+        std::cout << "X" << id << ": <- " << "X" << rhs.id << ": **copy**\n";
+        ++copies;
+    }
+
+    // This particular test doesn't exercise assignment, but for
+    // completeness:
+    X& operator=(BOOST_COPY_ASSIGN_REF(X) rhs)
+    {
+        std::cout << "X" << id << ": <- " << "X" << rhs.id << ": assign\n";
+        return *this;
+    }
+
+#ifndef NO_MOVE
+    X& operator=(BOOST_RV_REF(X) rhs)
+    {
+        std::cout << "X" << id << ": <- " << "X" << rhs.id << ": move assign\n";
+        return *this;
+    }
+    
+    X(BOOST_RV_REF(X) rhs) : id(instances++)
+    {
+        std::cout << "X" << id << ": <- " << "X" << rhs.id << ": ..move construct..\n";
+        ++copies;
+    }
+#endif 
+
+    ~X() { std::cout << "X" << id << ": destroy\n"; }
+
+    unsigned id;
+    
+    static unsigned copies;
+    static unsigned instances;
+
+    BOOST_COPYABLE_AND_MOVABLE(X)
+};
+
+unsigned X::copies = 0;
+unsigned X::instances = 0;
+
+#define CHECK_COPIES( stmt, min, max, comment )                         \
+{                                                                       \
+    unsigned const old_copies = X::copies;                              \
+                                                                        \
+    std::cout << "\n" comment "\n" #stmt "\n===========\n";             \
+    {                                                                   \
+        stmt;                                                           \
+    }                                                                   \
+    unsigned const n = X::copies - old_copies;                          \
+    if (n > max)                                                        \
+        std::cout << "*** max is too low or compiler is buggy ***\n";   \
+    if (n < min)                                                        \
+        std::cout << "*** min is too high or compiler is buggy ***\n";  \
+                                                                        \
+    std::cout << "-----------\n"                                        \
+              << n << "/" << max                                        \
+              << " possible copies/moves made\n"                        \
+              << max - n << "/" << max - min                            \
+              << " possible elisions performed\n\n";                    \
+                                                                        \
+    if (n > min)                                                        \
+        std::cout << "*** " << n - min                                  \
+                  << " possible elisions missed! ***\n";                \
+}
+
+struct trace
+{
+    trace(char const* name)
+        : name(name)
+    {
+        std::cout << "->: " << name << "\n";
+    }
+    
+    ~trace()
+    {
+        std::cout << "<-: " << name << "\n";
+    }
+    
+    char const* name;
+};
+
+void sink(X a)
+{
+  trace t("sink");
+}
+
+X nrvo_source()
+{
+    trace t("nrvo_source");
+    X a;
+    return a;
+}
+
+X urvo_source()
+{
+    trace t("urvo_source");
+    return X();
+}
+
+X identity(X a)
+{
+    trace t("identity");
+    return a;
+}
+
+X lvalue_;
+X& lvalue()
+{
+    return lvalue_;
+}
+typedef X rvalue;
+
+X ternary( bool y )
+{
+    X a, b;
+    return MOVE(y?a:b);
+}
+
+int main(int argc, char* argv[])
+{
+   (void)argv;
+    // Double parens prevent "most vexing parse"
+    CHECK_COPIES( X a(( lvalue() )), 1, 1, "Direct initialization from lvalue");
+    CHECK_COPIES( X a(( rvalue() )), 0, 1, "Direct initialization from rvalue");
+    
+    CHECK_COPIES( X a = lvalue(), 1, 1, "Copy initialization from lvalue" );
+    CHECK_COPIES( X a = rvalue(), 0, 1, "Copy initialization from rvalue" );
+
+    CHECK_COPIES( sink( lvalue() ), 1, 1, "Pass lvalue by value" );
+    CHECK_COPIES( sink( rvalue() ), 0, 1, "Pass rvalue by value" );
+
+    CHECK_COPIES( nrvo_source(), 0, 1, "Named return value optimization (NRVO)" );
+    CHECK_COPIES( urvo_source(), 0, 1, "Unnamed return value optimization (URVO)" );
+
+    // Just to prove these things compose properly
+    CHECK_COPIES( X a(urvo_source()), 0, 2, "Return value used as ctor arg" );
+    
+    // Expect to miss one possible elision here
+    CHECK_COPIES( identity( rvalue() ), 0, 2, "Return rvalue passed by value" );
+
+    // Expect to miss an elision in at least one of the following lines
+    CHECK_COPIES( X a = ternary( argc == 1000 ), 0, 2, "Return result of ternary operation" );
+    CHECK_COPIES( X a = ternary( argc != 1000 ), 0, 2, "Return result of ternary operation again" );
+    return 0;
+}