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libsigcplusplus/tests/test_cpp11_lambda.cc

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/* Copyright (C) 2012 The libsigc++ Development Team
*
* This file is part of libsigc++.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
// The purpose of this test case is threefold.
// - Test that C++11 lambda expressions can be used in connection with sigc::slot
// and sigc::signal.
// - Show that libsigc++ lambda expressions can be replaced by C++11 lambda
// expressions. It's shown here as a preparation for deprecating and eventually
// deleting the libsigc++ lambda expressions.
// See https://bugzilla.gnome.org/show_bug.cgi?id=672555
// - Test the code examples in the documentation in sigc++/adaptors/lambda/base.h
// and sigc++/adaptors/lambda/group.h.
//
// At present (August 2012) this test case contains approximately the same tests
// as test_lambda.cc, but with libsigc++ lambda expressions replaced by C++11
// lambda expressions, where possible.
// The only real disadvantage of the C++11 lambda expressions is that a slot that
// contains an object derived from sigc::trackable is not automatically disconnected
// when the object is deleted, if a reference to the object is stored in a C++11
// lambda expression, connected to the slot. But if you use sigc::track_obj(),
// the slot is automatically disconnected. Thus, the disadvantage is insignificant.
//
// To test the C++11 lambda expressions with gcc 4.6.3 (and probably some later
// versions of gcc; gcc 4.7.x also understands -std=c++11):
// make CXXFLAGS='-g -O2 -std=c++0x' test_cpp11_lambda
// ./test_cpp11_lambda
// echo $?
// If test_cpp11_lambda writes nothing and the return code is 0, the test has passed.
#include "testutilities.h"
#include <string>
#include <iostream>
#include <sstream>
#include <functional>
#include <cstdlib>
#include <sigc++/functors/functors.h>
#include <sigc++/bind.h>
#include <sigc++/reference_wrapper.h>
#include <sigc++/adaptors/track_obj.h>
#include <sigc++/signal.h>
namespace
{
std::ostringstream result_stream;
int foo(int i, int j)
{
result_stream << "foo(int " << i << ", int " << j << ") ";
return 4*i + j;
}
void foo_void(int i)
{
result_stream << "foo_void(int " << i << ")";
}
struct bar
{
int test(int i, int j)
{
result_stream << "bar::test(int " << i << ", int " << j << ") ";
return 4*i + j;
}
void test_void(int i)
{
result_stream << "bar::test_void(int " << i << ")";
}
};
void egon(std::string& str)
{
result_stream << "egon(string '" << str << "')";
str = "egon was here";
}
struct book : public sigc::trackable
{
explicit book(const std::string& name) : name_(name) {}
operator std::string& () { return name_; }
std::string name_;
};
inline std::ostringstream& operator << (std::ostringstream& s, const book& b)
{
s << b.name_;
return s;
}
void foo_group1(int i, int j)
{
result_stream << "foo_group1(int " << i << ", int " << j << ")";
}
int bar_group1(int i)
{
result_stream << "bar_group1(int " << i << ") ";
return i + 2;
}
void foo_group2(int i)
{
result_stream << "foo_group2(int " << i << ")";
}
void foo_group3(int& i)
{
result_stream << "foo_group3(int " << i << ")";
++i;
}
struct bar_group4 : public sigc::trackable
{
};
void foo_group4(bar_group4&)
{
result_stream << "foo_group4(bar_group4&)";
}
} // end anonymous namespace
int main(int argc, char* argv[])
{
auto util = TestUtilities::get_instance();
if (!util->check_command_args(argc, argv))
return util->get_result_and_delete_instance() ? EXIT_SUCCESS : EXIT_FAILURE;
// test lambda operators
//std::cout << "(_1 + _2) (3,4): " << (_1 + _2) (3,4) << std::endl;
result_stream << ([] (int a, int b) -> int { return a + b; }(3,4));
util->check_result(result_stream, "7");
//std::cout << "(_1 + 1) (3,4): " << (_1 + 1) (3,4) << std::endl;
result_stream << ([] (int a, int) -> int { return a + 1; }(3,4));
util->check_result(result_stream, "4");
//std::cout << "(_2 + 1) (3,4): " << (_2 + 1) (3,4) << std::endl;
result_stream << ([] (int, int b) -> int { return b + 1; }(3,4));
util->check_result(result_stream, "5");
//std::cout << "(2 + _1) (3,4): " << (2 + _1) (3,4) << std::endl;
result_stream << ([] (int a, int) -> int { return 2 + a; }(3,4));
util->check_result(result_stream, "5");
//std::cout << "(2 + _2) (3,4): " << (2 + _2) (3,4) << std::endl;
result_stream << ([] (int, int b) -> int { return 2 + b; }(3,4));
util->check_result(result_stream, "6");
//std::cout << "(_1+_2*_3)(1,2,3): " << (_1+_2*_3)(1,2,3) << std::endl;
result_stream << ([] (int a, int b, int c) -> int { return a + b*c; }(1,2,3));
util->check_result(result_stream, "7");
//std::cout << "((++_1)*2)(1): " << ((++_1)*2)(1) << std::endl;
result_stream << ([] (int a) -> int { return ++a * 2; }(1));
util->check_result(result_stream, "4");
//std::cout << "((++_1)*2)(a): " << ((++_1)*2)(a);
//std::cout << "; a: " << a << std::endl;
int a_outer = 1;
result_stream << ([] (int x) -> int { return ++x * 2; }(a_outer)) << " " << a_outer;
util->check_result(result_stream, "4 1");
// gcc can't compile libsigc++ lambda expressions with std::ref() parameters.
// See https://bugzilla.gnome.org/show_bug.cgi?id=669128
// std::cout << "((++_1)*2)(ref(a)): " << ((++_1)*2)(std::ref(a));
// std::cout << "; a: " << a << std::endl;
result_stream << ([] (std::reference_wrapper<int> x) -> int { return ++x * 2; }(std::ref(a_outer)));
result_stream << " " << a_outer;
util->check_result(result_stream, "4 2");
result_stream << ([] (int& x) -> int { return ++x * 2; }(a_outer));
result_stream << " " << a_outer;
util->check_result(result_stream, "6 3");
//std::cout << "((++(*_1))*2)(&a): " << ((++(*_1))*2)(&a);
//std::cout << "; a: " << a << std::endl;
result_stream << ([] (int* x) -> int { return ++(*x) * 2; }(&a_outer));
result_stream << " " << a_outer;
util->check_result(result_stream, "8 4");
// std::cout << "((--(*(&_1)))*2)(ref(a)): " << ((--(*(&_1)))*2)(std::ref(a));
// std::cout << "; a: " << a << std::endl;
result_stream << ([] (std::reference_wrapper<int> x) -> int { return --(*(&x)) * 2; }(std::ref(a_outer)));
result_stream << " " << a_outer;
util->check_result(result_stream, "6 3");
result_stream << ([] (int& x) -> int { return --(*(&x)) * 2; }(a_outer));
result_stream << " " << a_outer;
util->check_result(result_stream, "4 2");
//std::cout << "(-_1) (-5): " << (-_1) (-5) << std::endl;
result_stream << ([] (int x) -> int { return -x; }(-5));
util->check_result(result_stream, "5");
//std::cout << "(var(&a)[0])(): " << (sigc::var(&a)[0])() << std::endl;
result_stream << ([&a_outer]() -> int { return a_outer; }());
util->check_result(result_stream, "2");
//std::cout << "(_1[_2]) (&a,0): " << (_1[_2]) (&a,0) << std::endl;
result_stream << ([] (int* x, int y) -> int { return x[y]; }(&a_outer,0));
util->check_result(result_stream, "2");
//std::cout << "(*_1=_2) (&a,1): " << (*_1=_2) (&a,1) << std::endl;
result_stream << ([] (int* x, int y) -> int { *x = y; return *x; }(&a_outer,1));
util->check_result(result_stream, "1");
// Comma operator, https://bugzilla.gnome.org/show_bug.cgi?id=342911
a_outer = -1;
int b_outer = -1;
int c_outer = -1;
//std::cout << "(var(c) = (var(a) = _1, var(b) = _2))(2,3): "
// << (sigc::var(c) = (sigc::var(a) = _1, sigc::var(b) = _2))(2,3);
//std::cout << "; a: " << a << "; b: " << b << "; c: " << c << std::endl;
result_stream << ([&a_outer,&b_outer,&c_outer](int x, int y) -> int { return c_outer = (a_outer = x, b_outer = y); }(2,3));
result_stream << " " << a_outer << " " << b_outer << " " << c_outer;
util->check_result(result_stream, "3 2 3 3");
// c++ restrictions:
// - ref() must be used to indicate that the value shall not be copied
// - constant() is used to create a lambda and delay execution of "std::cout << 1"
// - var() is used to create a lambda that holds a reference and is interchangable with ref() in lambda operator expressions
// - cannot use std::endl without much hackery because it is defined as a template function
// - cannot use "\n" without var() because arrays cannot be copied
// (std::ref(std::cout) << sigc::constant(1) << sigc::var("\n"))();
[](){ result_stream << 1 << "\n"; }();
util->check_result(result_stream, "1\n");
//(std::ref(std::cout) << _1 << std::string("\n"))("hello world");
[](const char* a){ result_stream << a << std::string("\n"); }("hello world");
util->check_result(result_stream, "hello world\n");
//(std::ref(std::cout) << sigc::static_cast_<int>(_1) << std::string("\n"))(1.234);
[](double a){ result_stream << static_cast<int>(a) << std::string("\n"); }(1.234);
util->check_result(result_stream, "1\n");
// (sigc::var(std::cout) << 1 << sigc::var("\n"))();
[](){ result_stream << 1 << "\n"; }();
util->check_result(result_stream, "1\n");
//(sigc::var(std::cout) << _1 << std::string("\n"))("hello world");
[](const char* a){ result_stream << a << std::string("\n"); }("hello world");
util->check_result(result_stream, "hello world\n");
// auto-disconnect
// Here's an area where the libsigc++ lambda expressions are advantageous.
// If you want to auto-disconnect a slot with a C++11 lambda expression
// that contains references to sigc::trackable-derived objects, you must use
// sigc::track_obj().
sigc::slot<void, std::ostringstream&> sl1;
{
book guest_book("karl");
//sl1 = (sigc::var(std::cout) << std::ref(guest_book) << sigc::var("\n"));
// sl1 = [&guest_book](std::ostringstream& stream){ stream << guest_book << "\n"; }; // no auto-disconnect
sl1 = sigc::track_obj([&guest_book](std::ostringstream& stream){ stream << guest_book << "\n"; }, guest_book);
sl1(result_stream);
util->check_result(result_stream, "karl\n");
} // auto-disconnect
sl1(result_stream);
util->check_result(result_stream, "");
// test group adaptor, here replaced by std::bind
bar the_bar;
//std::cout << (sigc::group(&foo, _1, _2)) (1, 2) << std::endl;
result_stream << std::bind(&foo, std::placeholders::_1, std::placeholders::_2)(1, 2);
util->check_result(result_stream, "foo(int 1, int 2) 6");
//std::cout << (sigc::group(&foo, _2, _1)) (1, 2) << std::endl;
result_stream << std::bind(&foo, std::placeholders::_2, std::placeholders::_1)(1, 2);
util->check_result(result_stream, "foo(int 2, int 1) 9");
//std::cout << (sigc::group(sigc::mem_fun(&bar::test), _1, _2, _3)) (std::ref(the_bar), 1, 2) << std::endl;
// std::ref(the_bar) is not necessary. It can make the call ambiguous.
// Even without std::ref() the_bar is not copied.
result_stream << std::bind(std::mem_fn(&bar::test), std::placeholders::_1,
std::placeholders::_2, std::placeholders::_3)(the_bar, 1, 2);
util->check_result(result_stream, "bar::test(int 1, int 2) 6");
// same functionality as bind
//std::cout << (sigc::group(&foo, _1, 2)) (1) << std::endl;
result_stream << std::bind(&foo, std::placeholders::_1, 2)(1);
util->check_result(result_stream, "foo(int 1, int 2) 6");
//std::cout << (sigc::group(&foo, 1, 2)) () << std::endl;
result_stream << std::bind(&foo, 1, 2)();
util->check_result(result_stream, "foo(int 1, int 2) 6");
//(sigc::group(sigc::ptr_fun(&foo_void), 1)) ();
std::bind(sigc::ptr_fun(&foo_void), 1)();
util->check_result(result_stream, "foo_void(int 1)");
// std::bind() does not work well together with sigc::slot and sigc::signal::connect().
// std::bind() typically creates a functor whose operator()() is a variadic template.
// Our functor_trait can't deduce the result type of such a functor.
// If the result of std::bind() is assigned to a std::function, the created
// functor has an unambiguous operator()().
// auto-disconnect
sigc::slot<void> sl2;
{
book guest_book("karl");
//sl2 = sigc::group(&egon, std::ref(guest_book));
// sl2 = [&guest_book] () { egon(guest_book); }; // no auto-disconnect
// sl2 = std::bind(&egon, std::ref(guest_book)); // does not compile (gcc 4.6.3)
sl2 = sigc::track_obj([&guest_book] () { egon(guest_book); }, guest_book);
sl2();
util->check_result(result_stream, "egon(string 'karl')");
//std::cout << static_cast<std::string&>(guest_book) << std::endl;
result_stream << static_cast<std::string&>(guest_book);
util->check_result(result_stream, "egon was here");
} // auto-disconnect
sl2();
util->check_result(result_stream, "");
// More auto-disconnect
{
book guest_book("charlie");
//sl2 = sigc::group(&egon, std::ref(guest_book));
// sl2 = std::bind(&egon, std::ref(guest_book)); // does not compile (gcc 4.6.3)
auto fn2 = std::bind(&egon, std::ref(guest_book));
//sl2 = fn2; // no auto-disconnect
sl2 = sigc::track_obj(fn2, guest_book);
sl2();
util->check_result(result_stream, "egon(string 'charlie')");
//std::cout << static_cast<std::string&>(guest_book) << std::endl;
result_stream << static_cast<std::string&>(guest_book);
util->check_result(result_stream, "egon was here");
} // auto-disconnect
sl2();
util->check_result(result_stream, "");
// same functionality as hide
//std::cout << (sigc::group(&foo, _1, _2)) (1,2,3) << std::endl;
result_stream << std::bind(&foo, std::placeholders::_1, std::placeholders::_2)(1,2,3);
util->check_result(result_stream, "foo(int 1, int 2) 6");
//(sigc::group(sigc::ptr_fun(&foo_void), _2)) (1, 2);
std::bind(&foo_void, std::placeholders::_2)(1, 2);
util->check_result(result_stream, "foo_void(int 2)");
// same functionality as compose
//std::cout << (sigc::group(&foo, sigc::group(&foo, _1, _2), _3)) (1,2,3) << std::endl;
result_stream << std::bind(&foo, std::bind(&foo, std::placeholders::_1, std::placeholders::_2),
std::placeholders::_3)(1,2,3);
util->check_result(result_stream, "foo(int 1, int 2) foo(int 6, int 3) 27");
// same functionality as retype
//std::cout << (sigc::group(&foo, sigc::static_cast_<int>(_1), 2)) (1.234) << std::endl;
result_stream << ([] (double x) -> int { return foo(static_cast<int>(x), 2); }(1.234));
util->check_result(result_stream, "foo(int 1, int 2) 6");
// Code examples with C++11 lambda expressions and std::bind, which can replace
// libsigc++ examples in the documentation of libsigc++ lambdas and sigc::group.
// -----------------------------------------------------------------------------
//--- sigc++/adaptors/lambda/macros/base.h.m4
//std::cout << sigc::_1(10,20,30); // returns 10
result_stream << ([] (int x, int, int) -> int { return x; }(10,20,30));
util->check_result(result_stream, "10");
//std::cout << sigc::_2(10,20,30); // returns 20
result_stream << ([] (int, int y, int) -> int { return y; }(10,20,30));
util->check_result(result_stream, "20");
//std::cout << (sigc::_1 + 5)(3); // returns (3 + 5)
result_stream << ([] (int x) -> int { return x + 5; }(3));
util->check_result(result_stream, "8");
//std::cout << (sigc::_1 * sigc::_2)(7,10); // returns (7 * 10)
result_stream << ([] (int x, int y) -> int { return x * y; }(7,10));
util->check_result(result_stream, "70");
//int main(int argc, char* argv[])
//{
// int data;
// sigc::signal<int> readValue;
//
// readValue.connect(sigc::var(data));
//
// data = 3;
// std::cout << readValue() << std::endl; //Prints 3.
//
// data = 5;
// std::cout << readValue() << std::endl; //Prints 5.
//}
{
int data;
sigc::signal<int> readValue;
readValue.connect([&data] () -> int { return data; });
data = 3;
result_stream << readValue();
util->check_result(result_stream, "3");
data = 5;
result_stream << readValue();
util->check_result(result_stream, "5");
}
//--- sigc++/adaptors/lambda/macros/group.h.m4
// argument binding ...
//sigc::group(&foo,10,sigc::_1)(20); //fixes the first argument and calls foo(10,20)
std::bind(&foo_group1, 10, std::placeholders::_1)(20);
util->check_result(result_stream, "foo_group1(int 10, int 20)");
//sigc::group(&foo,sigc::_1,30)(40); //fixes the second argument and calls foo(40,30)
std::bind(&foo_group1, std::placeholders::_1, 30)(40);
util->check_result(result_stream, "foo_group1(int 40, int 30)");
// argument reordering ...
//sigc::group(&foo,sigc::_2,sigc::_1)(1,2); //calls foo(2,1)
std::bind(&foo_group1, std::placeholders::_2, std::placeholders::_1)(1,2);
util->check_result(result_stream, "foo_group1(int 2, int 1)");
// argument hiding ...
//sigc::group(&foo,sigc::_1,sigc::_2)(1,2,3); //calls foo(1,2)
std::bind(&foo_group1, std::placeholders::_1, std::placeholders::_2)(1,2,3);
util->check_result(result_stream, "foo_group1(int 1, int 2)");
// functor composition ...
//sigc::group(&foo,sigc::_1,sigc::group(&bar,sigc::_2))(1,2); //calls foo(1,bar(2))
std::bind(&foo_group1, std::placeholders::_1, std::bind(&bar_group1, std::placeholders::_2))(1,2);
util->check_result(result_stream, "bar_group1(int 2) foo_group1(int 1, int 4)");
// algebraic expressions ...
// sigc::group(&foo,sigc::_1*sigc::_2,sigc::_1/sigc::_2)(6,3); //calls foo(6*3,6/3)
[] (int x, int y) { foo_group1(x*y, x/y); }(6,3);
util->check_result(result_stream, "foo_group1(int 18, int 2)");
{
sigc::signal<void,int,int> some_signal;
//some_signal.connect(sigc::group(&foo,sigc::_2));
//some_signal.connect(std::bind(&foo_group2, std::placeholders::_2)); // does not compile (gcc 4.6.3)
some_signal.connect([](int, int y) { foo_group2(y); });
some_signal.emit(1,2);
util->check_result(result_stream, "foo_group2(int 2)");
}
{
int some_int = 0;
sigc::signal<void> some_signal;
//some_signal.connect(sigc::group(&foo,std::ref(some_int)));
//some_signal.connect(std::bind(&foo_group3, std::ref(some_int))); // does not compile (gcc 4.6.3)
//some_signal.connect(sigc::bind(&foo_group3, std::ref(some_int))); // compiles, but we prefer std::bind() or C++11 lambda
some_signal.connect([&some_int](){ foo_group3(some_int); });
some_signal.emit();
result_stream << " " << some_int;
util->check_result(result_stream, "foo_group3(int 0) 1");
}
{
//struct bar : public sigc::trackable {} some_bar;
sigc::signal<void> some_signal;
{
bar_group4 some_bar;
//some_signal.connect(sigc::group(&foo,std::ref(some_bar)));
// disconnected automatically if some_bar goes out of scope
//some_signal.connect([&some_bar](){ foo_group4(some_bar); }); // no auto-disconnect
//some_signal.connect(sigc::bind(&foo_group4, std::ref(some_bar))); // auto-disconnects, but we prefer C++11 lambda
some_signal.connect(sigc::track_obj([&some_bar](){ foo_group4(some_bar); }, some_bar));
some_signal.emit();
util->check_result(result_stream, "foo_group4(bar_group4&)");
}
some_signal.emit();
util->check_result(result_stream, "");
}
return util->get_result_and_delete_instance() ? EXIT_SUCCESS : EXIT_FAILURE;
} // end main()
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