diff options
Diffstat (limited to 'src/boost/libs/proto/test/examples.cpp')
| -rw-r--r-- | src/boost/libs/proto/test/examples.cpp | 498 |
1 files changed, 498 insertions, 0 deletions
diff --git a/src/boost/libs/proto/test/examples.cpp b/src/boost/libs/proto/test/examples.cpp new file mode 100644 index 000000000..35769bca2 --- /dev/null +++ b/src/boost/libs/proto/test/examples.cpp @@ -0,0 +1,498 @@ +/////////////////////////////////////////////////////////////////////////////// +// examples.hpp +// +// Copyright 2008 Eric Niebler. 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> +#include <boost/config.hpp> +#include <boost/mpl/min_max.hpp> +#include <boost/proto/core.hpp> +#include <boost/proto/transform.hpp> +#include <boost/proto/functional/fusion.hpp> +#include <boost/utility/result_of.hpp> +#include <boost/fusion/include/cons.hpp> +#include <boost/fusion/include/tuple.hpp> +#include <boost/fusion/include/pop_front.hpp> +#include <boost/test/unit_test.hpp> + +namespace mpl = boost::mpl; +namespace proto = boost::proto; +namespace fusion = boost::fusion; +using proto::_; + +template<int I> +struct placeholder +{}; + +namespace test1 +{ +//[ CalcGrammar + // This is the grammar for calculator expressions, + // to which we will attach transforms for computing + // the expressions' arity. + /*<< A Calculator expression is ... >>*/ + struct CalcArity + : proto::or_< + /*<< _1, or ... >>*/ + proto::terminal< placeholder<0> > + /*<< _2, or ... >>*/ + , proto::terminal< placeholder<1> > + /*<< some other terminal, or ... >>*/ + , proto::terminal< _ > + /*<< a unary expression where the operand is a calculator expression, or ... >>*/ + , proto::unary_expr< _, CalcArity > + /*<< a binary expression where the operands are calculator expressions >>*/ + , proto::binary_expr< _, CalcArity, CalcArity > + > + {}; +//] +} + +//[ binary_arity +/*<< The `CalculatorArity` is a transform for calculating +the arity of a calculator expression. It will be define in +terms of `binary_arity`, which is defined in terms of +`CalculatorArity`; hence, the definition is recursive.>>*/ +struct CalculatorArity; + +// A custom transform that returns the arity of a unary +// calculator expression by finding the arity of the +// child expression. +struct unary_arity + /*<< Custom transforms should inherit from + transform<>. In some cases, (e.g., when the transform + is a template), it is also necessary to specialize + the proto::is_callable<> trait. >>*/ + : proto::transform<unary_arity> +{ + template<typename Expr, typename State, typename Data> + /*<< Transforms have a nested `impl<>` that is + a valid TR1 function object. >>*/ + struct impl + : proto::transform_impl<Expr, State, Data> + { + /*<< Get the child. >>*/ + typedef typename proto::result_of::child<Expr>::type child_expr; + + /*<< Apply `CalculatorArity` to find the arity of the child. >>*/ + typedef typename boost::result_of<CalculatorArity(child_expr, State, Data)>::type result_type; + + /*<< The `unary_arity` transform doesn't have an interesting + runtime counterpart, so just return a default-constructed object + of the correct type. >>*/ + result_type operator ()(proto::ignore, proto::ignore, proto::ignore) const + { + return result_type(); + } + }; +}; + +// A custom transform that returns the arity of a binary +// calculator expression by finding the maximum of the +// arities of the mpl::int_<2> child expressions. +struct binary_arity + /*<< All custom transforms should inherit from + transform. In some cases, (e.g., when the transform + is a template), it is also necessary to specialize + the proto::is_callable<> trait. >>*/ + : proto::transform<binary_arity> +{ + template<typename Expr, typename State, typename Data> + /*<< Transforms have a nested `impl<>` that is + a valid TR1 function object. >>*/ + struct impl + : proto::transform_impl<Expr, State, Data> + { + /*<< Get the left and right children. >>*/ + typedef typename proto::result_of::left<Expr>::type left_expr; + typedef typename proto::result_of::right<Expr>::type right_expr; + + /*<< Apply `CalculatorArity` to find the arity of the left and right children. >>*/ + typedef typename boost::result_of<CalculatorArity(left_expr, State, Data)>::type left_arity; + typedef typename boost::result_of<CalculatorArity(right_expr, State, Data)>::type right_arity; + + /*<< The return type is the maximum of the children's arities. >>*/ + typedef typename mpl::max<left_arity, right_arity>::type result_type; + + /*<< The `unary_arity` transform doesn't have an interesting + runtime counterpart, so just return a default-constructed object + of the correct type. >>*/ + result_type operator ()(proto::ignore, proto::ignore, proto::ignore) const + { + return result_type(); + } + }; +}; +//] + +proto::terminal< placeholder<0> >::type const _1 = {}; +proto::terminal< placeholder<1> >::type const _2 = {}; + +//[ CalculatorArityGrammar +struct CalculatorArity + : proto::or_< + proto::when< proto::terminal< placeholder<0> >, mpl::int_<1>() > + , proto::when< proto::terminal< placeholder<1> >, mpl::int_<2>() > + , proto::when< proto::terminal<_>, mpl::int_<0>() > + , proto::when< proto::unary_expr<_, _>, unary_arity > + , proto::when< proto::binary_expr<_, _, _>, binary_arity > + > +{}; +//] + +//[ CalcArity +struct CalcArity + : proto::or_< + proto::when< proto::terminal< placeholder<0> >, + mpl::int_<1>() + > + , proto::when< proto::terminal< placeholder<1> >, + mpl::int_<2>() + > + , proto::when< proto::terminal<_>, + mpl::int_<0>() + > + , proto::when< proto::unary_expr<_, CalcArity>, + CalcArity(proto::_child) + > + , proto::when< proto::binary_expr<_, CalcArity, CalcArity>, + mpl::max<CalcArity(proto::_left), + CalcArity(proto::_right)>() + > + > +{}; +//] + +// BUGBUG find workaround for this +#if BOOST_WORKAROUND(BOOST_MSVC, == 1310) +#define _pop_front(x) call<proto::_pop_front(x)> +#define _value(x) call<proto::_value(x)> +#endif + +//[ AsArgList +// This transform matches function invocations such as foo(1,'a',"b") +// and transforms them into Fusion cons lists of their arguments. In this +// case, the result would be cons(1, cons('a', cons("b", nil()))). +struct ArgsAsList + : proto::when< + proto::function<proto::terminal<_>, proto::vararg<proto::terminal<_> > > + /*<< Use a `fold<>` transform to iterate over the children of this + node in forward order, building a fusion list from front to back. >>*/ + , proto::fold< + /*<< The first child expression of a `function<>` node is the + function being invoked. We don't want that in our list, so use + `pop_front()` to remove it. >>*/ + proto::_pop_front(_) + /*<< `nil` is the initial state used by the `fold<>` transform. >>*/ + , fusion::nil() + /*<< Put the rest of the function arguments in a fusion cons + list. >>*/ + , proto::functional::push_back(proto::_state, proto::_value) + > + > +{}; +//] + +//[ FoldTreeToList +// This transform matches expressions of the form (_1=1,'a',"b") +// (note the use of the comma operator) and transforms it into a +// Fusion cons list of their arguments. In this case, the result +// would be cons(1, cons('a', cons("b", nil()))). +struct FoldTreeToList + : proto::or_< + // This grammar describes what counts as the terminals in expressions + // of the form (_1=1,'a',"b"), which will be flattened using + // reverse_fold_tree<> below. + proto::when< proto::assign<_, proto::terminal<_> > + , proto::_value(proto::_right) + > + , proto::when< proto::terminal<_> + , proto::_value + > + , proto::when< + proto::comma<FoldTreeToList, FoldTreeToList> + /*<< Fold all terminals that are separated by commas into a Fusion cons list. >>*/ + , proto::reverse_fold_tree< + _ + , fusion::nil() + , fusion::cons<FoldTreeToList, proto::_state>(FoldTreeToList, proto::_state) + > + > + > +{}; +//] + +//[ Promote +// This transform finds all float terminals in an expression and promotes +// them to doubles. +struct Promote + : proto::or_< + /*<< Match a `terminal<float>`, then construct a + `terminal<double>::type` with the `float`. >>*/ + proto::when<proto::terminal<float>, proto::terminal<double>::type(proto::_value) > + , proto::when<proto::terminal<_> > + /*<< `nary_expr<>` has a pass-through transform which + will transform each child sub-expression using the + `Promote` transform. >>*/ + , proto::when<proto::nary_expr<_, proto::vararg<Promote> > > + > +{}; +//] + +//[ LazyMakePair +struct make_pair_tag {}; +proto::terminal<make_pair_tag>::type const make_pair_ = {{}}; + +// This transform matches lazy function invocations like +// `make_pair_(1, 3.14)` and actually builds a `std::pair<>` +// from the arguments. +struct MakePair + : proto::when< + /*<< Match expressions like `make_pair_(1, 3.14)` >>*/ + proto::function< + proto::terminal<make_pair_tag> + , proto::terminal<_> + , proto::terminal<_> + > + /*<< Return `std::pair<F,S>(f,s)` where `f` and `s` are the + first and second arguments to the lazy `make_pair_()` function. + (This uses `proto::make<>` under the covers to evaluate the + transform.)>>*/ + , std::pair< + proto::_value(proto::_child1) + , proto::_value(proto::_child2) + >( + proto::_value(proto::_child1) + , proto::_value(proto::_child2) + ) + > +{}; +//] + +namespace lazy_make_pair2 +{ + //[ LazyMakePair2 + struct make_pair_tag {}; + proto::terminal<make_pair_tag>::type const make_pair_ = {{}}; + + // Like std::make_pair(), only as a function object. + /*<<Inheriting from `proto::callable` lets Proto know + that this is a callable transform, so we can use it + without having to wrap it in `proto::call<>`.>>*/ + struct make_pair : proto::callable + { + template<typename Sig> struct result; + + template<typename This, typename First, typename Second> + struct result<This(First, Second)> + { + typedef + std::pair< + BOOST_PROTO_UNCVREF(First) + , BOOST_PROTO_UNCVREF(Second) + > + type; + }; + + template<typename First, typename Second> + std::pair<First, Second> + operator()(First const &first, Second const &second) const + { + return std::make_pair(first, second); + } + }; + + // This transform matches lazy function invocations like + // `make_pair_(1, 3.14)` and actually builds a `std::pair<>` + // from the arguments. + struct MakePair + : proto::when< + /*<< Match expressions like `make_pair_(1, 3.14)` >>*/ + proto::function< + proto::terminal<make_pair_tag> + , proto::terminal<_> + , proto::terminal<_> + > + /*<< Return `make_pair()(f,s)` where `f` and `s` are the + first and second arguments to the lazy `make_pair_()` function. + (This uses `proto::call<>` under the covers to evaluate the + transform.)>>*/ + , make_pair( + proto::_value(proto::_child1) + , proto::_value(proto::_child2) + ) + > + {}; + //] +} + + +//[ NegateInt +struct NegateInt + : proto::when<proto::terminal<int>, proto::negate<_>(_)> +{}; +//] + +#ifndef BOOST_MSVC +//[ SquareAndPromoteInt +struct SquareAndPromoteInt + : proto::when< + proto::terminal<int> + , proto::_make_multiplies( + proto::terminal<long>::type(proto::_value) + , proto::terminal<long>::type(proto::_value) + ) + > +{}; +//] +#endif + +namespace lambda_transform +{ + //[LambdaTransform + template<typename N> + struct placeholder : N {}; + + // A function object that calls fusion::at() + struct at : proto::callable + { + template<typename Sig> + struct result; + + template<typename This, typename Cont, typename Index> + struct result<This(Cont, Index)> + : fusion::result_of::at< + typename boost::remove_reference<Cont>::type + , typename boost::remove_reference<Index>::type + > + {}; + + template<typename Cont, typename Index> + typename fusion::result_of::at<Cont, Index>::type + operator ()(Cont &cont, Index const &) const + { + return fusion::at<Index>(cont); + } + }; + + // A transform that evaluates a lambda expression. + struct LambdaEval + : proto::or_< + /*<<When you match a placeholder ...>>*/ + proto::when< + proto::terminal<placeholder<_> > + /*<<... call at() with the data parameter, which + is a tuple, and the placeholder, which is an MPL + Integral Constant.>>*/ + , at(proto::_data, proto::_value) + > + /*<<Otherwise, use the _default<> transform, which + gives the operators their usual C++ meanings.>>*/ + , proto::otherwise< proto::_default<LambdaEval> > + > + {}; + + // Define the lambda placeholders + proto::terminal<placeholder<mpl::int_<0> > >::type const _1 = {}; + proto::terminal<placeholder<mpl::int_<1> > >::type const _2 = {}; + + void test_lambda() + { + // a tuple that contains the values + // of _1 and _2 + fusion::tuple<int, int> tup(2,3); + + // Use LambdaEval to evaluate a lambda expression + int j = LambdaEval()( _2 - _1, 0, tup ); + BOOST_CHECK_EQUAL(j, 1); + + // You can mutate leaves in an expression tree + proto::literal<int> k(42); + int &l = LambdaEval()( k += 4, 0, tup ); + BOOST_CHECK_EQUAL(k.get(), 46); + BOOST_CHECK_EQUAL(&l, &k.get()); + + // You can mutate the values in the tuple, too. + LambdaEval()( _1 += 4, 0, tup ); + BOOST_CHECK_EQUAL(6, fusion::at_c<0>(tup)); + } + //] +} + +void test_examples() +{ + //[ CalculatorArityTest + int i = 0; // not used, dummy state and data parameter + + std::cout << CalculatorArity()( proto::lit(100) * 200, i, i) << '\n'; + std::cout << CalculatorArity()( (_1 - _1) / _1 * 100, i, i) << '\n'; + std::cout << CalculatorArity()( (_2 - _1) / _2 * 100, i, i) << '\n'; + //] + + BOOST_CHECK_EQUAL(0, CalculatorArity()( proto::lit(100) * 200, i, i)); + BOOST_CHECK_EQUAL(1, CalculatorArity()( (_1 - _1) / _1 * 100, i, i)); + BOOST_CHECK_EQUAL(2, CalculatorArity()( (_2 - _1) / _2 * 100, i, i)); + + BOOST_CHECK_EQUAL(0, CalcArity()( proto::lit(100) * 200, i, i)); + BOOST_CHECK_EQUAL(1, CalcArity()( (_1 - _1) / _1 * 100, i, i)); + BOOST_CHECK_EQUAL(2, CalcArity()( (_2 - _1) / _2 * 100, i, i)); + + using boost::fusion::cons; + using boost::fusion::nil; + cons<int, cons<char, cons<std::string> > > args(ArgsAsList()( _1(1, 'a', std::string("b")), i, i )); + BOOST_CHECK_EQUAL(args.car, 1); + BOOST_CHECK_EQUAL(args.cdr.car, 'a'); + BOOST_CHECK_EQUAL(args.cdr.cdr.car, std::string("b")); + + cons<int, cons<char, cons<std::string> > > lst(FoldTreeToList()( (_1 = 1, 'a', std::string("b")), i, i )); + BOOST_CHECK_EQUAL(lst.car, 1); + BOOST_CHECK_EQUAL(lst.cdr.car, 'a'); + BOOST_CHECK_EQUAL(lst.cdr.cdr.car, std::string("b")); + + proto::plus< + proto::terminal<double>::type + , proto::terminal<double>::type + >::type p = Promote()( proto::lit(1.f) + 2.f, i, i ); + + //[ LazyMakePairTest + int j = 0; // not used, dummy state and data parameter + + std::pair<int, double> p2 = MakePair()( make_pair_(1, 3.14), j, j ); + + std::cout << p2.first << std::endl; + std::cout << p2.second << std::endl; + //] + + BOOST_CHECK_EQUAL(p2.first, 1); + BOOST_CHECK_EQUAL(p2.second, 3.14); + + std::pair<int, double> p3 = lazy_make_pair2::MakePair()( lazy_make_pair2::make_pair_(1, 3.14), j, j ); + + std::cout << p3.first << std::endl; + std::cout << p3.second << std::endl; + + BOOST_CHECK_EQUAL(p3.first, 1); + BOOST_CHECK_EQUAL(p3.second, 3.14); + + NegateInt()(proto::lit(1), i, i); + #ifndef BOOST_MSVC + SquareAndPromoteInt()(proto::lit(1), i, i); + #endif + + lambda_transform::test_lambda(); +} + +using namespace boost::unit_test; +/////////////////////////////////////////////////////////////////////////////// +// init_unit_test_suite +// +test_suite* init_unit_test_suite( int argc, char* argv[] ) +{ + test_suite *test = BOOST_TEST_SUITE("test examples from the documentation"); + + test->add(BOOST_TEST_CASE(&test_examples)); + + return test; +} |