boost/spirit/home/karma/auxiliary/lazy.hpp
// Copyright (c) 2001-2011 Hartmut Kaiser // Copyright (c) 2001-2011 Joel de Guzman // // 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) #if !defined(BOOST_SPIRIT_KARMA_LAZY_MARCH_27_2007_1231PM) #define BOOST_SPIRIT_KARMA_LAZY_MARCH_27_2007_1231PM #if defined(_MSC_VER) #pragma once #endif #include <boost/spirit/home/karma/domain.hpp> #include <boost/spirit/home/karma/delimit_out.hpp> #include <boost/spirit/home/karma/meta_compiler.hpp> #include <boost/spirit/home/karma/detail/attributes.hpp> #include <boost/spirit/home/support/unused.hpp> #include <boost/spirit/home/support/info.hpp> #include <boost/spirit/home/support/lazy.hpp> #include <boost/spirit/include/phoenix_core.hpp> #include <boost/fusion/include/at.hpp> #include <boost/utility/result_of.hpp> #include <boost/type_traits/remove_reference.hpp> #include <boost/mpl/not.hpp> namespace boost { namespace spirit { /////////////////////////////////////////////////////////////////////////// // Enablers /////////////////////////////////////////////////////////////////////////// template <typename Eval> struct use_terminal<karma::domain, phoenix::actor<Eval> > // enables phoenix actors : mpl::true_ {}; // forward declaration template <typename Terminal, typename Actor, int Arity> struct lazy_terminal; }} namespace boost { namespace spirit { namespace karma { using spirit::lazy; typedef modify<karma::domain> karma_modify; namespace detail { template <typename Generator, typename OutputIterator, typename Context , typename Delimiter, typename Attribute> bool lazy_generate_impl(Generator const& g, OutputIterator& sink , Context& context, Delimiter const& delim , Attribute const& attr, mpl::false_) { return g.generate(sink, context, delim, attr); } template <typename Generator, typename OutputIterator, typename Context , typename Delimiter, typename Attribute> bool lazy_generate_impl(Generator const& g, OutputIterator& sink , Context& context, Delimiter const& delim , Attribute const& /* attr */, mpl::true_) { // If DeducedAuto is false (semantic actions is present), the // component's attribute is unused. return g.generate(sink, context, delim, unused); } template <typename Generator, typename OutputIterator, typename Context , typename Delimiter, typename Attribute> bool lazy_generate_impl_main(Generator const& g, OutputIterator& sink , Context& context, Delimiter const& delim, Attribute const& attr) { // If DeducedAuto is true (no semantic action), we pass the parser's // attribute on to the component. typedef typename traits::has_semantic_action<Generator>::type auto_rule; return lazy_generate_impl(g, sink, context, delim, attr, auto_rule()); } } template <typename Function, typename Modifiers> struct lazy_generator : generator<lazy_generator<Function, Modifiers> > { typedef mpl::int_<generator_properties::all_properties> properties; template <typename Context, typename Iterator> struct attribute { typedef typename boost::result_of<karma_modify(tag::lazy_eval, Modifiers)>::type modifier; typedef typename remove_reference< typename boost::result_of<Function(unused_type, Context)>::type >::type expr_type; // If you got an error_invalid_expression error message here, // then the expression (expr_type) is not a valid spirit karma // expression. BOOST_SPIRIT_ASSERT_MATCH(karma::domain, expr_type); typedef typename result_of::compile<karma::domain, expr_type, modifier>::type generator_type; typedef typename traits::attribute_of<generator_type, Context, Iterator>::type type; }; lazy_generator(Function const& func, Modifiers const& modifiers) : func(func), modifiers(modifiers) {} template < typename OutputIterator, typename Context, typename Delimiter, typename Attribute > bool generate(OutputIterator& sink, Context& context, Delimiter const& d, Attribute const& attr) const { return detail::lazy_generate_impl_main( compile<karma::domain>(func(unused, context) , karma_modify()(tag::lazy_eval(), modifiers)) , sink, context, d, attr); } template <typename Context> info what(Context& context) const { return info("lazy" , compile<karma::domain>(func(unused, context) , karma_modify()(tag::lazy_eval(), modifiers)) .what(context) ); } Function func; Modifiers modifiers; private: // silence MSVC warning C4512: assignment operator could not be generated lazy_generator& operator= (lazy_generator const&); }; /////////////////////////////////////////////////////////////////////////// template <typename Function, typename Subject, typename Modifiers> struct lazy_directive : unary_generator<lazy_directive<Function, Subject, Modifiers> > { typedef mpl::int_<generator_properties::all_properties> properties; typedef Subject subject_type; template <typename Context, typename Iterator> struct attribute { typedef typename boost::result_of<karma_modify(tag::lazy_eval, Modifiers)>::type modifier; typedef typename remove_reference< typename boost::result_of<Function(unused_type, Context)>::type >::type directive_expr_type; typedef typename proto::result_of::make_expr< proto::tag::subscript , directive_expr_type , Subject >::type expr_type; // If you got an error_invalid_expression error message here, // then the expression (expr_type) is not a valid spirit karma // expression. BOOST_SPIRIT_ASSERT_MATCH(karma::domain, expr_type); typedef typename result_of::compile<karma::domain, expr_type, modifier>::type generator_type; typedef typename traits::attribute_of<generator_type, Context, Iterator>::type type; }; lazy_directive(Function const& function, Subject const& subject , Modifiers const& modifiers) : function(function), subject(subject), modifiers(modifiers) {} template <typename OutputIterator, typename Context, typename Delimiter , typename Attribute> bool generate(OutputIterator& sink, Context& ctx, Delimiter const& d , Attribute const& attr) const { return detail::lazy_generate_impl_main(compile<karma::domain>( proto::make_expr<proto::tag::subscript>( function(unused, ctx), subject) , karma_modify()(tag::lazy_eval(), modifiers)) , sink, ctx, d, attr); } template <typename Context> info what(Context& ctx) const { return info("lazy-directive" , compile<karma::domain>( proto::make_expr<proto::tag::subscript>( function(unused, ctx), subject) , karma_modify()(tag::lazy_eval(), modifiers)) .what(ctx) ); } Function function; Subject subject; Modifiers modifiers; }; /////////////////////////////////////////////////////////////////////////// // Generator generators: make_xxx function (objects) /////////////////////////////////////////////////////////////////////////// template <typename Eval, typename Modifiers> struct make_primitive<phoenix::actor<Eval>, Modifiers> { typedef lazy_generator<phoenix::actor<Eval>, Modifiers> result_type; result_type operator()(phoenix::actor<Eval> const& f , Modifiers const& modifiers) const { return result_type(f, modifiers); } }; template <typename Terminal, typename Actor, int Arity, typename Modifiers> struct make_primitive<lazy_terminal<Terminal, Actor, Arity>, Modifiers> { typedef lazy_generator<Actor, Modifiers> result_type; result_type operator()( lazy_terminal<Terminal, Actor, Arity> const& lt , Modifiers const& modifiers) const { return result_type(lt.actor, modifiers); } }; template < typename Terminal, typename Actor, int Arity, typename Subject , typename Modifiers> struct make_directive<lazy_terminal<Terminal, Actor, Arity> , Subject, Modifiers> { typedef lazy_directive<Actor, Subject, Modifiers> result_type; result_type operator()( lazy_terminal<Terminal, Actor, Arity> const& lt , Subject const& subject, Modifiers const& modifiers) const { return result_type(lt.actor, subject, modifiers); } }; }}} #endif