| /*============================================================================= |
| Copyright (c) 2001-2011 Hartmut Kaiser |
| |
| 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(SPIRIT_ALTERNATIVE_FUNCTION_APRIL_23_2007_1046AM) |
| #define SPIRIT_ALTERNATIVE_FUNCTION_APRIL_23_2007_1046AM |
| |
| #if defined(_MSC_VER) |
| #pragma once |
| #endif |
| |
| #include <boost/spirit/home/qi/domain.hpp> |
| #include <boost/spirit/home/qi/detail/assign_to.hpp> |
| #include <boost/spirit/home/support/unused.hpp> |
| #include <boost/spirit/home/qi/detail/attributes.hpp> |
| #include <boost/variant.hpp> |
| #include <boost/mpl/bool.hpp> |
| |
| namespace boost { namespace spirit { namespace qi { namespace detail |
| { |
| template <typename Variant, typename Expected> |
| struct find_substitute |
| { |
| // Get the typr from the variant that can be a substitute for Expected. |
| // If none is found, just return Expected |
| |
| typedef Variant variant_type; |
| typedef typename variant_type::types types; |
| typedef typename mpl::end<types>::type end; |
| |
| typedef typename |
| mpl::find_if<types, is_same<mpl::_1, Expected> >::type |
| iter_1; |
| |
| typedef typename |
| mpl::eval_if< |
| is_same<iter_1, end>, |
| mpl::find_if<types, traits::is_substitute<mpl::_1, Expected> >, |
| mpl::identity<iter_1> |
| >::type |
| iter; |
| |
| typedef typename |
| mpl::eval_if< |
| is_same<iter, end>, |
| mpl::identity<Expected>, |
| mpl::deref<iter> |
| >::type |
| type; |
| }; |
| |
| template <typename Iterator, typename Context, typename Skipper, |
| typename Attribute> |
| struct alternative_function |
| { |
| alternative_function( |
| Iterator& first_, Iterator const& last_, Context& context_, |
| Skipper const& skipper_, Attribute& attr_) |
| : first(first_), last(last_), context(context_), skipper(skipper_), |
| attr(attr_) |
| { |
| } |
| |
| template <typename Component> |
| bool call(Component const& component, mpl::true_) const |
| { |
| // if Attribute is not a variant, then pass it as-is |
| return component.parse(first, last, context, skipper, attr); |
| } |
| |
| template <typename Component> |
| bool call_optional_or_variant(Component const& component, mpl::true_) const |
| { |
| // If Attribute is an optional, then create an attribute for the Component |
| // with the type optional::value_type. If the expected attribute is unused type, |
| // use it instead. |
| typedef typename |
| traits::attribute_of<Component, Context, Iterator>::type |
| expected_type; |
| |
| typename mpl::if_< |
| is_same<expected_type, unused_type>, |
| unused_type, |
| typename Attribute::value_type>::type |
| val; |
| |
| if (component.parse(first, last, context, skipper, val)) |
| { |
| traits::assign_to(val, attr); |
| return true; |
| } |
| return false; |
| } |
| |
| template <typename Component> |
| bool call_variant(Component const& component, mpl::false_) const |
| { |
| // If Attribute is a variant, then search the variant types for a |
| // suitable substitute type. |
| |
| typename |
| find_substitute<Attribute, |
| typename traits::attribute_of<Component, Context, Iterator>::type |
| >::type |
| val; |
| |
| if (component.parse(first, last, context, skipper, val)) |
| { |
| traits::assign_to(val, attr); |
| return true; |
| } |
| return false; |
| } |
| |
| template <typename Component> |
| bool call_variant(Component const& component, mpl::true_) const |
| { |
| // If Attribute is a variant and the expected attribute is |
| // the same type (pass the variant as-is). |
| |
| return component.parse(first, last, context, skipper, attr); |
| } |
| |
| template <typename Component> |
| bool call_optional_or_variant(Component const& component, mpl::false_) const |
| { |
| // Attribute is a variant... |
| |
| typedef typename |
| traits::attribute_of<Component, Context, Iterator>::type |
| expected; |
| return call_variant(component, |
| is_same<Attribute, expected>()); |
| } |
| |
| template <typename Component> |
| bool call(Component const& component, mpl::false_) const |
| { |
| return call_optional_or_variant( |
| component, spirit::traits::not_is_variant<Attribute, qi::domain>()); |
| } |
| |
| template <typename Component> |
| bool call_unused(Component const& component, mpl::true_) const |
| { |
| // return true if the parser succeeds |
| return call(component, |
| mpl::and_< |
| spirit::traits::not_is_variant<Attribute, qi::domain>, |
| spirit::traits::not_is_optional<Attribute, qi::domain> |
| >()); |
| } |
| |
| template <typename Component> |
| bool call_unused(Component const& component, mpl::false_) const |
| { |
| return component.parse(first, last, context, skipper, unused); |
| } |
| |
| template <typename Component> |
| bool operator()(Component const& component) const |
| { |
| // return true if the parser succeeds |
| typedef typename traits::not_is_unused< |
| typename traits::attribute_of<Component, Context, Iterator>::type |
| >::type predicate; |
| |
| return call_unused(component, predicate()); |
| } |
| |
| Iterator& first; |
| Iterator const& last; |
| Context& context; |
| Skipper const& skipper; |
| Attribute& attr; |
| |
| private: |
| // silence MSVC warning C4512: assignment operator could not be generated |
| alternative_function& operator= (alternative_function const&); |
| }; |
| |
| template <typename Iterator, typename Context, typename Skipper> |
| struct alternative_function<Iterator, Context, Skipper, unused_type const> |
| { |
| alternative_function( |
| Iterator& first_, Iterator const& last_, Context& context_, |
| Skipper const& skipper_, unused_type) |
| : first(first_), last(last_), context(context_), skipper(skipper_) |
| { |
| } |
| |
| template <typename Component> |
| bool operator()(Component const& component) const |
| { |
| // return true if the parser succeeds |
| return component.parse(first, last, context, skipper, |
| unused); |
| } |
| |
| Iterator& first; |
| Iterator const& last; |
| Context& context; |
| Skipper const& skipper; |
| |
| private: |
| // silence MSVC warning C4512: assignment operator could not be generated |
| alternative_function& operator= (alternative_function const&); |
| }; |
| |
| }}}} |
| |
| #endif |
