70 lines
2.3 KiB
C++
70 lines
2.3 KiB
C++
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/*=============================================================================
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Copyright (c) 2001-2014 Joel de Guzman
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#if !defined(BOOST_SPIRIT_X3_GUARD_FERBRUARY_02_2013_0649PM)
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#define BOOST_SPIRIT_X3_GUARD_FERBRUARY_02_2013_0649PM
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#include <boost/spirit/home/x3/support/context.hpp>
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#include <boost/spirit/home/x3/directive/expect.hpp>
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namespace boost { namespace spirit { namespace x3
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{
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enum class error_handler_result
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{
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fail
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, retry
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, accept
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, rethrow
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};
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template <typename Subject, typename Handler>
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struct guard : unary_parser<Subject, guard<Subject, Handler>>
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{
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typedef unary_parser<Subject, guard<Subject, Handler>> base_type;
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static bool const is_pass_through_unary = true;
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constexpr guard(Subject const& subject, Handler handler)
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: base_type(subject), handler(handler) {}
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template <typename Iterator, typename Context
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, typename RuleContext, typename Attribute>
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bool parse(Iterator& first, Iterator const& last
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, Context const& context, RuleContext& rcontext, Attribute& attr) const
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{
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for (;;)
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{
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try
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{
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Iterator i = first;
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bool r = this->subject.parse(i, last, context, rcontext, attr);
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if (r)
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first = i;
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return r;
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}
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catch (expectation_failure<Iterator> const& x)
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{
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switch (handler(first, last, x, context))
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{
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case error_handler_result::fail:
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return false;
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case error_handler_result::retry:
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continue;
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case error_handler_result::accept:
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return true;
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case error_handler_result::rethrow:
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throw;
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}
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}
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}
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return false;
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}
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Handler handler;
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};
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}}}
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#endif
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