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/*=============================================================================
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_ERROR_HANDLER_APRIL_29_2007_1042PM)
#define BOOST_SPIRIT_ERROR_HANDLER_APRIL_29_2007_1042PM
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/spirit/home/qi/operator/expect.hpp>
#include <boost/spirit/home/qi/nonterminal/rule.hpp>
#include <boost/spirit/home/support/multi_pass_wrapper.hpp>
#include <boost/function.hpp>
#include <boost/assert.hpp>
namespace boost { namespace spirit { namespace qi
{
enum error_handler_result
{
fail
, retry
, accept
, rethrow
};
namespace detail
{
// Helper template allowing to manage the inhibit clear queue flag in
// a multi_pass iterator. This is the usual specialization used for
// anything but a multi_pass iterator.
template <typename Iterator, bool active>
struct reset_on_exit
{
reset_on_exit(Iterator&) {}
};
// For 'retry' or 'fail' error handlers we need to inhibit the flushing
// of the internal multi_pass buffers which otherwise might happen at
// deterministic expectation points inside the encapsulated right hand
// side of rule.
template <typename Iterator>
struct reset_on_exit<Iterator, true>
{
reset_on_exit(Iterator& it)
: it_(it)
, inhibit_clear_queue_(spirit::traits::inhibit_clear_queue(it))
{
spirit::traits::inhibit_clear_queue(it_, true);
}
~reset_on_exit()
{
// reset inhibit flag in multi_pass on exit
spirit::traits::inhibit_clear_queue(it_, inhibit_clear_queue_);
}
Iterator& it_;
bool inhibit_clear_queue_;
};
}
template <
typename Iterator, typename Context
, typename Skipper, typename F, error_handler_result action
>
struct error_handler
{
typedef function<
bool(Iterator& first, Iterator const& last
, Context& context
, Skipper const& skipper
)>
function_type;
error_handler(function_type subject, F f)
: subject(subject)
, f(f)
{
}
bool operator()(
Iterator& first, Iterator const& last
, Context& context, Skipper const& skipper) const
{
typedef qi::detail::reset_on_exit<Iterator
, traits::is_multi_pass<Iterator>::value &&
(action == retry || action == fail)> on_exit_type;
on_exit_type on_exit(first);
for(;;)
{
try
{
Iterator i = first;
bool r = subject(i, last, context, skipper);
if (r)
first = i;
return r;
}
catch (expectation_failure<Iterator> const& x)
{
typedef
fusion::vector<
Iterator&
, Iterator const&
, Iterator const&
, info const&>
params;
error_handler_result r = action;
params args(first, last, x.first, x.what_);
f(args, context, r);
// The assertions below will fire if you are using a
// multi_pass as the underlying iterator, one of your error
// handlers forced its guarded rule to 'fail' or 'retry',
// and the error handler has not been instantiated using
// either 'fail' or 'retry' in the first place. Please see
// the multi_pass docs for more information.
switch (r)
{
case fail:
BOOST_ASSERT(
!traits::is_multi_pass<Iterator>::value ||
action == retry || action == fail);
return false;
case retry:
BOOST_ASSERT(
!traits::is_multi_pass<Iterator>::value ||
action == retry || action == fail);
continue;
case accept: return true;
case rethrow: boost::throw_exception(x);
}
}
}
return false;
}
function_type subject;
F f;
};
template <
error_handler_result action
, typename Iterator, typename T0, typename T1, typename T2
, typename F>
void on_error(rule<Iterator, T0, T1, T2>& r, F f)
{
typedef rule<Iterator, T0, T1, T2> rule_type;
typedef
error_handler<
Iterator
, typename rule_type::context_type
, typename rule_type::skipper_type
, F
, action>
error_handler;
r.f = error_handler(r.f, f);
}
// Error handling support when <action> is not
// specified. We will default to <fail>.
template <typename Iterator, typename T0, typename T1
, typename T2, typename F>
void on_error(rule<Iterator, T0, T1, T2>& r, F f)
{
on_error<fail>(r, f);
}
}}}
#endif
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