boost/spirit/utility/lists.hpp
/*=============================================================================
Copyright (c) 2002-2003 Hartmut Kaiser
http://spirit.sourceforge.net/
Use, modification and distribution is subject to 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)
=============================================================================*/
#ifndef BOOST_SPIRIT_LISTS_HPP
#define BOOST_SPIRIT_LISTS_HPP
///////////////////////////////////////////////////////////////////////////////
#include <boost/config.hpp>
#include <boost/spirit/meta/as_parser.hpp>
#include <boost/spirit/core/parser.hpp>
#include <boost/spirit/core/composite/composite.hpp>
#include <boost/spirit/utility/lists_fwd.hpp>
#include <boost/spirit/utility/impl/lists.ipp>
///////////////////////////////////////////////////////////////////////////////
namespace boost { namespace spirit {
///////////////////////////////////////////////////////////////////////////////
//
// list_parser class
//
// List parsers allow to parse constructs like
//
// item >> *(delim >> item)
//
// where 'item' is an auxiliary expression to parse and 'delim' is an
// auxiliary delimiter to parse.
//
// The list_parser class also can match an optional closing delimiter
// represented by the 'end' parser at the end of the list:
//
// item >> *(delim >> item) >> !end.
//
// If ItemT is an action_parser_category type (parser with an attached
// semantic action) we have to do something special. This happens, if the
// user wrote something like:
//
// list_p(item[f], delim)
//
// where 'item' is the parser matching one item of the list sequence and
// 'f' is a functor to be called after matching one item. If we would do
// nothing, the resulting code would parse the sequence as follows:
//
// (item[f] - delim) >> *(delim >> (item[f] - delim))
//
// what in most cases is not what the user expects.
// (If this _is_ what you've expected, then please use one of the list_p
// generator functions 'direct()', which will inhibit re-attaching
// the actor to the item parser).
//
// To make the list parser behave as expected:
//
// (item - delim)[f] >> *(delim >> (item - delim)[f])
//
// the actor attached to the 'item' parser has to be re-attached to the
// *(item - delim) parser construct, which will make the resulting list
// parser 'do the right thing'.
//
// Additionally special care must be taken, if the item parser is a
// unary_parser_category type parser as
//
// list_p(*anychar_p, ',')
//
// which without any refactoring would result in
//
// (*anychar_p - ch_p(','))
// >> *( ch_p(',') >> (*anychar_p - ch_p(',')) )
//
// and will not give the expected result (the first *anychar_p will eat up
// all the input up to the end of the input stream). So we have to
// refactor this into:
//
// *(anychar_p - ch_p(','))
// >> *( ch_p(',') >> *(anychar_p - ch_p(',')) )
//
// what will give the correct result.
//
// The case, where the item parser is a combination of the two mentioned
// problems (i.e. the item parser is a unary parser with an attached
// action), is handled accordingly too:
//
// list_p((*anychar_p)[f], ',')
//
// will be parsed as expected:
//
// (*(anychar_p - ch_p(',')))[f]
// >> *( ch_p(',') >> (*(anychar_p - ch_p(',')))[f] ).
//
///////////////////////////////////////////////////////////////////////////////
template <
typename ItemT, typename DelimT, typename EndT, typename CategoryT
>
struct list_parser :
public parser<list_parser<ItemT, DelimT, EndT, CategoryT> > {
typedef list_parser<ItemT, DelimT, EndT, CategoryT> self_t;
typedef CategoryT parser_category_t;
list_parser(ItemT const &item_, DelimT const &delim_,
EndT const& end_ = no_list_endtoken())
: item(item_), delim(delim_), end(end_)
{}
template <typename ScannerT>
typename parser_result<self_t, ScannerT>::type
parse(ScannerT const& scan) const
{
return impl::list_parser_type<CategoryT>
::parse(scan, *this, item, delim, end);
}
private:
typename as_parser<ItemT>::type::embed_t item;
typename as_parser<DelimT>::type::embed_t delim;
typename as_parser<EndT>::type::embed_t end;
};
///////////////////////////////////////////////////////////////////////////////
//
// List parser generator template
//
// This is a helper for generating a correct list_parser<> from
// auxiliary parameters. There are the following types supported as
// parameters yet: parsers, single characters and strings (see
// as_parser<> in meta/as_parser.hpp).
//
// The list_parser_gen by itself can be used for parsing comma separated
// lists without item formatting:
//
// list_p.parse(...)
// matches any comma separated list.
//
// If list_p is used with one parameter, this parameter is used to match
// the delimiter:
//
// list_p(';').parse(...)
// matches any semicolon separated list.
//
// If list_p is used with two parameters, the first parameter is used to
// match the items and the second parameter matches the delimiters:
//
// list_p(uint_p, ',').parse(...)
// matches comma separated unsigned integers.
//
// If list_p is used with three parameters, the first parameter is used
// to match the items, the second one is used to match the delimiters and
// the third one is used to match an optional ending token sequence:
//
// list_p(real_p, ';', eol_p).parse(...)
// matches a semicolon separated list of real numbers optionally
// followed by an end of line.
//
// The list_p in the previous examples denotes the predefined parser
// generator, which should be used to define list parsers (see below).
//
///////////////////////////////////////////////////////////////////////////////
template <typename CharT = char>
struct list_parser_gen :
public list_parser<kleene_star<anychar_parser>, chlit<CharT> >
{
typedef list_parser_gen<CharT> self_t;
// construct the list_parser_gen object as an list parser for comma separated
// lists without item formatting.
list_parser_gen()
: list_parser<kleene_star<anychar_parser>, chlit<CharT> >
(*anychar_p, chlit<CharT>(','))
{}
// The following generator functions should be used under normal circumstances.
// (the operator()(...) functions)
// Generic generator functions for creation of concrete list parsers, which
// support 'normal' syntax:
//
// item >> *(delim >> item)
//
// If item isn't given, everything between two delimiters is matched.
template<typename DelimT>
list_parser<
kleene_star<anychar_parser>,
typename as_parser<DelimT>::type,
no_list_endtoken,
unary_parser_category // there is no action to re-attach
>
operator()(DelimT const &delim_) const
{
typedef kleene_star<anychar_parser> item_t;
typedef typename as_parser<DelimT>::type delim_t;
typedef
list_parser<item_t, delim_t, no_list_endtoken, unary_parser_category>
return_t;
return return_t(*anychar_p, as_parser<DelimT>::convert(delim_));
}
template<typename ItemT, typename DelimT>
list_parser<
typename as_parser<ItemT>::type,
typename as_parser<DelimT>::type,
no_list_endtoken,
typename as_parser<ItemT>::type::parser_category_t
>
operator()(ItemT const &item_, DelimT const &delim_) const
{
typedef typename as_parser<ItemT>::type item_t;
typedef typename as_parser<DelimT>::type delim_t;
typedef list_parser<item_t, delim_t, no_list_endtoken,
BOOST_DEDUCED_TYPENAME item_t::parser_category_t>
return_t;
return return_t(
as_parser<ItemT>::convert(item_),
as_parser<DelimT>::convert(delim_)
);
}
// Generic generator function for creation of concrete list parsers, which
// support 'extended' syntax:
//
// item >> *(delim >> item) >> !end
template<typename ItemT, typename DelimT, typename EndT>
list_parser<
typename as_parser<ItemT>::type,
typename as_parser<DelimT>::type,
typename as_parser<EndT>::type,
typename as_parser<ItemT>::type::parser_category_t
>
operator()(
ItemT const &item_, DelimT const &delim_, EndT const &end_) const
{
typedef typename as_parser<ItemT>::type item_t;
typedef typename as_parser<DelimT>::type delim_t;
typedef typename as_parser<EndT>::type end_t;
typedef list_parser<item_t, delim_t, end_t,
BOOST_DEDUCED_TYPENAME item_t::parser_category_t>
return_t;
return return_t(
as_parser<ItemT>::convert(item_),
as_parser<DelimT>::convert(delim_),
as_parser<EndT>::convert(end_)
);
}
// The following functions should be used, if the 'item' parser has an attached
// semantic action or is a unary_parser_category type parser and the structure
// of the resulting list parser should _not_ be refactored during parser
// construction (see comment above).
// Generic generator function for creation of concrete list parsers, which
// support 'normal' syntax:
//
// item >> *(delim >> item)
template<typename ItemT, typename DelimT>
list_parser<
typename as_parser<ItemT>::type,
typename as_parser<DelimT>::type,
no_list_endtoken,
plain_parser_category // inhibit action re-attachment
>
direct(ItemT const &item_, DelimT const &delim_) const
{
typedef typename as_parser<ItemT>::type item_t;
typedef typename as_parser<DelimT>::type delim_t;
typedef list_parser<item_t, delim_t, no_list_endtoken,
plain_parser_category>
return_t;
return return_t(
as_parser<ItemT>::convert(item_),
as_parser<DelimT>::convert(delim_)
);
}
// Generic generator function for creation of concrete list parsers, which
// support 'extended' syntax:
//
// item >> *(delim >> item) >> !end
template<typename ItemT, typename DelimT, typename EndT>
list_parser<
typename as_parser<ItemT>::type,
typename as_parser<DelimT>::type,
typename as_parser<EndT>::type,
plain_parser_category // inhibit action re-attachment
>
direct(
ItemT const &item_, DelimT const &delim_, EndT const &end_) const
{
typedef typename as_parser<ItemT>::type item_t;
typedef typename as_parser<DelimT>::type delim_t;
typedef typename as_parser<EndT>::type end_t;
typedef
list_parser<item_t, delim_t, end_t, plain_parser_category>
return_t;
return return_t(
as_parser<ItemT>::convert(item_),
as_parser<DelimT>::convert(delim_),
as_parser<EndT>::convert(end_)
);
}
};
///////////////////////////////////////////////////////////////////////////////
//
// Predefined list parser generator
//
// The list_p parser generator can be used
// - by itself for parsing comma separated lists without item formatting
// or
// - for generating list parsers with auxiliary parser parameters
// for the 'item', 'delim' and 'end' subsequences.
// (see comment above)
//
///////////////////////////////////////////////////////////////////////////////
const list_parser_gen<> list_p = list_parser_gen<>();
///////////////////////////////////////////////////////////////////////////////
}} // namespace boost::spirit
#endif
