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///////////////////////////////////////////////////////////////////////////////
// is_pure.hpp
//
// Copyright 2008 Eric Niebler. 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)
#ifndef BOOST_XPRESSIVE_DETAIL_STATIC_IS_PURE_HPP_EAN_10_04_2005
#define BOOST_XPRESSIVE_DETAIL_STATIC_IS_PURE_HPP_EAN_10_04_2005
// MS compatible compilers support #pragma once
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
#include <boost/ref.hpp>
#include <boost/mpl/and.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/assert.hpp>
#include <boost/mpl/not_equal_to.hpp>
#include <boost/xpressive/detail/detail_fwd.hpp>
#include <boost/xpressive/detail/static/width_of.hpp>
namespace boost { namespace xpressive { namespace detail
{
///////////////////////////////////////////////////////////////////////////////
// use_simple_repeat_terminal
//
template<typename Expr, typename Char, bool IsXpr = is_xpr<Expr>::value>
struct use_simple_repeat_terminal
: mpl::bool_<
Expr::quant == quant_fixed_width
|| (Expr::width != unknown_width::value && Expr::pure)
>
{};
template<typename Expr, typename Char>
struct use_simple_repeat_terminal<Expr, Char, false>
: mpl::true_ // char literals, string literals, etc.
{};
template<typename BidiIter, typename Char>
struct use_simple_repeat_terminal<tracking_ptr<regex_impl<BidiIter> >, Char, false>
: mpl::false_ // basic_regex
{};
template<typename BidiIter, typename Char>
struct use_simple_repeat_terminal<reference_wrapper<basic_regex<BidiIter> >, Char, false>
: mpl::false_ // basic_regex
{};
template<typename BidiIter, typename Char>
struct use_simple_repeat_terminal<reference_wrapper<basic_regex<BidiIter> const>, Char, false>
: mpl::false_ // basic_regex
{};
///////////////////////////////////////////////////////////////////////////////
// use_simple_repeat_
//
template<typename Expr, typename Char, typename Tag = typename Expr::proto_tag>
struct use_simple_repeat_
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::terminal>
: use_simple_repeat_terminal<typename proto::result_of::value<Expr>::type, Char>
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::shift_right>
: mpl::and_<
use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
, use_simple_repeat_<typename remove_reference<typename Expr::proto_child1>::type::proto_base_expr, Char>
>
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::bitwise_or>
: mpl::and_<
mpl::not_equal_to<unknown_width, width_of<Expr, Char> >
, use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
, use_simple_repeat_<typename remove_reference<typename Expr::proto_child1>::type::proto_base_expr, Char>
>
{};
template<typename Left>
struct use_simple_repeat_assign
{};
template<>
struct use_simple_repeat_assign<mark_placeholder>
: mpl::false_
{};
template<>
struct use_simple_repeat_assign<set_initializer>
: mpl::true_
{};
template<typename Nbr>
struct use_simple_repeat_assign<attribute_placeholder<Nbr> >
: mpl::false_
{};
// either (s1 = ...) or (a1 = ...) or (set = ...)
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::assign>
: use_simple_repeat_assign<
typename proto::result_of::value<
typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr
>::type
>
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, modifier_tag>
: use_simple_repeat_<typename remove_reference<typename Expr::proto_child1>::type::proto_base_expr, Char>
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, lookahead_tag>
: mpl::false_
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, lookbehind_tag>
: mpl::false_
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, keeper_tag>
: mpl::false_
{};
// when complementing a set or an assertion, the purity is that of the set (true) or the assertion
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::complement>
: use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
{};
// The comma is used in list-initialized sets, which are pure
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::comma>
: mpl::true_
{};
// The subscript operator[] is used for sets, as in set['a' | range('b','h')]
// It is also used for actions, which by definition have side-effects and thus are impure
template<typename Expr, typename Char, typename Left>
struct use_simple_repeat_subscript
: mpl::false_
{};
template<typename Expr, typename Char>
struct use_simple_repeat_subscript<Expr, Char, set_initializer_type>
: mpl::true_
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::subscript>
: use_simple_repeat_subscript<Expr, Char, typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr>
{};
// Quantified expressions are variable-width and cannot use the simple quantifier
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::unary_plus>
: mpl::false_
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::dereference>
: mpl::false_
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::logical_not>
: mpl::false_
{};
template<typename Expr, typename Char, uint_t Min, uint_t Max>
struct use_simple_repeat_<Expr, Char, generic_quant_tag<Min, Max> >
: mpl::false_
{};
template<typename Expr, typename Char, uint_t Count>
struct use_simple_repeat_<Expr, Char, generic_quant_tag<Count, Count> >
: use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
{};
template<typename Expr, typename Char>
struct use_simple_repeat_<Expr, Char, proto::tag::negate>
: use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
{};
///////////////////////////////////////////////////////////////////////////////
// use_simple_repeat
//
template<typename Expr, typename Char>
struct use_simple_repeat
: use_simple_repeat_<Expr, Char>
{
// should never try to repeat something of 0-width
BOOST_MPL_ASSERT_RELATION(0, !=, (width_of<Expr, Char>::value));
};
template<typename Expr, typename Char>
struct use_simple_repeat<Expr &, Char>
: use_simple_repeat_<Expr, Char>
{
// should never try to repeat something of 0-width
BOOST_MPL_ASSERT_RELATION(0, !=, (width_of<Expr, Char>::value));
};
}}} // namespace boost::xpressive::detail
#endif
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