///////////////////////////////////////////////////////////////////////////////

/// \file regex_compiler.hpp

/// Contains the definition of regex_compiler, a factory for building regex objects

/// from strings.

//

//  Copyright 2004 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_REGEX_COMPILER_HPP_EAN_10_04_2005

#define BOOST_XPRESSIVE_REGEX_COMPILER_HPP_EAN_10_04_2005

// MS compatible compilers support #pragma once

#if defined(_MSC_VER) && (_MSC_VER >= 1020)

# pragma once

#endif

#include <boost/xpressive/basic_regex.hpp>

#include <boost/xpressive/detail/dynamic/parser.hpp>

#include <boost/xpressive/detail/dynamic/parse_charset.hpp>

#include <boost/xpressive/detail/dynamic/parser_enum.hpp>

#include <boost/xpressive/detail/dynamic/parser_traits.hpp>

#include <boost/xpressive/detail/core/linker.hpp>

#include <boost/xpressive/detail/core/optimize.hpp>

namespace boost { namespace xpressive

{

///////////////////////////////////////////////////////////////////////////////

// regex_compiler

//

/// \brief Class template regex_compiler is a factory for building basic_regex objects from a string.

///

/// Class template regex_compiler is used to construct a basic_regex object from a string. The string

/// should contain a valid regular expression. You can imbue a regex_compiler object with a locale,

/// after which all basic_regex objects created with that regex_compiler object will use that locale.

/// After creating a regex_compiler object, and optionally imbueing it with a locale, you can call the

/// compile() method to construct a basic_regex object, passing it the string representing the regular

/// expression. You can call compile() multiple times on the same regex_compiler object. Two basic_regex

/// objects compiled from the same string will have different regex_id's.

template<typename BidiIter, typename RegexTraits, typename CompilerTraits>

struct regex_compiler

{

    typedef BidiIter iterator_type;

    typedef typename iterator_value<BidiIter>::type char_type;

    typedef std::basic_string<char_type> string_type;

    typedef regex_constants::syntax_option_type flag_type;

    typedef RegexTraits traits_type;

    typedef typename traits_type::char_class_type char_class_type;

    typedef typename traits_type::locale_type locale_type;

    explicit regex_compiler(RegexTraits const &traits = RegexTraits())

      : mark_count_(0)

      , hidden_mark_count_(0)

      , traits_(traits)

      , upper_(0)

    {

        this->upper_ = lookup_classname(this->rxtraits(), "upper");

        BOOST_ASSERT(0 != this->upper_);

    }

    ///////////////////////////////////////////////////////////////////////////

    // imbue

    /// Specify the locale to be used by a regex_compiler.

    ///

    /// \param loc The locale that this regex_compiler should use.

    /// \return The previous locale.

    locale_type imbue(locale_type loc)

    {

        locale_type oldloc = this->traits_.imbue(loc);

        this->upper_ = lookup_classname(this->rxtraits(), "upper");

        BOOST_ASSERT(0 != this->upper_);

        return oldloc;

    }

    ///////////////////////////////////////////////////////////////////////////

    // getloc

    /// Get the locale used by a regex_compiler.

    ///

    /// \param loc The locale that this regex_compiler uses.

    locale_type getloc() const

    {

        return this->traits_.getloc();

    }

    ///////////////////////////////////////////////////////////////////////////

    // compile

    /// Builds a basic_regex object from a std::string.

    ///

    /// \param  pat A std::string containing the regular expression pattern.

    /// \param  flags Optional bitmask that determines how the pat string is interpreted. (See syntax_option_type.)

    /// \return A basic_regex object corresponding to the regular expression represented by the string.

    /// \pre    The std::string pat contains a valid string-based representation of a regular expression.

    /// \throw  regex_error when the string has invalid regular expression syntax.

    basic_regex<BidiIter> compile(string_type pat, flag_type flags = regex_constants::ECMAScript)

    {

        this->reset();

        this->traits_.flags(flags);

        string_iterator begin = pat.begin(), end = pat.end();

        // at the top level, a regex is a sequence of alternates

        alternates_list alternates;

        this->parse_alternates(begin, end, alternates);

        detail::ensure(begin == end, regex_constants::error_paren, "mismatched parenthesis");

        // convert the alternates list to the appropriate matcher and terminate the sequence

        detail::sequence<BidiIter> seq = detail::alternates_to_matchable(alternates, alternates_factory());

        seq += detail::make_dynamic_xpression<BidiIter>(detail::end_matcher());

        // fill in the back-pointers by visiting the regex parse tree

        detail::xpression_linker<char_type> linker(this->rxtraits());

        seq.first->link(linker);

        // bundle the regex information into a regex_impl object

        detail::regex_impl<BidiIter> impl;

        impl.xpr_ = seq.first;

        impl.traits_.reset(new RegexTraits(this->rxtraits()));

        impl.mark_count_ = this->mark_count_;

        impl.hidden_mark_count_ = this->hidden_mark_count_;

        // optimization: get the peek chars OR the boyer-moore search string

        detail::optimize_regex(impl, this->rxtraits(), detail::is_random<BidiIter>());

        return detail::core_access<BidiIter>::make_regex(impl);

    }

private:

    typedef typename string_type::const_iterator string_iterator;

    typedef std::list<detail::sequence<BidiIter> > alternates_list;

    typedef detail::escape_value<char_type, char_class_type> escape_value;

    typedef detail::alternates_factory_impl<BidiIter, traits_type> alternates_factory;

    ///////////////////////////////////////////////////////////////////////////

    // reset

    /// INTERNAL ONLY

    void reset()

    {

        this->mark_count_ = 0;

        this->hidden_mark_count_ = 0;

        this->traits_.flags(regex_constants::ECMAScript);

    }

    ///////////////////////////////////////////////////////////////////////////

    // regex_traits

    /// INTERNAL ONLY

    traits_type &rxtraits()

    {

        return this->traits_.traits();

    }

    ///////////////////////////////////////////////////////////////////////////

    // regex_traits

    /// INTERNAL ONLY

    traits_type const &rxtraits() const

    {

        return this->traits_.traits();

    }

    ///////////////////////////////////////////////////////////////////////////

    // parse_alternates

    /// INTERNAL ONLY

    void parse_alternates(string_iterator &begin, string_iterator end, alternates_list &alternates)

    {

        using namespace regex_constants;

        string_iterator old_begin;

        do

        {

            alternates.push_back(this->parse_sequence(begin, end));

            old_begin = begin;

        }

        while(begin != end && token_alternate == this->traits_.get_token(begin, end));

        begin = old_begin;

    }

    ///////////////////////////////////////////////////////////////////////////

    // parse_group

    /// INTERNAL ONLY

    detail::sequence<BidiIter> parse_group(string_iterator &begin, string_iterator end)

    {

        using namespace regex_constants;

        int mark_nbr = 0;

        bool keeper = false;

        bool lookahead = false;

        bool lookbehind = false;

        bool negative = false;

        std::size_t old_mark_count = this->mark_count_;

        detail::sequence<BidiIter> seq, seq_end;

        string_iterator tmp = string_iterator();

        syntax_option_type old_flags = this->traits_.flags();

        switch(this->traits_.get_group_type(begin, end))

        {

        case token_no_mark:

            // Don't process empty groups like (?:) or (?i)

            // BUGBUG this doesn't handle the degenerate (?:)+ correctly

            if(token_group_end == this->traits_.get_token(tmp = begin, end))

            {

                return this->parse_atom(begin = tmp, end);

            }

            break;

        case token_negative_lookahead:

            negative = true; // fall-through

        case token_positive_lookahead:

            lookahead = true;

            seq_end = detail::make_dynamic_xpression<BidiIter>(detail::true_matcher());

            break;

        case token_negative_lookbehind:

            negative = true; // fall-through

        case token_positive_lookbehind:

            lookbehind = true;

            seq_end = detail::make_dynamic_xpression<BidiIter>(detail::true_matcher());

            break;

        case token_independent_sub_expression:

            keeper = true;

            seq_end = detail::make_dynamic_xpression<BidiIter>(detail::true_matcher());

            break;

        case token_comment:

            while(detail::ensure(begin != end, error_paren, "mismatched parenthesis"))

            {

                switch(this->traits_.get_token(begin, end))

                {

                case token_group_end: return this->parse_atom(begin, end);

                case token_escape: detail::ensure(begin != end, error_escape, "incomplete escape sequence");

                case token_literal: ++begin;

                default:;

                }

            }

            break;

        default:

            mark_nbr = static_cast<int>(++this->mark_count_);

            seq = detail::make_dynamic_xpression<BidiIter>(detail::mark_begin_matcher(mark_nbr));

            seq_end = detail::make_dynamic_xpression<BidiIter>(detail::mark_end_matcher(mark_nbr));

            break;

        }

        // alternates

        alternates_list alternates;

        this->parse_alternates(begin, end, alternates);

        detail::ensure

        (

            begin != end && token_group_end == this->traits_.get_token(begin, end)

          , error_paren

          , "mismatched parenthesis"

        );

        seq += detail::alternates_to_matchable(alternates, alternates_factory());

        seq += seq_end;

        typedef shared_ptr<detail::matchable<BidiIter> const> xpr_type;

        bool do_save = (this->mark_count_ != old_mark_count);

        if(lookahead)

        {

            detail::lookahead_matcher<xpr_type> lookahead(seq.first, negative, do_save);

            seq = detail::make_dynamic_xpression<BidiIter>(lookahead);

        }

        else if(lookbehind)

        {

            detail::lookbehind_matcher<xpr_type> lookbehind(seq.first, negative, do_save);

            seq = detail::make_dynamic_xpression<BidiIter>(lookbehind);

        }

        else if(keeper) // independent sub-expression

        {

            detail::keeper_matcher<xpr_type> keeper(seq.first, do_save);

            seq = detail::make_dynamic_xpression<BidiIter>(keeper);

        }

        // restore the modifiers

        this->traits_.flags(old_flags);

        return seq;

    }

    ///////////////////////////////////////////////////////////////////////////

    // parse_charset

    /// INTERNAL ONLY

    detail::sequence<BidiIter> parse_charset(string_iterator &begin, string_iterator end)

    {

        detail::compound_charset<traits_type> chset;

        // call out to a helper to actually parse the character set

        detail::parse_charset(begin, end, chset, this->traits_);

        return detail::make_charset_xpression<BidiIter>

        (

            chset

          , this->rxtraits()

          , this->traits_.flags()

        );

    }

    ///////////////////////////////////////////////////////////////////////////

    // parse_atom

    /// INTERNAL ONLY

    detail::sequence<BidiIter> parse_atom(string_iterator &begin, string_iterator end)

    {

        using namespace regex_constants;

        escape_value esc = { 0, 0, 0, detail::escape_char };

        string_iterator old_begin = begin;

        switch(this->traits_.get_token(begin, end))

        {

        case token_literal:

            return detail::make_literal_xpression<BidiIter>

            (

                this->parse_literal(begin, end), this->traits_.flags(), this->rxtraits()

            );

        case token_any:

            return detail::make_any_xpression<BidiIter>(this->traits_.flags(), this->rxtraits());

        case token_assert_begin_sequence:

            return detail::make_dynamic_xpression<BidiIter>(detail::assert_bos_matcher());

        case token_assert_end_sequence:

            return detail::make_dynamic_xpression<BidiIter>(detail::assert_eos_matcher());

        case token_assert_begin_line:

            return detail::make_assert_begin_line<BidiIter>(this->traits_.flags(), this->rxtraits());

        case token_assert_end_line:

            return detail::make_assert_end_line<BidiIter>(this->traits_.flags(), this->rxtraits());

        case token_assert_word_boundary:

            return detail::make_assert_word<BidiIter>(detail::word_boundary<true>(), this->rxtraits());

        case token_assert_not_word_boundary:

            return detail::make_assert_word<BidiIter>(detail::word_boundary<false>(), this->rxtraits());

        case token_assert_word_begin:

            return detail::make_assert_word<BidiIter>(detail::word_begin(), this->rxtraits());

        case token_assert_word_end:

            return detail::make_assert_word<BidiIter>(detail::word_end(), this->rxtraits());

        case token_escape:

            esc = this->parse_escape(begin, end);

            switch(esc.type_)

            {

            case detail::escape_mark:

                return detail::make_backref_xpression<BidiIter>

                (

                    esc.mark_nbr_, this->traits_.flags(), this->rxtraits()

                );

            case detail::escape_char:

                return detail::make_char_xpression<BidiIter>

                (

                    esc.ch_, this->traits_.flags(), this->rxtraits()

                );

            case detail::escape_class:

                return detail::make_posix_charset_xpression<BidiIter>

                (

                    esc.class_

                  , this->rxtraits().isctype(*begin++, this->upper_)

                  , this->traits_.flags()

                  , this->rxtraits()

                );

            }

        case token_group_begin:

            return this->parse_group(begin, end);

        case token_charset_begin:

            return this->parse_charset(begin, end);

        case token_invalid_quantifier:

            throw regex_error(error_badrepeat, "quantifier not expected");

        case token_quote_meta_begin:

            return detail::make_literal_xpression<BidiIter>

            (

                this->parse_quote_meta(begin, end), this->traits_.flags(), this->rxtraits()

            );

        case token_quote_meta_end:

            throw regex_error

            (

                error_escape

              , "found quote-meta end without corresponding quote-meta begin"

            );

        case token_end_of_pattern:

            break;

        default:

            begin = old_begin;

            break;

        }

        return detail::sequence<BidiIter>();

    }

    ///////////////////////////////////////////////////////////////////////////

    // parse_quant

    /// INTERNAL ONLY

    detail::sequence<BidiIter> parse_quant(string_iterator &begin, string_iterator end)

    {

        BOOST_ASSERT(begin != end);

        detail::quant_spec spec = { 0, 0, false };

        detail::sequence<BidiIter> seq = this->parse_atom(begin, end);

        // BUGBUG this doesn't handle the degenerate (?:)+ correctly

        if(!seq.is_empty() && begin != end && seq.first->is_quantifiable())

        {

            if(this->traits_.get_quant_spec(begin, end, spec))

            {

                BOOST_ASSERT(spec.min_ <= spec.max_);

                if(0 == spec.max_) // quant {0,0} is degenerate -- matches nothing.

                {

                    seq = this->parse_quant(begin, end);

                }

                else

                {

                    seq = seq.first->quantify(spec, this->hidden_mark_count_, seq, alternates_factory());

                }

            }

        }

        return seq;

    }

    ///////////////////////////////////////////////////////////////////////////

    // parse_sequence

    /// INTERNAL ONLY

    detail::sequence<BidiIter> parse_sequence(string_iterator &begin, string_iterator end)

    {

        detail::sequence<BidiIter> seq;

        while(begin != end)

        {

            detail::sequence<BidiIter> seq_quant = this->parse_quant(begin, end);

            // did we find a quantified atom?

            if(seq_quant.is_empty())

                break;

            // chain it to the end of the xpression sequence

            seq += seq_quant;

        }

        return seq;

    }

    ///////////////////////////////////////////////////////////////////////////

    // parse_literal

    //  scan ahead looking for char literals to be globbed together into a string literal

    /// INTERNAL ONLY

    string_type parse_literal(string_iterator &begin, string_iterator end)

    {

        using namespace regex_constants;

        BOOST_ASSERT(begin != end);

        BOOST_ASSERT(token_literal == this->traits_.get_token(begin, end));

        escape_value esc = { 0, 0, 0, detail::escape_char };

        string_type literal(1, *begin);

        for(string_iterator prev = begin, tmp = ++begin; begin != end; prev = begin, begin = tmp)

        {

            detail::quant_spec spec;

            if(this->traits_.get_quant_spec(tmp, end, spec))

            {

                if(literal.size() != 1)

                {

                    begin = prev;

                    literal.erase(literal.size() - 1);

                }

                return literal;

            }

            else switch(this->traits_.get_token(tmp, end))

            {

            case token_escape:

                esc = this->parse_escape(tmp, end);

                if(detail::escape_char != esc.type_) return literal;

                literal += esc.ch_;

                break;

            case token_literal:

                literal += *tmp++;

                break;

            default:

                return literal;

            }

        }

        return literal;

    }

    ///////////////////////////////////////////////////////////////////////////

    // parse_quote_meta

    //  scan ahead looking for char literals to be globbed together into a string literal

    /// INTERNAL ONLY

    string_type parse_quote_meta(string_iterator &begin, string_iterator end)

    {

        using namespace regex_constants;

        string_iterator old_begin = begin, old_end;

        while(end != (old_end = begin))

        {

            switch(this->traits_.get_token(begin, end))

            {

            case token_quote_meta_end: return string_type(old_begin, old_end);

            case token_escape: detail::ensure(begin != end, error_escape, "incomplete escape sequence");

            case token_literal: ++begin;

            default:;

            }

        }

        return string_type(old_begin, begin);

    }

    ///////////////////////////////////////////////////////////////////////////////

    // parse_escape

    /// INTERNAL ONLY

    escape_value parse_escape(string_iterator &begin, string_iterator end)

    {

        detail::ensure(begin != end, regex_constants::error_escape, "incomplete escape sequence");

        // first, check to see if this can be a backreference

        if(0 < this->rxtraits().value(*begin, 10))

        {

            // Parse at most 3 decimal digits.

            string_iterator tmp = begin;

            int mark_nbr = detail::toi(tmp, end, this->rxtraits(), 10, 999);

            // If the resulting number could conceivably be a backref, then it is.

            if(10 > mark_nbr || mark_nbr <= static_cast<int>(this->mark_count_))

            {

                begin = tmp;

                escape_value esc = {0, mark_nbr, 0, detail::escape_mark};

                return esc;

            }

        }

        // Not a backreference, defer to the parse_escape helper

        return detail::parse_escape(begin, end, this->traits_);

    }

    std::size_t mark_count_;

    std::size_t hidden_mark_count_;

    CompilerTraits traits_;

    typename RegexTraits::char_class_type upper_;

};

}} // namespace boost::xpressive

#endif