regeximpl.h

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#ifndef REGEXIMPL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
#define REGEXIMPL_H_62B23520_7C8E_11DE_8A39_0800200C9A66

#if defined(_MSC_VER) || (defined(__GNUC__) && (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4)) // GCC supports "pragma once" correctly since 3.4
#pragma once
#endif


#include "stream.h"
#include "stringsource.h"
#include "streamcharsource.h"

namespace YAML_PM
{
        // query matches
        inline bool RegEx::Matches(char ch) const {
                std::string str;
                str += ch;
                return Matches(str);
        }
        
        inline bool RegEx::Matches(const std::string& str) const {
                return Match(str) >= 0;
        }
        
        inline bool RegEx::Matches(const Stream& in) const {
                return Match(in) >= 0;
        }

        template <typename Source>
        inline bool RegEx::Matches(const Source& source) const {
                return Match(source) >= 0;
        }

        // Match
        // . Matches the given string against this regular expression.
        // . Returns the number of characters matched.
        // . Returns -1 if no characters were matched (the reason for
        //   not returning zero is that we may have an empty regex
        //   which is ALWAYS successful at matching zero characters).
        // . REMEMBER that we only match from the start of the buffer!  
        inline int RegEx::Match(const std::string& str) const
        {
                StringCharSource source(str.c_str(), str.size());
                return Match(source);
        }
        
        inline int RegEx::Match(const Stream& in) const
        {
                StreamCharSource source(in);
                return Match(source);
        }

        template <typename Source>
        inline bool RegEx::IsValidSource(const Source& source) const
        {
                return source;
        }
        
        template<>
        inline bool RegEx::IsValidSource<StringCharSource>(const StringCharSource&source) const
        {
                switch(m_op) {
                        case REGEX_MATCH:
                        case REGEX_RANGE:
                                return source;
                        default:
                                return true;
                }
        }

        template <typename Source>
        inline int RegEx::Match(const Source& source) const
        {
                return IsValidSource(source) ? MatchUnchecked(source) : -1;
        }
        
        template <typename Source>
        inline int RegEx::MatchUnchecked(const Source& source) const
        {
                switch(m_op) {
                        case REGEX_EMPTY:
                                return MatchOpEmpty(source);
                        case REGEX_MATCH:
                                return MatchOpMatch(source);
                        case REGEX_RANGE:
                                return MatchOpRange(source);
                        case REGEX_OR:
                                return MatchOpOr(source);
                        case REGEX_AND:
                                return MatchOpAnd(source);
                        case REGEX_NOT:
                                return MatchOpNot(source);
                        case REGEX_SEQ:
                                return MatchOpSeq(source);
                }
                
                return -1;
        }

        // Operators
        // Note: the convention MatchOp*<Source> is that we can assume IsSourceValid(source).
        //       So we do all our checks *before* we call these functions
        
        // EmptyOperator
        template <typename Source>
        inline int RegEx::MatchOpEmpty(const Source& source) const {
                return source[0] == Stream::eof() ? 0 : -1;
        }
        
        template <>
        inline int RegEx::MatchOpEmpty<StringCharSource>(const StringCharSource& source) const {
                return !source ? 0 : -1;  // the empty regex only is successful on the empty string
        }

        // MatchOperator
        template <typename Source>
        inline int RegEx::MatchOpMatch(const Source& source) const {
                if(source[0] != m_a)
                        return -1;
                return 1;
        }
        
        // RangeOperator
        template <typename Source>
        inline int RegEx::MatchOpRange(const Source& source) const {
                if(m_a > source[0] || m_z < source[0])
                        return -1;
                return 1;
        }
        
        // OrOperator
        template <typename Source>
        inline int RegEx::MatchOpOr(const Source& source) const {
                for(std::size_t i=0;i<m_params.size();i++) {
                        int n = m_params[i].MatchUnchecked(source);
                        if(n >= 0)
                                return n;
                }
                return -1;
        }
        
        // AndOperator
        // Note: 'AND' is a little funny, since we may be required to match things
        //       of different lengths. If we find a match, we return the length of
        //       the FIRST entry on the list.
        template <typename Source>
        inline int RegEx::MatchOpAnd(const Source& source) const {
                int first = -1;
                for(std::size_t i=0;i<m_params.size();i++) {
                        int n = m_params[i].MatchUnchecked(source);
                        if(n == -1)
                                return -1;
                        if(i == 0)
                                first = n;
                }
                return first;
        }
        
        // NotOperator
        template <typename Source>
        inline int RegEx::MatchOpNot(const Source& source) const {
                if(m_params.empty())
                        return -1;
                if(m_params[0].MatchUnchecked(source) >= 0)
                        return -1;
                return 1;
        }
        
        // SeqOperator
        template <typename Source>
        inline int RegEx::MatchOpSeq(const Source& source) const {
                int offset = 0;
                for(std::size_t i=0;i<m_params.size();i++) {
                        int n = m_params[i].Match(source + offset); // note Match, not MatchUnchecked because we need to check validity after the offset
                        if(n == -1)
                                return -1;
                        offset += n;
                }
                
                return offset;
        }
}

#endif // REGEXIMPL_H_62B23520_7C8E_11DE_8A39_0800200C9A66