#ifndef SASS_LEXER_H

#define SASS_LEXER_H

#include <cstring>

namespace Sass {

  namespace Prelexer {

    //####################################

    // BASIC CHARACTER MATCHERS

    //####################################

    // Match standard control chars

    const char* kwd_at(const char* src);

    const char* kwd_dot(const char* src);

    const char* kwd_comma(const char* src);

    const char* kwd_colon(const char* src);

    const char* kwd_star(const char* src);

    const char* kwd_plus(const char* src);

    const char* kwd_minus(const char* src);

    const char* kwd_slash(const char* src);

    //####################################

    // BASIC CLASS MATCHERS

    //####################################

    // These are locale independant

    bool is_space(const char& src);

    bool is_alpha(const char& src);

    bool is_punct(const char& src);

    bool is_digit(const char& src);

    bool is_alnum(const char& src);

    bool is_xdigit(const char& src);

    bool is_unicode(const char& src);

    bool is_nonascii(const char& src);

    bool is_character(const char& src);

    bool is_uri_character(const char& src);

    bool escapable_character(const char& src);

    // Match a single ctype predicate.

    const char* space(const char* src);

    const char* alpha(const char* src);

    const char* digit(const char* src);

    const char* xdigit(const char* src);

    const char* alnum(const char* src);

    const char* punct(const char* src);

    const char* hyphen(const char* src);

    const char* unicode(const char* src);

    const char* nonascii(const char* src);

    const char* character(const char* src);

    const char* uri_character(const char* src);

    const char* escapable_character(const char* src);

    // Match multiple ctype characters.

    const char* spaces(const char* src);

    const char* digits(const char* src);

    const char* hyphens(const char* src);

    // Whitespace handling.

    const char* no_spaces(const char* src);

    const char* optional_spaces(const char* src);

    // Match any single character (/./).

    const char* any_char(const char* src);

    // Assert word boundary (/\b/)

    // Is a zero-width positive lookaheads

    const char* word_boundary(const char* src);

    // Match a single linebreak (/(?:\n|\r\n?)/).

    const char* re_linebreak(const char* src);

    // Assert string boundaries (/\Z|\z|\A/)

    // There are zero-width positive lookaheads

    const char* end_of_line(const char* src);

    // Assert end_of_file boundary (/\z/)

    const char* end_of_file(const char* src);

    // const char* start_of_string(const char* src);

    // Type definition for prelexer functions

    typedef const char* (*prelexer)(const char*);

    //####################################

    // BASIC "REGEX" CONSTRUCTORS

    //####################################

    // Match a single character literal.

    // Regex equivalent: /(?:x)/

    template <char chr>

    const char* exactly(const char* src) {

      return *src == chr ? src + 1 : 0;

    }

    // Match the full string literal.

    // Regex equivalent: /(?:literal)/

    template <const char* str>

    const char* exactly(const char* src) {

      if (str == NULL) return 0;

      const char* pre = str;

      if (src == NULL) return 0;

      // there is a small chance that the search string

      // is longer than the rest of the string to look at

      while (*pre && *src == *pre) {

        ++src, ++pre;

      }

      // did the matcher finish?

      return *pre == 0 ? src : 0;

    }

    // Match the full string literal.

    // Regex equivalent: /(?:literal)/i

    // only define lower case alpha chars

    template <const char* str>

    const char* insensitive(const char* src) {

      if (str == NULL) return 0;

      const char* pre = str;

      if (src == NULL) return 0;

      // there is a small chance that the search string

      // is longer than the rest of the string to look at

      while (*pre && (*src == *pre || *src+32 == *pre)) {

        ++src, ++pre;

      }

      // did the matcher finish?

      return *pre == 0 ? src : 0;

    }

    // Match for members of char class.

    // Regex equivalent: /[axy]/

    template <const char* char_class>

    const char* class_char(const char* src) {

      const char* cc = char_class;

      while (*cc && *src != *cc) ++cc;

      return *cc ? src + 1 : 0;

    }

    // Match for members of char class.

    // Regex equivalent: /[axy]+/

    template <const char* char_class>

    const char* class_chars(const char* src) {

      const char* p = src;

      while (class_char<char_class>(p)) ++p;

      return p == src ? 0 : p;

    }

    // Match for members of char class.

    // Regex equivalent: /[^axy]/

    template <const char* neg_char_class>

    const char* neg_class_char(const char* src) {

      if (*src == 0) return 0;

      const char* cc = neg_char_class;

      while (*cc && *src != *cc) ++cc;

      return *cc ? 0 : src + 1;

    }

    // Match for members of char class.

    // Regex equivalent: /[^axy]+/

    template <const char* neg_char_class>

    const char* neg_class_chars(const char* src) {

      const char* p = src;

      while (neg_class_char<neg_char_class>(p)) ++p;

      return p == src ? 0 : p;

    }

    // Match all except the supplied one.

    // Regex equivalent: /[^x]/

    template <const char chr>

    const char* any_char_but(const char* src) {

      return (*src && *src != chr) ? src + 1 : 0;

    }

    // Succeeds if the matcher fails.

    // Aka. zero-width negative lookahead.

    // Regex equivalent: /(?!literal)/

    template <prelexer mx>

    const char* negate(const char* src) {

      return mx(src) ? 0 : src;

    }

    // Succeeds if the matcher succeeds.

    // Aka. zero-width positive lookahead.

    // Regex equivalent: /(?=literal)/

    // just hangs around until we need it

    template <prelexer mx>

    const char* lookahead(const char* src) {

      return mx(src) ? src : 0;

    }

    // Tries supplied matchers in order.

    // Succeeds if one of them succeeds.

    // Regex equivalent: /(?:FOO|BAR)/

    template <const prelexer mx>

    const char* alternatives(const char* src) {

      const char* rslt;

      if ((rslt = mx(src))) return rslt;

      return 0;

    }

    template <const prelexer mx1, const prelexer mx2, const prelexer... mxs>

    const char* alternatives(const char* src) {

      const char* rslt;

      if ((rslt = mx1(src))) return rslt;

      return alternatives<mx2, mxs...>(src);

    }

    // Tries supplied matchers in order.

    // Succeeds if all of them succeeds.

    // Regex equivalent: /(?:FOO)(?:BAR)/

    template <const prelexer mx1>

    const char* sequence(const char* src) {

      const char* rslt = src;

      if (!(rslt = mx1(rslt))) return 0;

      return rslt;

    }

    template <const prelexer mx1, const prelexer mx2, const prelexer... mxs>

    const char* sequence(const char* src) {

      const char* rslt = src;

      if (!(rslt = mx1(rslt))) return 0;

      return sequence<mx2, mxs...>(rslt);

    }

    // Match a pattern or not. Always succeeds.

    // Regex equivalent: /(?:literal)?/

    template <prelexer mx>

    const char* optional(const char* src) {

      const char* p = mx(src);

      return p ? p : src;

    }

    // Match zero or more of the patterns.

    // Regex equivalent: /(?:literal)*/

    template <prelexer mx>

    const char* zero_plus(const char* src) {

      const char* p = mx(src);

      while (p) src = p, p = mx(src);

      return src;

    }

    // Match one or more of the patterns.

    // Regex equivalent: /(?:literal)+/

    template <prelexer mx>

    const char* one_plus(const char* src) {

      const char* p = mx(src);

      if (!p) return 0;

      while (p) src = p, p = mx(src);

      return src;

    }

    // Match mx non-greedy until delimiter.

    // Other prelexers are greedy by default.

    // Regex equivalent: /(?:$mx)*?(?=$delim)\b/

    template <prelexer mx, prelexer delim>

    const char* non_greedy(const char* src) {

      while (!delim(src)) {

        const char* p = mx(src);

        if (p == src) return 0;

        if (p == 0) return 0;

        src = p;

      }

      return src;

    }

    //####################################

    // ADVANCED "REGEX" CONSTRUCTORS

    //####################################

    // Match with word boundary rule.

    // Regex equivalent: /(?:$mx)\b/i

    template <const char* str>

    const char* keyword(const char* src) {

      return sequence <

               insensitive < str >,

               word_boundary

             >(src);

    }

    // Match with word boundary rule.

    // Regex equivalent: /(?:$mx)\b/

    template <const char* str>

    const char* word(const char* src) {

      return sequence <

               exactly < str >,

               word_boundary

             >(src);

    }

    template <char chr>

    const char* loosely(const char* src) {

      return sequence <

               optional_spaces,

               exactly < chr >

             >(src);

    }

    template <const char* str>

    const char* loosely(const char* src) {

      return sequence <

               optional_spaces,

               exactly < str >

             >(src);

    }

  }

}

#endif