medit/moo/mooedit/moolang-rules.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4; coding: utf-8 -*-
 *
 *   moolang-rules.c
 *
 *   Copyright (C) 2004-2006 by Yevgen Muntyan <muntyan@math.tamu.edu>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   See COPYING file that comes with this distribution.
 */

#define MOOEDIT_COMPILATION
#include "mooedit/moolang-rules.h"
#include "mooedit/moolang-aux.h"


typedef MooRuleMatchFlags MatchFlags;
#define MATCH_START_ONLY MOO_RULE_MATCH_START_ONLY

#define MooRuleString MooRuleAsciiString
#define MooRuleChar MooRuleAsciiChar
#define MooRule2Char MooRuleAscii2Char
#define MooRuleAnyChar MooRuleAsciiAnyChar

typedef MooRule* (*MatchFunc)   (MooRule            *self,
                                 MooRuleMatchData   *data,
                                 MooRuleMatchResult *result,
                                 MooRuleMatchFlags   flags);
typedef void     (*DestroyFunc) (MooRule            *self);


static MooRule *rule_new            (MooRuleFlags    flags,
                                     const char     *style,
                                     MatchFunc       match_func,
                                     DestroyFunc     destroy_func);


static void     child_rules_match   (MooRuleArray   *array,
                                     MatchData      *data,
                                     MatchResult    *result);
static MooRule *rules_match_real    (MooRuleArray   *array,
                                     MatchData      *data,
                                     MatchResult    *result,
                                     MatchFlags      flags);


void
moo_match_data_init (MatchData          *data,
                     int                 line_number,
                     const GtkTextIter  *line_start,
                     const GtkTextIter  *line_end)
{
    GtkTextBuffer *buffer;

    g_assert (data != NULL);
    g_assert (line_start && gtk_text_iter_starts_line (line_start));
    g_assert (line_number == gtk_text_iter_get_line (line_start));
    g_assert (!line_end || gtk_text_iter_ends_line (line_end));

    data->line_start = *line_start;
    data->line_number = line_number;

    if (line_end)
    {
        data->line_end = *line_end;
    }
    else
    {
        data->line_end = *line_start;
        if (!gtk_text_iter_ends_line (&data->line_end))
            gtk_text_iter_forward_to_line_end (&data->line_end);
    }

    buffer = gtk_text_iter_get_buffer (line_start);
    data->line_string = gtk_text_buffer_get_slice (buffer, line_start, &data->line_end, TRUE);
    data->line_string_len = strlen (data->line_string);

    data->start_iter = *line_start;
    data->start = data->line_string;
    data->start_offset = 0;
}


void
moo_match_data_set_start (MatchData          *data,
                          const GtkTextIter  *start_iter,
                          char               *start,
                          int                 start_offset)
{
    g_assert (data != NULL);
    g_assert (start != NULL);
    g_assert (start_offset >= 0);

    data->start = start;
    data->start_offset = start_offset;

    if (start_iter)
    {
        data->start_iter = *start_iter;
    }
    else
    {
        data->start_iter = data->line_start;
        gtk_text_iter_forward_chars (&data->start_iter, start_offset);
    }
}


void
moo_match_data_destroy (MatchData *data)
{
    if (data->line_string)
        g_free (data->line_string);
}


static MooRule*
rules_match_real (MooRuleArray       *array,
                  MatchData          *data,
                  MatchResult        *result,
                  MatchFlags          flags)
{
    guint i;
    MooRule *matched = NULL;
    MatchResult tmp;

    g_assert (array != NULL);

    if (!array->len)
        return NULL;

    g_assert (data->line_string_len >= 0);

    if (flags & MATCH_START_ONLY)
    {
        data->limit = data->start;
        data->limit_offset = 0;
    }
    else
    {
        data->limit = data->line_string + data->line_string_len; /* this points to the zero char, so it's fine */
        data->limit_offset = SIZE_NOT_SET;
    }

    for (i = 0; i < array->len; ++i)
    {
        MooRule *rule = array->data[i];
        MooRule *matched_here = NULL;

        if (!(flags & MATCH_START_ONLY))
        {
            /* TODO: first-non-blank */
            if ((rule->flags & MOO_RULE_MATCH_FIRST_CHAR) && data->start != data->line_string)
                continue;
        }

        if ((rule->flags & MOO_RULE_MATCH_FIRST_LINE) && data->line_number != 0)
            continue;

        matched_here = rule->match (rule, data, &tmp, flags);

        if (matched_here)
        {
            if (!(flags & MATCH_START_ONLY))
            {
                if (!matched || tmp.match_start < result->match_start)
                {
                    matched = matched_here ? matched_here : rule;
                    *result = tmp;
                    data->limit = tmp.match_start;
                    data->limit_offset = tmp.match_offset;

                    if (data->limit == data->start)
                        break;

                    g_assert (data->limit_offset != 0);

                    data->limit = utf8_offset_to_pointer (data->limit, -1);

                    if (data->limit_offset > 0)
                        data->limit_offset -= 1;
                }

                if (tmp.match_start == data->start)
                    break;
            }
            else
            {
                matched = matched_here ? matched_here : rule;
                *result = tmp;
                break;
            }
        }
    }

    if (matched && matched->child_rules)
        child_rules_match (matched->child_rules, data, result);

    return matched;
}


static void
child_rules_match (MooRuleArray       *array,
                   MatchData          *data,
                   MatchResult        *result)
{
    MatchResult tmp;
    MooRule *matched;
    char *saved_start;

    g_assert (array != NULL);
    g_assert (result->match_start != NULL);
    g_assert (result->match_end != NULL);
    g_assert (result->match_start <= result->match_end);

    tmp = *result;
    saved_start = data->start;
    data->start = result->match_end;

    matched = rules_match_real (array, data, &tmp, MATCH_START_ONLY);

    if (matched)
    {
        g_return_if_fail (tmp.match_start == result->match_end);
        result->match_end = tmp.match_end;
        if (tmp.match_len >= 0)
        {
            if (result->match_len >= 0)
                result->match_len += tmp.match_len;
        }
        else
        {
            result->match_len = -1;
        }
    }

    data->start = saved_start;
}


MooRule*
moo_rule_array_match (MooRuleArray       *array,
                      MatchData          *data,
                      MatchResult        *result)
{
    return rules_match_real (array, data, result, 0);
}


static MooRule*
rule_new (MooRuleFlags    flags,
          const char     *style,
          MatchFunc       match_func,
          DestroyFunc     destroy_func)
{
    MooRule *rule;

    g_return_val_if_fail (match_func != NULL, NULL);

    rule = g_new0 (MooRule, 1);
    rule->match = match_func;
    rule->destroy = destroy_func;
    rule->flags = flags;
    rule->style = g_strdup (style);

    return rule;
}


void
moo_rule_free (MooRule *rule)
{
    guint i;

    if (!rule)
        return;

    if (rule->destroy)
        rule->destroy (rule);

    if (rule->child_rules)
    {
        for (i = 0; i < rule->child_rules->len; ++i)
            moo_rule_free (rule->child_rules->data[i]);
        g_ptr_array_free ((GPtrArray*) rule->child_rules, TRUE);
    }

    g_free (rule->description);
    g_free (rule->style);
    g_free (rule);
}


void
moo_rule_add_child_rule (MooRule   *rule,
                         MooRule   *child_rule)
{
    g_return_if_fail (rule != NULL && child_rule != NULL);

    if (!rule->child_rules)
        rule->child_rules = (MooRuleArray*) g_ptr_array_new ();

    g_ptr_array_add ((GPtrArray*) rule->child_rules, child_rule);
}


void
moo_rule_set_end_stay (MooRule            *rule)
{
    g_return_if_fail (rule != NULL);
    rule->exit.type = MOO_CONTEXT_STAY;
    rule->exit.num = 0;
}


void
moo_rule_set_end_pop (MooRule            *rule,
                      guint               num)
{
    g_return_if_fail (rule != NULL && num != 0);
    rule->exit.type = MOO_CONTEXT_POP;
    rule->exit.num = num;
}


void
moo_rule_set_end_switch (MooRule            *rule,
                         MooContext         *target)
{
    g_return_if_fail (rule != NULL && target != 0);
    rule->exit.type = MOO_CONTEXT_SWITCH;
    rule->exit.ctx = target;
}


/*************************************************************************/
/* String match
 */

static MooRule*
rule_string_match (MooRule        *rule,
                   MatchData      *data,
                   MatchResult    *result,
                   MatchFlags      flags)
{
    /* TODO: limit */

    result->match_start = NULL;

    if (rule->str.caseless)
    {
        if (flags & MATCH_START_ONLY)
        {
            if (!g_ascii_strncasecmp (data->start, rule->str.string, rule->str.length))
                result->match_start = data->start;
        }
        else
        {
            result->match_start = ascii_casestrstr (data->start, rule->str.string, data->limit);
        }
    }
    else
    {
        if (flags & MATCH_START_ONLY)
        {
            if (!strncmp (data->start, rule->str.string, rule->str.length))
                result->match_start = data->start;
        }
        else
        {
            result->match_start = strstr (data->start, rule->str.string);
        }
    }

    if (!result->match_start)
        return NULL;

    result->match_end = result->match_start + rule->str.length;
    result->match_len = rule->str.length;
    result->match_offset = -1;
    return rule;
}


static void
rule_string_destroy (MooRule *rule)
{
    g_free (rule->str.string);
}


MooRule*
moo_rule_string_new (const char         *string,
                     MooRuleFlags        flags,
                     const char         *style)
{
    MooRule *rule;
    guint length;

    g_return_val_if_fail (string && string[0], NULL);
    g_return_val_if_fail (g_utf8_validate (string, -1, NULL), NULL);
    g_return_val_if_fail (string_is_ascii (string), NULL);

    length = strlen (string);

    g_return_val_if_fail (length != 0, NULL);

    rule = rule_new (flags, style, rule_string_match, rule_string_destroy);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup_printf ("STRING %s", string);

    rule->str.caseless = (flags & MOO_RULE_MATCH_CASELESS) ? TRUE : FALSE;

    if (rule->str.caseless)
        rule->str.string = g_ascii_strdown (string, -1);
    else
        rule->str.string = g_strdup (string);

    rule->str.length = length;

    return rule;
}


/*************************************************************************/
/* Regex match
 */

static MooRule*
rule_regex_match (MooRule        *rule,
                  MatchData      *data,
                  MatchResult    *result,
                  MatchFlags      flags)
{
    /* TODO: limit */
    /* XXX line start and stuff */
    int n_matches, start_pos, end_pos;
    EggRegexMatchFlags regex_flags = 0;

    egg_regex_clear (rule->regex.regex);

    if (flags & MATCH_START_ONLY)
        regex_flags |= EGG_REGEX_MATCH_ANCHORED;

    n_matches = egg_regex_match_extended (rule->regex.regex,
                                          data->line_string,
                                          data->line_string_len,
                                          data->start - data->line_string,
                                          regex_flags);

    if (n_matches < 1)
        return NULL;

    egg_regex_fetch_pos (rule->regex.regex, data->line_string, 0,
                         &start_pos, &end_pos);

    if (data->line_string + start_pos > data->limit)
        return NULL;

    result->match_start = data->line_string + start_pos;
    result->match_end = data->line_string + end_pos;

    result->match_len = -1;
    result->match_offset = -1;

    return rule;
}


static void
rule_regex_destroy (MooRule *rule)
{
    egg_regex_free (rule->regex.regex);
}


MooRule*
moo_rule_regex_new (const char         *pattern,
                    gboolean            non_empty,
                    EggRegexCompileFlags regex_compile_options,
                    EggRegexMatchFlags  regex_match_options,
                    MooRuleFlags        flags,
                    const char         *style)
{
    MooRule *rule;
    EggRegex *regex;
    GError *error = NULL;

    g_return_val_if_fail (pattern && pattern[0], NULL);

    if (flags & MOO_RULE_MATCH_CASELESS)
        regex_compile_options |= EGG_REGEX_CASELESS;

    if (non_empty)
        regex_match_options |= EGG_REGEX_MATCH_NOTEMPTY;

    regex = egg_regex_new (pattern, regex_compile_options,
                           regex_match_options, &error);

    if (!regex)
    {
        g_warning ("could not compile pattern '%s': %s",
                   pattern, error->message);
        g_error_free (error);
        return NULL;
    }

    egg_regex_optimize (regex, &error);

    if (error)
    {
        g_warning ("egg_regex_optimize() failed: %s", error->message);
        g_error_free (error);
    }

    if (pattern[0] == '^')
        flags |= MOO_RULE_MATCH_FIRST_CHAR;

    rule = rule_new (flags, style, rule_regex_match, rule_regex_destroy);

    if (!rule)
    {
        egg_regex_free (regex);
        return NULL;
    }

    rule->description = g_strdup_printf ("REGEX %s", pattern);

    rule->regex.regex = regex;

    return rule;
}


/*************************************************************************/
/* Char match
 */

static MooRule*
rule_char_match (MooRule        *rule,
                 MatchData      *data,
                 MatchResult    *result,
                 MatchFlags      flags)
{
    result->match_start = NULL;

    if (flags & MATCH_START_ONLY)
    {
        if (rule->_char.caseless)
        {
            if (data->start[0] == rule->_char.ch)
                result->match_start = data->start;
        }
        else
        {
            if (g_ascii_tolower (data->start[0]) == rule->_char.ch)
                result->match_start = data->start;
        }
    }
    else
    {
        if (rule->_char.caseless)
            result->match_start = ascii_lower_strchr (data->start, rule->_char.ch, data->limit);
        else
            result->match_start = ascii_strchr (data->start, rule->_char.ch, data->limit);
    }

    if (!result->match_start)
        return NULL;

    result->match_end = result->match_start + 1;
    result->match_len = 1;
    result->match_offset = -1;

    return rule;
}


static MooRule*
rule_2char_match (MooRule        *rule,
                  MatchData      *data,
                  MatchResult    *result,
                  MatchFlags      flags)
{
    result->match_start = NULL;

    if (flags & MATCH_START_ONLY)
    {
        if (data->start[0] == rule->_2char.str[0] && data->start[1] == rule->_2char.str[1])
            result->match_start = data->start;
    }
    else
    {
        result->match_start = strstr (data->start, rule->_2char.str);
    }

    if (!result->match_start)
        return NULL;

    result->match_end = result->match_start + 2;
    result->match_len = 2;
    result->match_offset = -1;
    return rule;
}


MooRule*
moo_rule_char_new (char                ch,
                   MooRuleFlags        flags,
                   const char         *style)
{
    MooRule *rule;

    g_return_val_if_fail (ch && CHAR_IS_ASCII (ch), NULL);

    rule = rule_new (flags, style, rule_char_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup_printf ("CHAR %c", ch);

    if (flags & MOO_RULE_MATCH_CASELESS)
    {
        rule->_char.ch = g_ascii_tolower (ch);
        rule->_char.caseless = TRUE;
    }
    else
    {
        rule->_char.ch = ch;
    }

    return rule;
}


MooRule*
moo_rule_2char_new (char                ch1,
                    char                ch2,
                    MooRuleFlags        flags,
                    const char         *style)
{
    MooRule *rule;

    g_return_val_if_fail (ch1 && CHAR_IS_ASCII (ch1), NULL);
    g_return_val_if_fail (ch2 && CHAR_IS_ASCII (ch2), NULL);

    rule = rule_new (flags, style, rule_2char_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup_printf ("TWOCHARS %c%c", ch1, ch2);

    if (flags & MOO_RULE_MATCH_CASELESS)
    {
        ch1 = g_ascii_tolower (ch1);
        ch2 = g_ascii_tolower (ch2);
    }

    rule->_2char.str[0] = ch1;
    rule->_2char.str[1] = ch2;
    rule->_2char.str[2] = 0;

    return rule;
}


/*************************************************************************/
/* AnyChar match
 */

static MooRule*
rule_any_char_match (MooRule        *rule,
                     MatchData      *data,
                     MatchResult    *result,
                     MatchFlags      flags)
{
    guint i;

    result->match_start = NULL;

    if (flags & MATCH_START_ONLY)
    {
        for (i = 0; i < rule->anychar.n_chars; ++i)
        {
            if (data->start[0] == rule->anychar.chars[i])
            {
                result->match_start = data->start;
                break;
            }
        }
    }
    else
    {
        for (i = 0; i < rule->anychar.n_chars; ++i)
        {
            if (!result->match_start)
            {
                result->match_start = ascii_strchr (data->start, rule->anychar.chars[i], data->limit);
            }
            else if (result->match_start == data->start + 1)
            {
                if (data->start[0] == rule->anychar.chars[i])
                {
                    result->match_start = data->start;
                    break;
                }
            }
            else
            {
                char *tmp = ascii_strchr (data->start, rule->anychar.chars[i], data->limit);
                if (tmp < result->match_start)
                    result->match_start = tmp;
            }

            if (result->match_start == data->start)
                break;
        }
    }

    if (!result->match_start)
        return NULL;

    result->match_end = result->match_start + 1;
    result->match_len = 1;
    result->match_offset = -1;
    return rule;
}


static void
rule_any_char_destroy (MooRule *rule)
{
    g_free (rule->anychar.chars);
}


MooRule*
moo_rule_any_char_new (const char         *string,
                       MooRuleFlags        flags,
                       const char         *style)
{
    MooRule *rule;
    guint i, len;

    g_return_val_if_fail (string && string[0], NULL);

    len = strlen (string);

    for (i = 0; i < len; ++i)
        g_return_val_if_fail (CHAR_IS_ASCII (string[i]), NULL);

    rule = rule_new (flags, style, rule_any_char_match, rule_any_char_destroy);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup_printf ("ANYCHAR %s", string);

    rule->anychar.n_chars = len;
    rule->anychar.chars = g_strdup (string);

    return rule;
}


/*************************************************************************/
/* Keywords
 */

MooRule*
moo_rule_keywords_new (GSList             *words,
                       MooRuleFlags        flags,
                       gboolean            word_boundary,
                       const char         *style)
{
    GSList *l;
    GString *pattern;
    MooRule *rule = NULL;

    g_return_val_if_fail (words != NULL, NULL);

    if (word_boundary)
        pattern = g_string_new ("\\b(");
    else
        pattern = g_string_new ("(");

    for (l = words; l != NULL; l = l->next)
    {
        char *word = l->data;

        if (!word || !word[0])
        {
            g_warning ("%s: empty keyword", G_STRLOC);
            goto out;
        }

        if (l != words)
            g_string_append_c (pattern, '|');

        g_string_append (pattern, word);
    }

    if (word_boundary)
        g_string_append (pattern, ")\\b");
    else
        g_string_append (pattern, ")");

    rule = moo_rule_regex_new (pattern->str, TRUE, 0, 0, flags, style);

out:
    g_string_free (pattern, TRUE);
    return rule;
}


/*************************************************************************/
/* IncludeRules
 */

static MooRule*
rule_include_match (MooRule        *rule,
                    MatchData      *data,
                    MatchResult    *result,
                    MatchFlags      flags)
{
    return rules_match_real (rule->incl.ctx->rules, data, result, flags);
}


MooRule*
moo_rule_include_new (MooContext *ctx)
{
    MooRule *rule;

    g_return_val_if_fail (ctx != NULL, NULL);

    rule = rule_new (0, NULL, rule_include_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup_printf ("INCLUDE %s", ctx->name);

    rule->incl.ctx = ctx;

    return rule;
}


/*************************************************************************/
/* Special sequences
 */

inline static char *
find_digit (char *string,
            char *limit,
            char *line_start)
{
    while (TRUE)
    {
        while (string <= limit && !CHAR_IS_DIGIT (*string))
            string++;

        if (string > limit)
            return NULL;

        if (string == line_start || !CHAR_IS_WORD (string[-1]))
            return string;
    }

    return NULL;
}


static MooRule*
rule_int_match (MooRule        *rule,
                MatchData      *data,
                MatchResult    *result,
                MatchFlags      flags)
{
    guint i;
    char *limit = data->limit;
    char *start = data->start;

    if (flags & MATCH_START_ONLY)
        limit = start;

    while (start <= limit)
    {
        start = find_digit (start, limit, data->line_string);

        if (!start)
            return NULL;

        for (i = 1; CHAR_IS_DIGIT (start[i]); ++i) ;

        if (!CHAR_IS_WORD (start[i]))
        {
            result->match_start = start;
            result->match_end = start + i;
            result->match_len = i;
            result->match_offset = -1;
            return rule;
        }

        start = start + i;
    }

    return NULL;
}


MooRule*
moo_rule_int_new (MooRuleFlags   flags,
                  const char    *style)
{
    MooRule *rule = rule_new (flags, style, rule_int_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup ("INT");

    return rule;
}


static MooRule*
rule_float_match (MooRule        *rule,
                  MatchData      *data,
                  MatchResult    *result,
                  MatchFlags      flags)
{
    guint i;
    char *limit = data->limit;
    char *start = data->start;

    if (flags & MATCH_START_ONLY)
        limit = start;

    while (start <= limit)
    {
        while (start <= limit && !CHAR_IS_DIGIT (*start) && *start != '.')
            start++;

        if (start > limit)
            return NULL;

        if (*start == '.')
        {
            if (start > data->line_string && CHAR_IS_DIGIT (start[-1]))
            {
                do start++;
                while (start <= limit && CHAR_IS_DIGIT (*start));
                continue;
            }

            if (!CHAR_IS_DIGIT (start[1]))
            {
                start++;
                continue;
            }

            for (i = 2; CHAR_IS_DIGIT (start[i]); ++i) ;

            if (CHAR_IS_WORD (start[i]))
            {
                start = start + i;
                continue;
            }

            result->match_start = start;
            result->match_end = start + i;
            result->match_len = i;
            result->match_offset = -1;
            return rule;
        }
        else
        {
            if (start > data->line_string && CHAR_IS_WORD (start[-1]))
            {
                do start++;
                while (start <= limit && CHAR_IS_DIGIT (*start));
                continue;
            }

            for (i = 1; CHAR_IS_DIGIT (start[i]); ++i) ;

            if (start[i] != '.')
            {
                start = start + i;
                continue;
            }

            for (i = i + 1; CHAR_IS_DIGIT (start[i]); ++i) ;

            if (CHAR_IS_WORD (start[i]))
            {
                start = start + i;
                continue;
            }

            result->match_start = start;
            result->match_end = start + i;
            result->match_len = i;
            result->match_offset = -1;
            return rule;
        }
    }

    return NULL;
}


#define PATTERN_OCTAL       "0[0-7]+"
#define PATTERN_HEX         "0x[0-9A-Fa-f]+"
#define PATTERN_ESC_CHAR    "\\\\([abefnrtv\"'?\\\\]|0[0-7]*|x[0-9A-Fa-f])"
#define PATTERN_C_CHAR      "'" PATTERN_ESC_CHAR "'"
#define PATTERN_IDENTIFIER  "[a-zA-Z_][a-zA-Z0-9_]*"
#define PATTERN_WHITESPACE  "\\s+"


MooRule*
moo_rule_float_new (MooRuleFlags        flags,
                    const char         *style)
{
    MooRule *rule = rule_new (flags, style, rule_float_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup ("FLOAT");

    return rule;
}


static MooRule*
rule_octal_match (MooRule        *rule,
                  MatchData      *data,
                  MatchResult    *result,
                  MatchFlags      flags)
{
    guint i;
    char *limit = data->limit;
    char *start = data->start;

    if (flags & MATCH_START_ONLY)
        limit = start;

    while (start <= limit)
    {
        while (start <= limit && !CHAR_IS_DIGIT (*start))
            start++;

        if (start > limit)
            return NULL;

        if ((start != data->line_string && CHAR_IS_WORD (start[-1])) ||
             *start != '0')
        {
            while (start <= limit && CHAR_IS_DIGIT (*start))
                start++;
            continue;
        }

        for (i = 1; CHAR_IS_OCTAL (start[i]); ++i) ;

        if (CHAR_IS_WORD (start[i]) || i < 2)
        {
            start = start + i;
            continue;
        }

        result->match_start = start;
        result->match_end = start + i;
        result->match_len = i;
        result->match_offset = -1;
        return rule;
    }

    return NULL;
}


MooRule*
moo_rule_octal_new (MooRuleFlags        flags,
                    const char         *style)
{
    MooRule *rule = rule_new (flags, style, rule_octal_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup ("OCTAL");

    return rule;
}


static MooRule*
rule_hex_match (MooRule        *rule,
                MatchData      *data,
                MatchResult    *result,
                MatchFlags      flags)
{
    guint i;
    char *limit = data->limit;
    char *start = data->start;

    if (flags & MATCH_START_ONLY)
        limit = start;

    while (start <= limit)
    {
        while (start <= limit && *start != '0')
            start++;

        if (start > limit)
            return NULL;

        if ((start != data->line_string && CHAR_IS_WORD (start[-1])) ||
             (start[1] != 'x' && start[1] != 'X'))
        {
            start += 2;
            continue;
        }

        for (i = 2; CHAR_IS_HEX (start[i]); ++i) ;

        if (CHAR_IS_WORD (start[i]) || i < 2)
        {
            start = start + i;
            continue;
        }

        result->match_start = start;
        result->match_end = start + i;
        result->match_len = i;
        result->match_offset = -1;
        return rule;
    }

    return NULL;
}


MooRule*
moo_rule_hex_new (MooRuleFlags        flags,
                  const char         *style)
{
    MooRule *rule = rule_new (flags, style, rule_hex_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);

    rule->description = g_strdup ("HEX");

    return rule;
}


static MooRule*
rule_escaped_char_match (MooRule        *rule,
                         MatchData      *data,
                         MatchResult    *result,
                         MatchFlags      flags)
{
    guint i;
    char *limit = data->limit;
    char *start = data->start;

    if (flags & MATCH_START_ONLY)
        limit = start;

    while (start <= limit)
    {
        while (start <= limit && *start != '\\')
            start++;

        if (start > limit)
            return NULL;

        switch (start[1])
        {
            case '\\':
            case 'a':
            case 'b':
            case 'e':
            case 'f':
            case 'n':
            case 'r':
            case 't':
            case 'v':
            case '\"':
            case '\'':
            case '?':
                result->match_start = start;
                result->match_end = start + 2;
                result->match_len = 2;
                result->match_offset = -1;
                return rule;

            case '0':
                for (i = 2; CHAR_IS_OCTAL (start[i]); ++i) ;

                result->match_start = start;
                result->match_end = start + i;
                result->match_len = i;
                result->match_offset = -1;
                return rule;

            case 'x':
            case 'X':
                for (i = 2; CHAR_IS_HEX (start[i]); ++i) ;

                result->match_start = start;
                result->match_end = start + i;
                result->match_len = i;
                result->match_offset = -1;
                return rule;
        }

        start++;
    }

    return NULL;
}


MooRule*
moo_rule_escaped_char_new (MooRuleFlags        flags,
                           const char         *style)
{
    MooRule *rule = rule_new (flags, style, rule_escaped_char_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);
    rule->description = g_strdup ("ESCAPED CHAR");
    return rule;
}


static MooRule*
rule_c_char_match (MooRule        *rule,
                   MatchData      *data,
                   MatchResult    *result,
                   MatchFlags      flags)
{
    guint i;
    char *limit = data->limit;
    char *start = data->start;

    if (flags & MATCH_START_ONLY)
        limit = start;

    while (start <= limit)
    {
        while (start <= limit && *start != '\'')
            start++;

        if (start > limit)
            return NULL;

        if (start[1] != '\\')
        {
            if (start[2] != '\'')
            {
                start = start + 2;
                continue;
            }

            result->match_start = start;
            result->match_end = start + 3;
            result->match_len = 3;
            result->match_offset = -1;
            return rule;
        }

        switch (start[2])
        {
            case '\\':
            case 'a':
            case 'b':
            case 'e':
            case 'f':
            case 'n':
            case 'r':
            case 't':
            case 'v':
            case '\"':
            case '\'':
            case '?':
                if (start[3] != '\'')
                {
                    start = start + 3;
                    continue;
                }

                result->match_start = start;
                result->match_end = start + 4;
                result->match_len = 4;
                result->match_offset = -1;
                return rule;

            case '0':
                for (i = 3; CHAR_IS_OCTAL (start[i]); ++i) ;

                if (start[i] != '\'')
                {
                    start = start + i;
                    continue;
                }

                result->match_start = start;
                result->match_end = start + i + 1;
                result->match_len = i + 1;
                result->match_offset = -1;
                return rule;

            case 'x':
            case 'X':
                for (i = 3; CHAR_IS_HEX (start[i]); ++i) ;

                if (start[i] != '\'')
                {
                    start = start + i;
                    continue;
                }

                result->match_start = start;
                result->match_end = start + i + 1;
                result->match_len = i + 1;
                result->match_offset = -1;
                return rule;
        }

        start++;
    }

    return NULL;
}


MooRule*
moo_rule_c_char_new (MooRuleFlags        flags,
                     const char         *style)
{
    MooRule *rule = rule_new (flags, style, rule_c_char_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);
    rule->description = g_strdup ("C CHAR");
    return rule;
}


static MooRule*
rule_whitespace_match (MooRule        *rule,
                       MatchData      *data,
                       MatchResult    *result,
                       G_GNUC_UNUSED MatchFlags flags)
{
    guint i;
    char *start = data->start;

    if (!CHAR_IS_SPACE (*start))
        return NULL;

    for (i = 1; CHAR_IS_SPACE (start[i]); ++i) ;

    result->match_start = start;
    result->match_end = start + i;
    result->match_len = i;
    result->match_offset = -1;
    return rule;
}


MooRule*
moo_rule_whitespace_new (MooRuleFlags        flags,
                         const char         *style)
{
    MooRule *rule = rule_new (flags, style, rule_whitespace_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);
    rule->description = g_strdup ("WHITESPACE");
    return rule;
}


static MooRule*
rule_identifier_match (MooRule        *rule,
                       MatchData      *data,
                       MatchResult    *result,
                       MatchFlags      flags)
{
    guint i;
    char *limit = data->limit;
    char *start = data->start;

    if (flags & MATCH_START_ONLY)
        limit = start;

    while (start <= limit)
    {
        while (start <= limit && !CHAR_IS_WORD (*start))
            start++;

        if (start > limit)
            return NULL;

        if ((start != data->line_string && CHAR_IS_WORD (start[-1])) ||
             CHAR_IS_DIGIT (*start))
        {
            while (start <= limit && CHAR_IS_WORD (*start))
                start++;
            continue;
        }

        for (i = 1; CHAR_IS_WORD (start[i]); ++i) ;

        result->match_start = start;
        result->match_end = start + i;
        result->match_len = i;
        result->match_offset = -1;
        return rule;
    }

    return NULL;
}


MooRule*
moo_rule_identifier_new (MooRuleFlags        flags,
                         const char         *style)
{
    MooRule *rule = rule_new (flags, style, rule_identifier_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);
    rule->description = g_strdup ("WHITESPACE");
    return rule;
}


static MooRule*
rule_line_continue_match (MooRule        *rule,
                          MatchData      *data,
                          MatchResult    *result,
                          MatchFlags      flags)
{
    char *limit = data->limit;
    char *start;

    if (flags & MATCH_START_ONLY)
        limit = data->start;

    g_assert (data->line_string_len >= 0);

    if (data->line_string_len && data->line_string[data->line_string_len - 1] == '\\')
    {
        start = data->line_string + data->line_string_len - 1;

        if (start > limit)
            return NULL;

        result->match_start = start;
        result->match_end = start + 1;
        result->match_len = 1;
        result->match_offset = -1;
        return rule;
    }

    return NULL;
}


MooRule*
moo_rule_line_continue_new (MooRuleFlags        flags,
                            const char         *style)
{
    MooRule *rule = rule_new (flags, style, rule_line_continue_match, NULL);
    g_return_val_if_fail (rule != NULL, NULL);
    rule->description = g_strdup ("LINE_CONTINUE");
    rule->include_eol = TRUE;
    return rule;
}