tokenizer.c

/*
 * Copyright (C) 2010 Bjoern Biesenbach <bjoern@bjoern-b.de> (minor changes)
 * Copyright (C) 2003-2010 The Music Player Daemon Project
 * http://www.musicpd.org
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "tokenizer.h"

#include <stdbool.h>
#include <assert.h>
#include <string.h>

G_GNUC_CONST
static GQuark
tokenizer_quark(void)
{
    return g_quark_from_static_string("tokenizer");
}

static inline bool
valid_word_first_char(char ch)
{
    return g_ascii_isalpha(ch);
}

static inline bool
valid_word_char(char ch)
{
    return g_ascii_isalnum(ch) || ch == '_';
}

char *
tokenizer_next_word(char **input_p, GError **error_r)
{
    char *word, *input;

    assert(input_p != NULL);
    assert(*input_p != NULL);

    word = input = *input_p;

    if (*input == 0)
        return NULL;

    /* check the first character */

    if (!valid_word_first_char(*input)) {
        g_set_error(error_r, tokenizer_quark(), 0,
                "Letter expected");
        return NULL;
    }

    /* now iterate over the other characters until we find a
       whitespace or end-of-string */

    while (*++input != 0) {
        if (g_ascii_isspace(*input)) {
            /* a whitespace: the word ends here */
            *input = 0;
            /* skip all following spaces, too */
            input = g_strchug(input + 1);
            break;
        }

        if (!valid_word_char(*input)) {
            *input_p = input;
            g_set_error(error_r, tokenizer_quark(), 0,
                    "Invalid word character");
            return NULL;
        }
    }

    /* end of string: the string is already null-terminated
       here */

    *input_p = input;
    return word;
}

static inline bool
valid_unquoted_char(char ch)
{
    return (unsigned char)ch > 0x20 && ch != '"' && ch != '\'';
}

char *
tokenizer_next_unquoted(char **input_p, GError **error_r)
{
    char *word, *input;

    assert(input_p != NULL);
    assert(*input_p != NULL);

    word = input = *input_p;

    if (*input == 0)
        return NULL;

    /* check the first character */

    if (!valid_unquoted_char(*input)) {
        g_set_error(error_r, tokenizer_quark(), 0,
                "Invalid unquoted character");
        return NULL;
    }

    /* now iterate over the other characters until we find a
       whitespace or end-of-string */

    while (*++input != 0) {
        if (g_ascii_isspace(*input)) {
            /* a whitespace: the word ends here */
            *input = 0;
            /* skip all following spaces, too */
            input = g_strchug(input + 1);
            break;
        }

        if (!valid_unquoted_char(*input)) {
            *input_p = input;
            g_set_error(error_r, tokenizer_quark(), 0,
                    "Invalid unquoted character");
            return NULL;
        }
    }

    /* end of string: the string is already null-terminated
       here */

    *input_p = input;
    return word;
}

char *
tokenizer_next_string(char **input_p, GError **error_r)
{
    char *word, *dest, *input;

    assert(input_p != NULL);
    assert(*input_p != NULL);

    word = dest = input = *input_p;

    if (*input == 0)
        /* end of line */
        return NULL;

    /* check for the opening " */

    if (*input != '"') {
        g_set_error(error_r, tokenizer_quark(), 0,
                "'\"' expected");
        return NULL;
    }

    ++input;

    /* copy all characters */

    while (*input != '"') {
        if (*input == '\\')
            /* the backslash escapes the following
               character */
            ++input;

        if (*input == 0) {
            /* return input-1 so the caller can see the
               difference between "end of line" and
               "error" */
            *input_p = input - 1;
            g_set_error(error_r, tokenizer_quark(), 0,
                    "Missing closing '\"'");
            return NULL;
        }

        /* copy one character */
        *dest++ = *input++;
    }

    /* the following character must be a whitespace (or end of
       line) */

    ++input;
    if (*input != 0 && !g_ascii_isspace(*input)) {
        *input_p = input;
        g_set_error(error_r, tokenizer_quark(), 0,
                "Space expected after closing '\"'");
        return NULL;
    }

    /* finish the string and return it */

    *dest = 0;
    *input_p = g_strchug(input);
    return word;
}

char *
tokenizer_next_param(char **input_p, GError **error_r)
{
    assert(input_p != NULL);
    assert(*input_p != NULL);

    if (**input_p == '"')
        return tokenizer_next_string(input_p, error_r);
    else
        return tokenizer_next_unquoted(input_p, error_r);
}