/* $OpenBSD: regex.c,v 1.3 2015/11/19 23:20:34 tedu Exp $ */

/** regex - regular expression functions related to POSIX regex lib. */

/*  This file is part of flex. */

/*  Redistribution and use in source and binary forms, with or without */
/*  modification, are permitted provided that the following conditions */
/*  are met: */

/*  1. Redistributions of source code must retain the above copyright */
/*     notice, this list of conditions and the following disclaimer. */
/*  2. Redistributions in binary form must reproduce the above copyright */
/*     notice, this list of conditions and the following disclaimer in the */
/*     documentation and/or other materials provided with the distribution. */

/*  Neither the name of the University nor the names of its contributors */
/*  may be used to endorse or promote products derived from this software */
/*  without specific prior written permission. */

/*  THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR */
/*  IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED */
/*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
/*  PURPOSE. */

#include "flexdef.h"


static const char* REGEXP_LINEDIR = "^#line ([[:digit:]]+) \"(.*)\"";
static const char* REGEXP_BLANK_LINE = "^[[:space:]]*$";

regex_t regex_linedir; /**< matches line directives */
regex_t regex_blank_line; /**< matches blank lines */


/** Initialize the regular expressions.
 * @return true upon success.
 */
bool flex_init_regex(void)
{
    flex_regcomp(&regex_linedir, REGEXP_LINEDIR, REG_EXTENDED);
    flex_regcomp(&regex_blank_line, REGEXP_BLANK_LINE, REG_EXTENDED);

    return true;
}

/** Compiles a regular expression or dies trying.
 * @param preg  Same as for regcomp().
 * @param regex Same as for regcomp().
 * @param cflags Same as for regcomp().
 */
void flex_regcomp(regex_t *preg, const char *regex, int cflags)
{
    int err;

        memset (preg, 0, sizeof (regex_t));

        if ((err = regcomp (preg, regex, cflags)) != 0) {
        const int errbuf_sz = 200;
        char *errbuf, *rxerr;

                errbuf = (char*)malloc(errbuf_sz *sizeof(char));
                if (!errbuf)
                        flexfatal(_("Unable to allocate buffer to report regcomp"));
                rxerr = (char*)malloc(errbuf_sz *sizeof(char));
                if (!rxerr)
                        flexfatal(_("Unable to allocate buffer for regerror"));
                regerror (err, preg, rxerr, errbuf_sz);
                snprintf (errbuf, errbuf_sz, "regcomp for \"%s\" failed: %s", regex, rxerr);

                flexfatal (errbuf);
        free(errbuf);
        free(rxerr);
        }
}

/** Extract a copy of the match, or NULL if no match.
 * @param m A match as returned by regexec().
 * @param src The source string that was passed to regexec().
 * @return The allocated string.
 */
char   *regmatch_dup (regmatch_t * m, const char *src)
{
        char   *str;
        int     len;

        if (m == NULL || m->rm_so < 0)
                return NULL;
        len = m->rm_eo - m->rm_so;
        str = (char *) malloc ((len + 1) * sizeof (char));
        if (!str)
                flexfatal(_("Unable to allocate a copy of the match"));
        strncpy (str, src + m->rm_so, len);
        str[len] = 0;
        return str;
}

/** Copy the match.
 * @param m A match as returned by regexec().
 * @param dest The destination buffer.
 * @param src The source string that was passed to regexec().
 * @return dest
 */
char   *regmatch_cpy (regmatch_t * m, char *dest, const char *src)
{
        if (m == NULL || m->rm_so < 0) {
                if (dest)
                        dest[0] = '\0';
                return dest;
        }

        snprintf (dest, regmatch_len(m), "%s", src + m->rm_so);
    return dest;
}

/** Get the length in characters of the match.
 * @param m A match as returned by regexec().
 * @param src The source string that was passed to regexec().
 * @return The length of the match.
 */
int regmatch_len (regmatch_t * m)
{
        if (m == NULL || m->rm_so < 0) {
                return 0;
        }

        return m->rm_eo - m->rm_so;
}



/** Convert a regmatch_t object to an integer using the strtol() function.
 * @param m A match as returned by regexec().
 * @param src The source string that was passed to regexec().
 * @param endptr Same as the second argument to strtol().
 * @param base   Same as the third argument to strtol().
 * @return The converted integer or error (Return value is the same as for strtol()).
 */
int regmatch_strtol (regmatch_t * m, const char *src, char **endptr,
                     int base)
{
        int     n = 0;

#define bufsz 20
        char    buf[bufsz];
        char   *s;

        if (m == NULL || m->rm_so < 0)
                return 0;

        if (regmatch_len (m) < bufsz)
                s = regmatch_cpy (m, buf, src);
        else
                s = regmatch_dup (m, src);

        n = strtol (s, endptr, base);

        if (s != buf)
                free (s);

        return n;
}

/** Check for empty or non-existent match.
 * @param m A match as returned by regexec().
 * @return false if match length is non-zero.
 * Note that reg_empty returns true even if match did not occur at all.
 */
bool regmatch_empty (regmatch_t * m)
{
        return (m == NULL || m->rm_so < 0 || m->rm_so == m->rm_eo);
}