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/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* This code is based on pcreposix.h from the PCRE Library distribution,
 * as originally written by Philip Hazel <ph10@cam.ac.uk>, and forked by
 * the Apache HTTP Server project to provide POSIX-style regex function
 * wrappers around underlying PCRE library functions for httpd.
 * 
 * The original source file pcreposix.h is copyright and licensed as follows;

            Copyright (c) 1997-2004 University of Cambridge

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    * Redistributions of source code must retain the above copyright notice,
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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*/

/**
 * @file ap_regex.h
 * @brief Apache Regex defines
 */

#ifndef AP_REGEX_H
#define AP_REGEX_H

#include "apr.h"

/* Allow for C++ users */

#ifdef __cplusplus
extern "C" {
#endif

/* Options for ap_regcomp, ap_regexec, and ap_rxplus versions: */

#define AP_REG_ICASE    0x01 /** use a case-insensitive match */
#define AP_REG_NEWLINE  0x02 /** don't match newlines against '.' etc */
#define AP_REG_NOTBOL   0x04 /** ^ will not match against start-of-string */
#define AP_REG_NOTEOL   0x08 /** $ will not match against end-of-string */

#define AP_REG_EXTENDED (0)  /** unused */
#define AP_REG_NOSUB    (0)  /** unused */

#define AP_REG_MULTI 0x10    /* perl's /g (needs fixing) */
#define AP_REG_NOMEM 0x20    /* nomem in our code */
#define AP_REG_DOTALL 0x40   /* perl's /s flag */

#define AP_REG_DOLLAR_ENDONLY 0x200 /* '$' matches at end of subject string only */

#define AP_REG_NO_DEFAULT 0x400 /**< Don't implicitely add AP_REG_DEFAULT options */

#define AP_REG_MATCH "MATCH_" /**< suggested prefix for ap_regname */

#define AP_REG_DEFAULT (AP_REG_DOTALL|AP_REG_DOLLAR_ENDONLY)

/* Arguments for ap_pcre_version_string */
enum {
  AP_REG_PCRE_COMPILED = 0, /** PCRE version used during program compilation */
  AP_REG_PCRE_LOADED        /** PCRE version loaded at runtime */
};

/* Error values: */
enum {
  AP_REG_ASSERT = 1,  /** internal error ? */
  AP_REG_ESPACE,      /** failed to get memory */
  AP_REG_INVARG,      /** invalid argument */
  AP_REG_NOMATCH      /** match failed */
};

/* The structure representing a compiled regular expression. */
typedef struct {
    void *re_pcre;
    int re_nsub;
    apr_size_t re_erroffset;
} ap_regex_t;

/* The structure in which a captured offset is returned. */
typedef struct {
    int rm_so;
    int rm_eo;
} ap_regmatch_t;

/* The functions */

/**
 * Return PCRE version string.
 * @param which Either AP_REG_PCRE_COMPILED (PCRE version used
 *              during program compilation) or AP_REG_PCRE_LOADED
 *              (PCRE version used at runtime)
 * @return The PCRE version string
 */
AP_DECLARE(const char *) ap_pcre_version_string(int which);

/**
 * Get default compile flags
 * @return Bitwise OR of AP_REG_* flags
 */
AP_DECLARE(int) ap_regcomp_get_default_cflags(void);

/**
 * Set default compile flags
 * @param cflags Bitwise OR of AP_REG_* flags
 */
AP_DECLARE(void) ap_regcomp_set_default_cflags(int cflags);

/**
 * Get the AP_REG_* corresponding to the string.
 * @param name The name (i.e. AP_REG_<name>)
 * @return The AP_REG_*, or zero if the string is unknown
 *
 */
AP_DECLARE(int) ap_regcomp_default_cflag_by_name(const char *name);

/**
 * Compile a regular expression.
 * @param preg Returned compiled regex
 * @param regex The regular expression string
 * @param cflags Bitwise OR of AP_REG_* flags (ICASE and NEWLINE supported,
 *                                             other flags are ignored)
 * @return Zero on success or non-zero on error
 */
AP_DECLARE(int) ap_regcomp(ap_regex_t *preg, const char *regex, int cflags);

/**
 * Match a NUL-terminated string against a pre-compiled regex.
 * @param preg The pre-compiled regex
 * @param string The string to match
 * @param nmatch Provide information regarding the location of any matches
 * @param pmatch Provide information regarding the location of any matches
 * @param eflags Bitwise OR of AP_REG_* flags (NOTBOL and NOTEOL supported,
 *                                             other flags are ignored)
 * @return 0 for successful match, \p AP_REG_NOMATCH otherwise
 */
AP_DECLARE(int) ap_regexec(const ap_regex_t *preg, const char *string,
                           apr_size_t nmatch, ap_regmatch_t *pmatch, int eflags);

/**
 * Match a string with given length against a pre-compiled regex. The string
 * does not need to be NUL-terminated.
 * @param preg The pre-compiled regex
 * @param buff The string to match
 * @param len Length of the string to match
 * @param nmatch Provide information regarding the location of any matches
 * @param pmatch Provide information regarding the location of any matches
 * @param eflags Bitwise OR of AP_REG_* flags (NOTBOL and NOTEOL supported,
 *                                             other flags are ignored)
 * @return 0 for successful match, AP_REG_NOMATCH otherwise
 */
AP_DECLARE(int) ap_regexec_len(const ap_regex_t *preg, const char *buff,
                               apr_size_t len, apr_size_t nmatch,
                               ap_regmatch_t *pmatch, int eflags);

/**
 * Return the error code returned by regcomp or regexec into error messages
 * @param errcode the error code returned by regexec or regcomp
 * @param preg The precompiled regex
 * @param errbuf A buffer to store the error in
 * @param errbuf_size The size of the buffer
 */
AP_DECLARE(apr_size_t) ap_regerror(int errcode, const ap_regex_t *preg,
                                   char *errbuf, apr_size_t errbuf_size);

/**
 * Return an array of named regex backreferences
 * @param preg The precompiled regex
 * @param names The array to which the names will be added
 * @param prefix An optional prefix to add to the returned names.  AP_REG_MATCH
 * is the recommended prefix.
 * @param upper If non zero, uppercase the names
 */
AP_DECLARE(int) ap_regname(const ap_regex_t *preg,
                           apr_array_header_t *names, const char *prefix,
                           int upper);

/** Destroy a pre-compiled regex.
 * @param preg The pre-compiled regex to free.
 */
AP_DECLARE(void) ap_regfree(ap_regex_t *preg);

/* ap_rxplus: higher-level regexps */

typedef struct {
    ap_regex_t rx;
    apr_uint32_t flags;
    const char *subs;
    const char *match;
    apr_size_t nmatch;
    ap_regmatch_t *pmatch;
} ap_rxplus_t;

/**
 * Compile a pattern into a regexp.
 * supports perl-like formats
 *    match-string
 *    /match-string/flags
 *    s/match-string/replacement-string/flags
 *    Intended to support more perl-like stuff as and when round tuits happen
 * match-string is anything supported by ap_regcomp
 * replacement-string is a substitution string as supported in ap_pregsub
 * flags should correspond with perl syntax: treat failure to do so as a bug
 *                                           (documentation TBD)
 * @param pool Pool to allocate from
 * @param pattern Pattern to compile
 * @return Compiled regexp, or NULL in case of compile/syntax error
 */
AP_DECLARE(ap_rxplus_t*) ap_rxplus_compile(apr_pool_t *pool, const char *pattern);
/**
 * Apply a regexp operation to a string.
 * @param pool Pool to allocate from
 * @param rx The regex match to apply
 * @param pattern The string to apply it to
 *                NOTE: This MUST be kept in scope to use regexp memory
 * @param newpattern The modified string (ignored if the operation doesn't
 *                                        modify the string)
 * @return Number of times a match happens.  Normally 0 (no match) or 1
 *         (match found), but may be greater if a transforming pattern
 *         is applied with the 'g' flag.
 */
AP_DECLARE(int) ap_rxplus_exec(apr_pool_t *pool, ap_rxplus_t *rx,
                               const char *pattern, char **newpattern);
#ifdef DOXYGEN
/**
 * Number of matches in the regexp operation's memory
 * This may be 0 if no match is in memory, or up to nmatch from compilation
 * @param rx The regexp
 * @return Number of matches in memory
 */
AP_DECLARE(int) ap_rxplus_nmatch(ap_rxplus_t *rx);
#else
#define ap_rxplus_nmatch(rx) (((rx)->match != NULL) ? (rx)->nmatch : 0)
#endif
/**
 * Get a pointer to a match from regex memory
 * NOTE: this relies on the match pattern from the last call to
 *       ap_rxplus_exec still being valid (i.e. not freed or out-of-scope)
 * @param rx The regexp
 * @param n The match number to retrieve (must be between 0 and nmatch)
 * @param len Returns the length of the match.
 * @param match Returns the match pattern
 */
AP_DECLARE(void) ap_rxplus_match(ap_rxplus_t *rx, int n, int *len,
                                 const char **match);
/**
 * Get a match from regex memory in a string copy
 * NOTE: this relies on the match pattern from the last call to
 *       ap_rxplus_exec still being valid (i.e. not freed or out-of-scope)
 * @param pool Pool to allocate from
 * @param rx The regexp
 * @param n The match number to retrieve (must be between 0 and nmatch)
 * @return The matched string
 */
AP_DECLARE(char*) ap_rxplus_pmatch(apr_pool_t *pool, ap_rxplus_t *rx, int n);

#ifdef __cplusplus
}   /* extern "C" */
#endif

#endif /* AP_REGEX_T */