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ZREX(3) CZMQ Manual ZREX(3)

NAME

zrex - Class for work with regular expressions

SYNOPSIS

//  Constructor. Optionally, sets an expression against which we can match
//  text and capture hits. If there is an error in the expression, reports
//  zrex_valid() as false and provides the error in zrex_strerror(). If you
//  set a pattern, you can call zrex_matches() to test it against text.
CZMQ_EXPORT zrex_t *

zrex_new (const char *expression); // Destructor CZMQ_EXPORT void
zrex_destroy (zrex_t **self_p); // Return true if the expression was valid and compiled without errors. CZMQ_EXPORT bool
zrex_valid (zrex_t *self); // Return the error message generated during compilation of the expression. CZMQ_EXPORT const char *
zrex_strerror (zrex_t *self); // Returns true if the text matches the previously compiled expression. // Use this method to compare one expression against many strings. CZMQ_EXPORT bool
zrex_matches (zrex_t *self, const char *text); // Returns true if the text matches the supplied expression. Use this // method to compare one string against several expressions. CZMQ_EXPORT bool
zrex_eq (zrex_t *self, const char *text, const char *expression); // Returns number of hits from last zrex_matches or zrex_eq. If the text // matched, returns 1 plus the number of capture groups. If the text did // not match, returns zero. To retrieve individual capture groups, call // zrex_hit (). CZMQ_EXPORT int
zrex_hits (zrex_t *self); // Returns the Nth capture group from the last expression match, where // N is 0 to the value returned by zrex_hits(). Capture group 0 is the // whole matching string. Sequence 1 is the first capture group, if any, // and so on. CZMQ_EXPORT const char *
zrex_hit (zrex_t *self, uint index); // Fetches hits into string variables provided by caller; this makes for // nicer code than accessing hits by index. Caller should not modify nor // free the returned values. Returns number of strings returned. This // method starts at hit 1, i.e. first capture group, as hit 0 is always // the original matched string. CZMQ_EXPORT int
zrex_fetch (zrex_t *self, const char **string_p, ...); // Self test of this class CZMQ_EXPORT void
zrex_test (bool verbose); Please add '@interface' section in './../src/zrex.c'.

DESCRIPTION

Wraps a very simple regular expression library (SLRE) as a CZMQ class. Supports this syntax:

^               Match beginning of a buffer
$               Match end of a buffer
()              Grouping and substring capturing
[...]           Match any character from set
[^...]          Match any character but ones from set
.               Match any character
\s              Match whitespace
\S              Match non-whitespace
\d              Match decimal digit
\D              Match non decimal digit
\a              Match alphabetic character
\A              Match non-alphabetic character
\w              Match alphanumeric character
\W              Match non-alphanumeric character
\r              Match carriage return
\n              Match newline
+               Match one or more times (greedy)
+?              Match one or more times (non-greedy)
*               Match zero or more times (greedy)
*?              Match zero or more times (non-greedy)
?               Match zero or once
\xDD            Match byte with hex value 0xDD
\meta           Match one of the meta character: ^$().[*+?\

Please add @discuss section in ./../src/zrex.c.

EXAMPLE

From zrex_test method.

//  This shows the pattern of matching many lines to a single pattern
zrex_t *rex = zrex_new ("\\d+-\\d+-\\d+");
assert (rex);
assert (zrex_valid (rex));
bool matches = zrex_matches (rex, "123-456-789");
assert (matches);
assert (zrex_hits (rex) == 1);
assert (streq (zrex_hit (rex, 0), "123-456-789"));
assert (zrex_hit (rex, 1) == NULL);
zrex_destroy (&rex);
//  Here we pick out hits using capture groups
rex = zrex_new ("(\\d+)-(\\d+)-(\\d+)");
assert (rex);
assert (zrex_valid (rex));
matches = zrex_matches (rex, "123-456-ABC");
assert (!matches);
matches = zrex_matches (rex, "123-456-789");
assert (matches);
assert (zrex_hits (rex) == 4);
assert (streq (zrex_hit (rex, 0), "123-456-789"));
assert (streq (zrex_hit (rex, 1), "123"));
assert (streq (zrex_hit (rex, 2), "456"));
assert (streq (zrex_hit (rex, 3), "789"));
zrex_destroy (&rex);
//  This shows the pattern of matching one line against many
//  patterns and then handling the case when it hits
rex = zrex_new (NULL);      //  No initial pattern
assert (rex);
char *input = "Mechanism: CURVE";
matches = zrex_eq (rex, input, "Version: (.+)");
assert (!matches);
assert (zrex_hits (rex) == 0);
matches = zrex_eq (rex, input, "Mechanism: (.+)");
assert (matches);
assert (zrex_hits (rex) == 2);
const char *mechanism;
zrex_fetch (rex, &mechanism, NULL);
assert (streq (zrex_hit (rex, 1), "CURVE"));
assert (streq (mechanism, "CURVE"));
zrex_destroy (&rex);
#if defined (__WINDOWS__)
zsys_shutdown();
#endif

AUTHORS

The czmq manual was written by the authors in the AUTHORS file.

RESOURCES

Main web site:

Report bugs to the email <zeromq-dev@lists.zeromq.org[1]>

COPYRIGHT

Copyright (c) the Contributors as noted in the AUTHORS file. This file is part of CZMQ, the high-level C binding for 0MQ: http://czmq.zeromq.org. This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/. LICENSE included with the czmq distribution.

NOTES

1.
zeromq-dev@lists.zeromq.org
mailto:zeromq-dev@lists.zeromq.org
01/17/2021 CZMQ 4.2.1