This is the regex functionality from glibc
extracted into a separate library,
for Win32.
See the README
of the C library.
regcomp()
, regexec()
, regerror()
and regfree()
are POSIX regex
functions.
They conform to POSIX.1-2001
and POSIX.1-2008
standards.
They are defined as follows:
extern "C" {
pub fn regcomp(
preg: *mut regex_t,
pattern: *const c_char,
cflags: c_int,
) -> c_int;
pub fn regexec(
preg: *const regex_t,
string: *const c_char,
nmatch: usize,
pmatch: *mut regmatch_t,
eflags: c_int,
) -> c_int;
pub fn regerror(
errcode: c_int,
preg: *const regex_t,
errbuf: *mut c_char,
errbuf_size: usize,
) -> usize;
pub fn regfree(preg: *mut regex_t);
}
regcomp()
is used to compile a regular expression into a form that is suitable
for subsequent regexec()
searches.
regcomp()
is supplied with preg
, a pointer to a pattern buffer storage area;
pattern
, a pointer to the null-terminated string and cflags
, flags used to
determine the type of compilation.
All regular expression searching must be done via a compiled pattern buffer,
thus regexec()
must always be supplied with the address of a regcomp()
initialized pattern buffer.
cflags
may be the bitwise-or of zero or more of the following:
-
REG_EXTENDED
: Use POSIX Extended Regular Expression syntax when interpreting regex. If not set, POSIX Basic Regular Expression syntax is used. -
REG_ICASE
: Do not differentiate case. Subsequentregexec()
searches using this pattern buffer will be case insensitive. -
REG_NOSUB
: Do not report position of matches. The nmatch and pmatch arguments toregexec()
are ignored if the pattern buffer supplied was compiled with this flag set. -
REG_NEWLINE
: Match-any-character operators don't match a newline.- A nonmatching list (
[^...]
) not containing a newline does not match a newline. - Match-beginning-of-line operator (
^
) matches the empty string immediately after a newline, regardless of whethereflags
, the execution flags ofregexec()
, containsREG_NOTBOL
. - Match-end-of-line operator (
$
) matches the empty string immediately before a newline, regardless of whethereflags
containsREG_NOTEOL
.
- A nonmatching list (
regexec()
is used to match a null-terminated string against the precompiled
pattern buffer, preg
.
nmatch
and pmatch
are used to provide information regarding the location
of any matches.
eflags
may be the bitwise-or of one or both of REG_NOTBOL
and REG_NOTEOL
which cause changes in matching behavior described below:
-
REG_NOTBOL
: The match-beginning-of-line operator always fails to match (but see the compilation flagREG_NEWLINE
above). This flag may be used when different portions of a string are passed toregexec()
and the beginning of the string should not be interpreted as the beginning of the line. -
REG_NOTEOL
: The match-end-of-line operator always fails to match (but see the compilation flagREG_NEWLINE
above).
Unless REG_NOSUB
was set for the compilation of the pattern buffer,
it is possible to obtain match addressing information.
pmatch
must be dimensioned to have at least nmatch
elements.
These are filled in by regexec()
with substring match addresses.
The offsets of the subexpression starting at the i
th open parenthesis
are stored in pmatch[i]
.
The entire regular expression's match addresses are stored in pmatch[0]
.
(Note that to return the offsets of N
subexpression matches, nmatch
must be at least N + 1
.)
Any unused structure elements will contain the value -1
.
The regmatch_t
structure which is the type of pmatch
is defined as:
pub struct regmatch_t {
pub rm_so: regoff_t,
pub rm_eo: regoff_t,
}
Each rm_so
element that is not -1
indicates the start offset of the next
largest substring match within the string.
The relative rm_eo
element indicates the end offset of the match, which is
the offset of the first character after the matching text.
regerror()
is used to turn the error codes that can be returned by both
regcomp()
and regexec()
into error message strings.
regerror()
is passed the error code, errcode
, the pattern buffer, preg
,
a pointer to a character string buffer, errbuf
, and the size of the string
buffer, errbuf_size
.
It returns the size of the errbuf
required to contain the null-terminated
error message string.
If both errbuf
and errbuf_size
are nonzero, errbuf
is filled in with
the first errbuf_size - 1
characters of the error message and a terminating
null byte (\0
).
Supplying regfree()
with a precompiled pattern buffer, preg
will free the
memory allocated to the pattern buffer by the compiling process, regcomp()
.
regcomp()
returns zero for a successful compilation.
On failure, it returns one of the following errors (see reg_errcode_t
):
REG_BADBR
: Invalid use of back reference operator.REG_BADPAT
: Invalid use of pattern operators such as group or list.REG_BADRPT
: Invalid use of repetition operators such as using*
as the first character.REG_EBRACE
: Un-matched brace interval operators.REG_EBRACK
: Un-matched bracket list operators.REG_ECOLLATE
: Invalid collating element.REG_ECTYPE
: Unknown character class name.REG_EEND
: Nonspecific error. This is not defined by POSIX.2.REG_EESCAPE
: Trailing backslash.REG_EPAREN
: Un-matched parenthesis group operators.REG_ERANGE
: Invalid use of the range operator; for example, the ending point of the range occurs prior to the starting point.REG_ESIZE
: Compiled regular expression requires a pattern buffer larger than 64Kb. This is not defined by POSIX.2.REG_ESPACE
: The regex routines ran out of memory.REG_ESUBREG
: Invalid back reference to a subexpression.
regexec()
returns zero for a successful match or REG_NOMATCH
for failure.
regcomp()
andregexec()
are thread-safe only if the process locale is not modified during the call.regerror()
is thread-safe only if the process environment is not modified during the call.regfree()
is thread-safe.
This crate depends on some environment variables, and variants of those.
For each environment variable (e.g., CC
), the following are the accepted
variants of it:
<var>_<target>
, e.g.,CC_x86_64-pc-windows-gnu
.<var>_<target-with-underscores>
, e.g.,CC_x86_64_pc_windows_gnu
.TARGET_<var>
, e.g.,TARGET_CC
.<var>
, e.g.,CC
.
The following environment variables (and their variants) affect how this crate is built:
GNURX_LIB_DIR_PREFIX
CC
CFLAGS
AR
ARFLAGS
By default, this crate builds libgnurx
from sources and links statically
against it.
In order to change this behavior, and instruct this crate to dynamically link
against an externally built libgnurx-0.dll
library, please define
the environment variable GNURX_LIB_DIR_PREFIX
(or any of its variants)
when building.
The value of GNURX_LIB_DIR_PREFIX
needs to be the absolute prefix path where
the library is installed.
The libgnurx
header files are expected to reside
in <GNURX_LIB_DIR_PREFIX>/include/
, and the shared library should reside
in <GNURX_LIB_DIR_PREFIX>/bin/
.
This crate provides the following variables to other crates that depend on it:
DEP_GNURX_INCLUDE
: Path of the directory where library C header files reside.DEP_GNURX_LIB
: Path of the directory where the library binary resides.
This crate supports only the following target platforms:
x86_64-pc-windows-gnu
.i686-pc-windows-gnu
.
This is due to the nature of the libgnurx
library.
This project adheres to Semantic Versioning.
The CHANGELOG.md
file details notable changes over time.
Copyright (c) 2020-2023 Koutheir Attouchi.
See the LICENSE.txt
file at the top-level directory of this distribution.
Licensed under the LGPL version 2.1 license, or any later version thereof. This file may not be copied, modified, or distributed except according to those terms.