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Add re.fullmatch() function and regex.fullmatch() method, which anchor the 

pattern at both ends of the string to match.

Patch by Matthew Barnett.
Closes #16203.
This commit is contained in:
Georg Brandl 2013-10-13 09:18:45 +02:00
parent 57841ddb5c
commit 4300019e1a
5 changed files with 156 additions and 45 deletions
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28
Doc/library/re.rst
View File

@ -584,6 +584,16 @@ form.
instead (see also :ref:`search-vs-match`).
.. function:: fullmatch(pattern, string, flags=0)
If the whole *string* matches the regular expression *pattern*, return a
corresponding :ref:`match object <match-objects>`. Return ``None`` if the
string does not match the pattern; note that this is different from a
zero-length match.
.. versionadded:: 3.4
.. function:: split(pattern, string, maxsplit=0, flags=0)
Split *string* by the occurrences of *pattern*. If capturing parentheses are
@ -778,6 +788,24 @@ attributes:
:meth:`~regex.search` instead (see also :ref:`search-vs-match`).
.. method:: regex.fullmatch(string[, pos[, endpos]])
If the whole *string* matches this regular expression, return a corresponding
:ref:`match object <match-objects>`. Return ``None`` if the string does not
match the pattern; note that this is different from a zero-length match.
The optional *pos* and *endpos* parameters have the same meaning as for the
:meth:`~regex.search` method.
>>> pattern = re.compile("o[gh]")
>>> pattern.fullmatch("dog") # No match as "o" is not at the start of "dog".
>>> pattern.fullmatch("ogre") # No match as not the full string matches.
>>> pattern.fullmatch("doggie", 1, 3) # Matches within given limits.
<_sre.SRE_Match object at ...>
.. versionadded:: 3.4
.. method:: regex.split(string, maxsplit=0)
Identical to the :func:`split` function, using the compiled pattern.

28
Lib/re.py
View File

@ -85,16 +85,17 @@ resulting RE will match the second character.
\\ Matches a literal backslash.
This module exports the following functions:
match Match a regular expression pattern to the beginning of a string.
search Search a string for the presence of a pattern.
sub Substitute occurrences of a pattern found in a string.
subn Same as sub, but also return the number of substitutions made.
split Split a string by the occurrences of a pattern.
findall Find all occurrences of a pattern in a string.
finditer Return an iterator yielding a match object for each match.
compile Compile a pattern into a RegexObject.
purge Clear the regular expression cache.
escape Backslash all non-alphanumerics in a string.
match Match a regular expression pattern to the beginning of a string.
fullmatch Match a regular expression pattern to all of a string.
search Search a string for the presence of a pattern.
sub Substitute occurrences of a pattern found in a string.
subn Same as sub, but also return the number of substitutions made.
split Split a string by the occurrences of a pattern.
findall Find all occurrences of a pattern in a string.
finditer Return an iterator yielding a match object for each match.
compile Compile a pattern into a RegexObject.
purge Clear the regular expression cache.
escape Backslash all non-alphanumerics in a string.
Some of the functions in this module takes flags as optional parameters:
A ASCII For string patterns, make \w, \W, \b, \B, \d, \D
@ -123,7 +124,7 @@ import sre_compile
import sre_parse
# public symbols
__all__ = [ "match", "search", "sub", "subn", "split", "findall",
__all__ = [ "match", "fullmatch", "search", "sub", "subn", "split", "findall",
"compile", "purge", "template", "escape", "A", "I", "L", "M", "S", "X",
"U", "ASCII", "IGNORECASE", "LOCALE", "MULTILINE", "DOTALL", "VERBOSE",
"UNICODE", "error" ]
@ -154,6 +155,11 @@ def match(pattern, string, flags=0):
a match object, or None if no match was found."""
return _compile(pattern, flags).match(string)
def fullmatch(pattern, string, flags=0):
"""Try to apply the pattern to all of the string, returning
a match object, or None if no match was found."""
return _compile(pattern, flags).fullmatch(string)
def search(pattern, string, flags=0):
"""Scan through string looking for a match to the pattern, returning
a match object, or None if no match was found."""

24
Lib/test/test_re.py
View File

@ -1061,6 +1061,30 @@ class ReTests(unittest.TestCase):
self.assertEqual(m.group(1), "")
self.assertEqual(m.group(2), "y")
def test_fullmatch(self):
# Issue 16203: Proposal: add re.fullmatch() method.
self.assertEqual(re.fullmatch(r"a", "a").span(), (0, 1))
self.assertEqual(re.fullmatch(r"a|ab", "ab").span(), (0, 2))
self.assertEqual(re.fullmatch(r".*?$", "abc").span(), (0, 3))
self.assertEqual(re.fullmatch(r".*?", "abc").span(), (0, 3))
self.assertEqual(re.fullmatch(r"a.*?b", "ab").span(), (0, 2))
self.assertEqual(re.fullmatch(r"a.*?b", "abb").span(), (0, 3))
self.assertEqual(re.fullmatch(r"a.*?b", "axxb").span(), (0, 4))
self.assertEqual(re.fullmatch(r"abc$", "abc\n"), None)
self.assertEqual(re.fullmatch(r"abc\Z", "abc\n"), None)
self.assertEqual(re.fullmatch(r"(?m)abc$", "abc\n"), None)
self.assertEqual(re.fullmatch(r"ab(?=c)cd", "abcd").span(), (0, 4))
self.assertEqual(re.fullmatch(r"ab(?<=b)cd", "abcd").span(), (0, 4))
self.assertEqual(re.fullmatch(r"(?=a|ab)ab", "ab").span(), (0, 2))
self.assertEqual(
re.compile(r"bc").fullmatch("abcd", pos=1, endpos=3).span(), (1, 3))
self.assertEqual(
re.compile(r".*?$").fullmatch("abcd", pos=1, endpos=3).span(), (1, 3))
self.assertEqual(
re.compile(r".*?").fullmatch("abcd", pos=1, endpos=3).span(), (1, 3))
def run_re_tests():
from test.re_tests import tests, SUCCEED, FAIL, SYNTAX_ERROR
if verbose:

120
Modules/_sre.c
View File

@ -4,24 +4,25 @@
* regular expression matching engine
*
* partial history:
* 1999-10-24 fl created (based on existing template matcher code)
* 2000-03-06 fl first alpha, sort of
* 2000-08-01 fl fixes for 1.6b1
* 2000-08-07 fl use PyOS_CheckStack() if available
* 2000-09-20 fl added expand method
* 2001-03-20 fl lots of fixes for 2.1b2
* 2001-04-15 fl export copyright as Python attribute, not global
* 2001-04-28 fl added __copy__ methods (work in progress)
* 2001-05-14 fl fixes for 1.5.2 compatibility
* 2001-07-01 fl added BIGCHARSET support (from Martin von Loewis)
* 2001-10-18 fl fixed group reset issue (from Matthew Mueller)
* 2001-10-20 fl added split primitive; reenable unicode for 1.6/2.0/2.1
* 2001-10-21 fl added sub/subn primitive
* 2001-10-24 fl added finditer primitive (for 2.2 only)
* 2001-12-07 fl fixed memory leak in sub/subn (Guido van Rossum)
* 2002-11-09 fl fixed empty sub/subn return type
* 2003-04-18 mvl fully support 4-byte codes
* 2003-10-17 gn implemented non recursive scheme
* 1999-10-24 fl created (based on existing template matcher code)
* 2000-03-06 fl first alpha, sort of
* 2000-08-01 fl fixes for 1.6b1
* 2000-08-07 fl use PyOS_CheckStack() if available
* 2000-09-20 fl added expand method
* 2001-03-20 fl lots of fixes for 2.1b2
* 2001-04-15 fl export copyright as Python attribute, not global
* 2001-04-28 fl added __copy__ methods (work in progress)
* 2001-05-14 fl fixes for 1.5.2 compatibility
* 2001-07-01 fl added BIGCHARSET support (from Martin von Loewis)
* 2001-10-18 fl fixed group reset issue (from Matthew Mueller)
* 2001-10-20 fl added split primitive; reenable unicode for 1.6/2.0/2.1
* 2001-10-21 fl added sub/subn primitive
* 2001-10-24 fl added finditer primitive (for 2.2 only)
* 2001-12-07 fl fixed memory leak in sub/subn (Guido van Rossum)
* 2002-11-09 fl fixed empty sub/subn return type
* 2003-04-18 mvl fully support 4-byte codes
* 2003-10-17 gn implemented non recursive scheme
* 2013-02-04 mrab added fullmatch primitive
*
* Copyright (c) 1997-2001 by Secret Labs AB. All rights reserved.
*
@ -746,11 +747,12 @@ do { \
#define JUMP_ASSERT 12
#define JUMP_ASSERT_NOT 13
#define DO_JUMP(jumpvalue, jumplabel, nextpattern) \
#define DO_JUMP(jumpvalue, jumplabel, nextpattern, matchall) \
DATA_ALLOC(SRE_MATCH_CONTEXT, nextctx); \
nextctx->last_ctx_pos = ctx_pos; \
nextctx->jump = jumpvalue; \
nextctx->pattern = nextpattern; \
nextctx->match_all = matchall; \
ctx_pos = alloc_pos; \
ctx = nextctx; \
goto entrance; \
@ -769,6 +771,7 @@ typedef struct {
SRE_CODE chr;
SRE_REPEAT* rep;
} u;
int match_all;
} SRE_MATCH_CONTEXT;
/* check if string matches the given pattern. returns <0 for
@ -791,6 +794,7 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern)
ctx->last_ctx_pos = -1;
ctx->jump = JUMP_NONE;
ctx->pattern = pattern;
ctx->match_all = state->match_all;
ctx_pos = alloc_pos;
entrance:
@ -864,6 +868,8 @@ entrance:
case SRE_OP_SUCCESS:
/* end of pattern */
TRACE(("|%p|%p|SUCCESS\n", ctx->pattern, ctx->ptr));
if (ctx->match_all && ctx->ptr != state->end)
RETURN_FAILURE;
state->ptr = ctx->ptr;
RETURN_SUCCESS;
@ -972,7 +978,7 @@ entrance:
!SRE_CHARSET(ctx->pattern + 3, (SRE_CODE) SRE_CHARGET(state, ctx->ptr, 0))))
continue;
state->ptr = ctx->ptr;
DO_JUMP(JUMP_BRANCH, jump_branch, ctx->pattern+1);
DO_JUMP(JUMP_BRANCH, jump_branch, ctx->pattern+1, ctx->match_all);
if (ret) {
if (ctx->u.rep)
MARK_POP_DISCARD(ctx->lastmark);
@ -1019,7 +1025,8 @@ entrance:
if (ctx->count < (Py_ssize_t) ctx->pattern[1])
RETURN_FAILURE;
if (ctx->pattern[ctx->pattern[0]] == SRE_OP_SUCCESS) {
if (ctx->pattern[ctx->pattern[0]] == SRE_OP_SUCCESS &&
(!ctx->match_all || ctx->ptr == state->end)) {
/* tail is empty. we're finished */
state->ptr = ctx->ptr;
RETURN_SUCCESS;
@ -1042,7 +1049,7 @@ entrance:
break;
state->ptr = ctx->ptr;
DO_JUMP(JUMP_REPEAT_ONE_1, jump_repeat_one_1,
ctx->pattern+ctx->pattern[0]);
ctx->pattern+ctx->pattern[0], ctx->match_all);
if (ret) {
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
@ -1059,7 +1066,7 @@ entrance:
while (ctx->count >= (Py_ssize_t) ctx->pattern[1]) {
state->ptr = ctx->ptr;
DO_JUMP(JUMP_REPEAT_ONE_2, jump_repeat_one_2,
ctx->pattern+ctx->pattern[0]);
ctx->pattern+ctx->pattern[0], ctx->match_all);
if (ret) {
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
@ -1104,7 +1111,8 @@ entrance:
ctx->ptr += state->charsize * ctx->count;
}
if (ctx->pattern[ctx->pattern[0]] == SRE_OP_SUCCESS) {
if (ctx->pattern[ctx->pattern[0]] == SRE_OP_SUCCESS &&
(!ctx->match_all || ctx->ptr == state->end)) {
/* tail is empty. we're finished */
state->ptr = ctx->ptr;
RETURN_SUCCESS;
@ -1116,7 +1124,7 @@ entrance:
|| ctx->count <= (Py_ssize_t)ctx->pattern[2]) {
state->ptr = ctx->ptr;
DO_JUMP(JUMP_MIN_REPEAT_ONE,jump_min_repeat_one,
ctx->pattern+ctx->pattern[0]);
ctx->pattern+ctx->pattern[0], ctx->match_all);
if (ret) {
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
@ -1155,7 +1163,7 @@ entrance:
state->repeat = ctx->u.rep;
state->ptr = ctx->ptr;
DO_JUMP(JUMP_REPEAT, jump_repeat, ctx->pattern+ctx->pattern[0]);
DO_JUMP(JUMP_REPEAT, jump_repeat, ctx->pattern+ctx->pattern[0], ctx->match_all);
state->repeat = ctx->u.rep->prev;
PyObject_FREE(ctx->u.rep);
@ -1187,7 +1195,7 @@ entrance:
/* not enough matches */
ctx->u.rep->count = ctx->count;
DO_JUMP(JUMP_MAX_UNTIL_1, jump_max_until_1,
ctx->u.rep->pattern+3);
ctx->u.rep->pattern+3, ctx->match_all);
if (ret) {
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
@ -1209,7 +1217,7 @@ entrance:
DATA_PUSH(&ctx->u.rep->last_ptr);
ctx->u.rep->last_ptr = state->ptr;
DO_JUMP(JUMP_MAX_UNTIL_2, jump_max_until_2,
ctx->u.rep->pattern+3);
ctx->u.rep->pattern+3, ctx->match_all);
DATA_POP(&ctx->u.rep->last_ptr);
if (ret) {
MARK_POP_DISCARD(ctx->lastmark);
@ -1225,7 +1233,7 @@ entrance:
/* cannot match more repeated items here. make sure the
tail matches */
state->repeat = ctx->u.rep->prev;
DO_JUMP(JUMP_MAX_UNTIL_3, jump_max_until_3, ctx->pattern);
DO_JUMP(JUMP_MAX_UNTIL_3, jump_max_until_3, ctx->pattern, ctx->match_all);
RETURN_ON_SUCCESS(ret);
state->repeat = ctx->u.rep;
state->ptr = ctx->ptr;
@ -1250,7 +1258,7 @@ entrance:
/* not enough matches */
ctx->u.rep->count = ctx->count;
DO_JUMP(JUMP_MIN_UNTIL_1, jump_min_until_1,
ctx->u.rep->pattern+3);
ctx->u.rep->pattern+3, ctx->match_all);
if (ret) {
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
@ -1264,7 +1272,7 @@ entrance:
/* see if the tail matches */
state->repeat = ctx->u.rep->prev;
DO_JUMP(JUMP_MIN_UNTIL_2, jump_min_until_2, ctx->pattern);
DO_JUMP(JUMP_MIN_UNTIL_2, jump_min_until_2, ctx->pattern, ctx->match_all);
if (ret) {
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
@ -1285,7 +1293,7 @@ entrance:
DATA_PUSH(&ctx->u.rep->last_ptr);
ctx->u.rep->last_ptr = state->ptr;
DO_JUMP(JUMP_MIN_UNTIL_3,jump_min_until_3,
ctx->u.rep->pattern+3);
ctx->u.rep->pattern+3, ctx->match_all);
DATA_POP(&ctx->u.rep->last_ptr);
if (ret) {
RETURN_ON_ERROR(ret);
@ -1378,7 +1386,7 @@ entrance:
state->ptr = ctx->ptr - state->charsize * ctx->pattern[1];
if (state->ptr < state->beginning)
RETURN_FAILURE;
DO_JUMP(JUMP_ASSERT, jump_assert, ctx->pattern+2);
DO_JUMP(JUMP_ASSERT, jump_assert, ctx->pattern+2, 0);
RETURN_ON_FAILURE(ret);
ctx->pattern += ctx->pattern[0];
break;
@ -1390,7 +1398,7 @@ entrance:
ctx->ptr, ctx->pattern[1]));
state->ptr = ctx->ptr - state->charsize * ctx->pattern[1];
if (state->ptr >= state->beginning) {
DO_JUMP(JUMP_ASSERT_NOT, jump_assert_not, ctx->pattern+2);
DO_JUMP(JUMP_ASSERT_NOT, jump_assert_not, ctx->pattern+2, 0);
if (ret) {
RETURN_ON_ERROR(ret);
RETURN_FAILURE;
@ -1909,6 +1917,44 @@ pattern_match(PatternObject* self, PyObject* args, PyObject* kw)
return pattern_new_match(self, &state, status);
}
static PyObject*
pattern_fullmatch(PatternObject* self, PyObject* args, PyObject* kw)
{
SRE_STATE state;
Py_ssize_t status;
PyObject* string;
Py_ssize_t start = 0;
Py_ssize_t end = PY_SSIZE_T_MAX;
static char* kwlist[] = { "pattern", "pos", "endpos", NULL };
if (!PyArg_ParseTupleAndKeywords(args, kw, "O|nn:fullmatch", kwlist,
&string, &start, &end))
return NULL;
string = state_init(&state, self, string, start, end);
if (!string)
return NULL;
state.match_all = 1;
state.ptr = state.start;
TRACE(("|%p|%p|FULLMATCH\n", PatternObject_GetCode(self), state.ptr));
if (state.logical_charsize == 1) {
status = sre_match(&state, PatternObject_GetCode(self));
} else {
status = sre_umatch(&state, PatternObject_GetCode(self));
}
TRACE(("|%p|%p|END\n", PatternObject_GetCode(self), state.ptr));
if (PyErr_Occurred())
return NULL;
state_fini(&state);
return pattern_new_match(self, &state, status);
}
static PyObject*
pattern_search(PatternObject* self, PyObject* args, PyObject* kw)
{
@ -2530,6 +2576,10 @@ PyDoc_STRVAR(pattern_match_doc,
"match(string[, pos[, endpos]]) -> match object or None.\n\
Matches zero or more characters at the beginning of the string");
PyDoc_STRVAR(pattern_fullmatch_doc,
"fullmatch(string[, pos[, endpos]]) -> match object or None.\n\
Matches against all of the string");
PyDoc_STRVAR(pattern_search_doc,
"search(string[, pos[, endpos]]) -> match object or None.\n\
Scan through string looking for a match, and return a corresponding\n\
@ -2565,6 +2615,8 @@ PyDoc_STRVAR(pattern_doc, "Compiled regular expression objects");
static PyMethodDef pattern_methods[] = {
{"match", (PyCFunction) pattern_match, METH_VARARGS|METH_KEYWORDS,
pattern_match_doc},
{"fullmatch", (PyCFunction) pattern_fullmatch, METH_VARARGS|METH_KEYWORDS,
pattern_fullmatch_doc},
{"search", (PyCFunction) pattern_search, METH_VARARGS|METH_KEYWORDS,
pattern_search_doc},
{"sub", (PyCFunction) pattern_sub, METH_VARARGS|METH_KEYWORDS,

1
Modules/sre.h
View File

@ -89,6 +89,7 @@ typedef struct {
SRE_REPEAT *repeat;
/* hooks */
SRE_TOLOWER_HOOK lower;
int match_all;
} SRE_STATE;
typedef struct {