[Python-checkins] cpython: Issue 24454: Improve the usability of the re match object named group API

Sun Sep 11 08:55:46 EDT 2016

https://hg.python.org/cpython/rev/ac0643314d12
changeset: 103635:ac0643314d12
user: Eric V. Smith <eric at trueblade.com>
date: Sun Sep 11 08:55:43 2016 -0400
summary:
 Issue 24454: Improve the usability of the re match object named group API
files:
 Doc/library/re.rst | 16 ++++++++++++
 Lib/test/test_re.py | 44 +++++++++++++++++++++++++++++++++
 Misc/NEWS | 4 +++
 Modules/_sre.c | 19 +++++++++++++-
 4 files changed, 82 insertions(+), 1 deletions(-)

diff --git a/Doc/library/re.rst b/Doc/library/re.rst
--- a/Doc/library/re.rst
+++ b/Doc/library/re.rst
@@ -1015,6 +1015,22 @@
 'c3'
 
 
+.. method:: match.__getitem__(g)
+
+ This is identical to ``m.group(g)``. This allows easier access to
+ an individual group from a match:
+
+ >>> m = re.match(r"(\w+) (\w+)", "Isaac Newton, physicist")
+ >>> m[0] # The entire match
+ 'Isaac Newton'
+ >>> m[1] # The first parenthesized subgroup.
+ 'Isaac'
+ >>> m[2] # The second parenthesized subgroup.
+ 'Newton'
+
+ .. versionadded:: 3.6
+
+
 .. method:: match.groups(default=None)
 
 Return a tuple containing all the subgroups of the match, from 1 up to however
diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py
--- a/Lib/test/test_re.py
+++ b/Lib/test/test_re.py
@@ -441,6 +441,50 @@
 self.assertEqual(m.group(2, 1), ('b', 'a'))
 self.assertEqual(m.group(Index(2), Index(1)), ('b', 'a'))
 
+ def test_match_getitem(self):
+ pat = re.compile('(?:(?P<a1>a)|(?P<b2>b))(?P<c3>c)?')
+
+ m = pat.match('a')
+ self.assertEqual(m['a1'], 'a')
+ self.assertEqual(m['b2'], None)
+ self.assertEqual(m['c3'], None)
+ self.assertEqual('a1={a1} b2={b2} c3={c3}'.format_map(m), 'a1=a b2=None c3=None')
+ self.assertEqual(m[0], 'a')
+ self.assertEqual(m[1], 'a')
+ self.assertEqual(m[2], None)
+ self.assertEqual(m[3], None)
+ with self.assertRaisesRegex(IndexError, 'no such group'):
+ m['X']
+ with self.assertRaisesRegex(IndexError, 'no such group'):
+ m[-1]
+ with self.assertRaisesRegex(IndexError, 'no such group'):
+ m[4]
+ with self.assertRaisesRegex(IndexError, 'no such group'):
+ m[0, 1]
+ with self.assertRaisesRegex(IndexError, 'no such group'):
+ m[(0,)]
+ with self.assertRaisesRegex(IndexError, 'no such group'):
+ m[(0, 1)]
+ with self.assertRaisesRegex(KeyError, 'a2'):
+ 'a1={a2}'.format_map(m)
+
+ m = pat.match('ac')
+ self.assertEqual(m['a1'], 'a')
+ self.assertEqual(m['b2'], None)
+ self.assertEqual(m['c3'], 'c')
+ self.assertEqual('a1={a1} b2={b2} c3={c3}'.format_map(m), 'a1=a b2=None c3=c')
+ self.assertEqual(m[0], 'ac')
+ self.assertEqual(m[1], 'a')
+ self.assertEqual(m[2], None)
+ self.assertEqual(m[3], 'c')
+
+ # Cannot assign.
+ with self.assertRaises(TypeError):
+ m[0] = 1
+
+ # No len().
+ self.assertRaises(TypeError, len, m)
+
 def test_re_fullmatch(self):
 # Issue 16203: Proposal: add re.fullmatch() method.
 self.assertEqual(re.fullmatch(r"a", "a").span(), (0, 1))
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -143,6 +143,10 @@
 Library
 -------
 
+- Issue #24454: Regular expression match object groups are now
+ accessible using __getitem__. "mo[x]" is equivalent to
+ "mo.group(x)".
+
 - Issue #10740: sqlite3 no longer implicitly commit an open transaction
 before DDL statements.
 
diff --git a/Modules/_sre.c b/Modules/_sre.c
--- a/Modules/_sre.c
+++ b/Modules/_sre.c
@@ -2121,6 +2121,12 @@
 return result;
 }
 
+static PyObject*
+match_getitem(MatchObject* self, PyObject* name)
+{
+ return match_getslice(self, name, Py_None);
+}
+
 /*[clinic input]
 _sre.SRE_Match.groups
 
@@ -2416,6 +2422,9 @@
 Return subgroup(s) of the match by indices or names.\n\
 For 0 returns the entire match.");
 
+PyDoc_STRVAR(match_getitem_doc,
+"__getitem__(name) <==> group(name).\n");
+
 static PyObject *
 match_lastindex_get(MatchObject *self)
 {
@@ -2706,6 +2715,13 @@
 pattern_getset, /* tp_getset */
 };
 
+/* Match objects do not support length or assignment, but do support
+ __getitem__. */
+static PyMappingMethods match_as_mapping = {
+ NULL,
+ (binaryfunc)match_getitem,
+ NULL
+};
 
 static PyMethodDef match_methods[] = {
 {"group", (PyCFunction) match_group, METH_VARARGS, match_group_doc},
@@ -2717,6 +2733,7 @@
 _SRE_SRE_MATCH_EXPAND_METHODDEF
 _SRE_SRE_MATCH___COPY___METHODDEF
 _SRE_SRE_MATCH___DEEPCOPY___METHODDEF
+ {"__getitem__", (PyCFunction)match_getitem, METH_O|METH_COEXIST, match_getitem_doc},
 {NULL, NULL}
 };
 
@@ -2751,7 +2768,7 @@
 (reprfunc)match_repr, /* tp_repr */
 0, /* tp_as_number */
 0, /* tp_as_sequence */
- 0, /* tp_as_mapping */
+ &match_as_mapping, /* tp_as_mapping */
 0, /* tp_hash */
 0, /* tp_call */
 0, /* tp_str */
-- 
Repository URL: https://hg.python.org/cpython
