document regex match counting in the README

Describes -RPc and -CPc alongside the regex matching options they
modify. Kept with the feature rather than on the release branch, so the
README there documents only what that branch actually provides.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -88,7 +88,8 @@ The most commonly useful options (`wikiq --help` describes them all):
 - `-RP REGEX -RPl LABEL` searches revision text for a regular expression
   and reports the matches in a column named by the label; repeat the
   pair for multiple patterns. `-CP`/`-CPl` do the same for edit
-  summaries.
+  summaries. Adding `-RPc` or `-CPc` reports the number of matches
+  instead of the matched text.
 - `--resume` continues an interrupted run from the last complete line of
   an existing JSONL output file. Combined with `--time-limit HOURS`,
   this supports processing very large dumps in bounded chunks.

src/wikiq/__init__.py

@@ -274,10 +274,10 @@ def build_schema(
     return schema
 
 
-def make_regex_pairs(patterns, labels) -> list:
+def make_regex_pairs(patterns, labels, count_only=False) -> list:
     """Create RegexPair objects from patterns and labels."""
     if (patterns is not None and labels is not None) and (len(patterns) == len(labels)):
-        return [RegexPair(pattern, label) for pattern, label in zip(patterns, labels)]
+        return [RegexPair(pattern, label, count_only) for pattern, label in zip(patterns, labels)]
     elif patterns is None and labels is None:
         return []
     else:
@@ -502,21 +502,23 @@ If the pattern does not include a capture group, then only one output column wil
 
 
 class RegexPair(object):
-    def __init__(self, pattern, label):
+    def __init__(self, pattern, label, count_only=False):
         self.pattern = re.compile(pattern)
         self.label = label
+        self.count_only = count_only
         self.has_groups = bool(self.pattern.groupindex)
         if self.has_groups:
             self.capture_groups = list(self.pattern.groupindex.keys())
 
     def get_pyarrow_fields(self):
+        value_type = pa.int64() if self.count_only else pa.string()
         if self.has_groups:
             fields = [
-                pa.field(self._make_key(cap_group), pa.string())
+                pa.field(self._make_key(cap_group), value_type)
                 for cap_group in self.capture_groups
             ]
         else:
-            fields = [pa.field(self.label, pa.string())]
+            fields = [pa.field(self.label, value_type)]
 
         return fields
 
@@ -529,37 +531,48 @@ class RegexPair(object):
         if self.has_groups:
             # if there are matches of some sort in this revision content, fill the lists for each cap_group
             # content can be None when the text or comment was deleted/suppressed
-            if content is not None and self.pattern.search(content) is not None:
-                m = self.pattern.finditer(content)
-                matchobjects = list(m)
-
+            if content is not None and (matchobjects := list(self.pattern.finditer(content))):
                 for cap_group in self.capture_groups:
                     key = self._make_key(cap_group)
                     temp_list = []
                     for match in matchobjects:
                         # we only want to add the match for the capture group if the match is not None
-                        if match.group(cap_group) is not None:
-                            temp_list.append(match.group(cap_group))
+                        if (group := match.group(cap_group)) is not None:
+                            temp_list.append(group)
 
-                    # if temp_list of matches is empty just make that column None
+                    # if temp_list of matches is empty just make that column None (0 in count mode)
                     if len(temp_list) == 0:
+                        if self.count_only:
+                            temp_dict[key] = 0
+                        else:
                             temp_dict[key] = None
                     # else we put in the list we made in the for-loop above
+                    else:
+                        if self.count_only:
+                            temp_dict[key] = len(temp_list)
                         else:
                             temp_dict[key] = ", ".join(temp_list)
 
-            # there are no matches at all in this revision content, we default values to None
+            # there are no matches at all in this revision content, we default values to None (0 in count mode)
             else:
                 for cap_group in self.capture_groups:
                     key = self._make_key(cap_group)
+                    if self.count_only:
+                        temp_dict[key] = 0
+                    else:
                         temp_dict[key] = None
 
         # there are no capture groups, we just search for all the matches of the regex
         else:
             # given that there are matches to be made
-            if content is not None and self.pattern.search(content) is not None:
-                m = self.pattern.findall(content)
-                temp_dict[self.label] = ", ".join(m)
+            if content is not None and (matches := self.pattern.findall(content)):
+                if self.count_only:
+                    temp_dict[self.label] = len(matches)
+                else:
+                    temp_dict[self.label] = ", ".join(matches)
+            else:
+                if self.count_only:
+                    temp_dict[self.label] = 0
                 else:
                     temp_dict[self.label] = None
 
@@ -575,6 +588,8 @@ class WikiqParser:
         regex_match_comment: list[str],
         regex_revision_label: list[str],
         regex_comment_label: list[str],
+        regex_revision_output_count: bool = False,
+        regex_comment_output_count: bool = False,
         text: bool = False,
         diff: bool = False,
         collapse_user: bool = False,
@@ -626,10 +641,10 @@ class WikiqParser:
 
         self.regex_schemas = []
         self.regex_revision_pairs: list[RegexPair] = self.make_matchmake_pairs(
-            regex_match_revision, regex_revision_label
+            regex_match_revision, regex_revision_label, regex_revision_output_count
         )
         self.regex_comment_pairs: list[RegexPair] = self.make_matchmake_pairs(
-            regex_match_comment, regex_comment_label
+            regex_match_comment, regex_comment_label, regex_comment_output_count
         )
 
         # Initialize output
@@ -672,13 +687,13 @@ class WikiqParser:
         if timer is not None:
             timer.cancel()
 
-    def make_matchmake_pairs(self, patterns, labels) -> list[RegexPair]:
+    def make_matchmake_pairs(self, patterns, labels, count_only=False) -> list[RegexPair]:
         if (patterns is not None and labels is not None) and (
             len(patterns) == len(labels)
         ):
             result: list[RegexPair] = []
             for pattern, label in zip(patterns, labels):
-                rp = RegexPair(pattern, label)
+                rp = RegexPair(pattern, label, count_only)
                 result.append(rp)
                 self.regex_schemas = self.regex_schemas + rp.get_pyarrow_fields()
             return result
@@ -1220,6 +1235,14 @@ def main():
         help="The label for the outputted column based on matching the regex in revision text.",
     )
 
+    parser.add_argument(
+        "-RPc",
+        "--revision-pattern-count",
+        dest="regex_revision_output_count",
+        action="store_true",
+        help="If present, this will cause the revision patterns to return counts of the number of matches instead of the text of the matches themselves. It will affect all revision patterns.",
+    )
+
     parser.add_argument(
         "-CP",
         "--comment-pattern",
@@ -1240,6 +1263,14 @@ def main():
         help="The label for the outputted column based on matching the regex in comments.",
     )
 
+    parser.add_argument(
+        "-CPc",
+        "--comment-pattern-count",
+        dest="regex_comment_output_count",
+        action="store_true",
+        help="If present, this will cause the comment patterns to return counts of the number of matches instead of the text of the matches themselves. It will affect all comment patterns.",
+    )
+
     parser.add_argument(
         "-d",
         "--diff",
@@ -1378,8 +1409,8 @@ def main():
 
     # Handle --print-schema: build and output schema, then exit
     if args.print_schema:
-        regex_revision_pairs = make_regex_pairs(args.regex_match_revision, args.regex_revision_label)
-        regex_comment_pairs = make_regex_pairs(args.regex_match_comment, args.regex_comment_label)
+        regex_revision_pairs = make_regex_pairs(args.regex_match_revision, args.regex_revision_label, args.regex_revision_output_count)
+        regex_comment_pairs = make_regex_pairs(args.regex_match_comment, args.regex_comment_label, args.regex_comment_output_count)
 
         table, _, _ = build_table(
             text=args.text,
@@ -1457,8 +1488,10 @@ def main():
                 revert_radius=args.revert_radius,
                 regex_match_revision=args.regex_match_revision,
                 regex_revision_label=args.regex_revision_label,
+                regex_revision_output_count=args.regex_revision_output_count,
                 regex_match_comment=args.regex_match_comment,
                 regex_comment_label=args.regex_comment_label,
+                regex_comment_output_count=args.regex_comment_output_count,
                 text=args.text,
                 diff=args.diff,
                 output_jsonl=output_jsonl,
@@ -1514,8 +1547,10 @@ def main():
             revert_radius=args.revert_radius,
             regex_match_revision=args.regex_match_revision,
             regex_revision_label=args.regex_revision_label,
+            regex_revision_output_count=args.regex_revision_output_count,
             regex_match_comment=args.regex_match_comment,
             regex_comment_label=args.regex_comment_label,
+            regex_comment_output_count=args.regex_comment_output_count,
             diff=args.diff,
             text=args.text,
             batch_size=args.batch_size,

test/test_wikiq.py

@@ -427,6 +427,55 @@ def test_regex_deleted_revisions():
     assert deleted["npov_npov"].isna().all()
     assert deleted["talk_talk"].isna().all()
 
+def test_regex_count_only():
+    # count mode returns match counts instead of the matched text, with 0
+    # (never None) for revisions with no matches or deleted content
+    pair = RegexPair(r"\bcat\b", "cats", count_only=True)
+    assert pair.matchmake("cat cat dog cat") == {"cats": 3}
+    assert pair.matchmake("dog") == {"cats": 0}
+    assert pair.matchmake(None) == {"cats": 0}
+    assert pair.get_pyarrow_fields()[0].type == pa.int64()
+
+    pair = RegexPair(r"(?P<a>\bcat\b)|(?P<b>\bdog\b)", "pets", count_only=True)
+    assert pair.matchmake("cat dog cat") == {"pets_a": 2, "pets_b": 1}
+    assert pair.matchmake("bird") == {"pets_a": 0, "pets_b": 0}
+    assert pair.matchmake(None) == {"pets_a": 0, "pets_b": 0}
+    assert all(f.type == pa.int64() for f in pair.get_pyarrow_fields())
+
+    # without count_only the original behavior is unchanged
+    pair = RegexPair(r"\bcat\b", "cats")
+    assert pair.matchmake("cat cat dog cat") == {"cats": "cat, cat, cat"}
+    assert pair.get_pyarrow_fields()[0].type == pa.string()
+
+def test_regex_count_e2e():
+    # -RPc/-CPc produce integer columns whose values equal the number of
+    # matches in the revision text and comment respectively
+    tester = WikiqTester(wiki=REGEXTEST, case_name="regex_count")
+
+    try:
+        tester.call_wikiq(
+            "--text",
+            "-RP 'TestCase' -RPl testcases -RPc",
+            "-CP '\\b[Cc]hevalier\\b' -CPl chev -CPc",
+        )
+    except subprocess.CalledProcessError as exc:
+        pytest.fail(exc.stderr.decode("utf8"))
+
+    import re
+    test = pd.read_table(tester.output)
+
+    assert test["testcases"].dtype == "int64"
+    assert test["chev"].dtype == "int64"
+
+    for _, row in test.iterrows():
+        text = row["text"] if isinstance(row["text"], str) else None
+        expected = len(re.findall("TestCase", text)) if text is not None else 0
+        assert row["testcases"] == expected, f"revid {row['revid']}: {row['testcases']} != {expected}"
+
+        comment = row["edit_summary"] if isinstance(row["edit_summary"], str) else None
+        expected = len(re.findall(r"\b[Cc]hevalier\b", comment)) if comment is not None else 0
+        assert row["chev"] == expected, f"revid {row['revid']}: {row['chev']} != {expected}"
+
 def test_redirect_detection():
     from wikiq.tables import RedirectDetector