Merge pull request #290 from xxyzz/rel2abs

Implement `#rel2abs` parser function

src/wikitextprocessor/parserfns.py

@@ -8,6 +8,7 @@
 import urllib.parse
 from collections.abc import Callable, Sequence
 from datetime import datetime, timezone
+from pathlib import Path
 from typing import TYPE_CHECKING, Optional, Union
 
 import dateparser
@@ -1623,6 +1624,26 @@ def number_of_articles_fn(
     return str(wtp.saved_page_nums([0], False))
 
 
+def rel2abs_fn(
+    wtp: "Wtp", fn_name: str, args: list[str], expander: Callable[[str], str]
+) -> str:
+    # https://www.mediawiki.org/wiki/Help:Extension:ParserFunctions##rel2abs
+    # https://github.com/wikimedia/mediawiki-extensions-ParserFunctions/blob/ea4d4d94ee0c55b6039e05650ccc322e106ae06b/includes/ParserFunctions.php#L319
+    original_path_str = args[0].strip()
+    path = Path(original_path_str.removeprefix("/"))
+    base_path = Path("/" + (wtp.title or ""))
+    if len(args) > 1:
+        base_path = Path("/" + args[1].strip())
+    # not relative path
+    if (
+        not original_path_str.startswith(("/", "./", "../"))
+        and original_path_str != ".."
+    ):
+        base_path = Path("/")
+    path = base_path / path
+    return str(path.resolve()).removeprefix("/")
+
+
 # This list should include names of predefined parser functions and
 # predefined variables (some of which can take arguments using the same
 # syntax as parser functions and we treat them as parser functions).
@@ -1733,7 +1754,7 @@ def number_of_articles_fn(
     "anchorencode": anchorencode_fn,
     "ns": ns_fn,
     "nse": ns_fn,  # We don't have spaces in ns names
-    "#rel2abs": unimplemented_fn,
+    "#rel2abs": rel2abs_fn,
     "#titleparts": titleparts_fn,
     "#expr": expr_fn,
     "#if": if_fn,

tests/test_parserfns.py

@@ -164,3 +164,30 @@ def test_timel(self):
         time = datetime.fromisoformat(expanded)
         delta = datetime.now(timezone.utc) - time
         self.assertLess(abs(delta.total_seconds()), 1)
+
+    def test_rel2abs(self):
+        # https://www.mediawiki.org/wiki/Help:Extension:ParserFunctions##rel2abs
+        self.wtp.start_page("test")
+        test_cases = (
+            (
+                "{{#rel2abs: /quok | Help:Foo/bar/baz }}",
+                "Help:Foo/bar/baz/quok",
+            ),
+            (
+                "{{#rel2abs: ./quok | Help:Foo/bar/baz }}",
+                "Help:Foo/bar/baz/quok",
+            ),
+            ("{{#rel2abs: ../quok | Help:Foo/bar/baz }}", "Help:Foo/bar/quok"),
+            ("{{#rel2abs: ../. | Help:Foo/bar/baz }}", "Help:Foo/bar"),
+            (
+                "{{#rel2abs: ../quok/. | Help:Foo/bar/baz }}",
+                "Help:Foo/bar/quok",
+            ),
+            ("{{#rel2abs: ../../quok | Help:Foo/bar/baz }}", "Help:Foo/quok"),
+            ("{{#rel2abs: ../../../quok | Help:Foo/bar/baz }}", "quok"),
+            ("{{#rel2abs: b }}", "b"),
+            ("{{#rel2abs: /b }}", "test/b"),
+        )
+        for wikitext, result in test_cases:
+            with self.subTest(wikitext=wikitext, result=result):
+                self.assertEqual(self.wtp.expand(wikitext), result)