From 9c1e35f71e1a4b31ee7860d3efe3c033be2168d5 Mon Sep 17 00:00:00 2001
From: Ian Wilson <ian@gardentheory.com>
Date: Sat, 5 Sep 2026 14:29:59 -0700
Subject: [PATCH 1/5] gh-157003: Add flush() method to HTMLParser.

---
 Lib/html/parser.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Lib/html/parser.py b/Lib/html/parser.py
index fbe0d3665e073cc..d4877247cf56b86 100644
--- a/Lib/html/parser.py
+++ b/Lib/html/parser.py
@@ -192,6 +192,17 @@ def feed(self, data):
                 # Nothing was parsed; wait until the buffer doubles.
                 self._parse_threshold = len(self.rawdata)
 
+    def flush(self):
+        """Process all data fed insofar as it consists of complete elements.
+        Incomplete data remains buffered.
+        """
+        if self._pending:
+            self.rawdata += ''.join(self._pending)
+            self._pending.clear()
+            self._pending_len = 0
+            self._parse_threshold = 1
+        self.goahead(0)
+
     def close(self):
         """Handle any buffered data."""
         if self._pending:

From 44fc4b976f84e9ff716f03519abddceced760347 Mon Sep 17 00:00:00 2001
From: Ian Wilson <ian@gardentheory.com>
Date: Sat, 5 Sep 2026 14:37:18 -0700
Subject: [PATCH 2/5] gh-157003: Add docstring for HTMLParser.flush() method.

---
 Doc/library/html.parser.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Doc/library/html.parser.rst b/Doc/library/html.parser.rst
index 11f851d4f6c4b74..6b0b7f7ff0e44b7 100644
--- a/Doc/library/html.parser.rst
+++ b/Doc/library/html.parser.rst
@@ -101,6 +101,12 @@ The output will then be:
    :meth:`close` is called.  *data* must be :class:`str`.
 
 
+.. method:: HTMLParser.flush()
+
+   Process all data fed insofar as it consists of complete elements. Incomplete
+   data remains buffered.
+
+
 .. method:: HTMLParser.close()
 
    Force processing of all buffered data as if it were followed by an end-of-file

From 70db209d554efc67f83a42217db8779345cc0172 Mon Sep 17 00:00:00 2001
From: Ian Wilson <ian@gardentheory.com>
Date: Sat, 5 Sep 2026 14:45:21 -0700
Subject: [PATCH 3/5] Re-save off events.append when re-binding events.

---
 Lib/test/test_htmlparser.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/test/test_htmlparser.py b/Lib/test/test_htmlparser.py
index 3fdaed4ff46b9d0..850267111172375 100644
--- a/Lib/test/test_htmlparser.py
+++ b/Lib/test/test_htmlparser.py
@@ -42,7 +42,9 @@ def get_events(self):
             else:
                 L.append(event)
             prevtype = type
+        # Reset events and append for re-testing
         self.events = L
+        self.append = self.events.append
         return L
 
     # structure markup

From 11dfaf6fa8a20e10ba7b11d6f7ffd4926b326119 Mon Sep 17 00:00:00 2001
From: Ian Wilson <ian@gardentheory.com>
Date: Sat, 5 Sep 2026 14:45:45 -0700
Subject: [PATCH 4/5] Add test for HTMLParser.flush() method.

---
 Lib/test/test_htmlparser.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Lib/test/test_htmlparser.py b/Lib/test/test_htmlparser.py
index 850267111172375..b4452e7ad0551b4 100644
--- a/Lib/test/test_htmlparser.py
+++ b/Lib/test/test_htmlparser.py
@@ -1023,6 +1023,24 @@ def test_convert_charrefs_dropped_text(self):
              ('endtag', 'a'), ('data', ' bar & baz')]
         )
 
+    def test_flush(self):
+        attrs = [(f"a{i}", str(i)) for i in range(8)]
+        parts = ["<div", *[f' {attr[0]}="{attr[1]}"' for attr in attrs], ">", "</div>"]
+        parser = EventCollector()
+        for part in parts:
+            parser.feed(part)
+        # confirm the fed data is buffered and not processed yet
+        self.assertEqual(parser.get_events(), [])
+        parser.flush()
+        expected = [
+            ('starttag', 'div', attrs),
+            ('endtag', 'div'),
+        ]
+        self.assertEqual(parser.get_events(), expected)
+        parser.close()
+        # close should do nothing, event log is the same as before
+        self.assertEqual(parser.get_events(), expected)
+
     @support.requires_resource('cpu')
     def test_eof_no_quadratic_complexity(self):
         # Each of these examples used to take about an hour.

From b06b12ee548d9b45354210e0c94fffc004e8ebc7 Mon Sep 17 00:00:00 2001
From: Ian Wilson <ian@gardentheory.com>
Date: Sat, 5 Sep 2026 15:21:57 -0700
Subject: [PATCH 5/5] Add news blurb.

---
 .../Library/2026-09-05-15-21-00.gh-issue-157003.BOCIir.rst     | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2026-09-05-15-21-00.gh-issue-157003.BOCIir.rst

diff --git a/Misc/NEWS.d/next/Library/2026-09-05-15-21-00.gh-issue-157003.BOCIir.rst b/Misc/NEWS.d/next/Library/2026-09-05-15-21-00.gh-issue-157003.BOCIir.rst
new file mode 100644
index 000000000000000..eb42caf55d205e8
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-09-05-15-21-00.gh-issue-157003.BOCIir.rst
@@ -0,0 +1,3 @@
+Add ``HTMLParser.flush()`` to process all buffered data that consists of
+complete elements.  This method will be useful now that
+``HTMLParser.feed()``  utilizes more extensive buffering.