Add REPL history navigation with partial text

This changes add supports to navigate the history with arrow up
based on partial text in the buffer

Author: estyxx

Lib/_pyrepl/historical_reader.py

@@ -272,10 +272,21 @@ def collect_keymap(self) -> tuple[tuple[KeySpec, CommandName], ...]:
     def select_item(self, i: int) -> None:
         self.transient_history[self.historyi] = self.get_unicode()
         buf = self.transient_history.get(i)
+        self.historyi = i
+
+        if self.buffer:
+            filtered_history = [
+                (index, item)
+                for index, item in enumerate(self.history)
+                if item.startswith(self.get_unicode())
+                and item.strip() not in self.transient_history.values()
+            ]
+            if filtered_history:
+                self.historyi, buf = filtered_history[min(i, len(filtered_history) - 1)]
+
         if buf is None:
             buf = self.history[i].rstrip()
         self.buffer = list(buf)
-        self.historyi = i
         self.pos = len(self.buffer)
         self.dirty = True
         self.last_refresh_cache.invalidated = True

Lib/test/test_pyrepl/test_pyrepl.py

@@ -601,6 +601,46 @@ def test_history_navigation_with_up_arrow(self):
         self.assertEqual(output, "1+1")
         self.assertEqual(clean_screen(reader.screen), "1+1")
 
+    def test_history_navigation_with_up_arrow_and_partial_text(self):
+        events = itertools.chain(
+            code_to_events("spam = 1\nham = 2\neggs = 3\nsp"),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+            ],
+        )
+
+        reader = self.prepare_reader(events)
+
+        output = multiline_input(reader)
+        self.assertEqual(output, "spam = 1")
+
+    def test_history_navigation_with_up_arrow_and_partial_text_with_similar_entries(self):
+        events = itertools.chain(
+            code_to_events("a=111\na=11\na=1\na="),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+            ],
+        )
+
+        reader = self.prepare_reader(events)
+        print()
+        output = multiline_input(reader)
+        self.assertEqual(output, "a=111")
+        self.assertEqual(clean_screen(reader.screen), "a=111")
+        output = multiline_input(reader)
+        self.assertEqual(output, "a=11")
+        self.assertEqual(clean_screen(reader.screen), "a=11")
+        output = multiline_input(reader)
+        self.assertEqual(output, "a=1")
+        self.assertEqual(clean_screen(reader.screen), "a=1")
+        output = multiline_input(reader)
+        self.assertEqual(output, "a=111")
+        self.assertEqual(clean_screen(reader.screen), "a=111")
+
     def test_history_with_multiline_entries(self):
         code = "def foo():\nx = 1\ny = 2\nz = 3\n\ndef bar():\nreturn 42\n\n"
         events = list(itertools.chain(