pythongh-132267: fix unsynchronized cursor position and buffer mismatch after resize

Author: ImFeH2

Lib/_pyrepl/reader.py

@@ -344,7 +344,10 @@ def calc_screen(self) -> list[str]:
             pos -= line_len + 1
             prompt, prompt_len = self.process_prompt(prompt)
             chars, char_widths = disp_str(line)
-            wrapcount = (sum(char_widths) + prompt_len) // self.console.width
+            wrapcount = (sum(char_widths) + prompt_len) // (self.console.width - 1) # 1 for line continuations
+            if (sum(char_widths) + prompt_len) % (self.console.width - 1) == 0:
+                wrapcount -= 1
+
             trace("wrapcount = {wrapcount}", wrapcount=wrapcount)
             if wrapcount == 0 or not char_widths:
                 offset += line_len + 1  # Takes all of the line plus the newline

Lib/_pyrepl/unix_console.py

@@ -37,7 +37,7 @@
 from .fancy_termios import tcgetattr, tcsetattr
 from .trace import trace
 from .unix_eventqueue import EventQueue
-from .utils import wlen
+from .utils import wlen, ANSI_ESCAPE_SEQUENCE
 
 
 TYPE_CHECKING = False
@@ -233,7 +233,6 @@ def refresh(self, screen, c_xy):
         Parameters:
         - screen (list): List of strings representing the screen contents.
         - c_xy (tuple): Cursor position (x, y) on the screen.
-        - repaint (bool): If True, overwrite the old screen and not reuse.
         """
         cx, cy = c_xy
         if not self.__gone_tall:
@@ -338,47 +337,64 @@ def sync_screen(self):
         old_height, old_width = self.height, self.width
         new_height, new_width = self.getheightwidth()
 
-        groups = []
+        vlines = []
         x, y = 0, 0
         new_line = True
         for i, line in enumerate(self.screen):
             l = wlen(line)
             if i == py:
                 if new_line:
-                    y = sum(wlen(g) // new_width for g in groups) + len(groups) - 1
+                    y = sum(wlen(g) // new_width for g in vlines) + len(vlines)
                     x = px
                 else:
-                    y = sum(wlen(g) // new_width for g in groups[:-1]) + len(groups) - 1
-                    x = px + wlen(groups[-1])
+                    y = sum(wlen(g) // new_width for g in vlines[:-1]) + len(vlines) - 1
+                    x = px + wlen(vlines[-1])
                 if x >= new_width:
                     y += x // new_width
                     x %= new_width
 
             if new_line:
-                groups.append(line)
+                vlines.append(line)
                 new_line = False
             else:
-                groups[-1] += line
+                vlines[-1] += line
             if l != old_width:
                 new_line = True
 
         new_screen = []
-        for group in groups:
-            l = 0
-            line = ""
-            for c in group:
-                cw = wlen(c)
-                if l + cw > new_width:
-                    new_screen.append(line)
-                    line = c
-                    l = cw
-                else:
-                    line += c
-                    l += cw
-            if line:
-                new_screen.append(line)
+        for vline in vlines:
+            parts = []
+            last_end = 0
+            for match in ANSI_ESCAPE_SEQUENCE.finditer(vline):
+                if match.start() > last_end:
+                    parts.append((vline[last_end:match.start()], False))
+                parts.append((match.group(), True))
+                last_end = match.end()
+
+            if last_end < len(vline):
+                parts.append((vline[last_end:], False))
+
+            result = ""
+            length = 0
+            for part, is_escape in parts:
+                if is_escape:
+                    result += part
+                    continue
+                for char in part:
+                    lc = wlen(char)
+                    if lc + length > new_width:
+                        # save the current line
+                        new_screen.append(result)
+                        result = ""
+                        length = 0
+                    result += char
+                    length += lc
+
+            if result:
+                new_screen.append(result)
 
         self.posxy = x, y
+        self.screen = new_screen
         self.height, self.width = new_height, new_width
 
     def prepare(self):
@@ -745,13 +761,18 @@ def __write_changed_line(self, y, oldline, newline, px_coord):
             self.__write(newline[x_pos])
             self.posxy = character_width + 1, y
 
+            if newline[-1] != oldline[-1]:
+                self.__move(self.width, y)
+                self.__write(newline[-1])
+                self.posxy = self.width - 1, y
+
         else:
             self.__hide_cursor()
             self.__move(x_coord, y)
             if wlen(oldline) > wlen(newline):
                 self.__write_code(self._el)
             self.__write(newline[x_pos:])
-            self.posxy = wlen(newline), y
+            self.posxy = min(wlen(newline), self.width - 1), y
 
         if "\x1b" in newline:
             # ANSI escape characters are present, so we can't assume

Lib/_pyrepl/windows_console.py

@@ -40,7 +40,7 @@
 from ctypes import Structure, POINTER, Union
 from .console import Event, Console
 from .trace import trace
-from .utils import wlen
+from .utils import wlen, ANSI_ESCAPE_SEQUENCE
 from .windows_eventqueue import EventQueue
 
 try:
@@ -277,7 +277,7 @@ def __write_changed_line(
             self._move_relative(0, y + 1)
             self.posxy = 0, y + 1
         else:
-            self.posxy = wlen(newline), y
+            self.posxy = max(wlen(newline), self.width - 1), y
 
             if "\x1b" in newline or y != self.posxy[1] or '\x1a' in newline:
                 # ANSI escape characters are present, so we can't assume
@@ -398,47 +398,64 @@ def sync_screen(self):
         old_height, old_width = self.height, self.width
         new_height, new_width = self.getheightwidth()
 
-        groups = []
+        vlines = []
         x, y = 0, 0
         new_line = True
         for i, line in enumerate(self.screen):
             l = wlen(line)
             if i == py:
                 if new_line:
-                    y = sum(wlen(g) // new_width for g in groups) + len(groups) - 1
+                    y = sum(wlen(g) // new_width for g in vlines) + len(vlines)
                     x = px
                 else:
-                    y = sum(wlen(g) // new_width for g in groups[:-1]) + len(groups) - 1
-                    x = px + wlen(groups[-1])
+                    y = sum(wlen(g) // new_width for g in vlines[:-1]) + len(vlines) - 1
+                    x = px + wlen(vlines[-1])
                 if x >= new_width:
                     y += x // new_width
                     x %= new_width
 
             if new_line:
-                groups.append(line)
+                vlines.append(line)
                 new_line = False
             else:
-                groups[-1] += line
+                vlines[-1] += line
             if l != old_width:
                 new_line = True
 
         new_screen = []
-        for group in groups:
-            l = 0
-            line = ""
-            for c in group:
-                cw = wlen(c)
-                if l + cw > new_width:
-                    new_screen.append(line)
-                    line = c
-                    l = cw
-                else:
-                    line += c
-                    l += cw
-            if line:
-                new_screen.append(line)
+        for vline in vlines:
+            parts = []
+            last_end = 0
+            for match in ANSI_ESCAPE_SEQUENCE.finditer(vline):
+                if match.start() > last_end:
+                    parts.append((vline[last_end:match.start()], False))
+                parts.append((match.group(), True))
+                last_end = match.end()
+
+            if last_end < len(vline):
+                parts.append((vline[last_end:], False))
+
+            result = ""
+            length = 0
+            for part, is_escape in parts:
+                if is_escape:
+                    result += part
+                    continue
+                for char in part:
+                    lc = wlen(char)
+                    if lc + length > new_width:
+                        # save the current line
+                        new_screen.append(result)
+                        result = ""
+                        length = 0
+                    result += char
+                    length += lc
+
+            if result:
+                new_screen.append(result)
 
         self.posxy = x, y
+        self.screen = new_screen
         self.height, self.width = new_height, new_width
 
     def set_cursor_vis(self, visible: bool) -> None: