diff --git a/CHANGELOG.md b/CHANGELOG.md index 1dde4766..aad25891 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -4,6 +4,10 @@ * Bug Fixes * Fixed issue where persistent history file was not saved upon SIGHUP and SIGTERM signals. * Multiline commands are no longer fragmented in up-arrow history. + * Fixed bug where `async_alert()` overwrites readline's incremental and non-incremental search prompts. + * This fix introduces behavior where an updated prompt won't display after an aborted search + until a user presses Enter. See [async_printing.py](https://github.com/python-cmd2/cmd2/blob/master/examples/async_printing.py) + example for how to handle this case using `Cmd.need_prompt_refresh()`. * Enhancements * Removed dependency on `attrs` and replaced with [dataclasses](https://docs.python.org/3/library/dataclasses.html) * add `allow_clipboard` initialization parameter and attribute to disable ability to diff --git a/cmd2/ansi.py b/cmd2/ansi.py index 62b85384..93c2f019 100644 --- a/cmd2/ansi.py +++ b/cmd2/ansi.py @@ -1071,9 +1071,9 @@ def async_alert_str(*, terminal_columns: int, prompt: str, line: str, cursor_off # Calculate how many terminal lines are taken up by all prompt lines except for the last one. # That will be included in the input lines calculations since that is where the cursor is. num_prompt_terminal_lines = 0 - for line in prompt_lines[:-1]: - line_width = style_aware_wcswidth(line) - num_prompt_terminal_lines += int(line_width / terminal_columns) + 1 + for prompt_line in prompt_lines[:-1]: + prompt_line_width = style_aware_wcswidth(prompt_line) + num_prompt_terminal_lines += int(prompt_line_width / terminal_columns) + 1 # Now calculate how many terminal lines are take up by the input last_prompt_line = prompt_lines[-1] diff --git a/cmd2/cmd2.py b/cmd2/cmd2.py index 79fd2bf2..aec77f1b 100644 --- a/cmd2/cmd2.py +++ b/cmd2/cmd2.py @@ -130,8 +130,10 @@ from .rl_utils import ( RlType, rl_escape_prompt, + rl_get_display_prompt, rl_get_point, rl_get_prompt, + rl_in_search_mode, rl_set_prompt, rl_type, rl_warning, @@ -3295,6 +3297,12 @@ def _set_up_cmd2_readline(self) -> _SavedReadlineSettings: """ readline_settings = _SavedReadlineSettings() + if rl_type == RlType.GNU: + # To calculate line count when printing async_alerts, we rely on commands wider than + # the terminal to wrap across multiple lines. The default for horizontal-scroll-mode + # is "off" but a user may have overridden it in their readline initialization file. + readline.parse_and_bind("set horizontal-scroll-mode off") + if self._completion_supported(): # Set up readline for our tab completion needs if rl_type == RlType.GNU: @@ -5270,6 +5278,26 @@ class TestMyAppCase(Cmd2TestCase): # Return a failure error code to support automated transcript-based testing self.exit_code = 1 + def need_prompt_refresh(self, new_prompt: str) -> bool: # pragma: no cover + """ + Check if the onscreen prompt needs to be refreshed. + + There are two cases when the onscreen prompt needs to be refreshed. + 1. self.prompt differs from the new prompt. + 2. readline's prompt differs from the new prompt. + + This case occurs when async_alert() is called while a user is in search mode (e.g. Ctrl-r). + To prevent overwriting readline's onscreen search prompt, async_alert() does not update + readline's saved prompt value. Therefore when a user aborts a search, the old prompt + is still on screen until they press Enter or another call to async_alert() is made. + + This function is a convenient way for an async alert thread to check both cases. + + :param new_prompt: the new prompt string + :return: True if the onscreen prompt needs to be refreshed, otherwise False. + """ + return new_prompt != self.prompt or new_prompt != rl_get_prompt() + def async_alert(self, alert_msg: str, new_prompt: Optional[str] = None) -> None: # pragma: no cover """ Display an important message to the user while they are at a command line prompt. @@ -5277,7 +5305,7 @@ def async_alert(self, alert_msg: str, new_prompt: Optional[str] = None) -> None: text and cursor location is left alone. IMPORTANT: This function will not print an alert unless it can acquire self.terminal_lock to ensure - a prompt is onscreen. Therefore, it is best to acquire the lock before calling this function + a prompt is on screen. Therefore, it is best to acquire the lock before calling this function to guarantee the alert prints and to avoid raising a RuntimeError. This function is only needed when you need to print an alert while the main thread is blocking @@ -5309,20 +5337,21 @@ def async_alert(self, alert_msg: str, new_prompt: Optional[str] = None) -> None: if new_prompt is not None: self.prompt = new_prompt - # Check if the prompt to display has changed from what's currently displayed - cur_onscreen_prompt = rl_get_prompt() - new_onscreen_prompt = self.continuation_prompt if self._at_continuation_prompt else self.prompt - - if new_onscreen_prompt != cur_onscreen_prompt: - update_terminal = True + # We won't change the onscreen prompt while readline is in search mode (e.g. Ctrl-r). + # Otherwise the new prompt will overwrite readline's onscreen search prompt. + if not rl_in_search_mode(): + new_onscreen_prompt = self.continuation_prompt if self._at_continuation_prompt else self.prompt + if self.need_prompt_refresh(new_onscreen_prompt): + update_terminal = True + rl_set_prompt(new_onscreen_prompt) if update_terminal: import shutil - # Generate the string which will replace the current prompt and input lines with the alert + # Print a string which replaces the current prompt and input lines with the alert terminal_str = ansi.async_alert_str( terminal_columns=shutil.get_terminal_size().columns, - prompt=cur_onscreen_prompt, + prompt=rl_get_display_prompt(), line=readline.get_line_buffer(), cursor_offset=rl_get_point(), alert_msg=alert_msg, @@ -5333,9 +5362,6 @@ def async_alert(self, alert_msg: str, new_prompt: Optional[str] = None) -> None: elif rl_type == RlType.PYREADLINE: readline.rl.mode.console.write(terminal_str) - # Update Readline's prompt before we redraw it - rl_set_prompt(new_onscreen_prompt) - # Redraw the prompt and input lines below the alert rl_force_redisplay() diff --git a/cmd2/rl_utils.py b/cmd2/rl_utils.py index 28d9d2d6..9eb8c2c6 100644 --- a/cmd2/rl_utils.py +++ b/cmd2/rl_utils.py @@ -200,7 +200,7 @@ def rl_get_point() -> int: # pragma: no cover def rl_get_prompt() -> str: # pragma: no cover - """Gets Readline's current prompt""" + """Get Readline's prompt""" if rl_type == RlType.GNU: encoded_prompt = ctypes.c_char_p.in_dll(readline_lib, "rl_prompt").value if encoded_prompt is None: @@ -221,6 +221,24 @@ def rl_get_prompt() -> str: # pragma: no cover return rl_unescape_prompt(prompt) +def rl_get_display_prompt() -> str: # pragma: no cover + """ + Get Readline's currently displayed prompt. + + In GNU Readline, the displayed prompt sometimes differs from the prompt. + This occurs in functions that use the prompt string as a message area, such as incremental search. + """ + if rl_type == RlType.GNU: + encoded_prompt = ctypes.c_char_p.in_dll(readline_lib, "rl_display_prompt").value + if encoded_prompt is None: + prompt = '' + else: + prompt = encoded_prompt.decode(encoding='utf-8') + return rl_unescape_prompt(prompt) + else: + return rl_get_prompt() + + def rl_set_prompt(prompt: str) -> None: # pragma: no cover """ Sets Readline's prompt @@ -237,7 +255,8 @@ def rl_set_prompt(prompt: str) -> None: # pragma: no cover def rl_escape_prompt(prompt: str) -> str: - """Overcome bug in GNU Readline in relation to calculation of prompt length in presence of ANSI escape codes + """ + Overcome bug in GNU Readline in relation to calculation of prompt length in presence of ANSI escape codes :param prompt: original prompt :return: prompt safe to pass to GNU Readline @@ -276,3 +295,32 @@ def rl_unescape_prompt(prompt: str) -> str: prompt = prompt.replace(escape_start, "").replace(escape_end, "") return prompt + + +def rl_in_search_mode() -> bool: + """Check if readline is doing either an incremental (e.g. Ctrl-r) or non-incremental (e.g. Esc-p) search""" + if rl_type == RlType.GNU: + # GNU Readline defines constants that we can use to determine if in search mode. + # RL_STATE_ISEARCH 0x0000080 + # RL_STATE_NSEARCH 0x0000100 + IN_SEARCH_MODE = 0x0000180 + + readline_state = ctypes.c_int.in_dll(readline_lib, "rl_readline_state").value + return bool(IN_SEARCH_MODE & readline_state) + elif rl_type == RlType.PYREADLINE: + from pyreadline3.modes.emacs import ( # type: ignore[import] + EmacsMode, + ) + + # These search modes only apply to Emacs mode, which is the default. + if not isinstance(readline.rl.mode, EmacsMode): + return False + + # While in search mode, the current keyevent function is set one of the following. + search_funcs = ( + readline.rl.mode._process_incremental_search_keyevent, + readline.rl.mode._process_non_incremental_search_keyevent, + ) + return readline.rl.mode.process_keyevent_queue[-1] in search_funcs + else: + return False diff --git a/examples/async_printing.py b/examples/async_printing.py index 6ff3a262..c5655313 100755 --- a/examples/async_printing.py +++ b/examples/async_printing.py @@ -189,8 +189,9 @@ def _alerter_thread_func(self) -> None: new_title = "Alerts Printed: {}".format(self._alert_count) self.set_window_title(new_title) - # No alerts needed to be printed, check if the prompt changed - elif new_prompt != self.prompt: + # There are no alerts to print, but we should still check + # if the onscreen prompt needs to be refreshed. + elif self.need_prompt_refresh(new_prompt): self.async_update_prompt(new_prompt) # Don't forget to release the lock