python - 如果使用颜色提示，如何修复 Python readline 中的列计算

Question

我使用标准技巧来定制交互式 Python session :

$ cat ~/.bashrc
export PYTHONSTARTUP=~/.pystartup

$ cat ~/.pystartup
import os
import sys
import atexit
import readline
import rlcompleter

historyPath = os.path.expanduser("~/.pyhistory")

def save_history(historyPath=historyPath):
    import readline
    readline.write_history_file(historyPath)

if os.path.exists(historyPath):
    readline.read_history_file(historyPath)

term_with_colors = ['xterm', 'xterm-color', 'xterm-256color', 'linux', 'screen', 'screen-256color', 'screen-bce']
if os.environ.get('TERM') in term_with_colors:
    green='\033[32m'
    red='\033[31m'
    reset='\033[0m'
    sys.ps1 = red + '>>> ' + reset
    sys.ps2 = green + '... ' + reset
del term_with_colors

atexit.register(save_history)
del os, sys, atexit, readline, rlcompleter, save_history, historyPath

现在我得到了上下文相关的完成和颜色提示。

问题来自颜色提示 - 当我在交互式 Python session 中调用 history-search-backward(通过按 UP)时，Readline 会考虑终端转义序列，所以光标位置计算错误，文字显示错误。

在 Bash 手册页中，这个问题被提及并通过特殊标记修复:

    \[     begin a sequence of non-printing characters,
           which could be used to embed a
           terminal control sequence into the prompt
    \]     end a sequence of non-printing characters

如何解决 Python 提示的这个问题？

Answer 1

我打开info readline发现:

 -- Function: int rl_expand_prompt (char *prompt)
     Expand any special character sequences in PROMPT and set up the
     local Readline prompt redisplay variables.  This function is
     called by `readline()'.  It may also be called to expand the
     primary prompt if the `rl_on_new_line_with_prompt()' function or
     `rl_already_prompted' variable is used.  It returns the number of
     visible characters on the last line of the (possibly multi-line)
     prompt.  Applications may indicate that the prompt contains
     characters that take up no physical screen space when displayed by
     bracketing a sequence of such characters with the special markers
     `RL_PROMPT_START_IGNORE' and `RL_PROMPT_END_IGNORE' (declared in
     `readline.h'.  This may be used to embed terminal-specific escape
     sequences in prompts.

按照文字提示，我在 readline.h 中搜索了 RL_PROMPT_START_IGNORE 和 RL_PROMPT_END_IGNORE 定义，然后找到了下一个:

/* Definitions available for use by readline clients. */
#define RL_PROMPT_START_IGNORE  '\001'
#define RL_PROMPT_END_IGNORE    '\002'

所以我对我的 ~/.pystartup 进行了适当的更改:

    green='\001\033[32m\002'
    red='\001\033[31m\002'
    reset='\001\033[0m\002'

现在一切正常!!!