如果使用颜色提示，如何在Python readline中修复列计算 [英] How to fix column calculation in Python readline if using color prompt

问题描述

我使用标准技巧自定义交互式Python会话:

I use standard tips for customizing interactive 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，我得到上下文相关的完成和颜色提示.

Now I get context sensitive completion and color prompt.

问题来自颜色提示-当我在交互式Python会话中调用 history-search-backward (通过按 UP )时，Readline考虑了终端转义序列，因此光标位置计算错误，文本显示错误.

The problem comes from color prompt - when I invoke history-search-backward (by pressing UP) in an interactive Python session, Readline takes in account terminal escape sequences, so the cursor position is wrongly calculated and the text is wrongly displayed.

在Bash手册页中，通过特殊标记提到并解决了此问题:

In Bash man page this problem is mentioned and fixed by special markers:

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

如何为Python提示符解决此问题?

How to fix this issue for Python prompt?

推荐答案

我打开信息阅读行，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.

我说的是文字，我在 readline.h 中搜索 RL_PROMPT_START_IGNORE 和 RL_PROMPT_END_IGNORE 定义，然后找到下一个:

As say text I search for RL_PROMPT_START_IGNORE and RL_PROMPT_END_IGNORE definition in readline.h and found next:

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

因此，我对〜/.pystartup 进行了适当的更改:

So I put appropriate changes to my ~/.pystartup:

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

现在一切正常！

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