python - 如何在 Python 中着色用户输入？

Question

我正在创建一个命令行计算器工具，我想让它在用户输入时格式化用户输入，类似于 Fish 和 Powershell 所做的( screenshots )。
目前，我能想到的唯一简单的方法是一次获取一个字符，然后将格式化的行重新打印到屏幕上。

# This code is probably very dodgy, 
# it's just to give you an idea what I'm thinking
# Use external getch module to get input without echoing to screen
from getch import getch 
inp = ""
while True:
    char = getch()
    if char == '\n': break
    if char == '\b': inp = inp[:-1]
    else: inp += char
    # Print with carriage return so that next input overwrites it
    print(colourFormatInput(inp) + '\r') 
# Outside loop: process input and devliver results

虽然这在技术上可行，但我觉得这是大量的手动工作，如果我想添加诸如使用箭头键移动光标位置之类的功能，只会变得更加复杂。
有没有一种简单的方法来获得这种功能而不必自己编写所有代码？

Answer 1

你可以用 prompt_toolkit 来做到这一点
如果您需要，这里是文档:

Getting Started

Asking for input/prompts

您可以通过以下示例将语法突出显示添加到输入中:

Adding syntax highlighting is as simple as adding a lexer. All of the Pygments lexers can be used after wrapping them in a PygmentsLexer. It is also possible to create a custom lexer by implementing the Lexer abstract base class.

from pygments.lexers.html import HtmlLexer
from prompt_toolkit.shortcuts import prompt
from prompt_toolkit.lexers import PygmentsLexer

text = prompt('Enter HTML: ', lexer=PygmentsLexer(HtmlLexer))
print('You said: %s' % text)

以与上述相同的方式，您可以创建自定义 prompt_toolkit.lexers.Lexer计算器高亮就像下面的例子。在这里，我创建了一个自定义帮助器类:

from typing import Callable
from prompt_toolkit.document import Document
from prompt_toolkit.formatted_text.base import StyleAndTextTuples
from prompt_toolkit.formatted_text import FormattedText
from prompt_toolkit.shortcuts import prompt
import prompt_toolkit.lexers
import re

class CustomRegexLexer(prompt_toolkit.lexers.Lexer):
    def __init__(self, regex_mapping):
        super().__init__()
        self.regex_mapping = regex_mapping

    def lex_document(self, document: Document) -> Callable[[int], StyleAndTextTuples]:
        def lex(_: int):
            line = document.text
            tokens = []
            while len(line) != 0:
                for pattern, style_string in self.regex_mapping.items():
                    match: re.Match = pattern.search(line)

                    if not match:
                        continue
                    else:
                        # print(f"found_match: {match}")
                        pass
                    match_string = line[:match.span()[1]]
                    line = line[match.span()[1]:]
                    tokens.append((style_string, match_string))
                    break
            return tokens
        return lex

现在实现了上面的辅助类，我们可以创建我们的正则表达式模式和它们各自的样式，要了解更多关于样式字符串的内容，请访问 this page

# Making regex for different operators. Make sure you add `^` anchor
# to the start of all the patterns
operators_allowed = ["+", "-", "/", "*", "(", ")", "=", "^"]
operators = re.compile("^["+''.join([f"\\{x}" for x in operators_allowed])+"]")
numbers = re.compile(r"^\d+(\.\d+)?")
text = re.compile(r"^.")


regex_mapping = {
    operators: "#ff70e5",  # Change colors according to your requirement
    numbers: "#ffa500",
    text: "#2ef5ff",
}

MyCalculatorLexer = CustomRegexLexer(regex_mapping)

创建词法分析器后，您现在可以在函数提示中使用词法分析器:

text = prompt("Enter Equation: ", lexer=MyCalculatorLexer)

# Or

def input_maths(message):
    return prompt(message, lexer=MyCalculatorLexer)

text = input_maths("Enter Equation: ")

这是一些示例输出:

现在一切正常。也请查看 prompt_toolkit ， 你可以
创建大量自定义的东西，如图所示 gallery