python 实用库收集

一个好的REPL(Read-Eval-Print Loop)，交互式命令行程序，需要具备以下几个特点：

1. 最基本的命令行与回显
2. 回显带有分页效果，类似 more
3. 带有历史命令推荐
4. 关键词自动补全
5. 语法高亮

示例

我们以模拟Sql的REPL来将这些特性一点点来累加起来

基本命令行与回显

from prompt_toolkit import prompt


while 1:
    user_input = prompt('>')
    print(user_input)

添加分页效果

使用的是click.echo_via_pager

from prompt_toolkit import prompt
import click


while 1:
    user_input = prompt('>')
    click.echo_via_pager(user_input)

历史命令推荐

使用的是 prompt_toolkit.history 模块中的 FileHistory
会创建一个历史记录的文件，然后通过prompt_toolkit.auto_suggest.AutoSugguestFromHistory进行推荐。

from prompt_toolkit import prompt
from prompt_toolkit.history import FileHistory
from prompt_toolkit.auto_suggest import AutoSuggestFromHistory
import click


while 1:
    user_input = prompt('>',
                        history=FileHistory('history.txt'),
                        auto_suggest=AutoSuggestFromHistory(),
                        )
    click.echo_via_pager(user_input)

关键词补全

关键词补全有两种方法：

1. 用prompt_toolkit.completion.WordCompleter 直接定义单词
2. 用prompt_toolkit.completion 中的 Completer 和 Completion配合fuzzyfinder进行模糊查询，这种方法自定义程度更高

WordCompleter

from prompt_toolkit import prompt
from prompt_toolkit.history import FileHistory
from prompt_toolkit.auto_suggest import AutoSuggestFromHistory
import click
from prompt_toolkit.completion import WordCompleter


SQLCompleter = WordCompleter(
    ['select', 'from', 'insert', 'update', 'delete', 'drop'], ignore_case=True)


while 1:
    user_input = prompt('>',
                        history=FileHistory('history.txt'),
                        auto_suggest=AutoSuggestFromHistory(),
                        completer=SQLCompleter,
                        )
    click.echo_via_pager(user_input)

fuzzyfinder

from prompt_toolkit import prompt
from prompt_toolkit.history import FileHistory
from prompt_toolkit.auto_suggest import AutoSuggestFromHistory
import click
from prompt_toolkit.completion import Completer, Completion
from fuzzyfinder.main import fuzzyfinder


SQLKeywords = ['select', 'from', 'insert', 'update', 'delete', 'drop']




class SQLCompleter(Completer):
    def get_completions(self, document, complete_event):
        word_before_cursor = document.get_word_before_cursor(WORD=True)
        matches = fuzzyfinder(word_before_cursor, SQLKeywords)
        for m in matches:
            yield Completion(m, start_position=-len(word_before_cursor))




while 1:
    user_input = prompt('>',
                        history=FileHistory('history.txt'),
                        auto_suggest=AutoSuggestFromHistory(),
                        completer=SQLCompleter(),
                        )
    click.echo_via_pager(user_input)

语法高亮

高亮可以使用Pygments.lexers 模块

from prompt_toolkit import prompt
from prompt_toolkit.history import FileHistory
from prompt_toolkit.auto_suggest import AutoSuggestFromHistory
import click
from prompt_toolkit.completion import Completer, Completion
from fuzzyfinder.main import fuzzyfinder
from pygments.lexers.sql import SqlLexer
from prompt_toolkit.lexers import PygmentsLexer


SQLKeywords = ['select', 'from', 'insert', 'update', 'delete', 'drop']




class SQLCompleter(Completer):
    def get_completions(self, document, complete_event):
        word_before_cursor = document.get_word_before_cursor(WORD=True)
        matches = fuzzyfinder(word_before_cursor, SQLKeywords)
        for m in matches:
            yield Completion(m, start_position=-len(word_before_cursor))




while 1:
    user_input = prompt('SQL>',
                        history=FileHistory('history.txt'),
                        auto_suggest=AutoSuggestFromHistory(),
                        completer=SQLCompleter(),
                        lexer=PygmentsLexer(SqlLexer)
                        )
    click.echo_via_pager(user_input)

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