在pyparsing期间更改字符串

问题描述

在我的 pyparsing 代码中，我有以下表达式:

In my pyparsing code I have the following expressions:

exp1 = Literal("foo") + Suppress(Literal("="))  + Word(alphanums+'_-')
exp2 = Literal("foo") + Suppress(Literal("!=")) + Word(alphanums+'_-')
exp = Optional(exp1) & Optional(exp2)

我想把exp2中的foo改成bar，这样我就可以区分解析数据中的=和!=了.这可能吗?

I want to change foo in exp2 to bar, so that I can distinguish between = and != in the parsed data. Is this possible?

推荐答案

Karl Knechtel 的评论是有效的，但如果您想更改匹配的标记，您可以在解析操作中执行此操作.

Karl Knechtel's comment is valid, but if you want to change a matched token, you can do this in a parse action.

def changeText(s,l,t):
    return "boo" + t[0]

expr = Literal("A").setParseAction(changeText) + "B"
print expr.parseString("A B").asList()

将打印:

['booA', 'B']

如果只想用常量字符串替换表达式，请使用replaceWith:

If you just want to replace an expression with a constant literal string, use replaceWith:

expr = Literal("A").setParseAction(replaceWith("Z")) + "B"
print expr.parseString("A B").asList()

印刷品:

['Z', 'B']

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