python – 保留文本结构信息 – pyparsing

2019年7月21日 166次阅读

使用pyparsing,有没有办法在递归下降过程中提取您所处的上下文.让我解释一下我的意思.我有以下代码：

import pyparsing as pp

openBrace = pp.Suppress(pp.Literal("{"))
closeBrace = pp.Suppress(pp.Literal("}"))
ident = pp.Word(pp.alphanums + "_" + ".")
comment = pp.Literal("//") + pp.restOfLine
messageName = ident
messageKw = pp.Suppress(pp.Keyword("msg"))
text = pp.Word(pp.alphanums + "_" + "." + "-" + "+")
otherText = ~messageKw + pp.Suppress(text)
messageExpr = pp.Forward()
messageExpr << (messageKw + messageName + openBrace +
                pp.ZeroOrMore(otherText) + pp.ZeroOrMore(messageExpr) +
                pp.ZeroOrMore(otherText) + closeBrace).ignore(comment)
testStr = "msg msgName1 { some text msg msgName2 { some text } some text }"
print messageExpr.parseString(testStr)

产生这个输出：[‘msgName1′,’msgName2’]

在输出中,我想跟踪嵌入式匹配的结构.我的意思是,例如,我希望以下输出带有上面的测试字符串：[‘msgName1′,’msgName1.msgName2’]来跟踪文本中的层次结构.但是,我是pyparsing的新手,还没有找到一种方法来提取“msgName2”嵌入在“msgName1”结构中的事实.

有没有办法使用ParserElement的setParseAction()方法来执行此操作,或者使用结果命名？

有用的建议将不胜感激.

最佳答案 感谢Paul McGuire的忠告.以下是我所做的补充/更改,解决了以下问题：

msgNameStack = []

def pushMsgName(str, loc, tokens):
    msgNameStack.append(tokens[0])
    tokens[0] = '.'.join(msgNameStack)

def popMsgName(str, loc, tokens):
    msgNameStack.pop()

closeBrace = pp.Suppress(pp.Literal("}")).setParseAction(popMsgName)
messageName = ident.setParseAction(pushMsgName)

这是完整的代码：

import pyparsing as pp

msgNameStack = []


def pushMsgName(str, loc, tokens):
    msgNameStack.append(tokens[0])
    tokens[0] = '.'.join(msgNameStack)


def popMsgName(str, loc, tokens):
    msgNameStack.pop()

openBrace = pp.Suppress(pp.Literal("{"))
closeBrace = pp.Suppress(pp.Literal("}")).setParseAction(popMsgName)
ident = pp.Word(pp.alphanums + "_" + ".")
comment = pp.Literal("//") + pp.restOfLine
messageName = ident.setParseAction(pushMsgName)
messageKw = pp.Suppress(pp.Keyword("msg"))
text = pp.Word(pp.alphanums + "_" + "." + "-" + "+")
otherText = ~messageKw + pp.Suppress(text)
messageExpr = pp.Forward()
messageExpr << (messageKw + messageName + openBrace +
                pp.ZeroOrMore(otherText) + pp.ZeroOrMore(messageExpr) +
                pp.ZeroOrMore(otherText) + closeBrace).ignore(comment)

testStr = "msg msgName1 { some text msg msgName2 { some text } some text }"
print messageExpr.parseString(testStr)
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