如何忽略 pyparsing ParseException 并继续？

Question

我想忽略文件中与所有预定义解析器不匹配的行并继续。我想忽略的行范围很广，我无法为每个行检查和定义解析器。一旦 ParseException 被捕获，我就使用 try..except 和 pass。但是，解析会立即停止。try:    return parser.parseFile(filename, parse_all)except ParseException, err:    msg = 'Error during parsing of {}, line {}'.format(filename, err.lineno)    msg += '\n' + '-'*70 + '\n'    msg += err.line + '\n'    msg += ' '*(err.col-1) + '^\n'    msg += '-'*70 + '\n' + err.msg    err.msg = msg    print(err.msg)    pass即使有 ParseException，我也想继续。

Answer 1

Pyparsing 并没有真正的“出错时继续”选项，因此您需要调整解析器，使其不会首先引发 ParseException。您可能会尝试在解析器中添加类似| SkipTo(LineEnd())('errors*')最后一招的东西。然后，您可以查看错误结果名称以查看哪些行误入歧途（或向该表达式添加解析操作以捕获更多内容，而不仅仅是当前行）。

import pyparsing as pp

era = "The" + pp.oneOf("Age Years") + "of" + pp.Word(pp.alphas)

era.runTests("""

    The Age of Enlightenment

    The Years of Darkness

    The Spanish Inquisition

    """)

印刷：

The Age of Enlightenment

['The', 'Age', 'of', 'Enlightenment']

The Years of Darkness

['The', 'Years', 'of', 'Darkness']

The Spanish Inquisition

    ^

FAIL: Expected Age | Years (at char 4), (line:1, col:5)

添加这些行并再次调用 runTests：

# added to handle lines that don't match

unexpected = pp.SkipTo(pp.LineEnd(), include=True)("no_one_expects")

era = era | unexpected

印刷：

The Age of Enlightenment

['The', 'Age', 'of', 'Enlightenment']

The Years of Darkness

['The', 'Years', 'of', 'Darkness']

The Spanish Inquisition

['The Spanish Inquisition']

 - no_one_expects: 'The Spanish Inquisition'