301 lines
9.3 KiB
Python
301 lines
9.3 KiB
Python
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# exceptions.py
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import re
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import sys
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import typing
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from .util import (
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col,
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line,
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lineno,
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_collapse_string_to_ranges,
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replaced_by_pep8,
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)
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from .unicode import pyparsing_unicode as ppu
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class _ExceptionWordUnicodeSet(
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ppu.Latin1, ppu.LatinA, ppu.LatinB, ppu.Greek, ppu.Cyrillic
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):
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pass
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_extract_alphanums = _collapse_string_to_ranges(_ExceptionWordUnicodeSet.alphanums)
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_exception_word_extractor = re.compile("([" + _extract_alphanums + "]{1,16})|.")
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class ParseBaseException(Exception):
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"""base exception class for all parsing runtime exceptions"""
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loc: int
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msg: str
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pstr: str
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parser_element: typing.Any # "ParserElement"
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args: typing.Tuple[str, int, typing.Optional[str]]
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__slots__ = (
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"loc",
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"msg",
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"pstr",
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"parser_element",
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"args",
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)
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# Performance tuning: we construct a *lot* of these, so keep this
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# constructor as small and fast as possible
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def __init__(
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self,
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pstr: str,
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loc: int = 0,
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msg: typing.Optional[str] = None,
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elem=None,
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):
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self.loc = loc
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if msg is None:
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self.msg = pstr
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self.pstr = ""
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else:
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self.msg = msg
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self.pstr = pstr
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self.parser_element = elem
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self.args = (pstr, loc, msg)
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@staticmethod
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def explain_exception(exc, depth=16):
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"""
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Method to take an exception and translate the Python internal traceback into a list
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of the pyparsing expressions that caused the exception to be raised.
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Parameters:
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- exc - exception raised during parsing (need not be a ParseException, in support
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of Python exceptions that might be raised in a parse action)
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- depth (default=16) - number of levels back in the stack trace to list expression
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and function names; if None, the full stack trace names will be listed; if 0, only
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the failing input line, marker, and exception string will be shown
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Returns a multi-line string listing the ParserElements and/or function names in the
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exception's stack trace.
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"""
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import inspect
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from .core import ParserElement
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if depth is None:
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depth = sys.getrecursionlimit()
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ret = []
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if isinstance(exc, ParseBaseException):
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ret.append(exc.line)
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ret.append(" " * (exc.column - 1) + "^")
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ret.append(f"{type(exc).__name__}: {exc}")
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if depth <= 0:
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return "\n".join(ret)
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callers = inspect.getinnerframes(exc.__traceback__, context=depth)
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seen = set()
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for ff in callers[-depth:]:
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frm = ff[0]
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f_self = frm.f_locals.get("self", None)
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if isinstance(f_self, ParserElement):
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if not frm.f_code.co_name.startswith(("parseImpl", "_parseNoCache")):
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continue
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if id(f_self) in seen:
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continue
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seen.add(id(f_self))
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self_type = type(f_self)
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ret.append(f"{self_type.__module__}.{self_type.__name__} - {f_self}")
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elif f_self is not None:
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self_type = type(f_self)
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ret.append(f"{self_type.__module__}.{self_type.__name__}")
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else:
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code = frm.f_code
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if code.co_name in ("wrapper", "<module>"):
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continue
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ret.append(code.co_name)
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depth -= 1
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if not depth:
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break
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return "\n".join(ret)
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@classmethod
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def _from_exception(cls, pe):
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"""
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internal factory method to simplify creating one type of ParseException
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from another - avoids having __init__ signature conflicts among subclasses
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"""
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return cls(pe.pstr, pe.loc, pe.msg, pe.parser_element)
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@property
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def line(self) -> str:
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"""
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Return the line of text where the exception occurred.
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"""
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return line(self.loc, self.pstr)
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@property
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def lineno(self) -> int:
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"""
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Return the 1-based line number of text where the exception occurred.
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"""
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return lineno(self.loc, self.pstr)
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@property
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def col(self) -> int:
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"""
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Return the 1-based column on the line of text where the exception occurred.
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"""
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return col(self.loc, self.pstr)
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@property
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def column(self) -> int:
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"""
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Return the 1-based column on the line of text where the exception occurred.
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"""
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return col(self.loc, self.pstr)
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# pre-PEP8 compatibility
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@property
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def parserElement(self):
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return self.parser_element
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@parserElement.setter
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def parserElement(self, elem):
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self.parser_element = elem
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def __str__(self) -> str:
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if self.pstr:
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if self.loc >= len(self.pstr):
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foundstr = ", found end of text"
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else:
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# pull out next word at error location
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found_match = _exception_word_extractor.match(self.pstr, self.loc)
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if found_match is not None:
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found = found_match.group(0)
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else:
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found = self.pstr[self.loc : self.loc + 1]
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foundstr = (", found %r" % found).replace(r"\\", "\\")
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else:
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foundstr = ""
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return f"{self.msg}{foundstr} (at char {self.loc}), (line:{self.lineno}, col:{self.column})"
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def __repr__(self):
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return str(self)
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def mark_input_line(
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self, marker_string: typing.Optional[str] = None, *, markerString: str = ">!<"
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) -> str:
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"""
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Extracts the exception line from the input string, and marks
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the location of the exception with a special symbol.
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"""
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markerString = marker_string if marker_string is not None else markerString
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line_str = self.line
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line_column = self.column - 1
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if markerString:
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line_str = "".join(
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(line_str[:line_column], markerString, line_str[line_column:])
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)
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return line_str.strip()
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def explain(self, depth=16) -> str:
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"""
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Method to translate the Python internal traceback into a list
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of the pyparsing expressions that caused the exception to be raised.
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Parameters:
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- depth (default=16) - number of levels back in the stack trace to list expression
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and function names; if None, the full stack trace names will be listed; if 0, only
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the failing input line, marker, and exception string will be shown
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Returns a multi-line string listing the ParserElements and/or function names in the
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exception's stack trace.
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Example::
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# an expression to parse 3 integers
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expr = pp.Word(pp.nums) * 3
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try:
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# a failing parse - the third integer is prefixed with "A"
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expr.parse_string("123 456 A789")
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except pp.ParseException as pe:
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print(pe.explain(depth=0))
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prints::
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123 456 A789
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^
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ParseException: Expected W:(0-9), found 'A' (at char 8), (line:1, col:9)
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Note: the diagnostic output will include string representations of the expressions
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that failed to parse. These representations will be more helpful if you use `set_name` to
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give identifiable names to your expressions. Otherwise they will use the default string
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forms, which may be cryptic to read.
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Note: pyparsing's default truncation of exception tracebacks may also truncate the
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stack of expressions that are displayed in the ``explain`` output. To get the full listing
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of parser expressions, you may have to set ``ParserElement.verbose_stacktrace = True``
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"""
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return self.explain_exception(self, depth)
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# fmt: off
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markInputline = replaced_by_pep8("markInputline", mark_input_line)
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# fmt: on
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class ParseException(ParseBaseException):
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"""
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Exception thrown when a parse expression doesn't match the input string
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Example::
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integer = Word(nums).set_name("integer")
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try:
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integer.parse_string("ABC")
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except ParseException as pe:
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print(pe)
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print(f"column: {pe.column}")
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prints::
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Expected integer (at char 0), (line:1, col:1) column: 1
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"""
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class ParseFatalException(ParseBaseException):
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"""
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User-throwable exception thrown when inconsistent parse content
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is found; stops all parsing immediately
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"""
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class ParseSyntaxException(ParseFatalException):
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"""
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Just like :class:`ParseFatalException`, but thrown internally
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when an :class:`ErrorStop<And._ErrorStop>` ('-' operator) indicates
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that parsing is to stop immediately because an unbacktrackable
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syntax error has been found.
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"""
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class RecursiveGrammarException(Exception):
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"""
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Exception thrown by :class:`ParserElement.validate` if the
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grammar could be left-recursive; parser may need to enable
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left recursion using :class:`ParserElement.enable_left_recursion<ParserElement.enable_left_recursion>`
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"""
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def __init__(self, parseElementList):
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self.parseElementTrace = parseElementList
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def __str__(self) -> str:
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return f"RecursiveGrammarException: {self.parseElementTrace}"
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