pyparsing.py 文件源码

def _parseCache( self, instring, loc, doActions=True, callPreParse=True ):
        HIT, MISS = 0, 1
        lookup = (self, instring, loc, callPreParse, doActions)
        with ParserElement.packrat_cache_lock:
            cache = ParserElement.packrat_cache
            value = cache.get(lookup)
            if value is cache.not_in_cache:
                ParserElement.packrat_cache_stats[MISS] += 1
                try:
                    value = self._parseNoCache(instring, loc, doActions, callPreParse)
                except ParseBaseException as pe:
                    # cache a copy of the exception, without the traceback
                    cache.set(lookup, pe.__class__(*pe.args))
                    raise
                else:
                    cache.set(lookup, (value[0], value[1].copy()))
                    return value
            else:
                ParserElement.packrat_cache_stats[HIT] += 1
                if isinstance(value, Exception):
                    raise value
                return (value[0], value[1].copy())