def parseImpl( self, instring, loc, doActions=True ):
        startloc = loc
        instrlen = len(instring)
        expr = self.expr
        expr_parse = self.expr._parse
        self_failOn_canParseNext = self.failOn.canParseNext if self.failOn is not None else None
        self_ignoreExpr_tryParse = self.ignoreExpr.tryParse if self.ignoreExpr is not None else None
        
        tmploc = loc
        while tmploc <= instrlen:
            if self_failOn_canParseNext is not None:
                # break if failOn expression matches
                if self_failOn.canParseNext(instring, tmploc):
                    break
                    
            if self_ignoreExpr_tryParse is not None:
                # advance past ignore expressions
                while 1:
                    try:
                        tmploc = self_ignoreExpr_tryParse(instring, tmploc)
                    except ParseBaseException:
                        break
            
            try:
                expr_parse(instring, tmploc, doActions=False, callPreParse=False)
            except (ParseException, __HOLE__):
                # no match, advance loc in string
                tmploc += 1
            else:
                # matched skipto expr, done
                break

        else:
            # ran off the end of the input string without matching skipto expr, fail
            raise ParseException(instring, loc, self.errmsg, self)

        # build up return values
        loc = tmploc
        skiptext = instring[startloc:loc]
        skipresult = ParseResults(skiptext)
        
        if self.includeMatch:
            loc, mat = expr_parse(instring,loc,doActions,callPreParse=False)
            skipresult += mat

        return loc, skipresult
dataset/ETHPy150Open pypa/pip/pip/_vendor/pyparsing.py/SkipTo.parseImpl