(expr)
return rep
Helper to define an expression that is indirectly defined from
    the tokens matched in a previous expression, that is, it looks for
    a 'repeat' of a previous expression.  For example::

        first = Word(nums)
        second = matchPreviousExpr(first)
        matchExpr = first + ":" + second

    will match ``"1:1"``, but not ``"1:2"``.  Because this
    matches by expressions, will *not* match the leading ``"1:1"``
    in ``"1:10"``; the expressions are evaluated first, and then
    compared, so ``"1"`` is compared with ``"10"``. Do *not* use
    with packrat parsing enabled.
Helper to define an expression that is indirectly defined from
    the tokens matched in a previous expression, that is, it looks for
    a 'repeat' of a previous expression.  For example::
Helper to define an expression that is indirectly defined from the tokens matched in a previous expression that is it looks for a repeat of a previous expression . For example ::
def matchPreviousExpr(expr):
    """Helper to define an expression that is indirectly defined from
    the tokens matched in a previous expression, that is, it looks for
    a 'repeat' of a previous expression.  For example::

        first = Word(nums)
        second = matchPreviousExpr(first)
        matchExpr = first + ":" + second

    will match ``"1:1"``, but not ``"1:2"``.  Because this
    matches by expressions, will *not* match the leading ``"1:1"``
    in ``"1:10"``; the expressions are evaluated first, and then
    compared, so ``"1"`` is compared with ``"10"``. Do *not* use
    with packrat parsing enabled.
    """
    rep = Forward()
    e2 = expr.copy()
    rep <<= e2
    def copyTokenToRepeater(s,l,t):
        matchTokens = _flatten(t.asList())
        def mustMatchTheseTokens(s,l,t):
            theseTokens = _flatten(t.asList())
            if  theseTokens != matchTokens:
                raise ParseException("",0,"")
        rep.setParseAction( mustMatchTheseTokens, callDuringTry=True )
    expr.addParseAction(copyTokenToRepeater, callDuringTry=True)
    rep.setName('(prev) ' + _ustr(expr))
    return rep
def matchPreviousExpr ( expr ) : rep = Forward ( ) e2 = expr . copy ( ) rep <<= e2 def copyTokenToRepeater ( s , l , t ) : matchTokens = _flatten ( t . asList ( ) ) def mustMatchTheseTokens ( s , l , t ) : theseTokens = _flatten ( t . asList ( ) ) if theseTokens != matchTokens : raise ParseException ( "" , 0 , "" ) rep . setParseAction ( mustMatchTheseTokens , callDuringTry = True ) expr . addParseAction ( copyTokenToRepeater , callDuringTry = True ) rep . setName ( '(prev) ' + _ustr ( expr ) ) return rep