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Using ~x + ... seems to disallow whitespace skip with left recursion. Is this intended behavior? If so, what's the idiomatic way of doing it in left recursive grammars?
An example:
importpyparsingaspppp.ParserElement.inline_literals_using(pp.Suppress)
pp.ParserElement.enable_left_recursion()
Top=pp.Forward()
# an xyz word that doesn't start with xxxAtom=~pp.Literal('xxx') +pp.Word('xyz')
# ^--------- this negative lookahead seems # to mess with whitespace handling# in recursive grammars?## This workaround works:# Atom = pp.White()[0,1] + ~pp.Literal('xxx') + pp.Word('xyz')# (Minibug: pp.White(min=0) cannot match 0 whitespace)Expr0=pp.Forward()
Expr0<<=Expr0+'['+Top+']'|Atom# ... in my case there's many levels of expressions,# and they're constructed dynamically ...Expr1=TopExpr1<<=Top+'*'+Expr0|Expr0
The thought is that this would match anything like x[ x * x[y] ][y] * y with optional whitespaces anywhere, but whitespace is only skipped inside expressions, not at the start:
>>> Top.run_tests(['x[y*x]', 'x [y * xx ]', ' x', 'x[ y*xx]', ' x*y'])
x[y*x]
['x', 'y', 'x']
x [y * xx ]
['x', 'y', 'xx']
x
['x']
x[ y*xx]
x[ y*xx]
^
ParseException: Expected end of text, found '[' (at char 1), (line:1, col:2)
FAIL: Expected end of text, found '[' (at char 1), (line:1, col:2)
x*y
x*y
^
ParseException: Expected end of text, found '*' (at char 3), (line:1, col:4)
FAIL: Expected end of text, found '*' (at char 3), (line:1, col:4)
The text was updated successfully, but these errors were encountered:
Using
~x + ...seems to disallow whitespace skip with left recursion. Is this intended behavior? If so, what's the idiomatic way of doing it in left recursive grammars?An example:
The thought is that this would match anything like
x[ x * x[y] ][y] * ywith optional whitespaces anywhere, but whitespace is only skipped inside expressions, not at the start:The text was updated successfully, but these errors were encountered: