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Despite of parsing, the position in the input wasn't changed.


A token, which matches the text, must match at least one character. A token like


Token A:: = a*


Production ::= A


would match at any position of the text, because the character 'a' will be there at least null times.  A production like  ( A )* would cause an endless loop. An optional occurrence of a concatenation of 'a'-characters should be written as:


Token A ::= a+


Production ::= ( A )?


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