Re: Parsing expressions without outer parentheses

Frank Heckenbach wrote:


> expression: simple_expression | expression '=' simple_expression;
> simple_expression: term | simple_expression '+' term;
> term: factor | term '*' factor;
> factor: primary | factor '^' primary;
> primary: constant | '(' expression ')';
>
> Now I want to accept only expressions which are not completely
> enclosed in a pair of parentheses, e.g. `(1) + (2)' would be
> accepted, but `(1 + 2)' would not.


is this any more useful?


expression: constant
| factor '^' primary
| term '*' factor
| simple_expression '+' term
| fullexp '=' simple_expression
;
fullexp : expression
| '(' fullexp ')'
;
primary : constant | '(' fullexp ')'
;
(simple_expression, term, factor as before)


--
Peter J. Jinks, Room 2.99, Department of Computer Science,
University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.
(+44/0)161-275 6186 http://www.cs.man.ac.uk/~pjj

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