Hi, it's my first time posting in a mailing list like this so go easy on me
if I'm breaking some etiquette or anything :)
I'm trying to construct an expression in my tree grammar to recognize an AST
of simple mathematical expressions like 1+(-(a-b)) in tree format of (+ 1 (-
(- a b))) that is generated by my parser grammar.
I've tried a couple of different approaches and I can't figure out where I'm
going wrong. Could someone explain what's wrong with the following two
expressions:
expression
: (MINUS^)? term;
term
: constant | variable | ^(operator expression expression);
[constant and variables are both terminators, operator is plus/minus].
It seems whenever I try it I get a load of messages saying "node from line
0:0 no viable alternative at input 'UP'" and the program doesn't work on
anything with a negative term preceding it.
Thanks for the help. If I haven't included enough information to be useful
please let me know!
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Alex Storkey <[email protected]>
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