Next: The if-then-else Solution Up: No Title Previous: Precedence

The if-then-else Problem

A standard problem in parsing is the if-then-else:
$\begin{program} Statement~\=::=~\=IF~LPAREN~Expression~RPAREN~Statement~ \ ~~~~... ... gt$\vert$\ gt...~other~statements~... \ ~~~~~~~~~~~~~~~~~~\ gt;\end{program}$
reports a shift-reduce conflict. It resolves in favor of shifting, which is what we want. We can

Give ELSE higher priority than the production: precedence left ELSE.
Tell JavaCUP on the command line to expect one conflict: -expect 1.
Fix the grammar properly!

Christoph Zenger
4/6/2000