According to this post https://stackoverflow.com/questions/28397767/computing-leading-and-trailing-sets-for-context-free-grammar while constructing operator precendence parser we have to create tabel with operator. Actually i dont understand the rules which tells how to build such table.
For example take last production term -> '(' expr ')' do we use rule terminal nonterminal because of ( expr or do we use rule nonterminal terminal because of expr ) or do we use rule terminal nonterminal terminal shoudl we divide production or treat as whole? Then is there any other rule applicable in example from link then terminal nonterminal terminal ?
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I think that answer is clear (although of course I would do, because I wrote it).
What it says is:
if you find
$$nonterminal\; TERMINAL$$
in any production, then you add the precedence relations $TRAIL \gtrdot TERMINAL$ for every $TRAIL$ in $Trailing(nonterminal)$. Similarly, every occurrence of
$$TERMINAL\; nonterminal$$
generates the relationships $TERMINAL \lessdot LEAD$ for every $LEAD$ in $Leading(nonterminal)$.
So in $'(' expr ')'$, you have both an instance of $TERMINAL\; nonterminal$ and an instance of $nonterminal\; TERMINAL$, and you need to deal with both of them independently.
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$\begingroup$ Do we have
$operator in such gramma or we ignore it? $\endgroup$– whdMay 31, 2016 at 18:45 -
$\begingroup$ Do you mean the convention of augmenting grammars with an end-of-input symbol? If so, that is usually done in order to finish the parse. Since the only use of
$in the grammar will be in the augmented productionS' -> S $, we can conclude that every terminalTwhich has a relation with$has the relationT ⋗ $. In practice, it's easy to just add that relation to every terminal. $\endgroup$– riciMay 31, 2016 at 18:51