pegjs

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History

David Majda 1b2279e026 Error handling: Make predicates always return \|undefined\| After making the \|?\| operator return \|null\| instead of an empty string in the previous commit, empty strings were still returned from predicates. This didn't make much sense. Return value of a predicate is unimportant (if you have one in hand, you already know the predicate succeeded) and one could even argue that predicates shouldn't return any value at all. The closest thing to "return no value" in JavaScript is returning \|undefined\|, so I decided to make predicates return exactly that. Implements part of #198.	11 years ago
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passes	Error handling: Make predicates always return \|undefined\|	11 years ago
opcodes.js	Code generator rewrite	12 years ago

David Majda 1b2279e026 Error handling: Make predicates always return |undefined|

After making the |?| operator return |null| instead of an empty string
in the previous commit, empty strings were still returned from
predicates. This didn't make much sense.

Return value of a predicate is unimportant (if you have one in hand, you
already know the predicate succeeded) and one could even argue that
predicates shouldn't return any value at all. The closest thing to
"return no value" in JavaScript is returning |undefined|, so I decided
to make predicates return exactly that.

Implements part of #198.

passes

Error handling: Make predicates always return |undefined|

opcodes.js

Code generator rewrite