Parse EBNF: Difference between revisions
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-- The rules that applies() has to deal with are: |
-- The rules that applies() has to deal with are: |
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-- {factors} - if rule[1] is not string, just apply one after the other, |
-- {factors} - if rule[1] is not string, just apply one after the other, |
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-- |
-- recursively. As per term() above, originally had "factors", |
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-- but getting rid of it made the syntax tree much clearer) |
-- but getting rid of it made the syntax tree much clearer) |
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-- {"terminal", "a1"} -- literal constants |
-- {"terminal", "a1"} -- literal constants |
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-- {"or", <e1>, <e2>, ...} -- (any) one of n |
-- {"or", <e1>, <e2>, ...} -- (any) one of n |
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-- {"repeat", <e1>} -- as per "{}" in ebnf |
-- {"repeat", <e1>} -- as per "{}" in ebnf |
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-- {"optional", <e1>} -- as per " |
-- {"optional", <e1>} -- as per "[]" in ebnf |
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-- {"ident", <name>, idx} -- apply the sub-rule |
-- {"ident", <name>, idx} -- apply the sub-rule |
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end if |
end if |
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end for</lang> |
end for</lang> |
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In real use, I would be tempted to use numeric literals rather than string tags in such structures, but the latter certainly make things ten times easier to debug, plus I got an instantly legible dump practically for free. |
In real use, I would be tempted to use numeric literals rather than string tags in such structures, but the latter certainly make things ten times easier to debug, plus I got an instantly legible syntax tree dump (the bit just after "===>" below) practically for free. |
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{{out}} |
{{out}} |
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<pre> |
<pre> |
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