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14 lines
658 B
Racket
14 lines
658 B
Racket
8 years ago
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#lang brag
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## The following comes from: http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form
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<syntax> : <rule> | <rule> <syntax>
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<rule> : <opt-whitespace> "<" <RULE-NAME> ">" <opt-whitespace> "::="
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<opt-whitespace> <expression> <line-end>
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<opt-whitespace> : " " <opt-whitespace> | "" ## "" is empty string, i.e. no whitespace
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<expression> : <list> | <list> "|" <expression>
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<line-end> : <opt-whitespace> <EOL> | <line-end> <line-end>
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<list> : <term> | <term> <opt-whitespace> <list>
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<term> : <literal> | "<" <RULE-NAME> ">"
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<literal> : '"' <TEXT> '"' | "'" <TEXT> "'" ## actually, the original BNF did not use quotes
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