Annotated edit history of
BackusNaurForm version 1, including all changes.
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AristotlePagaltzis |
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This is a language to define the formal grammar of a language, whether that be a ProgrammingLanguage, a MarkupLanguage or simply the syntax of a configuration file. |
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An example grammar would be |
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<sentance> ::= <verb-part> <noun-part> |
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<verb-part> ::= <noun-part> <verb> |
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<noun-part> ::= <proper-noun> |
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| THE <noun> |
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<verb> ::= throws |
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| kicks |
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| hides |
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| fetches |
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<proper-noun> ::= John |
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| Jane |
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<noun> ::= ball |
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::= dog |
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This grammar accepts sentances such as |
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* Jane throws the ball |
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* The dog fetches the ball |
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* John kicks the dog |
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* John hides Jane |
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* The ball fetches Jane |
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but would not accept sentences such as |
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* John deflates the ball |
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* Jane hides in the basement |
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because __deflates__ is not a verb known in this grammer and __in the basement__ is not a noun. The grammar would have to be extended to cover such cases. |
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Because some common cases are inconvenient to define using pure [BNF], some extensions have been added in [EBNF]: |
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* __...__ means ''1 or more'' |
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* __[[ ]__ means ''optional'' |
