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BNF

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BNF, aka Backus鈥揘aur Form, is a grammar language created in 1956 by John Backus and Peter Naur.

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In computer science, Backus鈥揘aur form or Backus normal form (BNF) is a notation technique for context-free grammars, often used to describe the syntax of languages used in computing, such as computer programming languages, document formats, instruction sets and communication protocols. They are applied wherever exact descriptions of languages are needed: for instance, in official language specifications, in manuals, and in textbooks on programming language theory. Many extensions and variants of the original Backus鈥揘aur notation are used; some are exactly defined, including extended Backus鈥揘aur form (EBNF) and augmented Backus鈥揘aur form (ABNF).. Read more on Wikipedia...


Example from Wikipedia:
<syntax> ::= <rule> | <rule> <syntax> <rule> ::= <opt-whitespace> "<" <rule-name> ">" <opt-whitespace> "::=" <opt-whitespace> <expression> <line-end> <opt-whitespace> ::= " " <opt-whitespace> | "" <expression> ::= <list> | <list> <opt-whitespace> "|" <opt-whitespace> <expression> <line-end> ::= <opt-whitespace> <EOL> | <line-end> <line-end> <list> ::= <term> | <term> <opt-whitespace> <list> <term> ::= <literal> | "<" <rule-name> ">" <literal> ::= '"' <text1> '"' | "'" <text2> "'" <text1> ::= "" | <character1> <text1> <text2> ::= "" | <character2> <text2> <character> ::= <letter> | <digit> | <symbol> <letter> ::= "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J" | "K" | "L" | "M" | "N" | "O" | "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z" | "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" | "j" | "k" | "l" | "m" | "n" | "o" | "p" | "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z" <digit> ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" <symbol> ::= "|" | " " | "-" | "!" | "#" | "TEMPLATEquot; | "%" | "&" | "(" | ")" | "*" | "+" | "," | "-" | "." | "/" | ":" | ";" | ">" | "=" | "<" | "?" | "@" | "[" | "\" | "]" | "^" | "_" | "`" | "{" | "}" | "~" <character1> ::= <character> | "'" <character2> ::= <character> | '"' <rule-name> ::= <letter> | <rule-name> <rule-char> <rule-char> ::= <letter> | <digit> | "-"

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