| slovo | definícia |
backus
(encz) | Backus,Backus n: [jmén.] příjmení Zdeněk Brož a automatický překlad |
backus
(czen) | Backus,Backusn: [jmén.] příjmení Zdeněk Brož a automatický překlad |
| | podobné slovo | definícia |
augmented backus-naur form
(foldoc) | Augmented Backus-Naur Form
ABNF
An extension of Backus-Naur Form documented in
RFC 2234.
[Summary?]
(1997-11-23)
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backus normal form
(foldoc) | Backus-Naur Form
Backus Normal Form
(BNF, originally "Backus Normal Form") A
formal metasyntax used to express context-free grammars.
Backus Normal Form was renamed Backus-Naur Form at the
suggestion of Donald Knuth.
BNF is one of the most commonly used metasyntactic notations
for specifying the syntax of programming languages, command
sets, and the like. It is widely used for language
descriptions but seldom documented anywhere (how do you
document a metasyntax?), so that it must usually be learned
by osmosis (but see RFC 2234).
Consider this BNF for a US postal address:
::=
::= | "."
::= []
|
::= []
::= ","
This translates into English as: "A postal-address consists of
a name-part, followed by a street-address part, followed by a
zip-code part. A personal-part consists of either a first
name or an initial followed by a dot. A name-part consists of
either: a personal-part followed by a last name followed by an
optional "jr-part" (Jr., Sr., or dynastic number) and
end-of-line, or a personal part followed by a name part (this
rule illustrates the use of recursion in BNFs, covering the
case of people who use multiple first and middle names and/or
initials). A street address consists of an optional apartment
specifier, followed by a street number, followed by a street
name. A zip-part consists of a town-name, followed by a
comma, followed by a state code, followed by a ZIP-code
followed by an end-of-line."
Note that many things (such as the format of a personal-part,
apartment specifier, or ZIP-code) are left unspecified. These
lexical details are presumed to be obvious from context or
specified somewhere nearby.
There are many variants and extensions of BNF, possibly
containing some or all of the regexp wild cards such as
"*" or "+". EBNF is a common one. In fact the example
above isn't the pure form invented for the ALGOL 60 report.
"[]" was introduced a few years later in IBM's PL/I
definition but is now universally recognised. ABNF is
another extension.
(1997-11-23)
|
backus-naur form
(foldoc) | Backus-Naur Form
Backus Normal Form
(BNF, originally "Backus Normal Form") A
formal metasyntax used to express context-free grammars.
Backus Normal Form was renamed Backus-Naur Form at the
suggestion of Donald Knuth.
BNF is one of the most commonly used metasyntactic notations
for specifying the syntax of programming languages, command
sets, and the like. It is widely used for language
descriptions but seldom documented anywhere (how do you
document a metasyntax?), so that it must usually be learned
by osmosis (but see RFC 2234).
Consider this BNF for a US postal address:
::=
::= | "."
::= []
|
::= []
::= ","
This translates into English as: "A postal-address consists of
a name-part, followed by a street-address part, followed by a
zip-code part. A personal-part consists of either a first
name or an initial followed by a dot. A name-part consists of
either: a personal-part followed by a last name followed by an
optional "jr-part" (Jr., Sr., or dynastic number) and
end-of-line, or a personal part followed by a name part (this
rule illustrates the use of recursion in BNFs, covering the
case of people who use multiple first and middle names and/or
initials). A street address consists of an optional apartment
specifier, followed by a street number, followed by a street
name. A zip-part consists of a town-name, followed by a
comma, followed by a state code, followed by a ZIP-code
followed by an end-of-line."
Note that many things (such as the format of a personal-part,
apartment specifier, or ZIP-code) are left unspecified. These
lexical details are presumed to be obvious from context or
specified somewhere nearby.
There are many variants and extensions of BNF, possibly
containing some or all of the regexp wild cards such as
"*" or "+". EBNF is a common one. In fact the example
above isn't the pure form invented for the ALGOL 60 report.
"[]" was introduced a few years later in IBM's PL/I
definition but is now universally recognised. ABNF is
another extension.
(1997-11-23)
|
extended backus-naur form
(foldoc) | Extended Backus-Naur Form
Extended BNF
Any variation on the basic Backus-Naur Form (BNF)
meta-syntax notation with (some of) the following additional
constructs: square brackets "[..]" surrounding optional
items, suffix "*" for Kleene closure (a sequence of zero or
more of an item), suffix "+" for one or more of an item,
curly brackets enclosing a list of alternatives, and
super/subscripts indicating between n and m occurrences.
All these constructs can be expressed in plain BNF using extra
productions and have been added for readability and
succinctness.
(1995-04-28)
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