|
Metasyntax
A metasyntax is a syntax used to define the syntax of a programming language or formal language. It describes the allowable structure and composition of phrases and sentences of a metalanguage, which is used to describe either a natural language or a computer programming language.Sellink, Alex, and Chris Verhoef.Development, assessment, and reengineering of language descriptions" Software Maintenance and Reengineering, 2000. Proceedings of the Fourth European. IEEE, 2000. Some of the widely used formal metalanguages for computer languages are Backus–Naur form (BNF), extended Backus–Naur form (EBNF), Wirth syntax notation (WSN), and augmented Backus–Naur form (ABNF). Metalanguages have their own metasyntax each composed of terminal symbols, nonterminal symbols, and ''metasymbols''. A terminal symbol, such as a word or a token, is a stand-alone structure in a language being defined. A nonterminal symbol represents a syntactic category, which defines one or more valid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Augmented Backus–Naur Form
In computer science, augmented Backus–Naur form (ABNF) is a metalanguage based on Backus–Naur form (BNF) but consisting of its own syntax and derivation rules. The motive principle for ABNF is to describe a formal system of a language to be used as a bidirectional communications protocol. It is defined b''Internet Standard 68''("STD 68", type case sic), which was , and it often serves as the definition language for IETF communication protocols. supersedes . updates it, adding a syntax for specifying case-sensitive string literals. Overview An ABNF specification is a set of derivation rules, written as where rule is a case sensitivity, case-insensitive nonterminal, the definition consists of sequences of symbols that define the rule, a comment for documentation, and ending with a carriage return and line feed. Rule names are case-insensitive: , , , and all refer to the same rule. Rule names consist of a letter followed by letters, numbers, and hyphens. Angle brack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metalanguage
In logic and linguistics, a metalanguage is a language used to describe another language, often called the ''object language''. Expressions in a metalanguage are often distinguished from those in the object language by the use of italics, quotation marks, or writing on a separate line. The structure of sentences and phrases in a metalanguage can be described by a metasyntax. For example, to say that the word "noun" can be used as a noun in a sentence, one could write ''"noun" is a ''. Types of metalanguage There are a variety of recognized types of metalanguage, including ''embedded'', ''ordered'', and ''nested'' (or ''hierarchical'') metalanguages. Embedded An ''embedded metalanguage'' is a language formally, naturally and firmly fixed in an object language. This idea is found in Douglas Hofstadter's book, ''Gödel, Escher, Bach'', in a discussion of the relationship between formal languages and number theory: "... it is in the nature of any formalization of number theor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backus–Naur Form
In computer science, Backus–Naur form (BNF, pronounced ), also known as Backus normal form, is a notation system for defining the Syntax (programming languages), syntax of Programming language, programming languages and other Formal language, formal languages, developed by John Backus and Peter Naur. It is a metasyntax for Context-free grammar, context-free grammars, providing a precise way to outline the rules of a language's structure. It has been widely used in official specifications, manuals, and textbooks on programming language theory, as well as to describe Document format, document formats, Instruction set, instruction sets, and Communication protocol, communication protocols. Over time, variations such as extended Backus–Naur form (EBNF) and augmented Backus–Naur form (ABNF) have emerged, building on the original framework with added features. Structure BNF specifications outline how symbols are combined to form syntactically valid sequences. Each BNF consists of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wirth Syntax Notation
Wirth syntax notation (WSN) is a metasyntax, that is, a formal way to describe formal languages. Originally proposed by Niklaus Wirth in 1977 as an alternative to Backus–Naur form (BNF). It has several advantages over BNF in that it contains an explicit iteration construct, and it avoids the use of an explicit symbol for the empty string (such as or ε). WSN has been used in several international standards, starting with ISO 10303-21. It was also used to define the syntax of EXPRESS, the data modelling language of STEP. WSN defined in itself SYNTAX = . PRODUCTION = IDENTIFIER "=" EXPRESSION "." . EXPRESSION = TERM . TERM = FACTOR . FACTOR = IDENTIFIER , LITERAL , " EXPRESSION " , "(" EXPRESSION ")" , "" . IDENTIFIER = letter . LITERAL = """" character """" . The equals sign indicates a production. The element on the left is defined to be the combination of elements on the right. A production ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Augmented Backus–Naur Form
In computer science, augmented Backus–Naur form (ABNF) is a metalanguage based on Backus–Naur form (BNF) but consisting of its own syntax and derivation rules. The motive principle for ABNF is to describe a formal system of a language to be used as a bidirectional communications protocol. It is defined b''Internet Standard 68''("STD 68", type case sic), which was , and it often serves as the definition language for IETF communication protocols. supersedes . updates it, adding a syntax for specifying case-sensitive string literals. Overview An ABNF specification is a set of derivation rules, written as where rule is a case sensitivity, case-insensitive nonterminal, the definition consists of sequences of symbols that define the rule, a comment for documentation, and ending with a carriage return and line feed. Rule names are case-insensitive: , , , and all refer to the same rule. Rule names consist of a letter followed by letters, numbers, and hyphens. Angle brack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sans-serif
In typography and lettering, a sans-serif, sans serif (), gothic, or simply sans letterform is one that does not have extending features called "serifs" at the end of strokes. Sans-serif typefaces tend to have less stroke width variation than serif typefaces. They are often used to convey simplicity and Modern typography, modernity or minimalism. For the purposes of type classification, sans-serif designs are usually divided into these major groups: , , , , and . Sans-serif typefaces have become the most prevalent for display of text on computer screens. On lower-resolution digital displays, fine details like serifs may disappear or appear too large. The term comes from the French word , meaning "without" and "serif" of uncertain origin, possibly from the Dutch word meaning "line" or pen-stroke. In printed media, they are more commonly used for Display typeface, display use and less for body text. Before the term "sans-serif" became standard in English typography, a number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO/IEC
ISO/IEC JTC 1, entitled "Information technology", is a joint technical committee (JTC) of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Its purpose is to develop, maintain and promote standards in the fields of information and communications technology (ICT). JTC 1 has been responsible for many critical IT standards, ranging from the Joint Photographic Experts Group (JPEG) image formats and Moving Picture Experts Group (MPEG) audio and video formats to the C and C++ programming languages. History ISO/IEC JTC 1 was formed in 1987 as a merger between ISO/TC 97 (Information Technology) and IEC/TC 83, with IEC/SC 47B joining later. The intent was to bring together, in a single committee, the IT standardization activities of the two parent organizations in order to avoid duplicative or possibly incompatible standards. At the time of its formation, the mandate of JTC 1 was to develop base standards in information t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C (programming Language)
C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted Central processing unit, CPUs. It has found lasting use in operating systems code (especially in Kernel (operating system), kernels), device drivers, and protocol stacks, but its use in application software has been decreasing. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems. A successor to the programming language B (programming language), B, C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix. It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of the most widely used programming langu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java (programming Language)
Java is a High-level programming language, high-level, General-purpose programming language, general-purpose, Memory safety, memory-safe, object-oriented programming, object-oriented programming language. It is intended to let programmers ''write once, run anywhere'' (Write once, run anywhere, WORA), meaning that compiler, compiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled to Java bytecode, bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture. The syntax (programming languages), syntax of Java is similar to C (programming language), C and C++, but has fewer low-level programming language, low-level facilities than either of them. The Java runtime provides dynamic capabilities (such as Reflective programming, reflection and runtime code modification) that are typically not available in traditional compiled languages. Java gained popularity sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Italic Font
In typography, italic type is a cursive font based on a stylised form of calligraphic handwriting. Along with blackletter and roman type, it served as one of the major typefaces in the history of Western typography. Owing to the influence from calligraphy, italics normally slant slightly to the right, ''like so''. Different glyph shapes from roman type are usually usedanother influence from calligraphyand upper-case letters may have swashes, flourishes inspired by ornate calligraphy. Historically, italics were a distinct style of type used entirely separately from roman type, but they have come to be used in conjunction—most fonts now come with a roman type and an oblique version (generally called "italic" though often not true italics). In this usage, italics are a way to emphasise key points in a printed text, to identify many types of creative works, to cite foreign words or phrases, or, when quoting a speaker, a way to show which words they stressed. One manual o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programming Language
A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually defined by a formal language. Languages usually provide features such as a type system, Variable (computer science), variables, and mechanisms for Exception handling (programming), error handling. An Programming language implementation, implementation of a programming language is required in order to Execution (computing), execute programs, namely an Interpreter (computing), interpreter or a compiler. An interpreter directly executes the source code, while a compiler produces an executable program. Computer architecture has strongly influenced the design of programming languages, with the most common type (imperative languages—which implement operations in a specified order) developed to perform well on the popular von Neumann architecture. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J (programming Language)
The J programming language, developed in the early 1990s by Kenneth E. Iverson and Roger Hui, is an array programming language based primarily on APL (also by Iverson). To avoid repeating the APL special-character problem, J uses only the basic ASCII character set, resorting to the use of the dot and colon as ''inflections'' to form short words similar to '' digraphs''. Most such ''primary'' (or ''primitive'') J words serve as mathematical symbols, with the dot or colon extending the meaning of the basic characters available. Also, many characters which in other languages often must be paired (such as [] "" `` or ) are treated by J as stand-alone words or, when inflected, as single-character roots of multi-character words. J is a very terse array programming language, and is most suited to mathematical and statistical programming, especially when performing operations on matrices. It has also been used in extreme programming and network performance analysis. Like John B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
