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Lexerless Parsing
In computer science, scannerless parsing (also called lexerless parsing) performs tokenization (breaking a stream of characters into words) and parsing (arranging the words into phrases) in a single step, rather than breaking it up into a pipeline of a lexer followed by a parser, executing concurrently. A language grammar is scannerless if it uses a single formalism to express both the lexical (word level) and phrase level structure of the language. Dividing processing into a lexer followed by a parser is more modular; scannerless parsing is primarily used when a clear lexer–parser distinction is unneeded or unwanted. Examples of when this is appropriate include TeX, most wiki grammars, makefiles, simple application-specific scripting languages, and Raku. Advantages * Only one metalanguage is needed * Non-regular lexical structure is handled easily * "Token classification" is unneeded which removes the need for design accommodations such as "the lexer hack" and language re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Computer Science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, applied disciplines (including the design and implementation of Computer architecture, hardware and Software engineering, software). Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and preventing security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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ASF+SDF Meta Environment
ASF may refer to: Arts and entertainment * Alabama Shakespeare Festival, a drama festival * ''Asimov's Science Fiction'', a U.S.-based English-language science fiction magazine containing SF stories Science and technology Biological * African swine fever virus (ASFV), the causative agent of African swine fever (ASF) * Altered Schaedler flora, a standardized consortium of gastrointestinal microbial species * Serine/arginine-rich splicing factor 1, a protein also known as alternative splicing factor 1 (ASF) Computing * Advanced Synchronization Facility, a proposed extension to the x86 instruction set architecture * Advanced Systems Format (formerly "Advanced Streaming Format", .asf), a Microsoft streaming format * Alert Standard Format, a protocol for remote management and control of systems in OS-absent environments * Antispam, Anti Spam Filtering, software and hardware protection layers used to fight email spam * Apache Software Foundation, an umbrella non-profit organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Context-free Language
In formal language theory, a context-free language (CFL), also called a Chomsky type-2 language, is a language generated by a context-free grammar (CFG). Context-free languages have many applications in programming languages, in particular, most arithmetic expressions are generated by context-free grammars. Background Context-free grammar Different context-free grammars can generate the same context-free language. Intrinsic properties of the language can be distinguished from extrinsic properties of a particular grammar by comparing multiple grammars that describe the language. Automata The set of all context-free languages is identical to the set of languages accepted by pushdown automata, which makes these languages amenable to parsing. Further, for a given CFG, there is a direct way to produce a pushdown automaton for the grammar (and thereby the corresponding language), though going the other way (producing a grammar given an automaton) is not as direct. Examples An e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Metacompiler
In computer science, a compiler-compiler or compiler generator is a programming tool that creates a parser, interpreter, or compiler from some form of formal description of a programming language and machine. The most common type of compiler-compiler is called a parser generator. It handles only syntactic analysis. A formal description of a language is usually a grammar used as an input to a parser generator. It often resembles Backus–Naur form (BNF), extended Backus–Naur form (EBNF), or has its own syntax. Grammar files describe a syntax of a generated compiler's target programming language and actions that should be taken against its specific constructs. Source code for a parser of the programming language is returned as the parser generator's output. This source code can then be compiled into a parser, which may be either standalone or embedded. The compiled parser then accepts the source code of the target programming language as an input and performs an action or ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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TREE-META
The TREE-META (or Tree Meta, TREEMETA) Translator Writing System is a compiler-compiler system for context-free languages originally developed in the 1960s. Parsing statements of the metalanguage resemble augmented Backus–Naur form with embedded tree-building directives. Unparsing rules include extensive tree-scanning and code-generation constructs. History TREE-META was instrumental in the development of NLS (oN-Line System) and was ported to many systems including the UNIVAC 1108, GE 645, SDS 940, ICL 1906A, PERQ, and UCSD p-System. Example This is a complete example of a TREE-META program extracted (and untested) from the more complete (declarations, conditionals, and blocks) example in Appendix 6 of the ICL 1900 TREE-META manual. That document also has a definition of TREE-META in TREE-META in Appendix 3. This program is not only a recognizer, but also outputs the assembly language for the input. It demonstrates one of the key features of TREE-META, which is tree pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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META II
META II is a Domain-specific language, domain-specific programming language for writing compilers. It was created in 1963–1964 by Dewey Val Schorre at University of California, Los Angeles (UCLA). META II uses what Schorre called ''Syntax (programming languages), syntax equations''. Its operation is simply explained as: Each ''syntax equation'' is translated into a recursive Function (computer programming), subroutine which tests the input string for a particular phrase structure, and deletes it if found. Meta II programs are compiled into an Interpreter (computing), interpreted byte code language. VALGOL and SMALGOL compilers illustrating its capabilities were written in the META II language, VALGOL is a simple algebraic language designed for the purpose of illustrating META II. SMALGOL was a fairly large subset of ALGOL 60. Notation META II was first written in META I, a hand-compiled version of META II. The history is unclear as to whether META I was a full implementation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Raku Rules
Raku rules are the regular expression, string matching and general-purpose parsing facility of the Raku programming language, and are a core part of the language. Since Perl's pattern-matching constructs have exceeded the capabilities of formal regular expressions for some time, Raku documentation refers to them exclusively as ''regexes'', distancing the term from the formal definition. Raku provides a superset of Perl 5 features with respect to regexes, folding them into a larger framework called ''rules'', which provide the capabilities of a parsing expression grammar, as well as acting as a closure with respect to their lexical scope. Rules are introduced with the rule keyword, which has a usage quite similar to subroutine definitions. Anonymous rules can be introduced with the regex (or rx) keyword, or simply be used inline as regexes were in Perl 5 via the m (matching) or s (substitution) operators. History In ''Apocalypse 5'', a document outlining the preliminary design dec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Boolean Grammar
Boolean grammars, introduced by , are a class of formal grammars studied in formal language theory. They extend the basic type of grammars, the context-free grammars, with conjunction and negation operations. Besides these explicit operations, Boolean grammars allow implicit disjunction represented by multiple rules for a single nonterminal symbol, which is the only logical connective expressible in context-free grammars. Conjunction and negation can be used, in particular, to specify intersection and complement of languages. An intermediate class of grammars known as conjunctive grammars allows conjunction and disjunction, but not negation. The rules of a Boolean grammar are of the form A \to \alpha_1 \And \ldots \And \alpha_m \And \lnot\beta_1 \And \ldots \And \lnot\beta_n where A is a nonterminal, m+n \ge 1 and \alpha_1, ..., \alpha_m, \beta_1, ..., \beta_n are strings formed of symbols in \Sigma and N. Informally, such a rule asserts that every string w over \Sigma that sat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Scannerless Boolean Parser
{{Infobox Software , name = SBP , developer = Adam Megacz , latest release version = 1.0 , latest release date = 2009 , platform = Java Virtual Machine , genre = Parser generator , license = BSD license , website archived home page The Scannerless Boolean Parser is an open-source scannerless GLR parser generator for boolean grammars. It was implemented in the Java programming language and generates Java source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only .... SBP also integrates with Haskell via LambdaVM. External links SBP: the Scannerless Boolean ParserSBP LDTA'06 articleWIX - wiki markup parser in SBP Haskell Parser generators Free software programmed in Java (programming language) Software using the BSD license ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Spirit Parser Framework
The Spirit Parser Framework is an object oriented recursive descent parser generator framework implemented using template metaprogramming techniques. Expression templates allow users to approximate the syntax of extended Backus–Naur form (EBNF) completely in C++. Parser objects are composed through operator overloading and the result is a backtracking LL(∞) parser that is capable of parsing rather ambiguous grammars. Spirit can be used for both lexing and parsing, together or separately. This framework is part of the Boost libraries. Operators Because of limitations of the C++ language, the syntax of Spirit has been designed around the operator precedences of C++, while bearing resemblance to both EBNF and regular expressions A regular expression (shortened as regex or regexp), sometimes referred to as rational expression, is a sequence of character (computing), characters that specifies a pattern matching, match pattern in string (computer science), text. Usuall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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GLR Parser
A GLR parser (generalized left-to-right rightmost derivation parser) is an extension of an LR parser algorithm to handle non-deterministic and ambiguous grammars. The theoretical foundation was provided in a 1974 paper by Bernard Lang (along with other general context-free parsers such as GLL). It describes a systematic way to produce such algorithms, and provides uniform results regarding correctness proofs, complexity with respect to grammar classes, and optimization techniques. The first actual implementation of GLR was described in a 1984 paper by Masaru Tomita, it has also been referred to as a "parallel parser". Tomita presented five stages in his original work, though in practice it is the second stage that is recognized as the GLR parser. Though the algorithm has evolved since its original forms, the principles have remained intact. As shown by an earlier publication, Lang was primarily interested in more easily used and more flexible parsers for extensible programming l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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TXL (programming Language)
TXL is a special-purpose programming language originally designed by Charles Halpern-Hamu and James Cordy at the University of Toronto in 1985. The acronym "TXL" originally stood for "Turing eXtender Language" after the language's original purpose, the specification and rapid prototyping of variants and extensions of the Turing programming language, but no longer has any meaningful interpretation. Modern TXL is specifically designed for creating, manipulating and rapidly prototyping language-based descriptions, tools and applications using source transformation. It is a hybrid functional / rule-based language using first order functional programming at the higher level and term rewriting at the lower level. The formal semantics and implementation of TXL are based on formal term rewriting, but the term structures are largely hidden from the user due to the example-like style of pattern specification. Each TXL program has two components: a description of the source structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |