 | This article needs additional citations for verification .(July 2023) |
This is a list of notable lexer generators and parser generators for various language classes.
| | This article needs additional citations for verification .(July 2023) |
This is a list of notable lexer generators and parser generators for various language classes.
Regular languages are a category of languages (sometimes termed Chomsky Type 3) which can be matched by a state machine (more specifically, by a deterministic finite automaton or a nondeterministic finite automaton) constructed from a regular expression. In particular, a regular language can match constructs like "A follows B", "Either A or B", "A, followed by zero or more instances of B", but cannot match constructs which require consistency between non-adjacent elements, such as "some instances of A followed by the same number of instances of B", and also cannot express the concept of recursive "nesting" ("every A is eventually followed by a matching B"). A classic example of a problem which a regular grammar cannot handle is the question of whether a given string contains correctly nested parentheses. (This is typically handled by a Chomsky Type 2 grammar, also termed a context-free grammar.)
| Name | Lexer algorithm | Output languages | Grammar, code | Development platform | License |
|---|---|---|---|---|---|
| Alex | DFA | Haskell | Mixed | All | Free, BSD |
| AnnoFlex | DFA | Java | Mixed | Java virtual machine | Free, BSD |
| Astir | DFA table driven, with branching | C++ | Only grammar (actioned) | All | Free, MIT |
| AustenX | DFA | Java | Separate | All | Free, BSD |
| C# Flex | DFA | C# | Mixed | .NET CLR | Free, GNU GPL |
| C# Lex | DFA | C# | Mixed | .NET CLR | ? |
| CookCC | DFA | Java | Mixed | Java virtual machine | Free, Apache 2.0 |
| DFA | DFA compressed matrix | C, C++ | Separate | Windows, Visual Studio | BSD |
| Dolphin | DFA | C++ | Separate | All | Proprietary |
| Flex | DFA table driven | C, C++ | Mixed | All | Free, BSD |
| gelex | DFA | Eiffel | Mixed | Eiffel | Free, MIT |
| golex | DFA | Go | Mixed | Go | Free, BSD-style |
| gplex | DFA | C# | Mixed | .NET CLR | Free, BSD-like |
| JFlex | DFA | Java | Mixed | Java virtual machine | Free, BSD |
| JLex | DFA | Java | Mixed | Java virtual machine | Free, BSD-like |
| lex | DFA | C | Mixed | POSIX | Partial, proprietary, CDDL |
| lexertl | DFA | C++ | ? | All | Free, GNU LGPL |
| Quex | DFA direct code | C, C++ | Mixed | All | Free, GNU LGPL |
| Ragel | DFA | Go, C, C++, assembly | Mixed | All | Free, GNU GPL, MIT [1] [2] |
| RE/flex | DFA direct code, DFA table driven, and NFA regex libraries | C++ | Mixed | All | Free, BSD |
| re2c | DFA direct code | C, C++, Go, Rust | Mixed | All | Free, public domain |
Context-free languages are a category of languages (sometimes termed Chomsky Type 2) which can be matched by a sequence of replacement rules, each of which essentially maps each non-terminal element to a sequence of terminal elements and/or other nonterminal elements. Grammars of this type can match anything that can be matched by a regular grammar, and furthermore, can handle the concept of recursive "nesting" ("every A is eventually followed by a matching B"), such as the question of whether a given string contains correctly nested parentheses. The rules of Context-free grammars are purely local, however, and therefore cannot handle questions that require non-local analysis such as "Does a declaration exist for every variable that is used in a function?". To do so technically would require a more sophisticated grammar, like a Chomsky Type 1 grammar, also termed a context-sensitive grammar. However, parser generators for context-free grammars often support the ability for user-written code to introduce limited amounts of context-sensitivity. (For example, upon encountering a variable declaration, user-written code could save the name and type of the variable into an external data structure, so that these could be checked against later variable references detected by the parser.)
The deterministic context-free languages are a proper subset of the context-free languages which can be efficiently parsed by deterministic pushdown automata.
| Name | Parsing algorithm | Input grammar notation | Output languages | Grammar, code | Lexer | Development platform | IDE | License |
|---|---|---|---|---|---|---|---|---|
| ANTLR4 | Adaptive LL(*) [3] | EBNF | C#, Java, Python, JavaScript, C++, Swift, Go, PHP | Separate | generated | Java virtual machine | Yes | Free, BSD |
| ANTLR3 | LL(*) | EBNF | ActionScript, Ada95, C, C++, C#, Java, JavaScript, Objective-C, Perl, Python, Ruby | Mixed | generated | Java virtual machine | Yes | Free, BSD |
| APG [4] | Recursive descent, backtracking | ABNF | Python, JavaScript, C, Java | Separate | none | All | No | Free, BSD |
| Beaver [5] [6] | LALR(1) | EBNF | Java | Mixed | external | Java virtual machine | No | Free, BSD |
| Bison | LALR(1), LR(1), IELR(1), GLR | Yacc | C, C++, Java | Mixed | external | All | No | Free, GNU GPL with exception |
| BtYacc | Backtracking Bottom-up | ? | C++ | Mixed | external | All | No | Free, public domain |
| byacc | LALR(1) | Yacc | C | Mixed | external | All | No | Free, public domain |
| CL-Yacc [7] [8] | LALR(1) | Lisp | Common Lisp | Mixed | external | All | No | Free, MIT |
| Coco/R | LL(1) | EBNF | C, C++, C#, F#, Java, Ada, Object Pascal, Delphi, Modula-2, Oberon, Ruby, Swift, Unicon, Visual Basic .NET | Mixed | generated | Java virtual machine, .NET framework, Windows, POSIX (depends on output language) | No | Free, GNU GPL |
| CppCC [9] [10] | LL(k) | ? | C++ | Mixed | generated | POSIX | No | Free, GNU GPL |
| CUP [11] [12] | LALR(1) | ? | Java | Mixed | external | Java virtual machine | No | Free, BSD-like |
| Eli [13] [14] | LALR(1) | ? | C | Mixed | generated | POSIX | No | Free, GNU GPL, GNU LGPL |
| Essence [15] | LR(?) | ? | Scheme 48 | Mixed | external | All | No | Free, BSD |
| eyapp [16] | LALR(1) | ? | Perl | Mixed | external or generated | All | No | Free, Artistic |
| GOLD [17] | LALR(1) | BNF | x86 assembly language, ANSI C, C#, D, Java, Pascal, Object Pascal, Python, Visual Basic 6, Visual Basic .NET, Visual C++ | Separate | generated | Windows | Yes | Free, zlib modified |
| Hime Parser Generator [18] | LALR(1), GLR | BNF dialect | C#, Java, Rust | Separate | generated | .NET framework, Java virtual machine | No | Free, GNU LGPL |
| Hyacc [19] | LR(1), LALR(1), LR(0) | Yacc | C | Mixed | external | All | No | Free, GNU GPL |
| JavaCC [20] [21] | LL(k) | EBNF | Java, C++, JavaScript (via GWT compiler) [22] | Mixed | generated | Java virtual machine | Yes | Free, BSD |
| JFLAP | LL(1), LALR(1) | ? | Java | ? | ? | Java virtual machine | Yes | ? |
| JetPAG | LL(k) | ? | C++ | Mixed | generated | All | No | Free, GNU GPL |
| JS/CC | LALR(1) | EBNF | JavaScript, JScript, ECMAScript | Mixed | internal | All | Yes | Free, BSD |
| KDevelop-PG-Qt | LL(1), backtracking, shunting-yard | ? | C++ | Mixed | generated or external | All, KDE | No | Free, GNU LGPL |
| Kelbt | Backtracking LALR(1) | ? | C++ | Mixed | generated | POSIX | No | Free, GNU GPL |
| kmyacc | LALR(1) | ? | C, Java, Perl, JavaScript | Mixed | external | All | No | Free, GNU GPL |
| Lapg | LALR(1) | ? | C, C++, C#, Java, JavaScript | Mixed | generated | Java virtual machine | No | Free, GNU GPL |
| Lark | LALR(1), Earley (SPPF) | EBNF | Python, JavaScript | Mixed | generated | All | Yes | Free, MIT |
| Lemon | LALR(1) | BNF dialect [23] | C | Mixed | external | All | No | Free, public domain |
| Lezer [24] [25] [26] | LR(1), GLR | EBNF dialect | JavaScript | Separate | generated | Node.js, JavaScript | No | Free, MIT |
| Lime | LALR(1) | ? | PHP | Mixed | external | All | No | Free, GNU GPL |
| LISA | LR(?), LL(?), LALR(?), SLR(?) | ? | Java | Mixed | generated | Java virtual machine | Yes | Free, public domain |
| LLgen | LL(1) | ? | C | Mixed | external | POSIX | No | Free, BSD |
| LLnextgen | LL(1) | ? | C | Mixed | external | All | No | Free, GNU GPL |
| LLLPG | LL(k) + syntactic and semantic predicates | ANTLR-like | C# | Mixed | generated (?) | .NET framework, Mono | Visual Studio | Free, GNU LGPL |
| LPG | Backtracking LALR(k) | ? | Java | Mixed | generated | Java virtual machine | No | Free, EPL |
| LRSTAR [27] | LALR(1), LALR(*) | YACC, ANTLR, EBNF | C++ | Separate | generated | Windows | Visual Studio | Free, BSD |
| Menhir | LR(1) | ? | OCaml | Mixed | generated | All | No | Free, QPL |
| ML-Yacc | LALR(1) | ? | ML | Mixed | external | All | No | ? |
| Monkey | LR(1) | ? | Java | Separate | generated | Java virtual machine | No | Free, GNU GPL |
| Msta | LALR(k), LR(k) | YACC, EBNF | C, C++ | Mixed | external or generated | POSIX, Cygwin | No | Free, GNU GPL |
| MTP (More Than Parsing) | LL(1) | ? | Java | Separate | generated | Java virtual machine | No | Free, GNU GPL |
| MyParser | LL(*) | Markdown | C++11 | Separate | internal | Any with standard C++11 compiler | No | Free, MIT |
| NLT | GLR | C#/BNF-like | C# | Mixed | mixed | .NET framework | No | Free, MIT |
| ocamlyacc | LALR(1) | ? | OCaml | Mixed | external | All | No | Free, QPL |
| olex | LL(1) | ? | C++ | Mixed | generated | All | No | Free, GNU GPL |
| Parsec | LL, backtracking | Haskell | Haskell | Mixed | none | All | No | Free, BSD |
| yapp [16] | LALR(1) | ? | Perl | Mixed | external | All | No | Free, GNU GPL |
| Parser Objects | LL(k) | ? | Java | Mixed | ? | Java virtual machine | No | Free, zlib |
| PCCTS | LL | ? | C, C++ | ? | ? | All | No | ? |
| PLY | LALR(1) | BNF | Python | Mixed | generated | All | No | Free, MIT |
| PlyPlus | LALR(1) | EBNF | Python | Separate | generated | All | No | Free, MIT |
| PRECC | LL(k) | ? | C | Separate | generated | DOS, POSIX | No | Free, GNU GPL |
| racc [28] | LALR(1) | BNF-like, yacc-like [29] | Ruby | Mixed | ? | Windows, Linux, macOS, FreeBSD, NetBSD | No | LGPL |
| QLALR | LALR(1) | ? | C++ | Mixed | external | All | No | Free, GNU GPL |
| SableCC | LALR(1) | ? | C, C++, C#, Java, OCaml, Python | Separate | generated | Java virtual machine | No | Free, GNU LGPL |
| SLK [30] | LL(k) LR(k) LALR(k) | EBNF | C, C++, C#, Java, JavaScript | Separate | external | All | No | SLK [31] |
| SLY [32] | LALR(1) | BNF | Python | Mixed | generated | All | No | Free, MIT |
| SP (Simple Parser) | Recursive descent | Python | Python | Separate | generated | All | No | Free, GNU LGPL |
| Spirit | Recursive descent | ? | C++ | Mixed | internal | All | No | Free, Boost |
| Styx | LALR(1) | ? | C, C++ | Separate | generated | All | No | Free, GNU LGPL |
| Sweet Parser | LALR(1) | ? | C++ | Separate | generated | Windows | No | Free, zlib |
| Tap | LL(1) | ? | C++ | Mixed | generated | All | No | Free, GNU GPL |
| TextTransformer | LL(k) | ? | C++ | Mixed | generated | Windows | Yes | Proprietary |
| TinyPG | LL(1) | ? | C#, Visual Basic | ? | ? | Windows | Yes | Partial, CPOL 1.0 |
| Toy Parser Generator | Recursive descent | ? | Python | Mixed | generated | All | No | Free, GNU LGPL |
| TP Yacc | LALR(1) | ? | Turbo Pascal | Mixed | external | All | Yes | Free, GNU GPL |
| Tree-Sitter [33] | LR(1), GLR | JavaScript DSL, JSON | C, bindings (Rust, WebAssembly, JavaScript, Python, many other) | Separate | generated + external | All | Neovim, Visual Studio Code | Free, MIT |
| Tunnel Grammar Studio | Tunnel Parsing | ABNF | C++ | Separate | generated | Windows | Yes | Proprietary |
| UltraGram | LALR(1), LR(1), GLR | BNF | C++, Java, C#, Visual Basic .NET | Separate | external | Windows | Yes | Free, public domain |
| UniCC | LALR(1) | EBNF | C, C++, Python, JavaScript, JSON, XML | Mixed | generated | POSIX | No | Free, BSD |
| UrchinCC | LL(1) | ? | Java | ? | generated | Java virtual machine | No | ? |
| Yacc AT&T/Sun | LALR(1) | Yacc | C | Mixed | external | POSIX | No | Free, CPL & CDDL |
| Yacc++ | LR(1), LALR(1) | Yacc | C++, C# | Mixed | generated or external | All | No | Proprietary |
| Yapps | LL(1) | ? | Python | Mixed | generated | All | No | Free, MIT |
| yecc | LALR(1) | ? | Erlang | Separate | generated | All | No | Free, Apache 2.0 |
| Visual BNF | LR(1), LALR(1) | ? | C# | Separate | generated | .NET framework | Yes | Proprietary |
| YooParse | LR(1), LALR(1) | ? | C++ | Mixed | external | All | No | Free, MIT |
| Parse [34] | LR(1) | BNF in C++ types | ? | ? | none | C++11 standard compiler | No | Free, MIT |
| GGLL | LL(1) | Graph | Java | Mixed | generated | Windows | Yes | Free, MIT |
| Product | Parsing algorithm | Input grammar notation | Output languages | Grammar, code | Lexer | Development platform | IDE | License |
This table compares parser generators with parsing expression grammars, deterministic boolean grammars.
| Name | Parsing algorithm | Output languages | Grammar, code | Development platform | License |
|---|---|---|---|---|---|
| AustenX | Packrat (modified) | Java | Separate | All | Free, BSD |
| Aurochs | Packrat | C, OCaml, Java | Mixed | All | Free, GNU GPL |
| BNFlite | Recursive descent | C++ | Mixed | All | Free, MIT |
| Canopy | Packrat | Java, JavaScript, Python, Ruby | Separate | All | Free, GNU GPL |
| CL-peg | Packrat | Common Lisp | Mixed | All | Free, MIT |
| Drat! | Packrat | D | Mixed | All | Free, GNU GPL |
| Frisby | Packrat | Haskell | Mixed | All | Free, BSD |
| grammar::peg | Packrat | Tcl | Mixed | All | Free, BSD |
| Grako | Packrat + Cut + Left Recursion | Python, C++ (beta) | Separate | All | Free, BSD |
| IronMeta | Packrat | C# | Mixed | Windows | Free, BSD |
| Laja | 2-phase scannerless top-down backtracking + runtime support | Java | Separate | All | Free, GNU GPL |
| lars::Parser | Packrat (supporting left-recursion and grammar ambiguity) | C++ | Identical | All | Free, BSD |
| LPeg | Parsing machine | Lua | Mixed | All | Free, MIT |
| lug | Parsing machine | C++17 | Mixed | All | Free, MIT |
| Mouse | Recursive descent (modified, limited memoization and left-recursion) | Java | Separate | Java virtual machine | Free, Apache 2.0 |
| Narwhal | Packrat | C | Mixed | POSIX, Windows | Free, BSD |
| Nearley | Earley | JavaScript | Mixed | All | Free, MIT |
| Nemerle.Peg | Recursive descent + Pratt | Nemerle | Separate | All | Free, BSD |
| neotoma | Packrat | Erlang | Separate | All | Free, MIT |
| NPEG | Recursive descent | C# | Mixed | All | Free, MIT |
| OMeta | Packrat (modified, partial memoization) | JavaScript, Squeak, Python | Mixed | All | Free, MIT |
| PackCC | Packrat (modified, left-recursion support) | C | Mixed | All | Free, MIT |
| Packrat | Packrat | Scheme | Mixed | All | Free, MIT |
| Pappy | Packrat | Haskell | Mixed | All | Free, BSD |
| parboiled | Recursive descent | Java, Scala | Mixed | Java virtual machine | Free, Apache 2.0 |
| Lambda PEG | Recursive descent | Java | Mixed | Java virtual machine | Free, Apache 2.0 |
| parsepp | Recursive descent | C++ | Mixed | All | Free, public domain |
| Parsnip | Packrat | C++ | Mixed | Windows | Free, GNU GPL |
| Patterns | Parsing machine | Swift | Identical | All | Free, MIT |
| peg | Recursive descent | C | Mixed | All | Free, MIT |
| PEG.js | Packrat (partial memoization) | JavaScript | Mixed | All | Free, MIT |
| Peggy [35] | Packrat (partial memoization) | JavaScript | Mixed | All | Free, MIT |
| Pegasus | Recursive descent, Packrat (selectively) | C# | Mixed | Windows | Free, MIT |
| pegc | Recursive descent | C | Mixed | All | Free, public domain |
| pest | Recursive descent | Rust | Separate | All | Free, MIT, Apache 2.0 |
| PetitParser | Packrat | Smalltalk, Java, Dart | Mixed | All | Free, MIT |
| PEGTL [36] | Recursive descent | C++11, C++17 | Mixed | All | Free, Boost |
| Parser Grammar Engine (PGE) | Hybrid recursive descent / operator precedence [37] | Parrot bytecode | Mixed | Parrot virtual machine | Free, Artistic 2.0 |
| PyPy rlib | Packrat | Python | Mixed | All | Free, MIT |
| Rats! | Packrat | Java | Mixed | Java virtual machine | Free, GNU LGPL |
| Spirit2 | Recursive descent | C++ | Mixed | All | Free, Boost |
| Treetop | Recursive descent | Ruby | Mixed | All | Free, MIT |
| Yard | Recursive descent | C++ | Mixed | All | Free, MIT or public domain |
| Waxeye | Parsing machine | C, Java, JavaScript, Python, Racket, Ruby | Separate | All | Free, MIT |
| PHP PEG | PEG Parser? | PHP | Mixed | All | Free, BSD |
This table compares parser generator languages with a general context-free grammar, a conjunctive grammar, or a boolean grammar.
| Name | Parsing algorithm | Input grammar notation | Output languages | Grammar, code | Lexer | Development platform | IDE | License |
|---|---|---|---|---|---|---|---|---|
| ACCENT | Earley | Yacc variant | C | Mixed | external | All | No | Free, GNU GPL |
| APaGeD | GLR, LALR(1), LL(k) | ? | D | Mixed | generated | All | No | Free, Artistic |
| Bison | LALR(1), LR(1), IELR(1), GLR | Yacc | C, C++, Java, XML | Mixed, except XML | external | All | No | Free, GNU GPL |
| DMS Software Reengineering Toolkit | GLR | ? | Parlanse | Mixed | generated | Windows | No | Proprietary |
| DParser | Scannerless GLR | ? | C | Mixed | scannerless | POSIX | No | Free, BSD |
| Dypgen | Runtime-extensible GLR | ? | OCaml | Mixed | generated | All | No | Free, CeCILL-B |
| E3 | Earley | ? | OCaml | Mixed | external, or scannerless | All | No | ? |
| Elkhound | GLR | ? | C++, OCaml | Mixed | external | All | No | Free, BSD |
| GDK | LALR(1), GLR | ? | C, Lex, Haskell, HTML, Java, Object Pascal, Yacc | Mixed | generated | POSIX | No | Free, MIT |
| Happy | LALR, GLR | ? | Haskell | Mixed | external | All | No | Free, BSD |
| Hime Parser Generator | GLR | ? | C#, Java, Rust | Separate | generated | .NET framework, Java virtual machine | No | Free, GNU LGPL |
| IronText Library | LALR(1), GLR | C# | C# | Mixed | generated or external | .NET framework | No | Free, Apache 2.0 |
| Jison | LALR(1), LR(0), SLR(1) | Yacc | JavaScript, C#, PHP | Mixed | generated | All | No | Free, MIT |
| Syntax | LALR(1), LR(0), SLR(1) CLR(1) LL(1) | JSON/Yacc | JavaScript, Python, PHP, Ruby, C++, C#, Rust, Java | Mixed | generated | All | No | Free, MIT |
| Laja | Scannerless, two phase | Laja | Java | Separate | scannerless | All | No | Free, GNU GPL |
| ModelCC | Earley | Annotated class model | Java | Generated | generated | All | No | Free, BSD |
| P3 | Earley–combinators | BNF-like | OCaml | Mixed | external, or scannerless | All | No | ? |
| P4 | Earley–combinators, infinitary CFGs | BNF-like | OCaml | Mixed | external, or scannerless | All | No | ? |
| Scannerless Boolean Parser | Scannerless GLR (Boolean grammars) | ? | Haskell, Java | Separate | scannerless | Java virtual machine | No | Free, BSD |
| SDF/SGLR | Scannerless GLR | SDF | C, Java | Separate | scannerless | All | Yes | Free, BSD |
| SmaCC | GLR(1), LALR(1), LR(1) | ? | Smalltalk | Mixed | internal | All | Yes | Free, MIT |
| SPARK | Earley | ? | Python | Mixed | external | All | No | Free, MIT |
| Tom | GLR | ? | C | Generated | none | All | No | Free, "No licensing or copyright restrictions" |
| UltraGram | LALR, LR, GLR | ? | C++, C#, Java, Visual Basic .NET | Separate | generated | Windows | Yes | Proprietary |
| Wormhole | Pruning, LR, GLR, Scannerless GLR | ? | C, Python | Mixed | scannerless | Windows | No | Free, MIT |
| Whale Calf | General tabular, SLL(k), Linear normal form (conjunctive grammars), LR, Binary normal form (Boolean grammars) | ? | C++ | Separate | external | All | No | Proprietary |
| yaep | Earley | Yacc-like | C | Mixed | external | All | No | Free, GNU LGPL |
This table compares parser generators with context-sensitive grammars.
| Name | Parsing algorithm | Input grammar notation | Boolean grammar abilities | Development platform | License |
|---|---|---|---|---|---|
| bnf2xml | Recursive descent (is a text filter output is xml) | simple BNF [ clarification needed ] grammar (input matching), output is xml | ? | Beta, and not a full EBNF parser | Free, GNU GPL |
The Chomsky hierarchy in the fields of formal language theory, computer science, and linguistics, is a containment hierarchy of classes of formal grammars. A formal grammar describes how to form strings from a language's vocabulary that are valid according to the language's syntax. The linguist Noam Chomsky theorized that four different classes of formal grammars existed that could generate increasingly complex languages. Each class can also completely generate the language of all inferior classes.
In computer science, an LALR parser is part of the compiling process where human readable text is converted into a structured representation to be read by computers. An LALR parser is a software tool to process (parse) text into a very specific internal representation that other programs, such as compilers, can work with. This process happens according to a set of production rules specified by a formal grammar for a computer language.
In computer science, LR parsers are a type of bottom-up parser that analyse deterministic context-free languages in linear time. There are several variants of LR parsers: SLR parsers, LALR parsers, canonical LR(1) parsers, minimal LR(1) parsers, and generalized LR parsers. LR parsers can be generated by a parser generator from a formal grammar defining the syntax of the language to be parsed. They are widely used for the processing of computer languages.
Yacc is a computer program for the Unix operating system developed by Stephen C. Johnson. It is a lookahead left-to-right rightmost derivation (LALR) parser generator, generating a LALR parser based on a formal grammar, written in a notation similar to Backus–Naur form (BNF). Yacc is supplied as a standard utility on BSD and AT&T Unix. GNU-based Linux distributions include Bison, a forward-compatible Yacc replacement.
GNU Bison, commonly known as Bison, is a parser generator that is part of the GNU Project. Bison reads a specification in Bison syntax, warns about any parsing ambiguities, and generates a parser that reads sequences of tokens and decides whether the sequence conforms to the syntax specified by the grammar.
In computer science, Backus–Naur form is a notation used to describe the syntax of programming languages or other formal languages. It was developed by John Backus and Peter Naur. BNF can be described as a metasyntax notation for context-free grammars. Backus–Naur form is applied wherever exact descriptions of languages are needed, such as in official language specifications, in manuals, and in textbooks on programming language theory. BNF can be used to describe document formats, instruction sets, and communication protocols.
In computer science, a recursive descent parser is a kind of top-down parser built from a set of mutually recursive procedures where each such procedure implements one of the nonterminals of the grammar. Thus the structure of the resulting program closely mirrors that of the grammar it recognizes.
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.
In computer science, a Simple LR or SLR parser is a type of LR parser with small parse tables and a relatively simple parser generator algorithm. As with other types of LR(1) parser, an SLR parser is quite efficient at finding the single correct bottom-up parse in a single left-to-right scan over the input stream, without guesswork or backtracking. The parser is mechanically generated from a formal grammar for the language.
Originally, the word computing was synonymous with counting and calculating, and the science and technology of mathematical calculations. Today, "computing" means using computers and other computing machines. It includes their operation and usage, the electrical processes carried out within the computing hardware itself, and the theoretical concepts governing them.
In computing, code generation is part of the process chain of a compiler and converts intermediate representation of source code into a form that can be readily executed by the target system.
Parsing, syntax analysis, or syntactic analysis is the process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar. The term parsing comes from Latin pars (orationis), meaning part.
Berkeley Yacc (byacc) is a Unix parser generator designed to be compatible with Yacc. It was originally written by Robert Corbett and released in 1989. Due to its liberal license and because it was faster than the AT&T Yacc, it quickly became the most popular version of Yacc. It has the advantages of being written in ANSI C89 and being public domain software.
In computer science, the syntax of a computer language is the rules that define the combinations of symbols that are considered to be correctly structured statements or expressions in that language. This applies both to programming languages, where the document represents source code, and to markup languages, where the document represents data.
In computer programming, the lexer hack is a common solution to the problems in parsing ANSI C, due to the reference grammar being context-sensitive. In C, classifying a sequence of characters as a variable name or a type name requires contextual information of the phrase structure, which prevents one from having a context-free lexer.
In formal grammar theory, the deterministic context-free grammars (DCFGs) are a proper subset of the context-free grammars. They are the subset of context-free grammars that can be derived from deterministic pushdown automata, and they generate the deterministic context-free languages. DCFGs are always unambiguous, and are an important subclass of unambiguous CFGs; there are non-deterministic unambiguous CFGs, however.
In computer science, SYNTAX is a system used to generate lexical and syntactic analyzers (parsers) for all kinds of context-free grammars (CFGs) as well as some classes of contextual grammars. It has been developed at INRIA in France for several decades, mostly by Pierre Boullier, but has become free software since 2007 only. SYNTAX is distributed under the CeCILL license.
In computing, a compiler is a computer program that transforms source code written in a programming language or computer language, into another computer language. The most common reason for transforming source code is to create an executable program.
A lookahead LR parser (LALR) generator is a software tool that reads a context-free grammar (CFG) and creates an LALR parser which is capable of parsing files written in the context-free language defined by the CFG. LALR parsers are desirable because they are very fast and small in comparison to other types of parsers.
In formal language theory, an LL grammar is a context-free grammar that can be parsed by an LL parser, which parses the input from Left to right, and constructs a Leftmost derivation of the sentence. A language that has an LL grammar is known as an LL language. These form subsets of deterministic context-free grammars (DCFGs) and deterministic context-free languages (DCFLs), respectively. One says that a given grammar or language "is an LL grammar/language" or simply "is LL" to indicate that it is in this class.
{{cite journal}}: Cite journal requires |journal= (help)PGE rules provide the full power of recursive descent parsing and operator precedence parsing.