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Lexer hack. In computer programming, the lexer hack is a solution to parsing context-sensitive grammars such as C, where classifying a sequence of characters as a variable name or a type name requires contextual information, by feeding contextual information backwards from the parser to the lexer. Lexer hack is frowned upon in modern compilers ...
The algorithm, named after its inventor, Jay Earley, is a chart parser that uses dynamic programming; it is mainly used for parsing in computational linguistics. It was first introduced in his dissertation [ 2] in 1968 (and later appeared in an abbreviated, more legible, form in a journal [ 3] ).
ANSI escape code. Output of the system-monitor htop, an ncurses-application (which uses SGR and other ANSI/ISO control sequences). ANSI escape sequences are a standard for in-band signaling to control cursor location, color, font styling, and other options on video text terminals and terminal emulators. Certain sequences of bytes, most starting ...
An operator-precedence parser is a simple shift-reduce parser that is capable of parsing a subset of LR (1) grammars. More precisely, the operator-precedence parser can parse all LR (1) grammars where two consecutive nonterminals and epsilon never appear in the right-hand side of any rule. Operator-precedence parsers are not used often in ...
Backus–Naur form. In computer science, Backus–Naur form ( / ˌbækəs ˈnaʊər /) (BNF or Backus normal 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.
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 ...
Perl Compatible Regular Expressions ( PCRE) is a library written in C, which implements a regular expression engine, inspired by the capabilities of the Perl programming language. Philip Hazel started writing PCRE in summer 1997. [ 3] PCRE's syntax is much more powerful and flexible than either of the POSIX regular expression flavors (BRE, ERE ...
Parser combinator. In computer programming, a parser combinator is a higher-order function that accepts several parsers as input and returns a new parser as its output. In this context, a parser is a function accepting strings as input and returning some structure as output, typically a parse tree or a set of indices representing locations in ...