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Regular Expression Flavor Comparison – Detailed comparison of the most popular regular expression flavors; Regexp Syntax Summary; Online Regular Expression Testing – with support for Java, JavaScript, .Net, PHP, Python and Ruby; Implementing Regular Expressions – series of articles by Russ Cox, author of RE2; Regular Expression Engines
Since there is no state numbered higher than n, the regular expression R n 0j represents the set of all strings that take M from its start state q 0 to q j. If F = { q 1,...,q f} is the set of accept states, the regular expression R n 01 | ... | R n 0f represents the language accepted by M. The initial regular expressions, for k = -1, are ...
Regular expressions are used in search engines, in search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK, and in lexical analysis. Regular expressions are supported in many programming languages. Library implementations are often called an "engine", [4] [5] and many of these are ...
TRE is an open-source library for pattern matching in text, [2] which works like a regular expression engine with the ability to do approximate string matching. [3] It was developed by Ville Laurikari [1] and is distributed under a 2-clause BSD-like license.
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 ...
Bracket matching, also known as brace matching or parentheses matching, is a syntax highlighting feature of certain text editors and integrated development environments that highlights matching sets of brackets (square brackets, curly brackets, or parentheses) in languages such as Java, JavaScript, and C++ that use them. The purpose is to help ...
To decide whether two given regular expressions describe the same language, each can be converted into an equivalent minimal deterministic finite automaton via Thompson's construction, powerset construction, and DFA minimization. If, and only if, the resulting automata agree up to renaming of states, the regular expressions' languages agree.
RE/flex integrates indent and dedent matching directly in the regular expression syntax with new \i and \j anchors. These indentation anchors detect changes of line indentation in the input. This allows many practical scenarios to be covered to tokenize programming languages with indented block structures.