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re2c uses the following syntax for regular expressions: "foo" case-sensitive string literal 'foo' case-insensitive string literal [a-xyz], [^a-xyz] character class (possibly negated). any character except newline; R \ S difference of character classes; R* zero or more occurrences of R; R+ one or more occurrences of R; R? zero or one occurrence of R
Java Apache java.util.regex Java's User manual: Java GNU GPLv2 with Classpath exception jEdit: JRegex JRegex: Java BSD MATLAB: Regular Expressions: MATLAB Language: Proprietary Oniguruma: Kosako: C BSD Atom, Take Command Console, Tera Term, TextMate, Sublime Text, SubEthaEdit, EmEditor, jq, Ruby: Pattwo Stevesoft Java (compatible with Java 1.0 ...
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 ...
Algebraic laws for regular expressions can be obtained using a method by Gischer which is best explained along an example: In order to check whether (X+Y) ∗ and (X ∗ Y ∗) ∗ denote the same regular language, for all regular expressions X, Y, it is necessary and sufficient to check whether the particular regular expressions (a+b) ∗ and ...
The raw input, the 43 characters, must be explicitly split into the 9 tokens with a given space delimiter (i.e., matching the string " "or regular expression /\s{1}/). When a token class represents more than one possible lexeme, the lexer often saves enough information to reproduce the original lexeme, so that it can be used in semantic analysis .
In computer science, Thompson's construction algorithm, also called the McNaughton–Yamada–Thompson algorithm, [1] is a method of transforming a regular expression into an equivalent nondeterministic finite automaton (NFA). [2] This NFA can be used to match strings against the regular expression.
Python supports normal floating point numbers, which are created when a dot is used in a literal (e.g. 1.1), when an integer and a floating point number are used in an expression, or as a result of some mathematical operations ("true division" via the / operator, or exponentiation with a negative exponent).
That is, it performs a constant number of operations for each input symbol. This constant is quite low: GCC generates 12 instructions for the DFA match loop. [citation needed] Note that the constant is independent of the length of the token, the length of the regular expression and the size of the DFA.