Regex

Definition

Namespace: Corvus.Ecma262.RegularExpressions
Assembly: Corvus.Regex.Ecma262.dll
Source: Regex.cs

An ECMA-262 regular expression: the grammar and the answers of ECMAScript 2025, with the shape of System.Text.RegularExpressions.Regex. It matches UTF-16 text (String and ReadOnlySpan of Char) and UTF-8 text (ReadOnlySpan of Byte) natively, with no transcoding either way. An instance is immutable and safe to share between threads.

public sealed class Regex

Inheritance

Object → Regex

Constructors

Constructor	Description
Regex(...)	Initializes a new instance of the `Regex` class with no flags.

Properties

Property	Type	Description
Flags	`RegexFlags`	Gets the flags.
FlagsString	`string`	Gets the flags as the string `RegExp.prototype.flags` gives: the letters in alphabetical order.
GroupCount	`int`	Gets the number of capturing groups of the pattern.
IsUnicode	`bool`	Gets a value indicating whether the pattern is matched by code point (the `u` or `v` flag) rather than by UTF-16 code unit.
MatchTimeout	`TimeSpan`	Gets the time a match may take before it is abandoned, or `InfiniteMatchTimeout`.
Pattern	`string`	Gets the pattern.

Methods

Method	Description
Count	The number of matches in a text.
EnumerateMatches	Enumerates the matches in a UTF-16 text, allocating nothing.
EnumerateSplits	Enumerates the pieces a UTF-16 text splits into at the matches, as positions, allocating nothing. The pieces are those of `Split` without...
Escape(string) `static`	Escapes a text so that it matches itself as a pattern, as `RegExp.escape` of ECMAScript 2025 does: a first character that is a letter or a digit, the syntax characters, the other punctuators, white...
GetGroupNames()	The names of the named groups, in the order the pattern first uses them.
GroupNameFromNumber(int)	The name of a group, or its number as text when it has none.
GroupNumberFromName(string)	The number of the first group of a name, or -1 when the pattern has no group of that name.
IsMatch `static`	Whether a pattern matches anywhere in a text, with no flags.
IsValid(string, RegexFlags) `static`	Whether a pattern is a valid ECMA-262 pattern in the grammar of the flags.
Match `static`	The first match of a pattern in a text, with no flags.
Matches `static`	Every match of a pattern in a text.
ParseFlags(string) `static`	Reads the flags as the string `new RegExp(pattern, flags)` takes.
Replace `static`	Replaces the matches of a pattern in a text (every match with `Global`, the first otherwise).
Split `static`	Splits a text at the matches of a pattern, as `String.prototype.split` does.
ToString()
TryCreate(string, RegexFlags, Regex?, string?) `static`	Creates a regular expression without throwing for a pattern that is not valid.
TryMatch	Finds the first match in a UTF-16 text at or after a position and reports what each group captured, allocating nothing.
TryReplace	Replaces the matches in a UTF-16 text (every match with `Global`, the first otherwise) and writes the result to a span, allocating n...
Unescape(string) `static`	Reverses `Escape`: reads the escapes it writes, and a backslash before any other character as that character.

Fields

Field	Type	Description
InfiniteMatchTimeout `static`	`TimeSpan`	The match timeout that means no timeout.

Applies To

Product	Versions
.NET	9, 10
.NET Standard	2.0, 2.1

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