RegexDialectFeatures Enum

Namespace: Meziantou.Framework.Language.Regex
Assembly: Meziantou.Framework.Language.Regex.dll
Package: Meziantou.Framework.Language.Regex 4.0.7
Available in package assets: net10.0net11.0

The optional constructs a RegexDialect supports.

[Flags]
public enum RegexDialectFeatures : long

Remarks

A feature records a difference within a grammar family. Differences between families are handled by RegexDialectFamily, which selects the parser.

A construct the dialect does not have is not parsed as that construct. Where there is an ordinary reading it is used instead -- \A is the letter A where there is no such anchor -- and where there is not, the construct is reported as invalid.

Fields

Name	Value	Description
`None`	`0`
`ExtendedGroupSyntax`	`1`	The `(?…)` family of headers exists at all. POSIX has none of them, so a `?` after `(` is an ordinary quantifier with nothing to repeat rather than the start of a header.
`NonCapturingGroups`	`2`	Non-capturing groups, `(?:…)`.
`NamedGroups`	`4`	Named groups in any spelling.
`AngleNamedGroups`	`8`	Angle-bracket named groups, `(?<name>…)`.
`QuoteNamedGroups`	`16`	Single-quoted named groups, `(?'name'…)`.
`PythonNamedGroups`	`32`	Python-style named groups, `(?P<name>…)`.
`BalancingGroups`	`64`	Balancing groups, `(?<current-previous>…)`.
`AtomicGroups`	`128`	Atomic groups, `(?>…)`.
`BranchReset`	`256`	Branch reset groups, `(?\|…)`.
`Conditionals`	`512`	Conditional alternations, `(?(1)yes\|no)`.
`CommentGroups`	`1024`	Comment groups, `(?#…)`.
`InlineOptions`	`2048`	Inline options, `(?i)` and `(?i:…)`.
`Lookahead`	`4096`	Lookahead, `(?=…)` and `(?!…)`.
`Lookbehind`	`8192`	Lookbehind, `(?<=…)` and `(?<!…)`.
`AnchorsAZ`	`16384`	The `\A`, `\Z`, `\z`, and `\G` anchors.
`KeepOut`	`32768`	The `\K` match reset.
`Alternation`	`65536`	Alternation with `\|`.
`PlusAndQuestionQuantifiers`	`131072`	The `+` and `?` quantifiers.
`LazyQuantifiers`	`262144`	Lazy quantifiers, `a*?`.
`PossessiveQuantifiers`	`524288`	Possessive quantifiers, `a*+`.
`BareBraceIsLiteral`	`1048576`	A `{` that does not start a well-formed bound is an ordinary character rather than an error.
`Backreferences`	`2097152`	Backreferences.
`StrictEscapes`	`4194304`	An unrecognized alphabetic escape such as `\q` is an error. Where the dialect lacks this, the escape stands for the character itself.
`QuotedLiterals`	`8388608`	Quoted literal runs, `\Q…\E`.
`UnicodeCategories`	`16777216`	Unicode categories and blocks, `\p{L}` and `\P{L}`.
`UnicodeCategoriesRequireUnicodeFlag`	`33554432`	Unicode categories are recognized only when the pattern opts into Unicode mode.
`UnicodePropertyNames`	`67108864`	Unicode property names may name a property as well as a value, as `\p{Script=Greek}` does, and are not checked against the .NET category and block names.
`CharacterClassSubtraction`	`134217728`	Character class subtraction, `[a-z-[aeiou]]`.
`PosixBracketExpressions`	`268435456`	POSIX bracket expressions, `[[:alpha:]]`.
`Recursion`	`536870912`	Recursion, `(?R)` and `(?1)`.
`BacktrackingVerbs`	`1073741824`	Backtracking control verbs such as `(*SKIP)`.
`IgnorePatternWhitespace`	`2147483648`	Extended mode, in which whitespace and `#` comments are insignificant.
`EscapedGroupDelimiters`	`4294967296`	Groups and bounds are written escaped, as POSIX basic expressions write `\(` and `\{`.
`ClassSetOperations`	`8589934592`	The class set grammar: nested classes, `&&` and `--` operators, and `\q{…}` string disjunctions. JavaScript turns it on with the `v` flag rather than having it always.