Function regex_syntax::is_meta_character

pub fn is_meta_character(c: char) -> bool

Returns true if the given character has significance in a regex.

Generally speaking, these are the only characters which must be escaped in order to match their literal meaning. For example, to match a literal |, one could write \|. Sometimes escaping isn’t always necessary. For example, - is treated as a meta character because of its significance for writing ranges inside of character classes, but the regex - will match a literal - because - has no special meaning outside of character classes.

In order to determine whether a character may be escaped at all, the is_escapeable_character routine should be used. The difference between is_meta_character and is_escapeable_character is that the latter will return true for some characters that are not meta characters. For example, % and \% both match a literal % in all contexts. In other words, is_escapeable_character includes “superfluous” escapes.

Note that the set of characters for which this function returns true or false is fixed and won’t change in a semver compatible release. (In this case, “semver compatible release” actually refers to the regex crate itself, since reducing or expanding the set of meta characters would be a breaking change for not just regex-syntax but also regex itself.)

Example

use regex_syntax::is_meta_character;

assert!(is_meta_character('?'));
assert!(is_meta_character('-'));
assert!(is_meta_character('&'));
assert!(is_meta_character('#'));

assert!(!is_meta_character('%'));
assert!(!is_meta_character('/'));
assert!(!is_meta_character('!'));
assert!(!is_meta_character('"'));
assert!(!is_meta_character('e'));