Struct Config

impl Config

fn new() -> Config

Return a new default syntax configuration.

fn case_insensitive(self: Self, yes: bool) -> Config

Enable or disable the case insensitive flag by default.

When Unicode mode is enabled, case insensitivity is Unicode-aware. Specifically, it will apply the "simple" case folding rules as specified by Unicode.

By default this is disabled. It may alternatively be selectively enabled in the regular expression itself via the i flag.

fn multi_line(self: Self, yes: bool) -> Config

Enable or disable the multi-line matching flag by default.

When this is enabled, the ^ and $ look-around assertions will match immediately after and immediately before a new line character, respectively. Note that the \A and \z look-around assertions are unaffected by this setting and always correspond to matching at the beginning and end of the input.

By default this is disabled. It may alternatively be selectively enabled in the regular expression itself via the m flag.

fn dot_matches_new_line(self: Self, yes: bool) -> Config

Enable or disable the "dot matches any character" flag by default.

When this is enabled, . will match any character. When it's disabled, then . will match any character except for a new line character.

Note that . is impacted by whether the "unicode" setting is enabled or not. When Unicode is enabled (the default), . will match any UTF-8 encoding of any Unicode scalar value (sans a new line, depending on whether this "dot matches new line" option is enabled). When Unicode mode is disabled, . will match any byte instead. Because of this, when Unicode mode is disabled, . can only be used when the "allow invalid UTF-8" option is enabled, since . could otherwise match invalid UTF-8.

By default this is disabled. It may alternatively be selectively enabled in the regular expression itself via the s flag.

fn crlf(self: Self, yes: bool) -> Config

Enable or disable the "CRLF mode" flag by default.

By default this is disabled. It may alternatively be selectively enabled in the regular expression itself via the R flag.

When CRLF mode is enabled, the following happens:

• Unless dot_matches_new_line is enabled, . will match any character except for \r and \n.
• When multi_line mode is enabled, ^ and $ will treat \r\n, \r and \n as line terminators. And in particular, neither will match between a \r and a \n.

fn line_terminator(self: Self, byte: u8) -> Config

Sets the line terminator for use with (?u-s:.) and (?-us:.).

Namely, instead of . (by default) matching everything except for \n, this will cause . to match everything except for the byte given.

If . is used in a context where Unicode mode is enabled and this byte isn't ASCII, then an error will be returned. When Unicode mode is disabled, then any byte is permitted, but will return an error if UTF-8 mode is enabled and it is a non-ASCII byte.

In short, any ASCII value for a line terminator is always okay. But a non-ASCII byte might result in an error depending on whether Unicode mode or UTF-8 mode are enabled.

Note that if R mode is enabled then it always takes precedence and the line terminator will be treated as \r and \n simultaneously.

Note also that this doesn't impact the look-around assertions (?m:^) and (?m:$). That's usually controlled by additional configuration in the regex engine itself.

fn swap_greed(self: Self, yes: bool) -> Config

Enable or disable the "swap greed" flag by default.

When this is enabled, .* (for example) will become ungreedy and .*? will become greedy.

By default this is disabled. It may alternatively be selectively enabled in the regular expression itself via the U flag.

fn ignore_whitespace(self: Self, yes: bool) -> Config

Enable verbose mode in the regular expression.

When enabled, verbose mode permits insigificant whitespace in many places in the regular expression, as well as comments. Comments are started using # and continue until the end of the line.

By default, this is disabled. It may be selectively enabled in the regular expression by using the x flag regardless of this setting.

fn unicode(self: Self, yes: bool) -> Config

Enable or disable the Unicode flag (u) by default.

By default this is enabled. It may alternatively be selectively disabled in the regular expression itself via the u flag.

Note that unless "allow invalid UTF-8" is enabled (it's disabled by default), a regular expression will fail to parse if Unicode mode is disabled and a sub-expression could possibly match invalid UTF-8.

WARNING: Unicode mode can greatly increase the size of the compiled DFA, which can noticeably impact both memory usage and compilation time. This is especially noticeable if your regex contains character classes like \w that are impacted by whether Unicode is enabled or not. If Unicode is not necessary, you are encouraged to disable it.

fn utf8(self: Self, yes: bool) -> Config

When disabled, the builder will permit the construction of a regular expression that may match invalid UTF-8.

For example, when Config::unicode is disabled, then expressions like [^a] may match invalid UTF-8 since they can match any single byte that is not a. By default, these sub-expressions are disallowed to avoid returning offsets that split a UTF-8 encoded codepoint. However, in cases where matching at arbitrary locations is desired, this option can be disabled to permit all such sub-expressions.

When enabled (the default), the builder is guaranteed to produce a regex that will only ever match valid UTF-8 (otherwise, the builder will return an error).

fn nest_limit(self: Self, limit: u32) -> Config

Set the nesting limit used for the regular expression parser.

The nesting limit controls how deep the abstract syntax tree is allowed to be. If the AST exceeds the given limit (e.g., with too many nested groups), then an error is returned by the parser.

The purpose of this limit is to act as a heuristic to prevent stack overflow when building a finite automaton from a regular expression's abstract syntax tree. In particular, construction currently uses recursion. In the future, the implementation may stop using recursion and this option will no longer be necessary.

This limit is not checked until the entire AST is parsed. Therefore, if callers want to put a limit on the amount of heap space used, then they should impose a limit on the length, in bytes, of the concrete pattern string. In particular, this is viable since the parser will limit itself to heap space proportional to the length of the pattern string.

Note that a nest limit of 0 will return a nest limit error for most patterns but not all. For example, a nest limit of 0 permits a but not ab, since ab requires a concatenation AST item, which results in a nest depth of 1. In general, a nest limit is not something that manifests in an obvious way in the concrete syntax, therefore, it should not be used in a granular way.

fn octal(self: Self, yes: bool) -> Config

Whether to support octal syntax or not.

Octal syntax is a little-known way of uttering Unicode codepoints in a regular expression. For example, a, \x61, \u0061 and \141 are all equivalent regular expressions, where the last example shows octal syntax.

While supporting octal syntax isn't in and of itself a problem, it does make good error messages harder. That is, in PCRE based regex engines, syntax like \1 invokes a backreference, which is explicitly unsupported in Rust's regex engine. However, many users expect it to be supported. Therefore, when octal support is disabled, the error message will explicitly mention that backreferences aren't supported.

Octal syntax is disabled by default.

fn get_unicode(self: &Self) -> bool

Returns whether "unicode" mode is enabled.

fn get_case_insensitive(self: &Self) -> bool

Returns whether "case insensitive" mode is enabled.

fn get_multi_line(self: &Self) -> bool

Returns whether "multi line" mode is enabled.

fn get_dot_matches_new_line(self: &Self) -> bool

Returns whether "dot matches new line" mode is enabled.

fn get_crlf(self: &Self) -> bool

Returns whether "CRLF" mode is enabled.

fn get_line_terminator(self: &Self) -> u8

Returns the line terminator in this syntax configuration.

fn get_swap_greed(self: &Self) -> bool

Returns whether "swap greed" mode is enabled.

fn get_ignore_whitespace(self: &Self) -> bool

Returns whether "ignore whitespace" mode is enabled.

fn get_utf8(self: &Self) -> bool

Returns whether UTF-8 mode is enabled.

fn get_nest_limit(self: &Self) -> u32

Returns the "nest limit" setting.

fn get_octal(self: &Self) -> bool

Returns whether "octal" mode is enabled.

impl Clone for Config

fn clone(self: &Self) -> Config

impl Copy for Config

impl Debug for Config

fn fmt(self: &Self, f: &mut Formatter<'_>) -> Result

impl Default for Config

fn default() -> Config

impl Freeze for Config

impl RefUnwindSafe for Config

impl Send for Config

impl Sync for Config

impl Unpin for Config

impl UnsafeUnpin for Config

impl UnwindSafe for Config

impl<T> Any for Config

fn type_id(self: &Self) -> TypeId

impl<T> Borrow for Config

fn borrow(self: &Self) -> &T

impl<T> BorrowMut for Config

fn borrow_mut(self: &mut Self) -> &mut T

impl<T> CloneToUninit for Config

unsafe fn clone_to_uninit(self: &Self, dest: *mut u8)

impl<T> From for Config

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> ToOwned for Config

fn to_owned(self: &Self) -> T

fn clone_into(self: &Self, target: &mut T)

impl<T, U> Into for Config

fn into(self: Self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

impl<T, U> TryFrom for Config

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto for Config

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>