#![allow(warnings)]
// This module defines an internal builder that encapsulates all interaction
// with meta::Regex construction, and then 4 public API builders that wrap
// around it. The docs are essentially repeated on each of the 4 public
// builders, with tweaks to the examples as needed.
//
// The reason why there are so many builders is partially because of a misstep
// in the initial API design: the builder constructor takes in the pattern
// strings instead of using the `build` method to accept the pattern strings.
// This means `new` has a different signature for each builder. It probably
// would have been nicer to to use one builder with `fn new()`, and then add
// `build(pat)` and `build_many(pats)` constructors.
//
// The other reason is because I think the `bytes` module should probably
// have its own builder type. That way, it is completely isolated from the
// top-level API.
//
// If I could do it again, I'd probably have a `regex::Builder` and a
// `regex::bytes::Builder`. Each would have `build` and `build_set` (or
// `build_many`) methods for constructing a single pattern `Regex` and a
// multi-pattern `RegexSet`, respectively.
use alloc::{
string::{String, ToString},
sync::Arc,
vec,
vec::Vec,
};
use regex_automata::{
meta, nfa::thompson::WhichCaptures, util::syntax, MatchKind,
};
use crate::error::Error;
/// A builder for constructing a `Regex`, `bytes::Regex`, `RegexSet` or a
/// `bytes::RegexSet`.
///
/// This is essentially the implementation of the four different builder types
/// in the public API: `RegexBuilder`, `bytes::RegexBuilder`, `RegexSetBuilder`
/// and `bytes::RegexSetBuilder`.
#[derive(Clone, Debug)]
struct Builder {
pats: Vec<String>,
metac: meta::Config,
syntaxc: syntax::Config,
}
impl Default for Builder {
fn default() -> Builder {
let metac = meta::Config::new()
.nfa_size_limit(Some(10 * (1 << 20)))
.hybrid_cache_capacity(2 * (1 << 20));
Builder { pats: vec![], metac, syntaxc: syntax::Config::default() }
}
}
impl Builder {
fn new<I, S>(patterns: I) -> Builder
where
S: AsRef<str>,
I: IntoIterator<Item = S>,
{
let mut b = Builder::default();
b.pats.extend(patterns.into_iter().map(|p| p.as_ref().to_string()));
b
}
fn build_one_string(&self) -> Result<crate::Regex, Error> {
assert_eq!(1, self.pats.len());
let metac = self
.metac
.clone()
.match_kind(MatchKind::LeftmostFirst)
.utf8_empty(true);
let syntaxc = self.syntaxc.clone().utf8(true);
let pattern = Arc::from(self.pats[0].as_str());
meta::Builder::new()
.configure(metac)
.syntax(syntaxc)
.build(&pattern)
.map(|meta| crate::Regex { meta, pattern })
.map_err(Error::from_meta_build_error)
}
fn build_one_bytes(&self) -> Result<crate::bytes::Regex, Error> {
assert_eq!(1, self.pats.len());
let metac = self
.metac
.clone()
.match_kind(MatchKind::LeftmostFirst)
.utf8_empty(false);
let syntaxc = self.syntaxc.clone().utf8(false);
let pattern = Arc::from(self.pats[0].as_str());
meta::Builder::new()
.configure(metac)
.syntax(syntaxc)
.build(&pattern)
.map(|meta| crate::bytes::Regex { meta, pattern })
.map_err(Error::from_meta_build_error)
}
fn build_many_string(&self) -> Result<crate::RegexSet, Error> {
let metac = self
.metac
.clone()
.match_kind(MatchKind::All)
.utf8_empty(true)
.which_captures(WhichCaptures::None);
let syntaxc = self.syntaxc.clone().utf8(true);
let patterns = Arc::from(self.pats.as_slice());
meta::Builder::new()
.configure(metac)
.syntax(syntaxc)
.build_many(&patterns)
.map(|meta| crate::RegexSet { meta, patterns })
.map_err(Error::from_meta_build_error)
}
fn build_many_bytes(&self) -> Result<crate::bytes::RegexSet, Error> {
let metac = self
.metac
.clone()
.match_kind(MatchKind::All)
.utf8_empty(false)
.which_captures(WhichCaptures::None);
let syntaxc = self.syntaxc.clone().utf8(false);
let patterns = Arc::from(self.pats.as_slice());
meta::Builder::new()
.configure(metac)
.syntax(syntaxc)
.build_many(&patterns)
.map(|meta| crate::bytes::RegexSet { meta, patterns })
.map_err(Error::from_meta_build_error)
}
fn case_insensitive(&mut self, yes: bool) -> &mut Builder {
self.syntaxc = self.syntaxc.case_insensitive(yes);
self
}
fn multi_line(&mut self, yes: bool) -> &mut Builder {
self.syntaxc = self.syntaxc.multi_line(yes);
self
}
fn dot_matches_new_line(&mut self, yes: bool) -> &mut Builder {
self.syntaxc = self.syntaxc.dot_matches_new_line(yes);
self
}
fn crlf(&mut self, yes: bool) -> &mut Builder {
self.syntaxc = self.syntaxc.crlf(yes);
self
}
fn line_terminator(&mut self, byte: u8) -> &mut Builder {
self.metac = self.metac.clone().line_terminator(byte);
self.syntaxc = self.syntaxc.line_terminator(byte);
self
}
fn swap_greed(&mut self, yes: bool) -> &mut Builder {
self.syntaxc = self.syntaxc.swap_greed(yes);
self
}
fn ignore_whitespace(&mut self, yes: bool) -> &mut Builder {
self.syntaxc = self.syntaxc.ignore_whitespace(yes);
self
}
fn unicode(&mut self, yes: bool) -> &mut Builder {
self.syntaxc = self.syntaxc.unicode(yes);
self
}
fn octal(&mut self, yes: bool) -> &mut Builder {
self.syntaxc = self.syntaxc.octal(yes);
self
}
fn size_limit(&mut self, limit: usize) -> &mut Builder {
self.metac = self.metac.clone().nfa_size_limit(Some(limit));
self
}
fn dfa_size_limit(&mut self, limit: usize) -> &mut Builder {
self.metac = self.metac.clone().hybrid_cache_capacity(limit);
self
}
fn nest_limit(&mut self, limit: u32) -> &mut Builder {
self.syntaxc = self.syntaxc.nest_limit(limit);
self
}
}
pub(crate) mod string {
use crate::{error::Error, Regex, RegexSet};
use super::Builder;
/// A configurable builder for a [`Regex`].
///
/// This builder can be used to programmatically set flags such as `i`
/// (case insensitive) and `x` (for verbose mode). This builder can also be
/// used to configure things like the line terminator and a size limit on
/// the compiled regular expression.
#[derive(Clone, Debug)]
pub struct RegexBuilder {
builder: Builder,
}
impl RegexBuilder {
/// Create a new builder with a default configuration for the given
/// pattern.
///
/// If the pattern is invalid or exceeds the configured size limits,
/// then an error will be returned when [`RegexBuilder::build`] is
/// called.
pub fn new(pattern: &str) -> RegexBuilder {
RegexBuilder { builder: Builder::new([pattern]) }
}
/// Compiles the pattern given to `RegexBuilder::new` with the
/// configuration set on this builder.
///
/// If the pattern isn't a valid regex or if a configured size limit
/// was exceeded, then an error is returned.
pub fn build(&self) -> Result<Regex, Error> {
self.builder.build_one_string()
}
/// This configures Unicode mode for the entire pattern.
///
/// Enabling Unicode mode does a number of things:
///
/// * Most fundamentally, it causes the fundamental atom of matching
/// to be a single codepoint. When Unicode mode is disabled, it's a
/// single byte. For example, when Unicode mode is enabled, `.` will
/// match `💩` once, where as it will match 4 times when Unicode mode
/// is disabled. (Since the UTF-8 encoding of `💩` is 4 bytes long.)
/// * Case insensitive matching uses Unicode simple case folding rules.
/// * Unicode character classes like `\p{Letter}` and `\p{Greek}` are
/// available.
/// * Perl character classes are Unicode aware. That is, `\w`, `\s` and
/// `\d`.
/// * The word boundary assertions, `\b` and `\B`, use the Unicode
/// definition of a word character.
///
/// Note that if Unicode mode is disabled, then the regex will fail to
/// compile if it could match invalid UTF-8. For example, when Unicode
/// mode is disabled, then since `.` matches any byte (except for
/// `\n`), then it can match invalid UTF-8 and thus building a regex
/// from it will fail. Another example is `\w` and `\W`. Since `\w` can
/// only match ASCII bytes when Unicode mode is disabled, it's allowed.
/// But `\W` can match more than ASCII bytes, including invalid UTF-8,
/// and so it is not allowed. This restriction can be lifted only by
/// using a [`bytes::Regex`](crate::bytes::Regex).
///
/// For more details on the Unicode support in this crate, see the
/// [Unicode section](crate#unicode) in this crate's top-level
/// documentation.
///
/// The default for this is `true`.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r"\w")
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally greek letters would be included in \w, but since
/// // Unicode mode is disabled, it only matches ASCII letters.
/// assert!(!re.is_match("δ"));
///
/// let re = RegexBuilder::new(r"s")
/// .case_insensitive(true)
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally 'Å¿' is included when searching for 's' case
/// // insensitively due to Unicode's simple case folding rules. But
/// // when Unicode mode is disabled, only ASCII case insensitive rules
/// // are used.
/// assert!(!re.is_match("Å¿"));
/// ```
pub fn unicode(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.unicode(yes);
self
}
/// This configures whether to enable case insensitive matching for the
/// entire pattern.
///
/// This setting can also be configured using the inline flag `i`
/// in the pattern. For example, `(?i:foo)` matches `foo` case
/// insensitively while `(?-i:foo)` matches `foo` case sensitively.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r"foo(?-i:bar)quux")
/// .case_insensitive(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match("FoObarQuUx"));
/// // Even though case insensitive matching is enabled in the builder,
/// // it can be locally disabled within the pattern. In this case,
/// // `bar` is matched case sensitively.
/// assert!(!re.is_match("fooBARquux"));
/// ```
pub fn case_insensitive(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.case_insensitive(yes);
self
}
/// This configures multi-line mode for the entire pattern.
///
/// Enabling multi-line mode changes the behavior of the `^` and `$`
/// anchor assertions. Instead of only matching at the beginning and
/// end of a haystack, respectively, multi-line mode causes them to
/// match at the beginning and end of a line *in addition* to the
/// beginning and end of a haystack. More precisely, `^` will match at
/// the position immediately following a `\n` and `$` will match at the
/// position immediately preceding a `\n`.
///
/// The behavior of this option can be impacted by other settings too:
///
/// * The [`RegexBuilder::line_terminator`] option changes `\n` above
/// to any ASCII byte.
/// * The [`RegexBuilder::crlf`] option changes the line terminator to
/// be either `\r` or `\n`, but never at the position between a `\r`
/// and `\n`.
///
/// This setting can also be configured using the inline flag `m` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r"^foo$")
/// .multi_line(true)
/// .build()
/// .unwrap();
/// assert_eq!(Some(1..4), re.find("\nfoo\n").map(|m| m.range()));
/// ```
pub fn multi_line(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.multi_line(yes);
self
}
/// This configures dot-matches-new-line mode for the entire pattern.
///
/// Perhaps surprisingly, the default behavior for `.` is not to match
/// any character, but rather, to match any character except for the
/// line terminator (which is `\n` by default). When this mode is
/// enabled, the behavior changes such that `.` truly matches any
/// character.
///
/// This setting can also be configured using the inline flag `s` in
/// the pattern. For example, `(?s:.)` and `\p{any}` are equivalent
/// regexes.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r"foo.bar")
/// .dot_matches_new_line(true)
/// .build()
/// .unwrap();
/// let hay = "foo\nbar";
/// assert_eq!(Some("foo\nbar"), re.find(hay).map(|m| m.as_str()));
/// ```
pub fn dot_matches_new_line(
&mut self,
yes: bool,
) -> &mut RegexBuilder {
self.builder.dot_matches_new_line(yes);
self
}
/// This configures CRLF mode for the entire pattern.
///
/// When CRLF mode is enabled, both `\r` ("carriage return" or CR for
/// short) and `\n` ("line feed" or LF for short) are treated as line
/// terminators. This results in the following:
///
/// * Unless dot-matches-new-line mode is enabled, `.` will now match
/// any character except for `\n` and `\r`.
/// * When multi-line mode is enabled, `^` will match immediately
/// following a `\n` or a `\r`. Similarly, `$` will match immediately
/// preceding a `\n` or a `\r`. Neither `^` nor `$` will ever match
/// between `\r` and `\n`.
///
/// This setting can also be configured using the inline flag `R` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r"^foo$")
/// .multi_line(true)
/// .crlf(true)
/// .build()
/// .unwrap();
/// let hay = "\r\nfoo\r\n";
/// // If CRLF mode weren't enabled here, then '$' wouldn't match
/// // immediately after 'foo', and thus no match would be found.
/// assert_eq!(Some("foo"), re.find(hay).map(|m| m.as_str()));
/// ```
///
/// This example demonstrates that `^` will never match at a position
/// between `\r` and `\n`. (`$` will similarly not match between a `\r`
/// and a `\n`.)
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r"^")
/// .multi_line(true)
/// .crlf(true)
/// .build()
/// .unwrap();
/// let hay = "\r\n\r\n";
/// let ranges: Vec<_> = re.find_iter(hay).map(|m| m.range()).collect();
/// assert_eq!(ranges, vec![0..0, 2..2, 4..4]);
/// ```
pub fn crlf(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.crlf(yes);
self
}
/// Configures the line terminator to be used by the regex.
///
/// The line terminator is relevant in two ways for a particular regex:
///
/// * When dot-matches-new-line mode is *not* enabled (the default),
/// then `.` will match any character except for the configured line
/// terminator.
/// * When multi-line mode is enabled (not the default), then `^` and
/// `$` will match immediately after and before, respectively, a line
/// terminator.
///
/// In both cases, if CRLF mode is enabled in a particular context,
/// then it takes precedence over any configured line terminator.
///
/// This option cannot be configured from within the pattern.
///
/// The default line terminator is `\n`.
///
/// # Example
///
/// This shows how to treat the NUL byte as a line terminator. This can
/// be a useful heuristic when searching binary data.
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r"^foo$")
/// .multi_line(true)
/// .line_terminator(b'\x00')
/// .build()
/// .unwrap();
/// let hay = "\x00foo\x00";
/// assert_eq!(Some(1..4), re.find(hay).map(|m| m.range()));
/// ```
///
/// This example shows that the behavior of `.` is impacted by this
/// setting as well:
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r".")
/// .line_terminator(b'\x00')
/// .build()
/// .unwrap();
/// assert!(re.is_match("\n"));
/// assert!(!re.is_match("\x00"));
/// ```
///
/// This shows that building a regex will fail if the byte given
/// is not ASCII and the pattern could result in matching invalid
/// UTF-8. This is because any singular non-ASCII byte is not valid
/// UTF-8, and it is not permitted for a [`Regex`] to match invalid
/// UTF-8. (It is permissible to use a non-ASCII byte when building a
/// [`bytes::Regex`](crate::bytes::Regex).)
///
/// ```
/// use regex::RegexBuilder;
///
/// assert!(RegexBuilder::new(r".").line_terminator(0x80).build().is_err());
/// // Note that using a non-ASCII byte isn't enough on its own to
/// // cause regex compilation to fail. You actually have to make use
/// // of it in the regex in a way that leads to matching invalid
/// // UTF-8. If you don't, then regex compilation will succeed!
/// assert!(RegexBuilder::new(r"a").line_terminator(0x80).build().is_ok());
/// ```
pub fn line_terminator(&mut self, byte: u8) -> &mut RegexBuilder {
self.builder.line_terminator(byte);
self
}
/// This configures swap-greed mode for the entire pattern.
///
/// When swap-greed mode is enabled, patterns like `a+` will become
/// non-greedy and patterns like `a+?` will become greedy. In other
/// words, the meanings of `a+` and `a+?` are switched.
///
/// This setting can also be configured using the inline flag `U` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// let re = RegexBuilder::new(r"a+")
/// .swap_greed(true)
/// .build()
/// .unwrap();
/// assert_eq!(Some("a"), re.find("aaa").map(|m| m.as_str()));
/// ```
pub fn swap_greed(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.swap_greed(yes);
self
}
/// This configures verbose mode for the entire pattern.
///
/// When enabled, whitespace will treated as insignifcant in the
/// pattern and `#` can be used to start a comment until the next new
/// line.
///
/// Normally, in most places in a pattern, whitespace is treated
/// literally. For example ` +` will match one or more ASCII whitespace
/// characters.
///
/// When verbose mode is enabled, `\#` can be used to match a literal
/// `#` and `\ ` can be used to match a literal ASCII whitespace
/// character.
///
/// Verbose mode is useful for permitting regexes to be formatted and
/// broken up more nicely. This may make them more easily readable.
///
/// This setting can also be configured using the inline flag `x` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// let pat = r"
/// \b
/// (?<first>\p{Uppercase}\w*) # always start with uppercase letter
/// [\s--\n]+ # whitespace should separate names
/// (?: # middle name can be an initial!
/// (?:(?<initial>\p{Uppercase})\.|(?<middle>\p{Uppercase}\w*))
/// [\s--\n]+
/// )?
/// (?<last>\p{Uppercase}\w*)
/// \b
/// ";
/// let re = RegexBuilder::new(pat)
/// .ignore_whitespace(true)
/// .build()
/// .unwrap();
///
/// let caps = re.captures("Harry Potter").unwrap();
/// assert_eq!("Harry", &caps["first"]);
/// assert_eq!("Potter", &caps["last"]);
///
/// let caps = re.captures("Harry J. Potter").unwrap();
/// assert_eq!("Harry", &caps["first"]);
/// // Since a middle name/initial isn't required for an overall match,
/// // we can't assume that 'initial' or 'middle' will be populated!
/// assert_eq!(Some("J"), caps.name("initial").map(|m| m.as_str()));
/// assert_eq!(None, caps.name("middle").map(|m| m.as_str()));
/// assert_eq!("Potter", &caps["last"]);
///
/// let caps = re.captures("Harry James Potter").unwrap();
/// assert_eq!("Harry", &caps["first"]);
/// // Since a middle name/initial isn't required for an overall match,
/// // we can't assume that 'initial' or 'middle' will be populated!
/// assert_eq!(None, caps.name("initial").map(|m| m.as_str()));
/// assert_eq!(Some("James"), caps.name("middle").map(|m| m.as_str()));
/// assert_eq!("Potter", &caps["last"]);
/// ```
pub fn ignore_whitespace(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.ignore_whitespace(yes);
self
}
/// This configures octal mode for the entire pattern.
///
/// Octal syntax is a little-known way of uttering Unicode codepoints
/// in a pattern. For example, `a`, `\x61`, `\u0061` and `\141` are all
/// equivalent patterns, 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 this library. However, many users expect
/// backreferences to be supported. Therefore, when octal support
/// is disabled, the error message will explicitly mention that
/// backreferences aren't supported.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// // Normally this pattern would not compile, with an error message
/// // about backreferences not being supported. But with octal mode
/// // enabled, octal escape sequences work.
/// let re = RegexBuilder::new(r"\141")
/// .octal(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match("a"));
/// ```
pub fn octal(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.octal(yes);
self
}
/// Sets the approximate size limit, in bytes, of the compiled regex.
///
/// This roughly corresponds to the number of heap memory, in
/// bytes, occupied by a single regex. If the regex would otherwise
/// approximately exceed this limit, then compiling that regex will
/// fail.
///
/// The main utility of a method like this is to avoid compiling
/// regexes that use an unexpected amount of resources, such as
/// time and memory. Even if the memory usage of a large regex is
/// acceptable, its search time may not be. Namely, worst case time
/// complexity for search is `O(m * n)`, where `m ~ len(pattern)` and
/// `n ~ len(haystack)`. That is, search time depends, in part, on the
/// size of the compiled regex. This means that putting a limit on the
/// size of the regex limits how much a regex can impact search time.
///
/// For more information about regex size limits, see the section on
/// [untrusted inputs](crate#untrusted-input) in the top-level crate
/// documentation.
///
/// The default for this is some reasonable number that permits most
/// patterns to compile successfully.
///
/// # Example
///
/// ```
/// # if !cfg!(target_pointer_width = "64") { return; } // see #1041
/// use regex::RegexBuilder;
///
/// // It may surprise you how big some seemingly small patterns can
/// // be! Since \w is Unicode aware, this generates a regex that can
/// // match approximately 140,000 distinct codepoints.
/// assert!(RegexBuilder::new(r"\w").size_limit(45_000).build().is_err());
/// ```
pub fn size_limit(&mut self, bytes: usize) -> &mut RegexBuilder {
self.builder.size_limit(bytes);
self
}
/// Set the approximate capacity, in bytes, of the cache of transitions
/// used by the lazy DFA.
///
/// While the lazy DFA isn't always used, in tends to be the most
/// commonly use regex engine in default configurations. It tends to
/// adopt the performance profile of a fully build DFA, but without the
/// downside of taking worst case exponential time to build.
///
/// The downside is that it needs to keep a cache of transitions and
/// states that are built while running a search, and this cache
/// can fill up. When it fills up, the cache will reset itself. Any
/// previously generated states and transitions will then need to be
/// re-generated. If this happens too many times, then this library
/// will bail out of using the lazy DFA and switch to a different regex
/// engine.
///
/// If your regex provokes this particular downside of the lazy DFA,
/// then it may be beneficial to increase its cache capacity. This will
/// potentially reduce the frequency of cache resetting (ideally to
/// `0`). While it won't fix all potential performance problems with
/// the lazy DFA, increasing the cache capacity does fix some.
///
/// There is no easy way to determine, a priori, whether increasing
/// this cache capacity will help. In general, the larger your regex,
/// the more cache it's likely to use. But that isn't an ironclad rule.
/// For example, a regex like `[01]*1[01]{N}` would normally produce a
/// fully build DFA that is exponential in size with respect to `N`.
/// The lazy DFA will prevent exponential space blow-up, but it cache
/// is likely to fill up, even when it's large and even for smallish
/// values of `N`.
///
/// If you aren't sure whether this helps or not, it is sensible to
/// set this to some arbitrarily large number in testing, such as
/// `usize::MAX`. Namely, this represents the amount of capacity that
/// *may* be used. It's probably not a good idea to use `usize::MAX` in
/// production though, since it implies there are no controls on heap
/// memory used by this library during a search. In effect, set it to
/// whatever you're willing to allocate for a single regex search.
pub fn dfa_size_limit(&mut self, bytes: usize) -> &mut RegexBuilder {
self.builder.dfa_size_limit(bytes);
self
}
/// Set the nesting limit for this 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 for consumers that do structural induction on an AST using
/// explicit recursion. While this crate never does this (instead using
/// constant stack space and moving the call stack to the heap), other
/// crates may.
///
/// 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 this parser implementation will limit itself to heap
/// space proportional to the length of the pattern string. See also
/// the [untrusted inputs](crate#untrusted-input) section in the
/// top-level crate documentation for more information about this.
///
/// 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 an explicit concatenation,
/// 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.
///
/// # Example
///
/// ```
/// use regex::RegexBuilder;
///
/// assert!(RegexBuilder::new(r"a").nest_limit(0).build().is_ok());
/// assert!(RegexBuilder::new(r"ab").nest_limit(0).build().is_err());
/// ```
pub fn nest_limit(&mut self, limit: u32) -> &mut RegexBuilder {
self.builder.nest_limit(limit);
self
}
}
/// A configurable builder for a [`RegexSet`].
///
/// This builder can be used to programmatically set flags such as
/// `i` (case insensitive) and `x` (for verbose mode). This builder
/// can also be used to configure things like the line terminator
/// and a size limit on the compiled regular expression.
#[derive(Clone, Debug)]
pub struct RegexSetBuilder {
builder: Builder,
}
impl RegexSetBuilder {
/// Create a new builder with a default configuration for the given
/// patterns.
///
/// If the patterns are invalid or exceed the configured size limits,
/// then an error will be returned when [`RegexSetBuilder::build`] is
/// called.
pub fn new<I, S>(patterns: I) -> RegexSetBuilder
where
I: IntoIterator<Item = S>,
S: AsRef<str>,
{
RegexSetBuilder { builder: Builder::new(patterns) }
}
/// Compiles the patterns given to `RegexSetBuilder::new` with the
/// configuration set on this builder.
///
/// If the patterns aren't valid regexes or if a configured size limit
/// was exceeded, then an error is returned.
pub fn build(&self) -> Result<RegexSet, Error> {
self.builder.build_many_string()
}
/// This configures Unicode mode for the all of the patterns.
///
/// Enabling Unicode mode does a number of things:
///
/// * Most fundamentally, it causes the fundamental atom of matching
/// to be a single codepoint. When Unicode mode is disabled, it's a
/// single byte. For example, when Unicode mode is enabled, `.` will
/// match `💩` once, where as it will match 4 times when Unicode mode
/// is disabled. (Since the UTF-8 encoding of `💩` is 4 bytes long.)
/// * Case insensitive matching uses Unicode simple case folding rules.
/// * Unicode character classes like `\p{Letter}` and `\p{Greek}` are
/// available.
/// * Perl character classes are Unicode aware. That is, `\w`, `\s` and
/// `\d`.
/// * The word boundary assertions, `\b` and `\B`, use the Unicode
/// definition of a word character.
///
/// Note that if Unicode mode is disabled, then the regex will fail to
/// compile if it could match invalid UTF-8. For example, when Unicode
/// mode is disabled, then since `.` matches any byte (except for
/// `\n`), then it can match invalid UTF-8 and thus building a regex
/// from it will fail. Another example is `\w` and `\W`. Since `\w` can
/// only match ASCII bytes when Unicode mode is disabled, it's allowed.
/// But `\W` can match more than ASCII bytes, including invalid UTF-8,
/// and so it is not allowed. This restriction can be lifted only by
/// using a [`bytes::RegexSet`](crate::bytes::RegexSet).
///
/// For more details on the Unicode support in this crate, see the
/// [Unicode section](crate#unicode) in this crate's top-level
/// documentation.
///
/// The default for this is `true`.
///
/// # Example
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"\w"])
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally greek letters would be included in \w, but since
/// // Unicode mode is disabled, it only matches ASCII letters.
/// assert!(!re.is_match("δ"));
///
/// let re = RegexSetBuilder::new([r"s"])
/// .case_insensitive(true)
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally 'Å¿' is included when searching for 's' case
/// // insensitively due to Unicode's simple case folding rules. But
/// // when Unicode mode is disabled, only ASCII case insensitive rules
/// // are used.
/// assert!(!re.is_match("Å¿"));
/// ```
pub fn unicode(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.unicode(yes);
self
}
/// This configures whether to enable case insensitive matching for all
/// of the patterns.
///
/// This setting can also be configured using the inline flag `i`
/// in the pattern. For example, `(?i:foo)` matches `foo` case
/// insensitively while `(?-i:foo)` matches `foo` case sensitively.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"foo(?-i:bar)quux"])
/// .case_insensitive(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match("FoObarQuUx"));
/// // Even though case insensitive matching is enabled in the builder,
/// // it can be locally disabled within the pattern. In this case,
/// // `bar` is matched case sensitively.
/// assert!(!re.is_match("fooBARquux"));
/// ```
pub fn case_insensitive(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.case_insensitive(yes);
self
}
/// This configures multi-line mode for all of the patterns.
///
/// Enabling multi-line mode changes the behavior of the `^` and `$`
/// anchor assertions. Instead of only matching at the beginning and
/// end of a haystack, respectively, multi-line mode causes them to
/// match at the beginning and end of a line *in addition* to the
/// beginning and end of a haystack. More precisely, `^` will match at
/// the position immediately following a `\n` and `$` will match at the
/// position immediately preceding a `\n`.
///
/// The behavior of this option can be impacted by other settings too:
///
/// * The [`RegexSetBuilder::line_terminator`] option changes `\n`
/// above to any ASCII byte.
/// * The [`RegexSetBuilder::crlf`] option changes the line terminator
/// to be either `\r` or `\n`, but never at the position between a `\r`
/// and `\n`.
///
/// This setting can also be configured using the inline flag `m` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"^foo$"])
/// .multi_line(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match("\nfoo\n"));
/// ```
pub fn multi_line(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.multi_line(yes);
self
}
/// This configures dot-matches-new-line mode for the entire pattern.
///
/// Perhaps surprisingly, the default behavior for `.` is not to match
/// any character, but rather, to match any character except for the
/// line terminator (which is `\n` by default). When this mode is
/// enabled, the behavior changes such that `.` truly matches any
/// character.
///
/// This setting can also be configured using the inline flag `s` in
/// the pattern. For example, `(?s:.)` and `\p{any}` are equivalent
/// regexes.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"foo.bar"])
/// .dot_matches_new_line(true)
/// .build()
/// .unwrap();
/// let hay = "foo\nbar";
/// assert!(re.is_match(hay));
/// ```
pub fn dot_matches_new_line(
&mut self,
yes: bool,
) -> &mut RegexSetBuilder {
self.builder.dot_matches_new_line(yes);
self
}
/// This configures CRLF mode for all of the patterns.
///
/// When CRLF mode is enabled, both `\r` ("carriage return" or CR for
/// short) and `\n` ("line feed" or LF for short) are treated as line
/// terminators. This results in the following:
///
/// * Unless dot-matches-new-line mode is enabled, `.` will now match
/// any character except for `\n` and `\r`.
/// * When multi-line mode is enabled, `^` will match immediately
/// following a `\n` or a `\r`. Similarly, `$` will match immediately
/// preceding a `\n` or a `\r`. Neither `^` nor `$` will ever match
/// between `\r` and `\n`.
///
/// This setting can also be configured using the inline flag `R` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"^foo$"])
/// .multi_line(true)
/// .crlf(true)
/// .build()
/// .unwrap();
/// let hay = "\r\nfoo\r\n";
/// // If CRLF mode weren't enabled here, then '$' wouldn't match
/// // immediately after 'foo', and thus no match would be found.
/// assert!(re.is_match(hay));
/// ```
///
/// This example demonstrates that `^` will never match at a position
/// between `\r` and `\n`. (`$` will similarly not match between a `\r`
/// and a `\n`.)
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"^\n"])
/// .multi_line(true)
/// .crlf(true)
/// .build()
/// .unwrap();
/// assert!(!re.is_match("\r\n"));
/// ```
pub fn crlf(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.crlf(yes);
self
}
/// Configures the line terminator to be used by the regex.
///
/// The line terminator is relevant in two ways for a particular regex:
///
/// * When dot-matches-new-line mode is *not* enabled (the default),
/// then `.` will match any character except for the configured line
/// terminator.
/// * When multi-line mode is enabled (not the default), then `^` and
/// `$` will match immediately after and before, respectively, a line
/// terminator.
///
/// In both cases, if CRLF mode is enabled in a particular context,
/// then it takes precedence over any configured line terminator.
///
/// This option cannot be configured from within the pattern.
///
/// The default line terminator is `\n`.
///
/// # Example
///
/// This shows how to treat the NUL byte as a line terminator. This can
/// be a useful heuristic when searching binary data.
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"^foo$"])
/// .multi_line(true)
/// .line_terminator(b'\x00')
/// .build()
/// .unwrap();
/// let hay = "\x00foo\x00";
/// assert!(re.is_match(hay));
/// ```
///
/// This example shows that the behavior of `.` is impacted by this
/// setting as well:
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"."])
/// .line_terminator(b'\x00')
/// .build()
/// .unwrap();
/// assert!(re.is_match("\n"));
/// assert!(!re.is_match("\x00"));
/// ```
///
/// This shows that building a regex will fail if the byte given
/// is not ASCII and the pattern could result in matching invalid
/// UTF-8. This is because any singular non-ASCII byte is not valid
/// UTF-8, and it is not permitted for a [`RegexSet`] to match invalid
/// UTF-8. (It is permissible to use a non-ASCII byte when building a
/// [`bytes::RegexSet`](crate::bytes::RegexSet).)
///
/// ```
/// use regex::RegexSetBuilder;
///
/// assert!(
/// RegexSetBuilder::new([r"."])
/// .line_terminator(0x80)
/// .build()
/// .is_err()
/// );
/// // Note that using a non-ASCII byte isn't enough on its own to
/// // cause regex compilation to fail. You actually have to make use
/// // of it in the regex in a way that leads to matching invalid
/// // UTF-8. If you don't, then regex compilation will succeed!
/// assert!(
/// RegexSetBuilder::new([r"a"])
/// .line_terminator(0x80)
/// .build()
/// .is_ok()
/// );
/// ```
pub fn line_terminator(&mut self, byte: u8) -> &mut RegexSetBuilder {
self.builder.line_terminator(byte);
self
}
/// This configures swap-greed mode for all of the patterns.
///
/// When swap-greed mode is enabled, patterns like `a+` will become
/// non-greedy and patterns like `a+?` will become greedy. In other
/// words, the meanings of `a+` and `a+?` are switched.
///
/// This setting can also be configured using the inline flag `U` in
/// the pattern.
///
/// Note that this is generally not useful for a `RegexSet` since a
/// `RegexSet` can only report whether a pattern matches or not. Since
/// greediness never impacts whether a match is found or not (only the
/// offsets of the match), it follows that whether parts of a pattern
/// are greedy or not doesn't matter for a `RegexSet`.
///
/// The default for this is `false`.
pub fn swap_greed(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.swap_greed(yes);
self
}
/// This configures verbose mode for all of the patterns.
///
/// When enabled, whitespace will treated as insignifcant in the
/// pattern and `#` can be used to start a comment until the next new
/// line.
///
/// Normally, in most places in a pattern, whitespace is treated
/// literally. For example ` +` will match one or more ASCII whitespace
/// characters.
///
/// When verbose mode is enabled, `\#` can be used to match a literal
/// `#` and `\ ` can be used to match a literal ASCII whitespace
/// character.
///
/// Verbose mode is useful for permitting regexes to be formatted and
/// broken up more nicely. This may make them more easily readable.
///
/// This setting can also be configured using the inline flag `x` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexSetBuilder;
///
/// let pat = r"
/// \b
/// (?<first>\p{Uppercase}\w*) # always start with uppercase letter
/// [\s--\n]+ # whitespace should separate names
/// (?: # middle name can be an initial!
/// (?:(?<initial>\p{Uppercase})\.|(?<middle>\p{Uppercase}\w*))
/// [\s--\n]+
/// )?
/// (?<last>\p{Uppercase}\w*)
/// \b
/// ";
/// let re = RegexSetBuilder::new([pat])
/// .ignore_whitespace(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match("Harry Potter"));
/// assert!(re.is_match("Harry J. Potter"));
/// assert!(re.is_match("Harry James Potter"));
/// assert!(!re.is_match("harry J. Potter"));
/// ```
pub fn ignore_whitespace(
&mut self,
yes: bool,
) -> &mut RegexSetBuilder {
self.builder.ignore_whitespace(yes);
self
}
/// This configures octal mode for all of the patterns.
///
/// Octal syntax is a little-known way of uttering Unicode codepoints
/// in a pattern. For example, `a`, `\x61`, `\u0061` and `\141` are all
/// equivalent patterns, 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 this library. However, many users expect
/// backreferences to be supported. Therefore, when octal support
/// is disabled, the error message will explicitly mention that
/// backreferences aren't supported.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::RegexSetBuilder;
///
/// // Normally this pattern would not compile, with an error message
/// // about backreferences not being supported. But with octal mode
/// // enabled, octal escape sequences work.
/// let re = RegexSetBuilder::new([r"\141"])
/// .octal(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match("a"));
/// ```
pub fn octal(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.octal(yes);
self
}
/// Sets the approximate size limit, in bytes, of the compiled regex.
///
/// This roughly corresponds to the number of heap memory, in
/// bytes, occupied by a single regex. If the regex would otherwise
/// approximately exceed this limit, then compiling that regex will
/// fail.
///
/// The main utility of a method like this is to avoid compiling
/// regexes that use an unexpected amount of resources, such as
/// time and memory. Even if the memory usage of a large regex is
/// acceptable, its search time may not be. Namely, worst case time
/// complexity for search is `O(m * n)`, where `m ~ len(pattern)` and
/// `n ~ len(haystack)`. That is, search time depends, in part, on the
/// size of the compiled regex. This means that putting a limit on the
/// size of the regex limits how much a regex can impact search time.
///
/// For more information about regex size limits, see the section on
/// [untrusted inputs](crate#untrusted-input) in the top-level crate
/// documentation.
///
/// The default for this is some reasonable number that permits most
/// patterns to compile successfully.
///
/// # Example
///
/// ```
/// # if !cfg!(target_pointer_width = "64") { return; } // see #1041
/// use regex::RegexSetBuilder;
///
/// // It may surprise you how big some seemingly small patterns can
/// // be! Since \w is Unicode aware, this generates a regex that can
/// // match approximately 140,000 distinct codepoints.
/// assert!(
/// RegexSetBuilder::new([r"\w"])
/// .size_limit(45_000)
/// .build()
/// .is_err()
/// );
/// ```
pub fn size_limit(&mut self, bytes: usize) -> &mut RegexSetBuilder {
self.builder.size_limit(bytes);
self
}
/// Set the approximate capacity, in bytes, of the cache of transitions
/// used by the lazy DFA.
///
/// While the lazy DFA isn't always used, in tends to be the most
/// commonly use regex engine in default configurations. It tends to
/// adopt the performance profile of a fully build DFA, but without the
/// downside of taking worst case exponential time to build.
///
/// The downside is that it needs to keep a cache of transitions and
/// states that are built while running a search, and this cache
/// can fill up. When it fills up, the cache will reset itself. Any
/// previously generated states and transitions will then need to be
/// re-generated. If this happens too many times, then this library
/// will bail out of using the lazy DFA and switch to a different regex
/// engine.
///
/// If your regex provokes this particular downside of the lazy DFA,
/// then it may be beneficial to increase its cache capacity. This will
/// potentially reduce the frequency of cache resetting (ideally to
/// `0`). While it won't fix all potential performance problems with
/// the lazy DFA, increasing the cache capacity does fix some.
///
/// There is no easy way to determine, a priori, whether increasing
/// this cache capacity will help. In general, the larger your regex,
/// the more cache it's likely to use. But that isn't an ironclad rule.
/// For example, a regex like `[01]*1[01]{N}` would normally produce a
/// fully build DFA that is exponential in size with respect to `N`.
/// The lazy DFA will prevent exponential space blow-up, but it cache
/// is likely to fill up, even when it's large and even for smallish
/// values of `N`.
///
/// If you aren't sure whether this helps or not, it is sensible to
/// set this to some arbitrarily large number in testing, such as
/// `usize::MAX`. Namely, this represents the amount of capacity that
/// *may* be used. It's probably not a good idea to use `usize::MAX` in
/// production though, since it implies there are no controls on heap
/// memory used by this library during a search. In effect, set it to
/// whatever you're willing to allocate for a single regex search.
pub fn dfa_size_limit(
&mut self,
bytes: usize,
) -> &mut RegexSetBuilder {
self.builder.dfa_size_limit(bytes);
self
}
/// Set the nesting limit for this 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 for consumers that do structural induction on an AST using
/// explicit recursion. While this crate never does this (instead using
/// constant stack space and moving the call stack to the heap), other
/// crates may.
///
/// 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 this parser implementation will limit itself to heap
/// space proportional to the length of the pattern string. See also
/// the [untrusted inputs](crate#untrusted-input) section in the
/// top-level crate documentation for more information about this.
///
/// 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 an explicit concatenation,
/// 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.
///
/// # Example
///
/// ```
/// use regex::RegexSetBuilder;
///
/// assert!(RegexSetBuilder::new([r"a"]).nest_limit(0).build().is_ok());
/// assert!(RegexSetBuilder::new([r"ab"]).nest_limit(0).build().is_err());
/// ```
pub fn nest_limit(&mut self, limit: u32) -> &mut RegexSetBuilder {
self.builder.nest_limit(limit);
self
}
}
}
pub(crate) mod bytes {
use crate::{
bytes::{Regex, RegexSet},
error::Error,
};
use super::Builder;
/// A configurable builder for a [`Regex`].
///
/// This builder can be used to programmatically set flags such as `i`
/// (case insensitive) and `x` (for verbose mode). This builder can also be
/// used to configure things like the line terminator and a size limit on
/// the compiled regular expression.
#[derive(Clone, Debug)]
pub struct RegexBuilder {
builder: Builder,
}
impl RegexBuilder {
/// Create a new builder with a default configuration for the given
/// pattern.
///
/// If the pattern is invalid or exceeds the configured size limits,
/// then an error will be returned when [`RegexBuilder::build`] is
/// called.
pub fn new(pattern: &str) -> RegexBuilder {
RegexBuilder { builder: Builder::new([pattern]) }
}
/// Compiles the pattern given to `RegexBuilder::new` with the
/// configuration set on this builder.
///
/// If the pattern isn't a valid regex or if a configured size limit
/// was exceeded, then an error is returned.
pub fn build(&self) -> Result<Regex, Error> {
self.builder.build_one_bytes()
}
/// This configures Unicode mode for the entire pattern.
///
/// Enabling Unicode mode does a number of things:
///
/// * Most fundamentally, it causes the fundamental atom of matching
/// to be a single codepoint. When Unicode mode is disabled, it's a
/// single byte. For example, when Unicode mode is enabled, `.` will
/// match `💩` once, where as it will match 4 times when Unicode mode
/// is disabled. (Since the UTF-8 encoding of `💩` is 4 bytes long.)
/// * Case insensitive matching uses Unicode simple case folding rules.
/// * Unicode character classes like `\p{Letter}` and `\p{Greek}` are
/// available.
/// * Perl character classes are Unicode aware. That is, `\w`, `\s` and
/// `\d`.
/// * The word boundary assertions, `\b` and `\B`, use the Unicode
/// definition of a word character.
///
/// Note that unlike the top-level `Regex` for searching `&str`, it
/// is permitted to disable Unicode mode even if the resulting pattern
/// could match invalid UTF-8. For example, `(?-u:.)` is not a valid
/// pattern for a top-level `Regex`, but is valid for a `bytes::Regex`.
///
/// For more details on the Unicode support in this crate, see the
/// [Unicode section](crate#unicode) in this crate's top-level
/// documentation.
///
/// The default for this is `true`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r"\w")
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally greek letters would be included in \w, but since
/// // Unicode mode is disabled, it only matches ASCII letters.
/// assert!(!re.is_match("δ".as_bytes()));
///
/// let re = RegexBuilder::new(r"s")
/// .case_insensitive(true)
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally 'Å¿' is included when searching for 's' case
/// // insensitively due to Unicode's simple case folding rules. But
/// // when Unicode mode is disabled, only ASCII case insensitive rules
/// // are used.
/// assert!(!re.is_match("Å¿".as_bytes()));
/// ```
///
/// Since this builder is for constructing a [`bytes::Regex`](Regex),
/// one can disable Unicode mode even if it would match invalid UTF-8:
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r".")
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally greek letters would be included in \w, but since
/// // Unicode mode is disabled, it only matches ASCII letters.
/// assert!(re.is_match(b"\xFF"));
/// ```
pub fn unicode(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.unicode(yes);
self
}
/// This configures whether to enable case insensitive matching for the
/// entire pattern.
///
/// This setting can also be configured using the inline flag `i`
/// in the pattern. For example, `(?i:foo)` matches `foo` case
/// insensitively while `(?-i:foo)` matches `foo` case sensitively.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r"foo(?-i:bar)quux")
/// .case_insensitive(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match(b"FoObarQuUx"));
/// // Even though case insensitive matching is enabled in the builder,
/// // it can be locally disabled within the pattern. In this case,
/// // `bar` is matched case sensitively.
/// assert!(!re.is_match(b"fooBARquux"));
/// ```
pub fn case_insensitive(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.case_insensitive(yes);
self
}
/// This configures multi-line mode for the entire pattern.
///
/// Enabling multi-line mode changes the behavior of the `^` and `$`
/// anchor assertions. Instead of only matching at the beginning and
/// end of a haystack, respectively, multi-line mode causes them to
/// match at the beginning and end of a line *in addition* to the
/// beginning and end of a haystack. More precisely, `^` will match at
/// the position immediately following a `\n` and `$` will match at the
/// position immediately preceding a `\n`.
///
/// The behavior of this option can be impacted by other settings too:
///
/// * The [`RegexBuilder::line_terminator`] option changes `\n` above
/// to any ASCII byte.
/// * The [`RegexBuilder::crlf`] option changes the line terminator to
/// be either `\r` or `\n`, but never at the position between a `\r`
/// and `\n`.
///
/// This setting can also be configured using the inline flag `m` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r"^foo$")
/// .multi_line(true)
/// .build()
/// .unwrap();
/// assert_eq!(Some(1..4), re.find(b"\nfoo\n").map(|m| m.range()));
/// ```
pub fn multi_line(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.multi_line(yes);
self
}
/// This configures dot-matches-new-line mode for the entire pattern.
///
/// Perhaps surprisingly, the default behavior for `.` is not to match
/// any character, but rather, to match any character except for the
/// line terminator (which is `\n` by default). When this mode is
/// enabled, the behavior changes such that `.` truly matches any
/// character.
///
/// This setting can also be configured using the inline flag `s` in
/// the pattern. For example, `(?s:.)` and `\p{any}` are equivalent
/// regexes.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r"foo.bar")
/// .dot_matches_new_line(true)
/// .build()
/// .unwrap();
/// let hay = b"foo\nbar";
/// assert_eq!(Some(&b"foo\nbar"[..]), re.find(hay).map(|m| m.as_bytes()));
/// ```
pub fn dot_matches_new_line(
&mut self,
yes: bool,
) -> &mut RegexBuilder {
self.builder.dot_matches_new_line(yes);
self
}
/// This configures CRLF mode for the entire pattern.
///
/// When CRLF mode is enabled, both `\r` ("carriage return" or CR for
/// short) and `\n` ("line feed" or LF for short) are treated as line
/// terminators. This results in the following:
///
/// * Unless dot-matches-new-line mode is enabled, `.` will now match
/// any character except for `\n` and `\r`.
/// * When multi-line mode is enabled, `^` will match immediately
/// following a `\n` or a `\r`. Similarly, `$` will match immediately
/// preceding a `\n` or a `\r`. Neither `^` nor `$` will ever match
/// between `\r` and `\n`.
///
/// This setting can also be configured using the inline flag `R` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r"^foo$")
/// .multi_line(true)
/// .crlf(true)
/// .build()
/// .unwrap();
/// let hay = b"\r\nfoo\r\n";
/// // If CRLF mode weren't enabled here, then '$' wouldn't match
/// // immediately after 'foo', and thus no match would be found.
/// assert_eq!(Some(&b"foo"[..]), re.find(hay).map(|m| m.as_bytes()));
/// ```
///
/// This example demonstrates that `^` will never match at a position
/// between `\r` and `\n`. (`$` will similarly not match between a `\r`
/// and a `\n`.)
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r"^")
/// .multi_line(true)
/// .crlf(true)
/// .build()
/// .unwrap();
/// let hay = b"\r\n\r\n";
/// let ranges: Vec<_> = re.find_iter(hay).map(|m| m.range()).collect();
/// assert_eq!(ranges, vec![0..0, 2..2, 4..4]);
/// ```
pub fn crlf(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.crlf(yes);
self
}
/// Configures the line terminator to be used by the regex.
///
/// The line terminator is relevant in two ways for a particular regex:
///
/// * When dot-matches-new-line mode is *not* enabled (the default),
/// then `.` will match any character except for the configured line
/// terminator.
/// * When multi-line mode is enabled (not the default), then `^` and
/// `$` will match immediately after and before, respectively, a line
/// terminator.
///
/// In both cases, if CRLF mode is enabled in a particular context,
/// then it takes precedence over any configured line terminator.
///
/// This option cannot be configured from within the pattern.
///
/// The default line terminator is `\n`.
///
/// # Example
///
/// This shows how to treat the NUL byte as a line terminator. This can
/// be a useful heuristic when searching binary data.
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r"^foo$")
/// .multi_line(true)
/// .line_terminator(b'\x00')
/// .build()
/// .unwrap();
/// let hay = b"\x00foo\x00";
/// assert_eq!(Some(1..4), re.find(hay).map(|m| m.range()));
/// ```
///
/// This example shows that the behavior of `.` is impacted by this
/// setting as well:
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r".")
/// .line_terminator(b'\x00')
/// .build()
/// .unwrap();
/// assert!(re.is_match(b"\n"));
/// assert!(!re.is_match(b"\x00"));
/// ```
///
/// This shows that building a regex will work even when the byte
/// given is not ASCII. This is unlike the top-level `Regex` API where
/// matching invalid UTF-8 is not allowed.
///
/// Note though that you must disable Unicode mode. This is required
/// because Unicode mode requires matching one codepoint at a time,
/// and there is no way to match a non-ASCII byte as if it were a
/// codepoint.
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// assert!(
/// RegexBuilder::new(r".")
/// .unicode(false)
/// .line_terminator(0x80)
/// .build()
/// .is_ok(),
/// );
/// ```
pub fn line_terminator(&mut self, byte: u8) -> &mut RegexBuilder {
self.builder.line_terminator(byte);
self
}
/// This configures swap-greed mode for the entire pattern.
///
/// When swap-greed mode is enabled, patterns like `a+` will become
/// non-greedy and patterns like `a+?` will become greedy. In other
/// words, the meanings of `a+` and `a+?` are switched.
///
/// This setting can also be configured using the inline flag `U` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let re = RegexBuilder::new(r"a+")
/// .swap_greed(true)
/// .build()
/// .unwrap();
/// assert_eq!(Some(&b"a"[..]), re.find(b"aaa").map(|m| m.as_bytes()));
/// ```
pub fn swap_greed(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.swap_greed(yes);
self
}
/// This configures verbose mode for the entire pattern.
///
/// When enabled, whitespace will treated as insignifcant in the
/// pattern and `#` can be used to start a comment until the next new
/// line.
///
/// Normally, in most places in a pattern, whitespace is treated
/// literally. For example ` +` will match one or more ASCII whitespace
/// characters.
///
/// When verbose mode is enabled, `\#` can be used to match a literal
/// `#` and `\ ` can be used to match a literal ASCII whitespace
/// character.
///
/// Verbose mode is useful for permitting regexes to be formatted and
/// broken up more nicely. This may make them more easily readable.
///
/// This setting can also be configured using the inline flag `x` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// let pat = r"
/// \b
/// (?<first>\p{Uppercase}\w*) # always start with uppercase letter
/// [\s--\n]+ # whitespace should separate names
/// (?: # middle name can be an initial!
/// (?:(?<initial>\p{Uppercase})\.|(?<middle>\p{Uppercase}\w*))
/// [\s--\n]+
/// )?
/// (?<last>\p{Uppercase}\w*)
/// \b
/// ";
/// let re = RegexBuilder::new(pat)
/// .ignore_whitespace(true)
/// .build()
/// .unwrap();
///
/// let caps = re.captures(b"Harry Potter").unwrap();
/// assert_eq!(&b"Harry"[..], &caps["first"]);
/// assert_eq!(&b"Potter"[..], &caps["last"]);
///
/// let caps = re.captures(b"Harry J. Potter").unwrap();
/// assert_eq!(&b"Harry"[..], &caps["first"]);
/// // Since a middle name/initial isn't required for an overall match,
/// // we can't assume that 'initial' or 'middle' will be populated!
/// assert_eq!(
/// Some(&b"J"[..]),
/// caps.name("initial").map(|m| m.as_bytes()),
/// );
/// assert_eq!(None, caps.name("middle").map(|m| m.as_bytes()));
/// assert_eq!(&b"Potter"[..], &caps["last"]);
///
/// let caps = re.captures(b"Harry James Potter").unwrap();
/// assert_eq!(&b"Harry"[..], &caps["first"]);
/// // Since a middle name/initial isn't required for an overall match,
/// // we can't assume that 'initial' or 'middle' will be populated!
/// assert_eq!(None, caps.name("initial").map(|m| m.as_bytes()));
/// assert_eq!(
/// Some(&b"James"[..]),
/// caps.name("middle").map(|m| m.as_bytes()),
/// );
/// assert_eq!(&b"Potter"[..], &caps["last"]);
/// ```
pub fn ignore_whitespace(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.ignore_whitespace(yes);
self
}
/// This configures octal mode for the entire pattern.
///
/// Octal syntax is a little-known way of uttering Unicode codepoints
/// in a pattern. For example, `a`, `\x61`, `\u0061` and `\141` are all
/// equivalent patterns, 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 this library. However, many users expect
/// backreferences to be supported. Therefore, when octal support
/// is disabled, the error message will explicitly mention that
/// backreferences aren't supported.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// // Normally this pattern would not compile, with an error message
/// // about backreferences not being supported. But with octal mode
/// // enabled, octal escape sequences work.
/// let re = RegexBuilder::new(r"\141")
/// .octal(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match(b"a"));
/// ```
pub fn octal(&mut self, yes: bool) -> &mut RegexBuilder {
self.builder.octal(yes);
self
}
/// Sets the approximate size limit, in bytes, of the compiled regex.
///
/// This roughly corresponds to the number of heap memory, in
/// bytes, occupied by a single regex. If the regex would otherwise
/// approximately exceed this limit, then compiling that regex will
/// fail.
///
/// The main utility of a method like this is to avoid compiling
/// regexes that use an unexpected amount of resources, such as
/// time and memory. Even if the memory usage of a large regex is
/// acceptable, its search time may not be. Namely, worst case time
/// complexity for search is `O(m * n)`, where `m ~ len(pattern)` and
/// `n ~ len(haystack)`. That is, search time depends, in part, on the
/// size of the compiled regex. This means that putting a limit on the
/// size of the regex limits how much a regex can impact search time.
///
/// For more information about regex size limits, see the section on
/// [untrusted inputs](crate#untrusted-input) in the top-level crate
/// documentation.
///
/// The default for this is some reasonable number that permits most
/// patterns to compile successfully.
///
/// # Example
///
/// ```
/// # if !cfg!(target_pointer_width = "64") { return; } // see #1041
/// use regex::bytes::RegexBuilder;
///
/// // It may surprise you how big some seemingly small patterns can
/// // be! Since \w is Unicode aware, this generates a regex that can
/// // match approximately 140,000 distinct codepoints.
/// assert!(RegexBuilder::new(r"\w").size_limit(45_000).build().is_err());
/// ```
pub fn size_limit(&mut self, bytes: usize) -> &mut RegexBuilder {
self.builder.size_limit(bytes);
self
}
/// Set the approximate capacity, in bytes, of the cache of transitions
/// used by the lazy DFA.
///
/// While the lazy DFA isn't always used, in tends to be the most
/// commonly use regex engine in default configurations. It tends to
/// adopt the performance profile of a fully build DFA, but without the
/// downside of taking worst case exponential time to build.
///
/// The downside is that it needs to keep a cache of transitions and
/// states that are built while running a search, and this cache
/// can fill up. When it fills up, the cache will reset itself. Any
/// previously generated states and transitions will then need to be
/// re-generated. If this happens too many times, then this library
/// will bail out of using the lazy DFA and switch to a different regex
/// engine.
///
/// If your regex provokes this particular downside of the lazy DFA,
/// then it may be beneficial to increase its cache capacity. This will
/// potentially reduce the frequency of cache resetting (ideally to
/// `0`). While it won't fix all potential performance problems with
/// the lazy DFA, increasing the cache capacity does fix some.
///
/// There is no easy way to determine, a priori, whether increasing
/// this cache capacity will help. In general, the larger your regex,
/// the more cache it's likely to use. But that isn't an ironclad rule.
/// For example, a regex like `[01]*1[01]{N}` would normally produce a
/// fully build DFA that is exponential in size with respect to `N`.
/// The lazy DFA will prevent exponential space blow-up, but it cache
/// is likely to fill up, even when it's large and even for smallish
/// values of `N`.
///
/// If you aren't sure whether this helps or not, it is sensible to
/// set this to some arbitrarily large number in testing, such as
/// `usize::MAX`. Namely, this represents the amount of capacity that
/// *may* be used. It's probably not a good idea to use `usize::MAX` in
/// production though, since it implies there are no controls on heap
/// memory used by this library during a search. In effect, set it to
/// whatever you're willing to allocate for a single regex search.
pub fn dfa_size_limit(&mut self, bytes: usize) -> &mut RegexBuilder {
self.builder.dfa_size_limit(bytes);
self
}
/// Set the nesting limit for this 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 for consumers that do structural induction on an AST using
/// explicit recursion. While this crate never does this (instead using
/// constant stack space and moving the call stack to the heap), other
/// crates may.
///
/// 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 this parser implementation will limit itself to heap
/// space proportional to the length of the pattern string. See also
/// the [untrusted inputs](crate#untrusted-input) section in the
/// top-level crate documentation for more information about this.
///
/// 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 an explicit concatenation,
/// 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.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexBuilder;
///
/// assert!(RegexBuilder::new(r"a").nest_limit(0).build().is_ok());
/// assert!(RegexBuilder::new(r"ab").nest_limit(0).build().is_err());
/// ```
pub fn nest_limit(&mut self, limit: u32) -> &mut RegexBuilder {
self.builder.nest_limit(limit);
self
}
}
/// A configurable builder for a [`RegexSet`].
///
/// This builder can be used to programmatically set flags such as `i`
/// (case insensitive) and `x` (for verbose mode). This builder can also be
/// used to configure things like the line terminator and a size limit on
/// the compiled regular expression.
#[derive(Clone, Debug)]
pub struct RegexSetBuilder {
builder: Builder,
}
impl RegexSetBuilder {
/// Create a new builder with a default configuration for the given
/// patterns.
///
/// If the patterns are invalid or exceed the configured size limits,
/// then an error will be returned when [`RegexSetBuilder::build`] is
/// called.
pub fn new<I, S>(patterns: I) -> RegexSetBuilder
where
I: IntoIterator<Item = S>,
S: AsRef<str>,
{
RegexSetBuilder { builder: Builder::new(patterns) }
}
/// Compiles the patterns given to `RegexSetBuilder::new` with the
/// configuration set on this builder.
///
/// If the patterns aren't valid regexes or if a configured size limit
/// was exceeded, then an error is returned.
pub fn build(&self) -> Result<RegexSet, Error> {
self.builder.build_many_bytes()
}
/// This configures Unicode mode for the all of the patterns.
///
/// Enabling Unicode mode does a number of things:
///
/// * Most fundamentally, it causes the fundamental atom of matching
/// to be a single codepoint. When Unicode mode is disabled, it's a
/// single byte. For example, when Unicode mode is enabled, `.` will
/// match `💩` once, where as it will match 4 times when Unicode mode
/// is disabled. (Since the UTF-8 encoding of `💩` is 4 bytes long.)
/// * Case insensitive matching uses Unicode simple case folding rules.
/// * Unicode character classes like `\p{Letter}` and `\p{Greek}` are
/// available.
/// * Perl character classes are Unicode aware. That is, `\w`, `\s` and
/// `\d`.
/// * The word boundary assertions, `\b` and `\B`, use the Unicode
/// definition of a word character.
///
/// Note that unlike the top-level `RegexSet` for searching `&str`,
/// it is permitted to disable Unicode mode even if the resulting
/// pattern could match invalid UTF-8. For example, `(?-u:.)` is not
/// a valid pattern for a top-level `RegexSet`, but is valid for a
/// `bytes::RegexSet`.
///
/// For more details on the Unicode support in this crate, see the
/// [Unicode section](crate#unicode) in this crate's top-level
/// documentation.
///
/// The default for this is `true`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"\w"])
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally greek letters would be included in \w, but since
/// // Unicode mode is disabled, it only matches ASCII letters.
/// assert!(!re.is_match("δ".as_bytes()));
///
/// let re = RegexSetBuilder::new([r"s"])
/// .case_insensitive(true)
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally 'Å¿' is included when searching for 's' case
/// // insensitively due to Unicode's simple case folding rules. But
/// // when Unicode mode is disabled, only ASCII case insensitive rules
/// // are used.
/// assert!(!re.is_match("Å¿".as_bytes()));
/// ```
///
/// Since this builder is for constructing a
/// [`bytes::RegexSet`](RegexSet), one can disable Unicode mode even if
/// it would match invalid UTF-8:
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"."])
/// .unicode(false)
/// .build()
/// .unwrap();
/// // Normally greek letters would be included in \w, but since
/// // Unicode mode is disabled, it only matches ASCII letters.
/// assert!(re.is_match(b"\xFF"));
/// ```
pub fn unicode(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.unicode(yes);
self
}
/// This configures whether to enable case insensitive matching for all
/// of the patterns.
///
/// This setting can also be configured using the inline flag `i`
/// in the pattern. For example, `(?i:foo)` matches `foo` case
/// insensitively while `(?-i:foo)` matches `foo` case sensitively.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"foo(?-i:bar)quux"])
/// .case_insensitive(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match(b"FoObarQuUx"));
/// // Even though case insensitive matching is enabled in the builder,
/// // it can be locally disabled within the pattern. In this case,
/// // `bar` is matched case sensitively.
/// assert!(!re.is_match(b"fooBARquux"));
/// ```
pub fn case_insensitive(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.case_insensitive(yes);
self
}
/// This configures multi-line mode for all of the patterns.
///
/// Enabling multi-line mode changes the behavior of the `^` and `$`
/// anchor assertions. Instead of only matching at the beginning and
/// end of a haystack, respectively, multi-line mode causes them to
/// match at the beginning and end of a line *in addition* to the
/// beginning and end of a haystack. More precisely, `^` will match at
/// the position immediately following a `\n` and `$` will match at the
/// position immediately preceding a `\n`.
///
/// The behavior of this option can be impacted by other settings too:
///
/// * The [`RegexSetBuilder::line_terminator`] option changes `\n`
/// above to any ASCII byte.
/// * The [`RegexSetBuilder::crlf`] option changes the line terminator
/// to be either `\r` or `\n`, but never at the position between a `\r`
/// and `\n`.
///
/// This setting can also be configured using the inline flag `m` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"^foo$"])
/// .multi_line(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match(b"\nfoo\n"));
/// ```
pub fn multi_line(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.multi_line(yes);
self
}
/// This configures dot-matches-new-line mode for the entire pattern.
///
/// Perhaps surprisingly, the default behavior for `.` is not to match
/// any character, but rather, to match any character except for the
/// line terminator (which is `\n` by default). When this mode is
/// enabled, the behavior changes such that `.` truly matches any
/// character.
///
/// This setting can also be configured using the inline flag `s` in
/// the pattern. For example, `(?s:.)` and `\p{any}` are equivalent
/// regexes.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"foo.bar"])
/// .dot_matches_new_line(true)
/// .build()
/// .unwrap();
/// let hay = b"foo\nbar";
/// assert!(re.is_match(hay));
/// ```
pub fn dot_matches_new_line(
&mut self,
yes: bool,
) -> &mut RegexSetBuilder {
self.builder.dot_matches_new_line(yes);
self
}
/// This configures CRLF mode for all of the patterns.
///
/// When CRLF mode is enabled, both `\r` ("carriage return" or CR for
/// short) and `\n` ("line feed" or LF for short) are treated as line
/// terminators. This results in the following:
///
/// * Unless dot-matches-new-line mode is enabled, `.` will now match
/// any character except for `\n` and `\r`.
/// * When multi-line mode is enabled, `^` will match immediately
/// following a `\n` or a `\r`. Similarly, `$` will match immediately
/// preceding a `\n` or a `\r`. Neither `^` nor `$` will ever match
/// between `\r` and `\n`.
///
/// This setting can also be configured using the inline flag `R` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"^foo$"])
/// .multi_line(true)
/// .crlf(true)
/// .build()
/// .unwrap();
/// let hay = b"\r\nfoo\r\n";
/// // If CRLF mode weren't enabled here, then '$' wouldn't match
/// // immediately after 'foo', and thus no match would be found.
/// assert!(re.is_match(hay));
/// ```
///
/// This example demonstrates that `^` will never match at a position
/// between `\r` and `\n`. (`$` will similarly not match between a `\r`
/// and a `\n`.)
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"^\n"])
/// .multi_line(true)
/// .crlf(true)
/// .build()
/// .unwrap();
/// assert!(!re.is_match(b"\r\n"));
/// ```
pub fn crlf(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.crlf(yes);
self
}
/// Configures the line terminator to be used by the regex.
///
/// The line terminator is relevant in two ways for a particular regex:
///
/// * When dot-matches-new-line mode is *not* enabled (the default),
/// then `.` will match any character except for the configured line
/// terminator.
/// * When multi-line mode is enabled (not the default), then `^` and
/// `$` will match immediately after and before, respectively, a line
/// terminator.
///
/// In both cases, if CRLF mode is enabled in a particular context,
/// then it takes precedence over any configured line terminator.
///
/// This option cannot be configured from within the pattern.
///
/// The default line terminator is `\n`.
///
/// # Example
///
/// This shows how to treat the NUL byte as a line terminator. This can
/// be a useful heuristic when searching binary data.
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"^foo$"])
/// .multi_line(true)
/// .line_terminator(b'\x00')
/// .build()
/// .unwrap();
/// let hay = b"\x00foo\x00";
/// assert!(re.is_match(hay));
/// ```
///
/// This example shows that the behavior of `.` is impacted by this
/// setting as well:
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let re = RegexSetBuilder::new([r"."])
/// .line_terminator(b'\x00')
/// .build()
/// .unwrap();
/// assert!(re.is_match(b"\n"));
/// assert!(!re.is_match(b"\x00"));
/// ```
///
/// This shows that building a regex will work even when the byte given
/// is not ASCII. This is unlike the top-level `RegexSet` API where
/// matching invalid UTF-8 is not allowed.
///
/// Note though that you must disable Unicode mode. This is required
/// because Unicode mode requires matching one codepoint at a time,
/// and there is no way to match a non-ASCII byte as if it were a
/// codepoint.
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// assert!(
/// RegexSetBuilder::new([r"."])
/// .unicode(false)
/// .line_terminator(0x80)
/// .build()
/// .is_ok(),
/// );
/// ```
pub fn line_terminator(&mut self, byte: u8) -> &mut RegexSetBuilder {
self.builder.line_terminator(byte);
self
}
/// This configures swap-greed mode for all of the patterns.
///
/// When swap-greed mode is enabled, patterns like `a+` will become
/// non-greedy and patterns like `a+?` will become greedy. In other
/// words, the meanings of `a+` and `a+?` are switched.
///
/// This setting can also be configured using the inline flag `U` in
/// the pattern.
///
/// Note that this is generally not useful for a `RegexSet` since a
/// `RegexSet` can only report whether a pattern matches or not. Since
/// greediness never impacts whether a match is found or not (only the
/// offsets of the match), it follows that whether parts of a pattern
/// are greedy or not doesn't matter for a `RegexSet`.
///
/// The default for this is `false`.
pub fn swap_greed(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.swap_greed(yes);
self
}
/// This configures verbose mode for all of the patterns.
///
/// When enabled, whitespace will treated as insignifcant in the
/// pattern and `#` can be used to start a comment until the next new
/// line.
///
/// Normally, in most places in a pattern, whitespace is treated
/// literally. For example ` +` will match one or more ASCII whitespace
/// characters.
///
/// When verbose mode is enabled, `\#` can be used to match a literal
/// `#` and `\ ` can be used to match a literal ASCII whitespace
/// character.
///
/// Verbose mode is useful for permitting regexes to be formatted and
/// broken up more nicely. This may make them more easily readable.
///
/// This setting can also be configured using the inline flag `x` in
/// the pattern.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// let pat = r"
/// \b
/// (?<first>\p{Uppercase}\w*) # always start with uppercase letter
/// [\s--\n]+ # whitespace should separate names
/// (?: # middle name can be an initial!
/// (?:(?<initial>\p{Uppercase})\.|(?<middle>\p{Uppercase}\w*))
/// [\s--\n]+
/// )?
/// (?<last>\p{Uppercase}\w*)
/// \b
/// ";
/// let re = RegexSetBuilder::new([pat])
/// .ignore_whitespace(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match(b"Harry Potter"));
/// assert!(re.is_match(b"Harry J. Potter"));
/// assert!(re.is_match(b"Harry James Potter"));
/// assert!(!re.is_match(b"harry J. Potter"));
/// ```
pub fn ignore_whitespace(
&mut self,
yes: bool,
) -> &mut RegexSetBuilder {
self.builder.ignore_whitespace(yes);
self
}
/// This configures octal mode for all of the patterns.
///
/// Octal syntax is a little-known way of uttering Unicode codepoints
/// in a pattern. For example, `a`, `\x61`, `\u0061` and `\141` are all
/// equivalent patterns, 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 this library. However, many users expect
/// backreferences to be supported. Therefore, when octal support
/// is disabled, the error message will explicitly mention that
/// backreferences aren't supported.
///
/// The default for this is `false`.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// // Normally this pattern would not compile, with an error message
/// // about backreferences not being supported. But with octal mode
/// // enabled, octal escape sequences work.
/// let re = RegexSetBuilder::new([r"\141"])
/// .octal(true)
/// .build()
/// .unwrap();
/// assert!(re.is_match(b"a"));
/// ```
pub fn octal(&mut self, yes: bool) -> &mut RegexSetBuilder {
self.builder.octal(yes);
self
}
/// Sets the approximate size limit, in bytes, of the compiled regex.
///
/// This roughly corresponds to the number of heap memory, in
/// bytes, occupied by a single regex. If the regex would otherwise
/// approximately exceed this limit, then compiling that regex will
/// fail.
///
/// The main utility of a method like this is to avoid compiling
/// regexes that use an unexpected amount of resources, such as
/// time and memory. Even if the memory usage of a large regex is
/// acceptable, its search time may not be. Namely, worst case time
/// complexity for search is `O(m * n)`, where `m ~ len(pattern)` and
/// `n ~ len(haystack)`. That is, search time depends, in part, on the
/// size of the compiled regex. This means that putting a limit on the
/// size of the regex limits how much a regex can impact search time.
///
/// For more information about regex size limits, see the section on
/// [untrusted inputs](crate#untrusted-input) in the top-level crate
/// documentation.
///
/// The default for this is some reasonable number that permits most
/// patterns to compile successfully.
///
/// # Example
///
/// ```
/// # if !cfg!(target_pointer_width = "64") { return; } // see #1041
/// use regex::bytes::RegexSetBuilder;
///
/// // It may surprise you how big some seemingly small patterns can
/// // be! Since \w is Unicode aware, this generates a regex that can
/// // match approximately 140,000 distinct codepoints.
/// assert!(
/// RegexSetBuilder::new([r"\w"])
/// .size_limit(45_000)
/// .build()
/// .is_err()
/// );
/// ```
pub fn size_limit(&mut self, bytes: usize) -> &mut RegexSetBuilder {
self.builder.size_limit(bytes);
self
}
/// Set the approximate capacity, in bytes, of the cache of transitions
/// used by the lazy DFA.
///
/// While the lazy DFA isn't always used, in tends to be the most
/// commonly use regex engine in default configurations. It tends to
/// adopt the performance profile of a fully build DFA, but without the
/// downside of taking worst case exponential time to build.
///
/// The downside is that it needs to keep a cache of transitions and
/// states that are built while running a search, and this cache
/// can fill up. When it fills up, the cache will reset itself. Any
/// previously generated states and transitions will then need to be
/// re-generated. If this happens too many times, then this library
/// will bail out of using the lazy DFA and switch to a different regex
/// engine.
///
/// If your regex provokes this particular downside of the lazy DFA,
/// then it may be beneficial to increase its cache capacity. This will
/// potentially reduce the frequency of cache resetting (ideally to
/// `0`). While it won't fix all potential performance problems with
/// the lazy DFA, increasing the cache capacity does fix some.
///
/// There is no easy way to determine, a priori, whether increasing
/// this cache capacity will help. In general, the larger your regex,
/// the more cache it's likely to use. But that isn't an ironclad rule.
/// For example, a regex like `[01]*1[01]{N}` would normally produce a
/// fully build DFA that is exponential in size with respect to `N`.
/// The lazy DFA will prevent exponential space blow-up, but it cache
/// is likely to fill up, even when it's large and even for smallish
/// values of `N`.
///
/// If you aren't sure whether this helps or not, it is sensible to
/// set this to some arbitrarily large number in testing, such as
/// `usize::MAX`. Namely, this represents the amount of capacity that
/// *may* be used. It's probably not a good idea to use `usize::MAX` in
/// production though, since it implies there are no controls on heap
/// memory used by this library during a search. In effect, set it to
/// whatever you're willing to allocate for a single regex search.
pub fn dfa_size_limit(
&mut self,
bytes: usize,
) -> &mut RegexSetBuilder {
self.builder.dfa_size_limit(bytes);
self
}
/// Set the nesting limit for this 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 for consumers that do structural induction on an AST using
/// explicit recursion. While this crate never does this (instead using
/// constant stack space and moving the call stack to the heap), other
/// crates may.
///
/// 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 this parser implementation will limit itself to heap
/// space proportional to the length of the pattern string. See also
/// the [untrusted inputs](crate#untrusted-input) section in the
/// top-level crate documentation for more information about this.
///
/// 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 an explicit concatenation,
/// 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.
///
/// # Example
///
/// ```
/// use regex::bytes::RegexSetBuilder;
///
/// assert!(RegexSetBuilder::new([r"a"]).nest_limit(0).build().is_ok());
/// assert!(RegexSetBuilder::new([r"ab"]).nest_limit(0).build().is_err());
/// ```
pub fn nest_limit(&mut self, limit: u32) -> &mut RegexSetBuilder {
self.builder.nest_limit(limit);
self
}
}
}
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