/*!
A DFA-backed `Regex`.
This module provides [`Regex`], which is defined generically over the
[`Automaton`] trait. A `Regex` implements convenience routines you might have
come to expect, such as finding the start/end of a match and iterating over
all non-overlapping matches. This `Regex` type is limited in its capabilities
to what a DFA can provide. Therefore, APIs involving capturing groups, for
example, are not provided.
Internally, a `Regex` is composed of two DFAs. One is a "forward" DFA that
finds the end offset of a match, where as the other is a "reverse" DFA that
find the start offset of a match.
See the [parent module](crate::dfa) for examples.
*/
#[cfg(feature = "alloc")]
use alloc::vec::Vec;
#[cfg(feature = "dfa-build")]
use crate::dfa::dense::BuildError;
use crate::{
dfa::{automaton::Automaton, dense},
util::{iter, search::Input},
Anchored, Match, MatchError,
};
#[cfg(feature = "alloc")]
use crate::{
dfa::{sparse, StartKind},
util::search::MatchKind,
};
// When the alloc feature is enabled, the regex type sets its A type parameter
// to default to an owned dense DFA. But without alloc, we set no default. This
// makes things a lot more convenient in the common case, since writing out the
// DFA types is pretty annoying.
//
// Since we have two different definitions but only want to write one doc
// string, we use a macro to capture the doc and other attributes once and then
// repeat them for each definition.
macro_rules! define_regex_type {
($(#[$doc:meta])*) => {
#[cfg(feature = "alloc")]
$(#[$doc])*
pub struct Regex<A = dense::OwnedDFA> {
forward: A,
reverse: A,
}
#[cfg(not(feature = "alloc"))]
$(#[$doc])*
pub struct Regex<A> {
forward: A,
reverse: A,
}
};
}
define_regex_type!(
/// A regular expression that uses deterministic finite automata for fast
/// searching.
///
/// A regular expression is comprised of two DFAs, a "forward" DFA and a
/// "reverse" DFA. The forward DFA is responsible for detecting the end of
/// a match while the reverse DFA is responsible for detecting the start
/// of a match. Thus, in order to find the bounds of any given match, a
/// forward search must first be run followed by a reverse search. A match
/// found by the forward DFA guarantees that the reverse DFA will also find
/// a match.
///
/// The type of the DFA used by a `Regex` corresponds to the `A` type
/// parameter, which must satisfy the [`Automaton`] trait. Typically,
/// `A` is either a [`dense::DFA`](crate::dfa::dense::DFA) or a
/// [`sparse::DFA`](crate::dfa::sparse::DFA), where dense DFAs use more
/// memory but search faster, while sparse DFAs use less memory but search
/// more slowly.
///
/// # Crate features
///
/// Note that despite what the documentation auto-generates, the _only_
/// crate feature needed to use this type is `dfa-search`. You do _not_
/// need to enable the `alloc` feature.
///
/// By default, a regex's automaton type parameter is set to
/// `dense::DFA<Vec<u32>>` when the `alloc` feature is enabled. For most
/// in-memory work loads, this is the most convenient type that gives the
/// best search performance. When the `alloc` feature is disabled, no
/// default type is used.
///
/// # When should I use this?
///
/// Generally speaking, if you can afford the overhead of building a full
/// DFA for your regex, and you don't need things like capturing groups,
/// then this is a good choice if you're looking to optimize for matching
/// speed. Note however that its speed may be worse than a general purpose
/// regex engine if you don't provide a [`dense::Config::prefilter`] to the
/// underlying DFA.
///
/// # Sparse DFAs
///
/// Since a `Regex` is generic over the [`Automaton`] trait, it can be
/// used with any kind of DFA. While this crate constructs dense DFAs by
/// default, it is easy enough to build corresponding sparse DFAs, and then
/// build a regex from them:
///
/// ```
/// use regex_automata::dfa::regex::Regex;
///
/// // First, build a regex that uses dense DFAs.
/// let dense_re = Regex::new("foo[0-9]+")?;
///
/// // Second, build sparse DFAs from the forward and reverse dense DFAs.
/// let fwd = dense_re.forward().to_sparse()?;
/// let rev = dense_re.reverse().to_sparse()?;
///
/// // Third, build a new regex from the constituent sparse DFAs.
/// let sparse_re = Regex::builder().build_from_dfas(fwd, rev);
///
/// // A regex that uses sparse DFAs can be used just like with dense DFAs.
/// assert_eq!(true, sparse_re.is_match(b"foo123"));
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// Alternatively, one can use a [`Builder`] to construct a sparse DFA
/// more succinctly. (Note though that dense DFAs are still constructed
/// first internally, and then converted to sparse DFAs, as in the example
/// above.)
///
/// ```
/// use regex_automata::dfa::regex::Regex;
///
/// let sparse_re = Regex::builder().build_sparse(r"foo[0-9]+")?;
/// // A regex that uses sparse DFAs can be used just like with dense DFAs.
/// assert!(sparse_re.is_match(b"foo123"));
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// # Fallibility
///
/// Most of the search routines defined on this type will _panic_ when the
/// underlying search fails. This might be because the DFA gave up because
/// it saw a quit byte, whether configured explicitly or via heuristic
/// Unicode word boundary support, although neither are enabled by default.
/// Or it might fail because an invalid `Input` configuration is given,
/// for example, with an unsupported [`Anchored`] mode.
///
/// If you need to handle these error cases instead of allowing them to
/// trigger a panic, then the lower level [`Regex::try_search`] provides
/// a fallible API that never panics.
///
/// # Example
///
/// This example shows how to cause a search to terminate if it sees a
/// `\n` byte, and handle the error returned. This could be useful if, for
/// example, you wanted to prevent a user supplied pattern from matching
/// across a line boundary.
///
/// ```
/// # if cfg!(miri) { return Ok(()); } // miri takes too long
/// use regex_automata::{dfa::{self, regex::Regex}, Input, MatchError};
///
/// let re = Regex::builder()
/// .dense(dfa::dense::Config::new().quit(b'\n', true))
/// .build(r"foo\p{any}+bar")?;
///
/// let input = Input::new("foo\nbar");
/// // Normally this would produce a match, since \p{any} contains '\n'.
/// // But since we instructed the automaton to enter a quit state if a
/// // '\n' is observed, this produces a match error instead.
/// let expected = MatchError::quit(b'\n', 3);
/// let got = re.try_search(&input).unwrap_err();
/// assert_eq!(expected, got);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[derive(Clone, Debug)]
);
#[cfg(all(feature = "syntax", feature = "dfa-build"))]
impl Regex {
/// Parse the given regular expression using the default configuration and
/// return the corresponding regex.
///
/// If you want a non-default configuration, then use the [`Builder`] to
/// set your own configuration.
///
/// # Example
///
/// ```
/// use regex_automata::{Match, dfa::regex::Regex};
///
/// let re = Regex::new("foo[0-9]+bar")?;
/// assert_eq!(
/// Some(Match::must(0, 3..14)),
/// re.find(b"zzzfoo12345barzzz"),
/// );
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn new(pattern: &str) -> Result<Regex, BuildError> {
Builder::new().build(pattern)
}
/// Like `new`, but parses multiple patterns into a single "regex set."
/// This similarly uses the default regex configuration.
///
/// # Example
///
/// ```
/// use regex_automata::{Match, dfa::regex::Regex};
///
/// let re = Regex::new_many(&["[a-z]+", "[0-9]+"])?;
///
/// let mut it = re.find_iter(b"abc 1 foo 4567 0 quux");
/// assert_eq!(Some(Match::must(0, 0..3)), it.next());
/// assert_eq!(Some(Match::must(1, 4..5)), it.next());
/// assert_eq!(Some(Match::must(0, 6..9)), it.next());
/// assert_eq!(Some(Match::must(1, 10..14)), it.next());
/// assert_eq!(Some(Match::must(1, 15..16)), it.next());
/// assert_eq!(Some(Match::must(0, 17..21)), it.next());
/// assert_eq!(None, it.next());
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn new_many<P: AsRef<str>>(
patterns: &[P],
) -> Result<Regex, BuildError> {
Builder::new().build_many(patterns)
}
}
#[cfg(all(feature = "syntax", feature = "dfa-build"))]
impl Regex<sparse::DFA<Vec<u8>>> {
/// Parse the given regular expression using the default configuration,
/// except using sparse DFAs, and return the corresponding regex.
///
/// If you want a non-default configuration, then use the [`Builder`] to
/// set your own configuration.
///
/// # Example
///
/// ```
/// use regex_automata::{Match, dfa::regex::Regex};
///
/// let re = Regex::new_sparse("foo[0-9]+bar")?;
/// assert_eq!(
/// Some(Match::must(0, 3..14)),
/// re.find(b"zzzfoo12345barzzz"),
/// );
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn new_sparse(
pattern: &str,
) -> Result<Regex<sparse::DFA<Vec<u8>>>, BuildError> {
Builder::new().build_sparse(pattern)
}
/// Like `new`, but parses multiple patterns into a single "regex set"
/// using sparse DFAs. This otherwise similarly uses the default regex
/// configuration.
///
/// # Example
///
/// ```
/// use regex_automata::{Match, dfa::regex::Regex};
///
/// let re = Regex::new_many_sparse(&["[a-z]+", "[0-9]+"])?;
///
/// let mut it = re.find_iter(b"abc 1 foo 4567 0 quux");
/// assert_eq!(Some(Match::must(0, 0..3)), it.next());
/// assert_eq!(Some(Match::must(1, 4..5)), it.next());
/// assert_eq!(Some(Match::must(0, 6..9)), it.next());
/// assert_eq!(Some(Match::must(1, 10..14)), it.next());
/// assert_eq!(Some(Match::must(1, 15..16)), it.next());
/// assert_eq!(Some(Match::must(0, 17..21)), it.next());
/// assert_eq!(None, it.next());
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn new_many_sparse<P: AsRef<str>>(
patterns: &[P],
) -> Result<Regex<sparse::DFA<Vec<u8>>>, BuildError> {
Builder::new().build_many_sparse(patterns)
}
}
/// Convenience routines for regex construction.
impl Regex<dense::DFA<&'static [u32]>> {
/// Return a builder for configuring the construction of a `Regex`.
///
/// This is a convenience routine to avoid needing to import the
/// [`Builder`] type in common cases.
///
/// # Example
///
/// This example shows how to use the builder to disable UTF-8 mode
/// everywhere.
///
/// ```
/// # if cfg!(miri) { return Ok(()); } // miri takes too long
/// use regex_automata::{
/// dfa::regex::Regex, nfa::thompson, util::syntax, Match,
/// };
///
/// let re = Regex::builder()
/// .syntax(syntax::Config::new().utf8(false))
/// .thompson(thompson::Config::new().utf8(false))
/// .build(r"foo(?-u:[^b])ar.*")?;
/// let haystack = b"\xFEfoo\xFFarzz\xE2\x98\xFF\n";
/// let expected = Some(Match::must(0, 1..9));
/// let got = re.find(haystack);
/// assert_eq!(expected, got);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn builder() -> Builder {
Builder::new()
}
}
/// Standard search routines for finding and iterating over matches.
impl<A: Automaton> Regex<A> {
/// Returns true if and only if this regex matches the given haystack.
///
/// This routine may short circuit if it knows that scanning future input
/// will never lead to a different result. In particular, if the underlying
/// DFA enters a match state or a dead state, then this routine will return
/// `true` or `false`, respectively, without inspecting any future input.
///
/// # Panics
///
/// This routine panics if the search could not complete. This can occur
/// in a number of circumstances:
///
/// * The configuration of the DFA may permit it to "quit" the search.
/// For example, setting quit bytes or enabling heuristic support for
/// Unicode word boundaries. The default configuration does not enable any
/// option that could result in the DFA quitting.
/// * When the provided `Input` configuration is not supported. For
/// example, by providing an unsupported anchor mode.
///
/// When a search panics, callers cannot know whether a match exists or
/// not.
///
/// Use [`Regex::try_search`] if you want to handle these error conditions.
///
/// # Example
///
/// ```
/// use regex_automata::dfa::regex::Regex;
///
/// let re = Regex::new("foo[0-9]+bar")?;
/// assert_eq!(true, re.is_match("foo12345bar"));
/// assert_eq!(false, re.is_match("foobar"));
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[inline]
pub fn is_match<'h, I: Into<Input<'h>>>(&self, input: I) -> bool {
// Not only can we do an "earliest" search, but we can avoid doing a
// reverse scan too.
let input = input.into().earliest(true);
self.forward().try_search_fwd(&input).map(|x| x.is_some()).unwrap()
}
/// Returns the start and end offset of the leftmost match. If no match
/// exists, then `None` is returned.
///
/// # Panics
///
/// This routine panics if the search could not complete. This can occur
/// in a number of circumstances:
///
/// * The configuration of the DFA may permit it to "quit" the search.
/// For example, setting quit bytes or enabling heuristic support for
/// Unicode word boundaries. The default configuration does not enable any
/// option that could result in the DFA quitting.
/// * When the provided `Input` configuration is not supported. For
/// example, by providing an unsupported anchor mode.
///
/// When a search panics, callers cannot know whether a match exists or
/// not.
///
/// Use [`Regex::try_search`] if you want to handle these error conditions.
///
/// # Example
///
/// ```
/// use regex_automata::{Match, dfa::regex::Regex};
///
/// // Greediness is applied appropriately.
/// let re = Regex::new("foo[0-9]+")?;
/// assert_eq!(Some(Match::must(0, 3..11)), re.find("zzzfoo12345zzz"));
///
/// // Even though a match is found after reading the first byte (`a`),
/// // the default leftmost-first match semantics demand that we find the
/// // earliest match that prefers earlier parts of the pattern over latter
/// // parts.
/// let re = Regex::new("abc|a")?;
/// assert_eq!(Some(Match::must(0, 0..3)), re.find("abc"));
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[inline]
pub fn find<'h, I: Into<Input<'h>>>(&self, input: I) -> Option<Match> {
self.try_search(&input.into()).unwrap()
}
/// Returns an iterator over all non-overlapping leftmost matches in the
/// given bytes. If no match exists, then the iterator yields no elements.
///
/// This corresponds to the "standard" regex search iterator.
///
/// # Panics
///
/// If the search returns an error during iteration, then iteration
/// panics. See [`Regex::find`] for the panic conditions.
///
/// Use [`Regex::try_search`] with
/// [`util::iter::Searcher`](crate::util::iter::Searcher) if you want to
/// handle these error conditions.
///
/// # Example
///
/// ```
/// use regex_automata::{Match, dfa::regex::Regex};
///
/// let re = Regex::new("foo[0-9]+")?;
/// let text = "foo1 foo12 foo123";
/// let matches: Vec<Match> = re.find_iter(text).collect();
/// assert_eq!(matches, vec![
/// Match::must(0, 0..4),
/// Match::must(0, 5..10),
/// Match::must(0, 11..17),
/// ]);
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[inline]
pub fn find_iter<'r, 'h, I: Into<Input<'h>>>(
&'r self,
input: I,
) -> FindMatches<'r, 'h, A> {
let it = iter::Searcher::new(input.into());
FindMatches { re: self, it }
}
}
/// Lower level fallible search routines that permit controlling where the
/// search starts and ends in a particular sequence.
impl<A: Automaton> Regex<A> {
/// Returns the start and end offset of the leftmost match. If no match
/// exists, then `None` is returned.
///
/// This is like [`Regex::find`] but with two differences:
///
/// 1. It is not generic over `Into<Input>` and instead accepts a
/// `&Input`. This permits reusing the same `Input` for multiple searches
/// without needing to create a new one. This _may_ help with latency.
/// 2. It returns an error if the search could not complete where as
/// [`Regex::find`] will panic.
///
/// # Errors
///
/// This routine errors if the search could not complete. This can occur
/// in the following circumstances:
///
/// * The configuration of the DFA may permit it to "quit" the search.
/// For example, setting quit bytes or enabling heuristic support for
/// Unicode word boundaries. The default configuration does not enable any
/// option that could result in the DFA quitting.
/// * When the provided `Input` configuration is not supported. For
/// example, by providing an unsupported anchor mode.
///
/// When a search returns an error, callers cannot know whether a match
/// exists or not.
#[inline]
pub fn try_search(
&self,
input: &Input<'_>,
) -> Result<Option<Match>, MatchError> {
let (fwd, rev) = (self.forward(), self.reverse());
let end = match fwd.try_search_fwd(input)? {
None => return Ok(None),
Some(end) => end,
};
// This special cases an empty match at the beginning of the search. If
// our end matches our start, then since a reverse DFA can't match past
// the start, it must follow that our starting position is also our end
// position. So short circuit and skip the reverse search.
if input.start() == end.offset() {
return Ok(Some(Match::new(
end.pattern(),
end.offset()..end.offset(),
)));
}
// We can also skip the reverse search if we know our search was
// anchored. This occurs either when the input config is anchored or
// when we know the regex itself is anchored. In this case, we know the
// start of the match, if one is found, must be the start of the
// search.
if self.is_anchored(input) {
return Ok(Some(Match::new(
end.pattern(),
input.start()..end.offset(),
)));
}
// N.B. I have tentatively convinced myself that it isn't necessary
// to specify the specific pattern for the reverse search since the
// reverse search will always find the same pattern to match as the
// forward search. But I lack a rigorous proof. Why not just provide
// the pattern anyway? Well, if it is needed, then leaving it out
// gives us a chance to find a witness. (Also, if we don't need to
// specify the pattern, then we don't need to build the reverse DFA
// with 'starts_for_each_pattern' enabled.)
//
// We also need to be careful to disable 'earliest' for the reverse
// search, since it could be enabled for the forward search. In the
// reverse case, to satisfy "leftmost" criteria, we need to match
// as much as we can. We also need to be careful to make the search
// anchored. We don't want the reverse search to report any matches
// other than the one beginning at the end of our forward search.
let revsearch = input
.clone()
.span(input.start()..end.offset())
.anchored(Anchored::Yes)
.earliest(false);
let start = rev
.try_search_rev(&revsearch)?
.expect("reverse search must match if forward search does");
assert_eq!(
start.pattern(),
end.pattern(),
"forward and reverse search must match same pattern",
);
assert!(start.offset() <= end.offset());
Ok(Some(Match::new(end.pattern(), start.offset()..end.offset())))
}
/// Returns true if either the given input specifies an anchored search
/// or if the underlying DFA is always anchored.
fn is_anchored(&self, input: &Input<'_>) -> bool {
match input.get_anchored() {
Anchored::No => self.forward().is_always_start_anchored(),
Anchored::Yes | Anchored::Pattern(_) => true,
}
}
}
/// Non-search APIs for querying information about the regex and setting a
/// prefilter.
impl<A: Automaton> Regex<A> {
/// Return the underlying DFA responsible for forward matching.
///
/// This is useful for accessing the underlying DFA and converting it to
/// some other format or size. See the [`Builder::build_from_dfas`] docs
/// for an example of where this might be useful.
pub fn forward(&self) -> &A {
&self.forward
}
/// Return the underlying DFA responsible for reverse matching.
///
/// This is useful for accessing the underlying DFA and converting it to
/// some other format or size. See the [`Builder::build_from_dfas`] docs
/// for an example of where this might be useful.
pub fn reverse(&self) -> &A {
&self.reverse
}
/// Returns the total number of patterns matched by this regex.
///
/// # Example
///
/// ```
/// # if cfg!(miri) { return Ok(()); } // miri takes too long
/// use regex_automata::dfa::regex::Regex;
///
/// let re = Regex::new_many(&[r"[a-z]+", r"[0-9]+", r"\w+"])?;
/// assert_eq!(3, re.pattern_len());
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn pattern_len(&self) -> usize {
assert_eq!(self.forward().pattern_len(), self.reverse().pattern_len());
self.forward().pattern_len()
}
}
/// An iterator over all non-overlapping matches for an infallible search.
///
/// The iterator yields a [`Match`] value until no more matches could be found.
/// If the underlying regex engine returns an error, then a panic occurs.
///
/// The type parameters are as follows:
///
/// * `A` represents the type of the underlying DFA that implements the
/// [`Automaton`] trait.
///
/// The lifetime parameters are as follows:
///
/// * `'h` represents the lifetime of the haystack being searched.
/// * `'r` represents the lifetime of the regex object itself.
///
/// This iterator can be created with the [`Regex::find_iter`] method.
#[derive(Debug)]
pub struct FindMatches<'r, 'h, A> {
re: &'r Regex<A>,
it: iter::Searcher<'h>,
}
impl<'r, 'h, A: Automaton> Iterator for FindMatches<'r, 'h, A> {
type Item = Match;
#[inline]
fn next(&mut self) -> Option<Match> {
let FindMatches { re, ref mut it } = *self;
it.advance(|input| re.try_search(input))
}
}
/// A builder for a regex based on deterministic finite automatons.
///
/// This builder permits configuring options for the syntax of a pattern, the
/// NFA construction, the DFA construction and finally the regex searching
/// itself. This builder is different from a general purpose regex builder in
/// that it permits fine grain configuration of the construction process. The
/// trade off for this is complexity, and the possibility of setting a
/// configuration that might not make sense. For example, there are two
/// different UTF-8 modes:
///
/// * [`syntax::Config::utf8`](crate::util::syntax::Config::utf8) controls
/// whether the pattern itself can contain sub-expressions that match invalid
/// UTF-8.
/// * [`thompson::Config::utf8`](crate::nfa::thompson::Config::utf8) controls
/// how the regex iterators themselves advance the starting position of the
/// next search when a match with zero length is found.
///
/// Generally speaking, callers will want to either enable all of these or
/// disable all of these.
///
/// Internally, building a regex requires building two DFAs, where one is
/// responsible for finding the end of a match and the other is responsible
/// for finding the start of a match. If you only need to detect whether
/// something matched, or only the end of a match, then you should use a
/// [`dense::Builder`] to construct a single DFA, which is cheaper than
/// building two DFAs.
///
/// # Build methods
///
/// This builder has a few "build" methods. In general, it's the result of
/// combining the following parameters:
///
/// * Building one or many regexes.
/// * Building a regex with dense or sparse DFAs.
///
/// The simplest "build" method is [`Builder::build`]. It accepts a single
/// pattern and builds a dense DFA using `usize` for the state identifier
/// representation.
///
/// The most general "build" method is [`Builder::build_many`], which permits
/// building a regex that searches for multiple patterns simultaneously while
/// using a specific state identifier representation.
///
/// The most flexible "build" method, but hardest to use, is
/// [`Builder::build_from_dfas`]. This exposes the fact that a [`Regex`] is
/// just a pair of DFAs, and this method allows you to specify those DFAs
/// exactly.
///
/// # Example
///
/// This example shows how to disable UTF-8 mode in the syntax and the regex
/// itself. This is generally what you want for matching on arbitrary bytes.
///
/// ```
/// # if cfg!(miri) { return Ok(()); } // miri takes too long
/// use regex_automata::{
/// dfa::regex::Regex, nfa::thompson, util::syntax, Match,
/// };
///
/// let re = Regex::builder()
/// .syntax(syntax::Config::new().utf8(false))
/// .thompson(thompson::Config::new().utf8(false))
/// .build(r"foo(?-u:[^b])ar.*")?;
/// let haystack = b"\xFEfoo\xFFarzz\xE2\x98\xFF\n";
/// let expected = Some(Match::must(0, 1..9));
/// let got = re.find(haystack);
/// assert_eq!(expected, got);
/// // Notice that `(?-u:[^b])` matches invalid UTF-8,
/// // but the subsequent `.*` does not! Disabling UTF-8
/// // on the syntax permits this.
/// assert_eq!(b"foo\xFFarzz", &haystack[got.unwrap().range()]);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[derive(Clone, Debug)]
pub struct Builder {
#[cfg(feature = "dfa-build")]
dfa: dense::Builder,
}
impl Builder {
/// Create a new regex builder with the default configuration.
pub fn new() -> Builder {
Builder {
#[cfg(feature = "dfa-build")]
dfa: dense::Builder::new(),
}
}
/// Build a regex from the given pattern.
///
/// If there was a problem parsing or compiling the pattern, then an error
/// is returned.
#[cfg(all(feature = "syntax", feature = "dfa-build"))]
pub fn build(&self, pattern: &str) -> Result<Regex, BuildError> {
self.build_many(&[pattern])
}
/// Build a regex from the given pattern using sparse DFAs.
///
/// If there was a problem parsing or compiling the pattern, then an error
/// is returned.
#[cfg(all(feature = "syntax", feature = "dfa-build"))]
pub fn build_sparse(
&self,
pattern: &str,
) -> Result<Regex<sparse::DFA<Vec<u8>>>, BuildError> {
self.build_many_sparse(&[pattern])
}
/// Build a regex from the given patterns.
#[cfg(all(feature = "syntax", feature = "dfa-build"))]
pub fn build_many<P: AsRef<str>>(
&self,
patterns: &[P],
) -> Result<Regex, BuildError> {
let forward = self.dfa.build_many(patterns)?;
let reverse = self
.dfa
.clone()
.configure(
dense::Config::new()
.prefilter(None)
.specialize_start_states(false)
.start_kind(StartKind::Anchored)
.match_kind(MatchKind::All),
)
.thompson(crate::nfa::thompson::Config::new().reverse(true))
.build_many(patterns)?;
Ok(self.build_from_dfas(forward, reverse))
}
/// Build a sparse regex from the given patterns.
#[cfg(all(feature = "syntax", feature = "dfa-build"))]
pub fn build_many_sparse<P: AsRef<str>>(
&self,
patterns: &[P],
) -> Result<Regex<sparse::DFA<Vec<u8>>>, BuildError> {
let re = self.build_many(patterns)?;
let forward = re.forward().to_sparse()?;
let reverse = re.reverse().to_sparse()?;
Ok(self.build_from_dfas(forward, reverse))
}
/// Build a regex from its component forward and reverse DFAs.
///
/// This is useful when deserializing a regex from some arbitrary
/// memory region. This is also useful for building regexes from other
/// types of DFAs.
///
/// If you're building the DFAs from scratch instead of building new DFAs
/// from other DFAs, then you'll need to make sure that the reverse DFA is
/// configured correctly to match the intended semantics. Namely:
///
/// * It should be anchored.
/// * It should use [`MatchKind::All`] semantics.
/// * It should match in reverse.
/// * Otherwise, its configuration should match the forward DFA.
///
/// If these conditions aren't satisfied, then the behavior of searches is
/// unspecified.
///
/// Note that when using this constructor, no configuration is applied.
/// Since this routine provides the DFAs to the builder, there is no
/// opportunity to apply other configuration options.
///
/// # Example
///
/// This example is a bit a contrived. The usual use of these methods
/// would involve serializing `initial_re` somewhere and then deserializing
/// it later to build a regex. But in this case, we do everything in
/// memory.
///
/// ```
/// use regex_automata::dfa::regex::Regex;
///
/// let initial_re = Regex::new("foo[0-9]+")?;
/// assert_eq!(true, initial_re.is_match(b"foo123"));
///
/// let (fwd, rev) = (initial_re.forward(), initial_re.reverse());
/// let re = Regex::builder().build_from_dfas(fwd, rev);
/// assert_eq!(true, re.is_match(b"foo123"));
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// This example shows how to build a `Regex` that uses sparse DFAs instead
/// of dense DFAs without using one of the convenience `build_sparse`
/// routines:
///
/// ```
/// use regex_automata::dfa::regex::Regex;
///
/// let initial_re = Regex::new("foo[0-9]+")?;
/// assert_eq!(true, initial_re.is_match(b"foo123"));
///
/// let fwd = initial_re.forward().to_sparse()?;
/// let rev = initial_re.reverse().to_sparse()?;
/// let re = Regex::builder().build_from_dfas(fwd, rev);
/// assert_eq!(true, re.is_match(b"foo123"));
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn build_from_dfas<A: Automaton>(
&self,
forward: A,
reverse: A,
) -> Regex<A> {
Regex { forward, reverse }
}
/// Set the syntax configuration for this builder using
/// [`syntax::Config`](crate::util::syntax::Config).
///
/// This permits setting things like case insensitivity, Unicode and multi
/// line mode.
#[cfg(all(feature = "syntax", feature = "dfa-build"))]
pub fn syntax(
&mut self,
config: crate::util::syntax::Config,
) -> &mut Builder {
self.dfa.syntax(config);
self
}
/// Set the Thompson NFA configuration for this builder using
/// [`nfa::thompson::Config`](crate::nfa::thompson::Config).
///
/// This permits setting things like whether additional time should be
/// spent shrinking the size of the NFA.
#[cfg(all(feature = "syntax", feature = "dfa-build"))]
pub fn thompson(
&mut self,
config: crate::nfa::thompson::Config,
) -> &mut Builder {
self.dfa.thompson(config);
self
}
/// Set the dense DFA compilation configuration for this builder using
/// [`dense::Config`].
///
/// This permits setting things like whether the underlying DFAs should
/// be minimized.
#[cfg(feature = "dfa-build")]
pub fn dense(&mut self, config: dense::Config) -> &mut Builder {
self.dfa.configure(config);
self
}
}
impl Default for Builder {
fn default() -> Builder {
Builder::new()
}
}
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