Revision control
Copy as Markdown
Other Tools
use core::{
fmt::Debug,
panic::{RefUnwindSafe, UnwindSafe},
};
use alloc::{string::String, sync::Arc, vec::Vec};
use crate::{
automaton::{self, Automaton, OverlappingState},
dfa,
nfa::{contiguous, noncontiguous},
util::{
error::{BuildError, MatchError},
prefilter::Prefilter,
primitives::{PatternID, StateID},
search::{Anchored, Input, Match, MatchKind, StartKind},
},
};
/// An automaton for searching multiple strings in linear time.
///
/// The `AhoCorasick` type supports a few basic ways of constructing an
/// automaton, with the default being [`AhoCorasick::new`]. However, there
/// are a fair number of configurable options that can be set by using
/// [`AhoCorasickBuilder`] instead. Such options include, but are not limited
/// to, how matches are determined, simple case insensitivity, whether to use a
/// DFA or not and various knobs for controlling the space-vs-time trade offs
/// taken when building the automaton.
///
/// # Resource usage
///
/// Aho-Corasick automatons are always constructed in `O(p)` time, where
/// `p` is the combined length of all patterns being searched. With that
/// said, building an automaton can be fairly costly because of high constant
/// factors, particularly when enabling the [DFA](AhoCorasickKind::DFA) option
/// with [`AhoCorasickBuilder::kind`]. For this reason, it's generally a good
/// idea to build an automaton once and reuse it as much as possible.
///
/// Aho-Corasick automatons can also use a fair bit of memory. To get
/// a concrete idea of how much memory is being used, try using the
/// [`AhoCorasick::memory_usage`] method.
///
/// To give a quick idea of the differences between Aho-Corasick
/// implementations and their resource usage, here's a sample of construction
/// times and heap memory used after building an automaton from 100,000
/// randomly selected titles from Wikipedia:
///
/// * 99MB for a [`noncontiguous::NFA`] in 240ms.
/// * 21MB for a [`contiguous::NFA`] in 275ms.
/// * 1.6GB for a [`dfa::DFA`] in 1.88s.
///
/// (Note that the memory usage above reflects the size of each automaton and
/// not peak memory usage. For example, building a contiguous NFA requires
/// first building a noncontiguous NFA. Once the contiguous NFA is built, the
/// noncontiguous NFA is freed.)
///
/// This experiment very strongly argues that a contiguous NFA is often the
/// best balance in terms of resource usage. It takes a little longer to build,
/// but its memory usage is quite small. Its search speed (not listed) is
/// also often faster than a noncontiguous NFA, but a little slower than a
/// DFA. Indeed, when no specific [`AhoCorasickKind`] is used (which is the
/// default), a contiguous NFA is used in most cases.
///
/// The only "catch" to using a contiguous NFA is that, because of its variety
/// of compression tricks, it may not be able to support automatons as large as
/// what the noncontiguous NFA supports. In which case, building a contiguous
/// NFA will fail and (by default) `AhoCorasick` will automatically fall
/// back to a noncontiguous NFA. (This typically only happens when building
/// automatons from millions of patterns.) Otherwise, the small additional time
/// for building a contiguous NFA is almost certainly worth it.
///
/// # Cloning
///
/// The `AhoCorasick` type uses thread safe reference counting internally. It
/// is guaranteed that it is cheap to clone.
///
/// # Search configuration
///
/// Most of the search routines accept anything that can be cheaply converted
/// to an [`Input`]. This includes `&[u8]`, `&str` and `Input` itself.
///
/// # Construction failure
///
/// It is generally possible for building an Aho-Corasick automaton to fail.
/// Construction can fail in generally one way: when the inputs provided are
/// too big. Whether that's a pattern that is too long, too many patterns
/// or some combination of both. A first approximation for the scale at which
/// construction can fail is somewhere around "millions of patterns."
///
/// For that reason, if you're building an Aho-Corasick automaton from
/// untrusted input (or input that doesn't have any reasonable bounds on its
/// size), then it is strongly recommended to handle the possibility of an
/// error.
///
/// If you're constructing an Aho-Corasick automaton from static or trusted
/// data, then it is likely acceptable to panic (by calling `unwrap()` or
/// `expect()`) if construction fails.
///
/// # Fallibility
///
/// The `AhoCorasick` type provides a number of methods for searching, as one
/// might expect. Depending on how the Aho-Corasick automaton was built and
/// depending on the search configuration, it is possible for a search to
/// return an error. Since an error is _never_ dependent on the actual contents
/// of the haystack, this type provides both infallible and fallible methods
/// for searching. The infallible methods panic if an error occurs, and can be
/// used for convenience and when you know the search will never return an
/// error.
///
/// For example, the [`AhoCorasick::find_iter`] method is the infallible
/// version of the [`AhoCorasick::try_find_iter`] method.
///
/// Examples of errors that can occur:
///
/// * Running a search that requires [`MatchKind::Standard`] semantics (such
/// as a stream or overlapping search) with an automaton that was built with
/// [`MatchKind::LeftmostFirst`] or [`MatchKind::LeftmostLongest`] semantics.
/// * Running an anchored search with an automaton that only supports
/// unanchored searches. (By default, `AhoCorasick` only supports unanchored
/// searches. But this can be toggled with [`AhoCorasickBuilder::start_kind`].)
/// * Running an unanchored search with an automaton that only supports
/// anchored searches.
///
/// The common thread between the different types of errors is that they are
/// all rooted in the automaton construction and search configurations. If
/// those configurations are a static property of your program, then it is
/// reasonable to call infallible routines since you know an error will never
/// occur. And if one _does_ occur, then it's a bug in your program.
///
/// To re-iterate, if the patterns, build or search configuration come from
/// user or untrusted data, then you should handle errors at build or search
/// time. If only the haystack comes from user or untrusted data, then there
/// should be no need to handle errors anywhere and it is generally encouraged
/// to `unwrap()` (or `expect()`) both build and search time calls.
///
/// # Examples
///
/// This example shows how to search for occurrences of multiple patterns
/// simultaneously in a case insensitive fashion. Each match includes the
/// pattern that matched along with the byte offsets of the match.
///
/// ```
/// use aho_corasick::{AhoCorasick, PatternID};
///
/// let patterns = &["apple", "maple", "snapple"];
/// let haystack = "Nobody likes maple in their apple flavored Snapple.";
///
/// let ac = AhoCorasick::builder()
/// .ascii_case_insensitive(true)
/// .build(patterns)
/// .unwrap();
/// let mut matches = vec![];
/// for mat in ac.find_iter(haystack) {
/// matches.push((mat.pattern(), mat.start(), mat.end()));
/// }
/// assert_eq!(matches, vec![
/// (PatternID::must(1), 13, 18),
/// (PatternID::must(0), 28, 33),
/// (PatternID::must(2), 43, 50),
/// ]);
/// ```
///
/// This example shows how to replace matches with some other string:
///
/// ```
/// use aho_corasick::AhoCorasick;
///
/// let patterns = &["fox", "brown", "quick"];
/// let haystack = "The quick brown fox.";
/// let replace_with = &["sloth", "grey", "slow"];
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let result = ac.replace_all(haystack, replace_with);
/// assert_eq!(result, "The slow grey sloth.");
/// ```
#[derive(Clone)]
pub struct AhoCorasick {
/// The underlying Aho-Corasick automaton. It's one of
/// nfa::noncontiguous::NFA, nfa::contiguous::NFA or dfa::DFA.
aut: Arc<dyn AcAutomaton>,
/// The specific Aho-Corasick kind chosen. This makes it possible to
/// inspect any `AhoCorasick` and know what kind of search strategy it
/// uses.
kind: AhoCorasickKind,
/// The start kind of this automaton as configured by the caller.
///
/// We don't really *need* to put this here, since the underlying automaton
/// will correctly return errors if the caller requests an unsupported
/// search type. But we do keep this here for API behavior consistency.
/// Namely, the NFAs in this crate support both unanchored and anchored
/// searches unconditionally. There's no way to disable one or the other.
/// They always both work. But the DFA in this crate specifically only
/// supports both unanchored and anchored searches if it's configured to
/// do so. Why? Because for the DFA, supporting both essentially requires
/// two copies of the transition table: one generated by following failure
/// transitions from the original NFA and one generated by not following
/// those failure transitions.
///
/// So why record the start kind here? Well, consider what happens
/// when no specific 'AhoCorasickKind' is selected by the caller and
/// 'StartKind::Unanchored' is used (both are the default). It *might*
/// result in using a DFA or it might pick an NFA. If it picks an NFA, the
/// caller would then be able to run anchored searches, even though the
/// caller only asked for support for unanchored searches. Maybe that's
/// fine, but what if the DFA was chosen instead? Oops, the caller would
/// get an error.
///
/// Basically, it seems bad to return an error or not based on some
/// internal implementation choice. So we smooth things out and ensure
/// anchored searches *always* report an error when only unanchored support
/// was asked for (and vice versa), even if the underlying automaton
/// supports it.
start_kind: StartKind,
}
/// Convenience constructors for an Aho-Corasick searcher. To configure the
/// searcher, use an [`AhoCorasickBuilder`] instead.
impl AhoCorasick {
/// Create a new Aho-Corasick automaton using the default configuration.
///
/// The default configuration optimizes for less space usage, but at the
/// expense of longer search times. To change the configuration, use
/// [`AhoCorasickBuilder`].
///
/// This uses the default [`MatchKind::Standard`] match semantics, which
/// reports a match as soon as it is found. This corresponds to the
/// standard match semantics supported by textbook descriptions of the
/// Aho-Corasick algorithm.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::{AhoCorasick, PatternID};
///
/// let ac = AhoCorasick::new(&["foo", "bar", "baz"]).unwrap();
/// assert_eq!(
/// Some(PatternID::must(1)),
/// ac.find("xxx bar xxx").map(|m| m.pattern()),
/// );
/// ```
pub fn new<I, P>(patterns: I) -> Result<AhoCorasick, BuildError>
where
I: IntoIterator<Item = P>,
P: AsRef<[u8]>,
{
AhoCorasickBuilder::new().build(patterns)
}
/// A convenience method for returning a new Aho-Corasick builder.
///
/// This usually permits one to just import the `AhoCorasick` type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::{AhoCorasick, Match, MatchKind};
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(&["samwise", "sam"])
/// .unwrap();
/// assert_eq!(Some(Match::must(0, 0..7)), ac.find("samwise"));
/// ```
pub fn builder() -> AhoCorasickBuilder {
AhoCorasickBuilder::new()
}
}
/// Infallible search routines. These APIs panic when the underlying search
/// would otherwise fail. Infallible routines are useful because the errors are
/// a result of both search-time configuration and what configuration is used
/// to build the Aho-Corasick searcher. Both of these things are not usually
/// the result of user input, and thus, an error is typically indicative of a
/// programmer error. In cases where callers want errors instead of panics, use
/// the corresponding `try` method in the section below.
impl AhoCorasick {
/// Returns true if and only if this automaton matches the haystack at any
/// position.
///
/// `input` may be any type that is cheaply convertible to an `Input`. This
/// includes, but is not limited to, `&str` and `&[u8]`.
///
/// Aside from convenience, when `AhoCorasick` was built with
/// leftmost-first or leftmost-longest semantics, this might result in a
/// search that visits less of the haystack than [`AhoCorasick::find`]
/// would otherwise. (For standard semantics, matches are always
/// immediately returned once they are seen, so there is no way for this to
/// do less work in that case.)
///
/// Note that there is no corresponding fallible routine for this method.
/// If you need a fallible version of this, then [`AhoCorasick::try_find`]
/// can be used with [`Input::earliest`] enabled.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::AhoCorasick;
///
/// let ac = AhoCorasick::new(&[
/// "foo", "bar", "quux", "baz",
/// ]).unwrap();
/// assert!(ac.is_match("xxx bar xxx"));
/// assert!(!ac.is_match("xxx qux xxx"));
/// ```
pub fn is_match<'h, I: Into<Input<'h>>>(&self, input: I) -> bool {
self.aut
.try_find(&input.into().earliest(true))
.expect("AhoCorasick::try_find is not expected to fail")
.is_some()
}
/// Returns the location of the first match according to the match
/// semantics that this automaton was constructed with.
///
/// `input` may be any type that is cheaply convertible to an `Input`. This
/// includes, but is not limited to, `&str` and `&[u8]`.
///
/// This is the infallible version of [`AhoCorasick::try_find`].
///
/// # Panics
///
/// This panics when [`AhoCorasick::try_find`] would return an error.
///
/// # Examples
///
/// Basic usage, with standard semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::Standard) // default, not necessary
/// .build(patterns)
/// .unwrap();
/// let mat = ac.find(haystack).expect("should have a match");
/// assert_eq!("b", &haystack[mat.start()..mat.end()]);
/// ```
///
/// Now with leftmost-first semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let mat = ac.find(haystack).expect("should have a match");
/// assert_eq!("abc", &haystack[mat.start()..mat.end()]);
/// ```
///
/// And finally, leftmost-longest semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostLongest)
/// .build(patterns)
/// .unwrap();
/// let mat = ac.find(haystack).expect("should have a match");
/// ```
///
/// # Example: configuring a search
///
/// Because this method accepts anything that can be turned into an
/// [`Input`], it's possible to provide an `Input` directly in order to
/// configure the search. In this example, we show how to use the
/// `earliest` option to force the search to return as soon as it knows
/// a match has occurred.
///
/// ```
/// use aho_corasick::{AhoCorasick, Input, MatchKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostLongest)
/// .build(patterns)
/// .unwrap();
/// let mat = ac.find(Input::new(haystack).earliest(true))
/// .expect("should have a match");
/// // The correct leftmost-longest match here is 'abcd', but since we
/// // told the search to quit as soon as it knows a match has occurred,
/// // we get a different match back.
/// assert_eq!("b", &haystack[mat.start()..mat.end()]);
/// ```
pub fn find<'h, I: Into<Input<'h>>>(&self, input: I) -> Option<Match> {
self.try_find(input)
.expect("AhoCorasick::try_find is not expected to fail")
}
/// Returns the location of the first overlapping match in the given
/// input with respect to the current state of the underlying searcher.
///
/// `input` may be any type that is cheaply convertible to an `Input`. This
/// includes, but is not limited to, `&str` and `&[u8]`.
///
/// Overlapping searches do not report matches in their return value.
/// Instead, matches can be accessed via [`OverlappingState::get_match`]
/// after a search call.
///
/// This is the infallible version of
/// [`AhoCorasick::try_find_overlapping`].
///
/// # Panics
///
/// This panics when [`AhoCorasick::try_find_overlapping`] would
/// return an error. For example, when the Aho-Corasick searcher
/// doesn't support overlapping searches. (Only searchers built with
/// [`MatchKind::Standard`] semantics support overlapping searches.)
///
/// # Example
///
/// This shows how we can repeatedly call an overlapping search without
/// ever needing to explicitly re-slice the haystack. Overlapping search
/// works this way because searches depend on state saved during the
/// previous search.
///
/// ```
/// use aho_corasick::{
/// automaton::OverlappingState,
/// AhoCorasick, Input, Match,
/// };
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let mut state = OverlappingState::start();
///
/// ac.find_overlapping(haystack, &mut state);
/// assert_eq!(Some(Match::must(2, 0..3)), state.get_match());
///
/// ac.find_overlapping(haystack, &mut state);
/// assert_eq!(Some(Match::must(0, 0..6)), state.get_match());
///
/// ac.find_overlapping(haystack, &mut state);
/// assert_eq!(Some(Match::must(2, 11..14)), state.get_match());
///
/// ac.find_overlapping(haystack, &mut state);
/// assert_eq!(Some(Match::must(2, 22..25)), state.get_match());
///
/// ac.find_overlapping(haystack, &mut state);
/// assert_eq!(Some(Match::must(0, 22..28)), state.get_match());
///
/// ac.find_overlapping(haystack, &mut state);
/// assert_eq!(Some(Match::must(1, 22..31)), state.get_match());
///
/// // No more match matches to be found.
/// ac.find_overlapping(haystack, &mut state);
/// assert_eq!(None, state.get_match());
/// ```
pub fn find_overlapping<'h, I: Into<Input<'h>>>(
&self,
input: I,
state: &mut OverlappingState,
) {
self.try_find_overlapping(input, state).expect(
"AhoCorasick::try_find_overlapping is not expected to fail",
)
}
/// Returns an iterator of non-overlapping matches, using the match
/// semantics that this automaton was constructed with.
///
/// `input` may be any type that is cheaply convertible to an `Input`. This
/// includes, but is not limited to, `&str` and `&[u8]`.
///
/// This is the infallible version of [`AhoCorasick::try_find_iter`].
///
/// # Panics
///
/// This panics when [`AhoCorasick::try_find_iter`] would return an error.
///
/// # Examples
///
/// Basic usage, with standard semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind, PatternID};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::Standard) // default, not necessary
/// .build(patterns)
/// .unwrap();
/// let matches: Vec<PatternID> = ac
/// .find_iter(haystack)
/// .map(|mat| mat.pattern())
/// .collect();
/// assert_eq!(vec![
/// PatternID::must(2),
/// PatternID::must(2),
/// PatternID::must(2),
/// ], matches);
/// ```
///
/// Now with leftmost-first semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind, PatternID};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let matches: Vec<PatternID> = ac
/// .find_iter(haystack)
/// .map(|mat| mat.pattern())
/// .collect();
/// assert_eq!(vec![
/// PatternID::must(0),
/// PatternID::must(2),
/// PatternID::must(0),
/// ], matches);
/// ```
///
/// And finally, leftmost-longest semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind, PatternID};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostLongest)
/// .build(patterns)
/// .unwrap();
/// let matches: Vec<PatternID> = ac
/// .find_iter(haystack)
/// .map(|mat| mat.pattern())
/// .collect();
/// assert_eq!(vec![
/// PatternID::must(0),
/// PatternID::must(2),
/// PatternID::must(1),
/// ], matches);
/// ```
pub fn find_iter<'a, 'h, I: Into<Input<'h>>>(
&'a self,
input: I,
) -> FindIter<'a, 'h> {
self.try_find_iter(input)
.expect("AhoCorasick::try_find_iter is not expected to fail")
}
/// Returns an iterator of overlapping matches. Stated differently, this
/// returns an iterator of all possible matches at every position.
///
/// `input` may be any type that is cheaply convertible to an `Input`. This
/// includes, but is not limited to, `&str` and `&[u8]`.
///
/// This is the infallible version of
/// [`AhoCorasick::try_find_overlapping_iter`].
///
/// # Panics
///
/// This panics when `AhoCorasick::try_find_overlapping_iter` would return
/// an error. For example, when the Aho-Corasick searcher is built with
/// either leftmost-first or leftmost-longest match semantics. Stated
/// differently, overlapping searches require one to build the searcher
/// with [`MatchKind::Standard`] (it is the default).
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::{AhoCorasick, PatternID};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let matches: Vec<PatternID> = ac
/// .find_overlapping_iter(haystack)
/// .map(|mat| mat.pattern())
/// .collect();
/// assert_eq!(vec![
/// PatternID::must(2),
/// PatternID::must(0),
/// PatternID::must(2),
/// PatternID::must(2),
/// PatternID::must(0),
/// PatternID::must(1),
/// ], matches);
/// ```
pub fn find_overlapping_iter<'a, 'h, I: Into<Input<'h>>>(
&'a self,
input: I,
) -> FindOverlappingIter<'a, 'h> {
self.try_find_overlapping_iter(input).expect(
"AhoCorasick::try_find_overlapping_iter is not expected to fail",
)
}
/// Replace all matches with a corresponding value in the `replace_with`
/// slice given. Matches correspond to the same matches as reported by
/// [`AhoCorasick::find_iter`].
///
/// Replacements are determined by the index of the matching pattern.
/// For example, if the pattern with index `2` is found, then it is
/// replaced by `replace_with[2]`.
///
/// This is the infallible version of [`AhoCorasick::try_replace_all`].
///
/// # Panics
///
/// This panics when [`AhoCorasick::try_replace_all`] would return an
/// error.
///
/// This also panics when `replace_with.len()` does not equal
/// [`AhoCorasick::patterns_len`].
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let result = ac.replace_all(haystack, &["x", "y", "z"]);
/// assert_eq!("x the z to the xage", result);
/// ```
pub fn replace_all<B>(&self, haystack: &str, replace_with: &[B]) -> String
where
B: AsRef<str>,
{
self.try_replace_all(haystack, replace_with)
.expect("AhoCorasick::try_replace_all is not expected to fail")
}
/// Replace all matches using raw bytes with a corresponding value in the
/// `replace_with` slice given. Matches correspond to the same matches as
/// reported by [`AhoCorasick::find_iter`].
///
/// Replacements are determined by the index of the matching pattern.
/// For example, if the pattern with index `2` is found, then it is
/// replaced by `replace_with[2]`.
///
/// This is the infallible version of
/// [`AhoCorasick::try_replace_all_bytes`].
///
/// # Panics
///
/// This panics when [`AhoCorasick::try_replace_all_bytes`] would return an
/// error.
///
/// This also panics when `replace_with.len()` does not equal
/// [`AhoCorasick::patterns_len`].
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = b"append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let result = ac.replace_all_bytes(haystack, &["x", "y", "z"]);
/// assert_eq!(b"x the z to the xage".to_vec(), result);
/// ```
pub fn replace_all_bytes<B>(
&self,
haystack: &[u8],
replace_with: &[B],
) -> Vec<u8>
where
B: AsRef<[u8]>,
{
self.try_replace_all_bytes(haystack, replace_with)
.expect("AhoCorasick::try_replace_all_bytes should not fail")
}
/// Replace all matches using a closure called on each match.
/// Matches correspond to the same matches as reported by
/// [`AhoCorasick::find_iter`].
///
/// The closure accepts three parameters: the match found, the text of
/// the match and a string buffer with which to write the replaced text
/// (if any). If the closure returns `true`, then it continues to the next
/// match. If the closure returns `false`, then searching is stopped.
///
/// Note that any matches with boundaries that don't fall on a valid UTF-8
/// boundary are silently skipped.
///
/// This is the infallible version of
/// [`AhoCorasick::try_replace_all_with`].
///
/// # Panics
///
/// This panics when [`AhoCorasick::try_replace_all_with`] would return an
/// error.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let mut result = String::new();
/// ac.replace_all_with(haystack, &mut result, |mat, _, dst| {
/// dst.push_str(&mat.pattern().as_usize().to_string());
/// true
/// });
/// assert_eq!("0 the 2 to the 0age", result);
/// ```
///
/// Stopping the replacement by returning `false` (continued from the
/// example above):
///
/// ```
/// # use aho_corasick::{AhoCorasick, MatchKind, PatternID};
/// # let patterns = &["append", "appendage", "app"];
/// # let haystack = "append the app to the appendage";
/// # let ac = AhoCorasick::builder()
/// # .match_kind(MatchKind::LeftmostFirst)
/// # .build(patterns)
/// # .unwrap();
/// let mut result = String::new();
/// ac.replace_all_with(haystack, &mut result, |mat, _, dst| {
/// dst.push_str(&mat.pattern().as_usize().to_string());
/// mat.pattern() != PatternID::must(2)
/// });
/// assert_eq!("0 the 2 to the appendage", result);
/// ```
pub fn replace_all_with<F>(
&self,
haystack: &str,
dst: &mut String,
replace_with: F,
) where
F: FnMut(&Match, &str, &mut String) -> bool,
{
self.try_replace_all_with(haystack, dst, replace_with)
.expect("AhoCorasick::try_replace_all_with should not fail")
}
/// Replace all matches using raw bytes with a closure called on each
/// match. Matches correspond to the same matches as reported by
/// [`AhoCorasick::find_iter`].
///
/// The closure accepts three parameters: the match found, the text of
/// the match and a byte buffer with which to write the replaced text
/// (if any). If the closure returns `true`, then it continues to the next
/// match. If the closure returns `false`, then searching is stopped.
///
/// This is the infallible version of
/// [`AhoCorasick::try_replace_all_with_bytes`].
///
/// # Panics
///
/// This panics when [`AhoCorasick::try_replace_all_with_bytes`] would
/// return an error.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = b"append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let mut result = vec![];
/// ac.replace_all_with_bytes(haystack, &mut result, |mat, _, dst| {
/// dst.extend(mat.pattern().as_usize().to_string().bytes());
/// true
/// });
/// assert_eq!(b"0 the 2 to the 0age".to_vec(), result);
/// ```
///
/// Stopping the replacement by returning `false` (continued from the
/// example above):
///
/// ```
/// # use aho_corasick::{AhoCorasick, MatchKind, PatternID};
/// # let patterns = &["append", "appendage", "app"];
/// # let haystack = b"append the app to the appendage";
/// # let ac = AhoCorasick::builder()
/// # .match_kind(MatchKind::LeftmostFirst)
/// # .build(patterns)
/// # .unwrap();
/// let mut result = vec![];
/// ac.replace_all_with_bytes(haystack, &mut result, |mat, _, dst| {
/// dst.extend(mat.pattern().as_usize().to_string().bytes());
/// mat.pattern() != PatternID::must(2)
/// });
/// assert_eq!(b"0 the 2 to the appendage".to_vec(), result);
/// ```
pub fn replace_all_with_bytes<F>(
&self,
haystack: &[u8],
dst: &mut Vec<u8>,
replace_with: F,
) where
F: FnMut(&Match, &[u8], &mut Vec<u8>) -> bool,
{
self.try_replace_all_with_bytes(haystack, dst, replace_with)
.expect("AhoCorasick::try_replace_all_with_bytes should not fail")
}
/// Returns an iterator of non-overlapping matches in the given
/// stream. Matches correspond to the same matches as reported by
/// [`AhoCorasick::find_iter`].
///
/// The matches yielded by this iterator use absolute position offsets in
/// the stream given, where the first byte has index `0`. Matches are
/// yieled until the stream is exhausted.
///
/// Each item yielded by the iterator is an `Result<Match,
/// std::io::Error>`, where an error is yielded if there was a problem
/// reading from the reader given.
///
/// When searching a stream, an internal buffer is used. Therefore, callers
/// should avoiding providing a buffered reader, if possible.
///
/// This is the infallible version of
/// [`AhoCorasick::try_stream_find_iter`]. Note that both methods return
/// iterators that produce `Result` values. The difference is that this
/// routine panics if _construction_ of the iterator failed. The `Result`
/// values yield by the iterator come from whether the given reader returns
/// an error or not during the search.
///
/// # Memory usage
///
/// In general, searching streams will use a constant amount of memory for
/// its internal buffer. The one requirement is that the internal buffer
/// must be at least the size of the longest possible match. In most use
/// cases, the default buffer size will be much larger than any individual
/// match.
///
/// # Panics
///
/// This panics when [`AhoCorasick::try_stream_find_iter`] would return
/// an error. For example, when the Aho-Corasick searcher doesn't support
/// stream searches. (Only searchers built with [`MatchKind::Standard`]
/// semantics support stream searches.)
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::{AhoCorasick, PatternID};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let mut matches = vec![];
/// for result in ac.stream_find_iter(haystack.as_bytes()) {
/// let mat = result?;
/// matches.push(mat.pattern());
/// }
/// assert_eq!(vec![
/// PatternID::must(2),
/// PatternID::must(2),
/// PatternID::must(2),
/// ], matches);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[cfg(feature = "std")]
pub fn stream_find_iter<'a, R: std::io::Read>(
&'a self,
rdr: R,
) -> StreamFindIter<'a, R> {
self.try_stream_find_iter(rdr)
.expect("AhoCorasick::try_stream_find_iter should not fail")
}
}
/// Fallible search routines. These APIs return an error in cases where the
/// infallible routines would panic.
impl AhoCorasick {
/// Returns the location of the first match according to the match
/// semantics that this automaton was constructed with, and according
/// to the given `Input` configuration.
///
/// This is the fallible version of [`AhoCorasick::find`].
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the given `Input` configuration.
///
/// For example, if the Aho-Corasick searcher only supports anchored
/// searches or only supports unanchored searches, then providing an
/// `Input` that requests an anchored (or unanchored) search when it isn't
/// supported would result in an error.
///
/// # Example: leftmost-first searching
///
/// Basic usage with leftmost-first semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind, Input};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "foo abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let mat = ac.try_find(haystack)?.expect("should have a match");
/// assert_eq!("abc", &haystack[mat.span()]);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// # Example: anchored leftmost-first searching
///
/// This shows how to anchor the search, so that even if the haystack
/// contains a match somewhere, a match won't be reported unless one can
/// be found that starts at the beginning of the search:
///
/// ```
/// use aho_corasick::{AhoCorasick, Anchored, Input, MatchKind, StartKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "foo abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .start_kind(StartKind::Anchored)
/// .build(patterns)
/// .unwrap();
/// let input = Input::new(haystack).anchored(Anchored::Yes);
/// assert_eq!(None, ac.try_find(input)?);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// If the beginning of the search is changed to where a match begins, then
/// it will be found:
///
/// ```
/// use aho_corasick::{AhoCorasick, Anchored, Input, MatchKind, StartKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "foo abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .start_kind(StartKind::Anchored)
/// .build(patterns)
/// .unwrap();
/// let input = Input::new(haystack).range(4..).anchored(Anchored::Yes);
/// let mat = ac.try_find(input)?.expect("should have a match");
/// assert_eq!("abc", &haystack[mat.span()]);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// # Example: earliest leftmost-first searching
///
/// This shows how to run an "earliest" search even when the Aho-Corasick
/// searcher was compiled with leftmost-first match semantics. In this
/// case, the search is stopped as soon as it is known that a match has
/// occurred, even if it doesn't correspond to the leftmost-first match.
///
/// ```
/// use aho_corasick::{AhoCorasick, Input, MatchKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "foo abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let input = Input::new(haystack).earliest(true);
/// let mat = ac.try_find(input)?.expect("should have a match");
/// assert_eq!("b", &haystack[mat.span()]);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn try_find<'h, I: Into<Input<'h>>>(
&self,
input: I,
) -> Result<Option<Match>, MatchError> {
let input = input.into();
enforce_anchored_consistency(self.start_kind, input.get_anchored())?;
self.aut.try_find(&input)
}
/// Returns the location of the first overlapping match in the given
/// input with respect to the current state of the underlying searcher.
///
/// Overlapping searches do not report matches in their return value.
/// Instead, matches can be accessed via [`OverlappingState::get_match`]
/// after a search call.
///
/// This is the fallible version of [`AhoCorasick::find_overlapping`].
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the given `Input` configuration or if overlapping search is not
/// supported.
///
/// One example is that only Aho-Corasicker searchers built with
/// [`MatchKind::Standard`] semantics support overlapping searches. Using
/// any other match semantics will result in this returning an error.
///
/// # Example: basic usage
///
/// This shows how we can repeatedly call an overlapping search without
/// ever needing to explicitly re-slice the haystack. Overlapping search
/// works this way because searches depend on state saved during the
/// previous search.
///
/// ```
/// use aho_corasick::{
/// automaton::OverlappingState,
/// AhoCorasick, Input, Match,
/// };
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let mut state = OverlappingState::start();
///
/// ac.try_find_overlapping(haystack, &mut state)?;
/// assert_eq!(Some(Match::must(2, 0..3)), state.get_match());
///
/// ac.try_find_overlapping(haystack, &mut state)?;
/// assert_eq!(Some(Match::must(0, 0..6)), state.get_match());
///
/// ac.try_find_overlapping(haystack, &mut state)?;
/// assert_eq!(Some(Match::must(2, 11..14)), state.get_match());
///
/// ac.try_find_overlapping(haystack, &mut state)?;
/// assert_eq!(Some(Match::must(2, 22..25)), state.get_match());
///
/// ac.try_find_overlapping(haystack, &mut state)?;
/// assert_eq!(Some(Match::must(0, 22..28)), state.get_match());
///
/// ac.try_find_overlapping(haystack, &mut state)?;
/// assert_eq!(Some(Match::must(1, 22..31)), state.get_match());
///
/// // No more match matches to be found.
/// ac.try_find_overlapping(haystack, &mut state)?;
/// assert_eq!(None, state.get_match());
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// # Example: implementing your own overlapping iteration
///
/// The previous example can be easily adapted to implement your own
/// iteration by repeatedly calling `try_find_overlapping` until either
/// an error occurs or no more matches are reported.
///
/// This is effectively equivalent to the iterator returned by
/// [`AhoCorasick::try_find_overlapping_iter`], with the only difference
/// being that the iterator checks for errors before construction and
/// absolves the caller of needing to check for errors on every search
/// call. (Indeed, if the first `try_find_overlapping` call succeeds and
/// the same `Input` is given to subsequent calls, then all subsequent
/// calls are guaranteed to succeed.)
///
/// ```
/// use aho_corasick::{
/// automaton::OverlappingState,
/// AhoCorasick, Input, Match,
/// };
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let mut state = OverlappingState::start();
/// let mut matches = vec![];
///
/// loop {
/// ac.try_find_overlapping(haystack, &mut state)?;
/// let mat = match state.get_match() {
/// None => break,
/// Some(mat) => mat,
/// };
/// matches.push(mat);
/// }
/// let expected = vec![
/// Match::must(2, 0..3),
/// Match::must(0, 0..6),
/// Match::must(2, 11..14),
/// Match::must(2, 22..25),
/// Match::must(0, 22..28),
/// Match::must(1, 22..31),
/// ];
/// assert_eq!(expected, matches);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// # Example: anchored iteration
///
/// The previous example can also be adapted to implement
/// iteration over all anchored matches. In particular,
/// [`AhoCorasick::try_find_overlapping_iter`] does not support this
/// because it isn't totally clear what the match semantics ought to be.
///
/// In this example, we will find all overlapping matches that start at
/// the beginning of our search.
///
/// ```
/// use aho_corasick::{
/// automaton::OverlappingState,
/// AhoCorasick, Anchored, Input, Match, StartKind,
/// };
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .start_kind(StartKind::Anchored)
/// .build(patterns)
/// .unwrap();
/// let input = Input::new(haystack).anchored(Anchored::Yes);
/// let mut state = OverlappingState::start();
/// let mut matches = vec![];
///
/// loop {
/// ac.try_find_overlapping(input.clone(), &mut state)?;
/// let mat = match state.get_match() {
/// None => break,
/// Some(mat) => mat,
/// };
/// matches.push(mat);
/// }
/// let expected = vec![
/// Match::must(2, 0..3),
/// Match::must(0, 0..6),
/// ];
/// assert_eq!(expected, matches);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn try_find_overlapping<'h, I: Into<Input<'h>>>(
&self,
input: I,
state: &mut OverlappingState,
) -> Result<(), MatchError> {
let input = input.into();
enforce_anchored_consistency(self.start_kind, input.get_anchored())?;
self.aut.try_find_overlapping(&input, state)
}
/// Returns an iterator of non-overlapping matches, using the match
/// semantics that this automaton was constructed with.
///
/// This is the fallible version of [`AhoCorasick::find_iter`].
///
/// Note that the error returned by this method occurs during construction
/// of the iterator. The iterator itself yields `Match` values. That is,
/// once the iterator is constructed, the iteration itself will never
/// report an error.
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the given `Input` configuration.
///
/// For example, if the Aho-Corasick searcher only supports anchored
/// searches or only supports unanchored searches, then providing an
/// `Input` that requests an anchored (or unanchored) search when it isn't
/// supported would result in an error.
///
/// # Example: leftmost-first searching
///
/// Basic usage with leftmost-first semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, Input, MatchKind, PatternID};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let matches: Vec<PatternID> = ac
/// .try_find_iter(Input::new(haystack))?
/// .map(|mat| mat.pattern())
/// .collect();
/// assert_eq!(vec![
/// PatternID::must(0),
/// PatternID::must(2),
/// PatternID::must(0),
/// ], matches);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// # Example: anchored leftmost-first searching
///
/// This shows how to anchor the search, such that all matches must begin
/// at the starting location of the search. For an iterator, an anchored
/// search implies that all matches are adjacent.
///
/// ```
/// use aho_corasick::{
/// AhoCorasick, Anchored, Input, MatchKind, PatternID, StartKind,
/// };
///
/// let patterns = &["foo", "bar", "quux"];
/// let haystack = "fooquuxbar foo";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .start_kind(StartKind::Anchored)
/// .build(patterns)
/// .unwrap();
/// let matches: Vec<PatternID> = ac
/// .try_find_iter(Input::new(haystack).anchored(Anchored::Yes))?
/// .map(|mat| mat.pattern())
/// .collect();
/// assert_eq!(vec![
/// PatternID::must(0),
/// PatternID::must(2),
/// PatternID::must(1),
/// // The final 'foo' is not found because it is not adjacent to the
/// // 'bar' match. It needs to be adjacent because our search is
/// // anchored.
/// ], matches);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn try_find_iter<'a, 'h, I: Into<Input<'h>>>(
&'a self,
input: I,
) -> Result<FindIter<'a, 'h>, MatchError> {
let input = input.into();
enforce_anchored_consistency(self.start_kind, input.get_anchored())?;
Ok(FindIter(self.aut.try_find_iter(input)?))
}
/// Returns an iterator of overlapping matches.
///
/// This is the fallible version of [`AhoCorasick::find_overlapping_iter`].
///
/// Note that the error returned by this method occurs during construction
/// of the iterator. The iterator itself yields `Match` values. That is,
/// once the iterator is constructed, the iteration itself will never
/// report an error.
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the given `Input` configuration or does not support overlapping
/// searches.
///
/// One example is that only Aho-Corasicker searchers built with
/// [`MatchKind::Standard`] semantics support overlapping searches. Using
/// any other match semantics will result in this returning an error.
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::{AhoCorasick, Input, PatternID};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let matches: Vec<PatternID> = ac
/// .try_find_overlapping_iter(Input::new(haystack))?
/// .map(|mat| mat.pattern())
/// .collect();
/// assert_eq!(vec![
/// PatternID::must(2),
/// PatternID::must(0),
/// PatternID::must(2),
/// PatternID::must(2),
/// PatternID::must(0),
/// PatternID::must(1),
/// ], matches);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// # Example: anchored overlapping search returns an error
///
/// It isn't clear what the match semantics for anchored overlapping
/// iterators *ought* to be, so currently an error is returned. Callers
/// may use [`AhoCorasick::try_find_overlapping`] to implement their own
/// semantics if desired.
///
/// ```
/// use aho_corasick::{AhoCorasick, Anchored, Input, StartKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "appendappendage app";
///
/// let ac = AhoCorasick::builder()
/// .start_kind(StartKind::Anchored)
/// .build(patterns)
/// .unwrap();
/// let input = Input::new(haystack).anchored(Anchored::Yes);
/// assert!(ac.try_find_overlapping_iter(input).is_err());
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn try_find_overlapping_iter<'a, 'h, I: Into<Input<'h>>>(
&'a self,
input: I,
) -> Result<FindOverlappingIter<'a, 'h>, MatchError> {
let input = input.into();
enforce_anchored_consistency(self.start_kind, input.get_anchored())?;
Ok(FindOverlappingIter(self.aut.try_find_overlapping_iter(input)?))
}
/// Replace all matches with a corresponding value in the `replace_with`
/// slice given. Matches correspond to the same matches as reported by
/// [`AhoCorasick::try_find_iter`].
///
/// Replacements are determined by the index of the matching pattern.
/// For example, if the pattern with index `2` is found, then it is
/// replaced by `replace_with[2]`.
///
/// # Panics
///
/// This panics when `replace_with.len()` does not equal
/// [`AhoCorasick::patterns_len`].
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the default `Input` configuration. More specifically, this occurs only
/// when the Aho-Corasick searcher does not support unanchored searches
/// since this replacement routine always does an unanchored search.
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let result = ac.try_replace_all(haystack, &["x", "y", "z"])?;
/// assert_eq!("x the z to the xage", result);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn try_replace_all<B>(
&self,
haystack: &str,
replace_with: &[B],
) -> Result<String, MatchError>
where
B: AsRef<str>,
{
enforce_anchored_consistency(self.start_kind, Anchored::No)?;
self.aut.try_replace_all(haystack, replace_with)
}
/// Replace all matches using raw bytes with a corresponding value in the
/// `replace_with` slice given. Matches correspond to the same matches as
/// reported by [`AhoCorasick::try_find_iter`].
///
/// Replacements are determined by the index of the matching pattern.
/// For example, if the pattern with index `2` is found, then it is
/// replaced by `replace_with[2]`.
///
/// This is the fallible version of [`AhoCorasick::replace_all_bytes`].
///
/// # Panics
///
/// This panics when `replace_with.len()` does not equal
/// [`AhoCorasick::patterns_len`].
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the default `Input` configuration. More specifically, this occurs only
/// when the Aho-Corasick searcher does not support unanchored searches
/// since this replacement routine always does an unanchored search.
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = b"append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let result = ac.try_replace_all_bytes(haystack, &["x", "y", "z"])?;
/// assert_eq!(b"x the z to the xage".to_vec(), result);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn try_replace_all_bytes<B>(
&self,
haystack: &[u8],
replace_with: &[B],
) -> Result<Vec<u8>, MatchError>
where
B: AsRef<[u8]>,
{
enforce_anchored_consistency(self.start_kind, Anchored::No)?;
self.aut.try_replace_all_bytes(haystack, replace_with)
}
/// Replace all matches using a closure called on each match.
/// Matches correspond to the same matches as reported by
/// [`AhoCorasick::try_find_iter`].
///
/// The closure accepts three parameters: the match found, the text of
/// the match and a string buffer with which to write the replaced text
/// (if any). If the closure returns `true`, then it continues to the next
/// match. If the closure returns `false`, then searching is stopped.
///
/// Note that any matches with boundaries that don't fall on a valid UTF-8
/// boundary are silently skipped.
///
/// This is the fallible version of [`AhoCorasick::replace_all_with`].
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the default `Input` configuration. More specifically, this occurs only
/// when the Aho-Corasick searcher does not support unanchored searches
/// since this replacement routine always does an unanchored search.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let mut result = String::new();
/// ac.try_replace_all_with(haystack, &mut result, |mat, _, dst| {
/// dst.push_str(&mat.pattern().as_usize().to_string());
/// true
/// })?;
/// assert_eq!("0 the 2 to the 0age", result);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// Stopping the replacement by returning `false` (continued from the
/// example above):
///
/// ```
/// # use aho_corasick::{AhoCorasick, MatchKind, PatternID};
/// # let patterns = &["append", "appendage", "app"];
/// # let haystack = "append the app to the appendage";
/// # let ac = AhoCorasick::builder()
/// # .match_kind(MatchKind::LeftmostFirst)
/// # .build(patterns)
/// # .unwrap();
/// let mut result = String::new();
/// ac.try_replace_all_with(haystack, &mut result, |mat, _, dst| {
/// dst.push_str(&mat.pattern().as_usize().to_string());
/// mat.pattern() != PatternID::must(2)
/// })?;
/// assert_eq!("0 the 2 to the appendage", result);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn try_replace_all_with<F>(
&self,
haystack: &str,
dst: &mut String,
replace_with: F,
) -> Result<(), MatchError>
where
F: FnMut(&Match, &str, &mut String) -> bool,
{
enforce_anchored_consistency(self.start_kind, Anchored::No)?;
self.aut.try_replace_all_with(haystack, dst, replace_with)
}
/// Replace all matches using raw bytes with a closure called on each
/// match. Matches correspond to the same matches as reported by
/// [`AhoCorasick::try_find_iter`].
///
/// The closure accepts three parameters: the match found, the text of
/// the match and a byte buffer with which to write the replaced text
/// (if any). If the closure returns `true`, then it continues to the next
/// match. If the closure returns `false`, then searching is stopped.
///
/// This is the fallible version of
/// [`AhoCorasick::replace_all_with_bytes`].
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the default `Input` configuration. More specifically, this occurs only
/// when the Aho-Corasick searcher does not support unanchored searches
/// since this replacement routine always does an unanchored search.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = b"append the app to the appendage";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let mut result = vec![];
/// ac.try_replace_all_with_bytes(haystack, &mut result, |mat, _, dst| {
/// dst.extend(mat.pattern().as_usize().to_string().bytes());
/// true
/// })?;
/// assert_eq!(b"0 the 2 to the 0age".to_vec(), result);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// Stopping the replacement by returning `false` (continued from the
/// example above):
///
/// ```
/// # use aho_corasick::{AhoCorasick, MatchKind, PatternID};
/// # let patterns = &["append", "appendage", "app"];
/// # let haystack = b"append the app to the appendage";
/// # let ac = AhoCorasick::builder()
/// # .match_kind(MatchKind::LeftmostFirst)
/// # .build(patterns)
/// # .unwrap();
/// let mut result = vec![];
/// ac.try_replace_all_with_bytes(haystack, &mut result, |mat, _, dst| {
/// dst.extend(mat.pattern().as_usize().to_string().bytes());
/// mat.pattern() != PatternID::must(2)
/// })?;
/// assert_eq!(b"0 the 2 to the appendage".to_vec(), result);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn try_replace_all_with_bytes<F>(
&self,
haystack: &[u8],
dst: &mut Vec<u8>,
replace_with: F,
) -> Result<(), MatchError>
where
F: FnMut(&Match, &[u8], &mut Vec<u8>) -> bool,
{
enforce_anchored_consistency(self.start_kind, Anchored::No)?;
self.aut.try_replace_all_with_bytes(haystack, dst, replace_with)
}
/// Returns an iterator of non-overlapping matches in the given
/// stream. Matches correspond to the same matches as reported by
/// [`AhoCorasick::try_find_iter`].
///
/// The matches yielded by this iterator use absolute position offsets in
/// the stream given, where the first byte has index `0`. Matches are
/// yieled until the stream is exhausted.
///
/// Each item yielded by the iterator is an `Result<Match,
/// std::io::Error>`, where an error is yielded if there was a problem
/// reading from the reader given.
///
/// When searching a stream, an internal buffer is used. Therefore, callers
/// should avoiding providing a buffered reader, if possible.
///
/// This is the fallible version of [`AhoCorasick::stream_find_iter`].
/// Note that both methods return iterators that produce `Result` values.
/// The difference is that this routine returns an error if _construction_
/// of the iterator failed. The `Result` values yield by the iterator
/// come from whether the given reader returns an error or not during the
/// search.
///
/// # Memory usage
///
/// In general, searching streams will use a constant amount of memory for
/// its internal buffer. The one requirement is that the internal buffer
/// must be at least the size of the longest possible match. In most use
/// cases, the default buffer size will be much larger than any individual
/// match.
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the default `Input` configuration. More specifically, this occurs only
/// when the Aho-Corasick searcher does not support unanchored searches
/// since this stream searching routine always does an unanchored search.
///
/// This also returns an error if the searcher does not support stream
/// searches. Only searchers built with [`MatchKind::Standard`] semantics
/// support stream searches.
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::{AhoCorasick, PatternID};
///
/// let patterns = &["append", "appendage", "app"];
/// let haystack = "append the app to the appendage";
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let mut matches = vec![];
/// for result in ac.try_stream_find_iter(haystack.as_bytes())? {
/// let mat = result?;
/// matches.push(mat.pattern());
/// }
/// assert_eq!(vec![
/// PatternID::must(2),
/// PatternID::must(2),
/// PatternID::must(2),
/// ], matches);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[cfg(feature = "std")]
pub fn try_stream_find_iter<'a, R: std::io::Read>(
&'a self,
rdr: R,
) -> Result<StreamFindIter<'a, R>, MatchError> {
enforce_anchored_consistency(self.start_kind, Anchored::No)?;
self.aut.try_stream_find_iter(rdr).map(StreamFindIter)
}
/// Search for and replace all matches of this automaton in
/// the given reader, and write the replacements to the given
/// writer. Matches correspond to the same matches as reported by
/// [`AhoCorasick::try_find_iter`].
///
/// Replacements are determined by the index of the matching pattern. For
/// example, if the pattern with index `2` is found, then it is replaced by
/// `replace_with[2]`.
///
/// After all matches are replaced, the writer is _not_ flushed.
///
/// If there was a problem reading from the given reader or writing to the
/// given writer, then the corresponding `io::Error` is returned and all
/// replacement is stopped.
///
/// When searching a stream, an internal buffer is used. Therefore, callers
/// should avoiding providing a buffered reader, if possible. However,
/// callers may want to provide a buffered writer.
///
/// Note that there is currently no infallible version of this routine.
///
/// # Memory usage
///
/// In general, searching streams will use a constant amount of memory for
/// its internal buffer. The one requirement is that the internal buffer
/// must be at least the size of the longest possible match. In most use
/// cases, the default buffer size will be much larger than any individual
/// match.
///
/// # Panics
///
/// This panics when `replace_with.len()` does not equal
/// [`AhoCorasick::patterns_len`].
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the default `Input` configuration. More specifically, this occurs only
/// when the Aho-Corasick searcher does not support unanchored searches
/// since this stream searching routine always does an unanchored search.
///
/// This also returns an error if the searcher does not support stream
/// searches. Only searchers built with [`MatchKind::Standard`] semantics
/// support stream searches.
///
/// # Example: basic usage
///
/// ```
/// use aho_corasick::AhoCorasick;
///
/// let patterns = &["fox", "brown", "quick"];
/// let haystack = "The quick brown fox.";
/// let replace_with = &["sloth", "grey", "slow"];
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let mut result = vec![];
/// ac.try_stream_replace_all(
/// haystack.as_bytes(),
/// &mut result,
/// replace_with,
/// )?;
/// assert_eq!(b"The slow grey sloth.".to_vec(), result);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[cfg(feature = "std")]
pub fn try_stream_replace_all<R, W, B>(
&self,
rdr: R,
wtr: W,
replace_with: &[B],
) -> Result<(), std::io::Error>
where
R: std::io::Read,
W: std::io::Write,
B: AsRef<[u8]>,
{
enforce_anchored_consistency(self.start_kind, Anchored::No)
.map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e))?;
self.aut.try_stream_replace_all(rdr, wtr, replace_with)
}
/// Search the given reader and replace all matches of this automaton
/// using the given closure. The result is written to the given
/// writer. Matches correspond to the same matches as reported by
/// [`AhoCorasick::try_find_iter`].
///
/// The closure accepts three parameters: the match found, the text of
/// the match and the writer with which to write the replaced text (if any).
///
/// After all matches are replaced, the writer is _not_ flushed.
///
/// If there was a problem reading from the given reader or writing to the
/// given writer, then the corresponding `io::Error` is returned and all
/// replacement is stopped.
///
/// When searching a stream, an internal buffer is used. Therefore, callers
/// should avoiding providing a buffered reader, if possible. However,
/// callers may want to provide a buffered writer.
///
/// Note that there is currently no infallible version of this routine.
///
/// # Memory usage
///
/// In general, searching streams will use a constant amount of memory for
/// its internal buffer. The one requirement is that the internal buffer
/// must be at least the size of the longest possible match. In most use
/// cases, the default buffer size will be much larger than any individual
/// match.
///
/// # Errors
///
/// This returns an error when this Aho-Corasick searcher does not support
/// the default `Input` configuration. More specifically, this occurs only
/// when the Aho-Corasick searcher does not support unanchored searches
/// since this stream searching routine always does an unanchored search.
///
/// This also returns an error if the searcher does not support stream
/// searches. Only searchers built with [`MatchKind::Standard`] semantics
/// support stream searches.
///
/// # Example: basic usage
///
/// ```
/// use std::io::Write;
/// use aho_corasick::AhoCorasick;
///
/// let patterns = &["fox", "brown", "quick"];
/// let haystack = "The quick brown fox.";
///
/// let ac = AhoCorasick::new(patterns).unwrap();
/// let mut result = vec![];
/// ac.try_stream_replace_all_with(
/// haystack.as_bytes(),
/// &mut result,
/// |mat, _, wtr| {
/// wtr.write_all(mat.pattern().as_usize().to_string().as_bytes())
/// },
/// )?;
/// assert_eq!(b"The 2 1 0.".to_vec(), result);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[cfg(feature = "std")]
pub fn try_stream_replace_all_with<R, W, F>(
&self,
rdr: R,
wtr: W,
replace_with: F,
) -> Result<(), std::io::Error>
where
R: std::io::Read,
W: std::io::Write,
F: FnMut(&Match, &[u8], &mut W) -> Result<(), std::io::Error>,
{
enforce_anchored_consistency(self.start_kind, Anchored::No)
.map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e))?;
self.aut.try_stream_replace_all_with(rdr, wtr, replace_with)
}
}
/// Routines for querying information about the Aho-Corasick automaton.
impl AhoCorasick {
/// Returns the kind of the Aho-Corasick automaton used by this searcher.
///
/// Knowing the Aho-Corasick kind is principally useful for diagnostic
/// purposes. In particular, if no specific kind was given to
/// [`AhoCorasickBuilder::kind`], then one is automatically chosen and
/// this routine will report which one.
///
/// Note that the heuristics used for choosing which `AhoCorasickKind`
/// may be changed in a semver compatible release.
///
/// # Examples
///
/// ```
/// use aho_corasick::{AhoCorasick, AhoCorasickKind};
///
/// let ac = AhoCorasick::new(&["foo", "bar", "quux", "baz"]).unwrap();
/// // The specific Aho-Corasick kind chosen is not guaranteed!
/// assert_eq!(AhoCorasickKind::DFA, ac.kind());
/// ```
pub fn kind(&self) -> AhoCorasickKind {
self.kind
}
/// Returns the type of starting search configuration supported by this
/// Aho-Corasick automaton.
///
/// # Examples
///
/// ```
/// use aho_corasick::{AhoCorasick, StartKind};
///
/// let ac = AhoCorasick::new(&["foo", "bar", "quux", "baz"]).unwrap();
/// assert_eq!(StartKind::Unanchored, ac.start_kind());
/// ```
pub fn start_kind(&self) -> StartKind {
self.start_kind
}
/// Returns the match kind used by this automaton.
///
/// The match kind is important because it determines what kinds of
/// matches are returned. Also, some operations (such as overlapping
/// search and stream searching) are only supported when using the
/// [`MatchKind::Standard`] match kind.
///
/// # Examples
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let ac = AhoCorasick::new(&["foo", "bar", "quux", "baz"]).unwrap();
/// assert_eq!(MatchKind::Standard, ac.match_kind());
/// ```
pub fn match_kind(&self) -> MatchKind {
self.aut.match_kind()
}
/// Returns the length of the shortest pattern matched by this automaton.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::AhoCorasick;
///
/// let ac = AhoCorasick::new(&["foo", "bar", "quux", "baz"]).unwrap();
/// assert_eq!(3, ac.min_pattern_len());
/// ```
///
/// Note that an `AhoCorasick` automaton has a minimum length of `0` if
/// and only if it can match the empty string:
///
/// ```
/// use aho_corasick::AhoCorasick;
///
/// let ac = AhoCorasick::new(&["foo", "", "quux", "baz"]).unwrap();
/// assert_eq!(0, ac.min_pattern_len());
/// ```
pub fn min_pattern_len(&self) -> usize {
self.aut.min_pattern_len()
}
/// Returns the length of the longest pattern matched by this automaton.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::AhoCorasick;
///
/// let ac = AhoCorasick::new(&["foo", "bar", "quux", "baz"]).unwrap();
/// assert_eq!(4, ac.max_pattern_len());
/// ```
pub fn max_pattern_len(&self) -> usize {
self.aut.max_pattern_len()
}
/// Return the total number of patterns matched by this automaton.
///
/// This includes patterns that may never participate in a match. For
/// example, if [`MatchKind::LeftmostFirst`] match semantics are used, and
/// the patterns `Sam` and `Samwise` were used to build the automaton (in
/// that order), then `Samwise` can never participate in a match because
/// `Sam` will always take priority.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::AhoCorasick;
///
/// let ac = AhoCorasick::new(&["foo", "bar", "baz"]).unwrap();
/// assert_eq!(3, ac.patterns_len());
/// ```
pub fn patterns_len(&self) -> usize {
self.aut.patterns_len()
}
/// Returns the approximate total amount of heap used by this automaton, in
/// units of bytes.
///
/// # Examples
///
/// This example shows the difference in heap usage between a few
/// configurations:
///
/// ```
/// # if !cfg!(target_pointer_width = "64") { return; }
/// use aho_corasick::{AhoCorasick, AhoCorasickKind, MatchKind};
///
/// let ac = AhoCorasick::builder()
/// .kind(None) // default
/// .build(&["foobar", "bruce", "triskaidekaphobia", "springsteen"])
/// .unwrap();
/// assert_eq!(5_632, ac.memory_usage());
///
/// let ac = AhoCorasick::builder()
/// .kind(None) // default
/// .ascii_case_insensitive(true)
/// .build(&["foobar", "bruce", "triskaidekaphobia", "springsteen"])
/// .unwrap();
/// assert_eq!(11_136, ac.memory_usage());
///
/// let ac = AhoCorasick::builder()
/// .kind(Some(AhoCorasickKind::NoncontiguousNFA))
/// .ascii_case_insensitive(true)
/// .build(&["foobar", "bruce", "triskaidekaphobia", "springsteen"])
/// .unwrap();
/// assert_eq!(10_879, ac.memory_usage());
///
/// let ac = AhoCorasick::builder()
/// .kind(Some(AhoCorasickKind::ContiguousNFA))
/// .ascii_case_insensitive(true)
/// .build(&["foobar", "bruce", "triskaidekaphobia", "springsteen"])
/// .unwrap();
/// assert_eq!(2_584, ac.memory_usage());
///
/// let ac = AhoCorasick::builder()
/// .kind(Some(AhoCorasickKind::DFA))
/// .ascii_case_insensitive(true)
/// .build(&["foobar", "bruce", "triskaidekaphobia", "springsteen"])
/// .unwrap();
/// // While this shows the DFA being the biggest here by a small margin,
/// // don't let the difference fool you. With such a small number of
/// // patterns, the difference is small, but a bigger number of patterns
/// // will reveal that the rate of growth of the DFA is far bigger than
/// // the NFAs above. For a large number of patterns, it is easy for the
/// // DFA to take an order of magnitude more heap space (or more!).
/// assert_eq!(11_136, ac.memory_usage());
/// ```
pub fn memory_usage(&self) -> usize {
self.aut.memory_usage()
}
}
// We provide a manual debug impl so that we don't include the 'start_kind',
// principally because it's kind of weird to do so and because it screws with
// the carefully curated debug output for the underlying automaton.
impl core::fmt::Debug for AhoCorasick {
fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
f.debug_tuple("AhoCorasick").field(&self.aut).finish()
}
}
/// An iterator of non-overlapping matches in a particular haystack.
///
/// This iterator yields matches according to the [`MatchKind`] used by this
/// automaton.
///
/// This iterator is constructed via the [`AhoCorasick::find_iter`] and
/// [`AhoCorasick::try_find_iter`] methods.
///
/// The lifetime `'a` refers to the lifetime of the `AhoCorasick` automaton.
///
/// The lifetime `'h` refers to the lifetime of the haystack being searched.
#[derive(Debug)]
pub struct FindIter<'a, 'h>(automaton::FindIter<'a, 'h, Arc<dyn AcAutomaton>>);
impl<'a, 'h> Iterator for FindIter<'a, 'h> {
type Item = Match;
#[inline]
fn next(&mut self) -> Option<Match> {
self.0.next()
}
}
/// An iterator of overlapping matches in a particular haystack.
///
/// This iterator will report all possible matches in a particular haystack,
/// even when the matches overlap.
///
/// This iterator is constructed via the [`AhoCorasick::find_overlapping_iter`]
/// and [`AhoCorasick::try_find_overlapping_iter`] methods.
///
/// The lifetime `'a` refers to the lifetime of the `AhoCorasick` automaton.
///
/// The lifetime `'h` refers to the lifetime of the haystack being searched.
#[derive(Debug)]
pub struct FindOverlappingIter<'a, 'h>(
automaton::FindOverlappingIter<'a, 'h, Arc<dyn AcAutomaton>>,
);
impl<'a, 'h> Iterator for FindOverlappingIter<'a, 'h> {
type Item = Match;
#[inline]
fn next(&mut self) -> Option<Match> {
self.0.next()
}
}
/// An iterator that reports Aho-Corasick matches in a stream.
///
/// This iterator yields elements of type `Result<Match, std::io::Error>`,
/// where an error is reported if there was a problem reading from the
/// underlying stream. The iterator terminates only when the underlying stream
/// reaches `EOF`.
///
/// This iterator is constructed via the [`AhoCorasick::stream_find_iter`] and
/// [`AhoCorasick::try_stream_find_iter`] methods.
///
/// The type variable `R` refers to the `io::Read` stream that is being read
/// from.
///
/// The lifetime `'a` refers to the lifetime of the corresponding
/// [`AhoCorasick`] searcher.
#[cfg(feature = "std")]
#[derive(Debug)]
pub struct StreamFindIter<'a, R>(
automaton::StreamFindIter<'a, Arc<dyn AcAutomaton>, R>,
);
#[cfg(feature = "std")]
impl<'a, R: std::io::Read> Iterator for StreamFindIter<'a, R> {
type Item = Result<Match, std::io::Error>;
fn next(&mut self) -> Option<Result<Match, std::io::Error>> {
self.0.next()
}
}
/// A builder for configuring an Aho-Corasick automaton.
///
/// # Quick advice
///
/// * Use [`AhoCorasickBuilder::match_kind`] to configure your searcher
/// with [`MatchKind::LeftmostFirst`] if you want to match how backtracking
/// regex engines execute searches for `pat1|pat2|..|patN`. Use
/// [`MatchKind::LeftmostLongest`] if you want to match how POSIX regex engines
/// do it.
/// * If you need an anchored search, use [`AhoCorasickBuilder::start_kind`] to
/// set the [`StartKind::Anchored`] mode since [`StartKind::Unanchored`] is the
/// default. Or just use [`StartKind::Both`] to support both types of searches.
/// * You might want to use [`AhoCorasickBuilder::kind`] to set your searcher
/// to always use a [`AhoCorasickKind::DFA`] if search speed is critical and
/// memory usage isn't a concern. Otherwise, not setting a kind will probably
/// make the right choice for you. Beware that if you use [`StartKind::Both`]
/// to build a searcher that supports both unanchored and anchored searches
/// _and_ you set [`AhoCorasickKind::DFA`], then the DFA will essentially be
/// duplicated to support both simultaneously. This results in very high memory
/// usage.
/// * For all other options, their defaults are almost certainly what you want.
#[derive(Clone, Debug, Default)]
pub struct AhoCorasickBuilder {
nfa_noncontiguous: noncontiguous::Builder,
nfa_contiguous: contiguous::Builder,
dfa: dfa::Builder,
kind: Option<AhoCorasickKind>,
start_kind: StartKind,
}
impl AhoCorasickBuilder {
/// Create a new builder for configuring an Aho-Corasick automaton.
///
/// The builder provides a way to configure a number of things, including
/// ASCII case insensitivity and what kind of match semantics are used.
pub fn new() -> AhoCorasickBuilder {
AhoCorasickBuilder::default()
}
/// Build an Aho-Corasick automaton using the configuration set on this
/// builder.
///
/// A builder may be reused to create more automatons.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::{AhoCorasickBuilder, PatternID};
///
/// let patterns = &["foo", "bar", "baz"];
/// let ac = AhoCorasickBuilder::new().build(patterns).unwrap();
/// assert_eq!(
/// Some(PatternID::must(1)),
/// ac.find("xxx bar xxx").map(|m| m.pattern()),
/// );
/// ```
pub fn build<I, P>(&self, patterns: I) -> Result<AhoCorasick, BuildError>
where
I: IntoIterator<Item = P>,
P: AsRef<[u8]>,
{
let nfa = self.nfa_noncontiguous.build(patterns)?;
let (aut, kind): (Arc<dyn AcAutomaton>, AhoCorasickKind) =
match self.kind {
None => {
debug!(
"asked for automatic Aho-Corasick implementation, \
criteria: <patterns: {:?}, max pattern len: {:?}, \
start kind: {:?}>",
nfa.patterns_len(),
nfa.max_pattern_len(),
self.start_kind,
);
self.build_auto(nfa)
}
Some(AhoCorasickKind::NoncontiguousNFA) => {
debug!("forcefully chose noncontiguous NFA");
(Arc::new(nfa), AhoCorasickKind::NoncontiguousNFA)
}
Some(AhoCorasickKind::ContiguousNFA) => {
debug!("forcefully chose contiguous NFA");
let cnfa =
self.nfa_contiguous.build_from_noncontiguous(&nfa)?;
(Arc::new(cnfa), AhoCorasickKind::ContiguousNFA)
}
Some(AhoCorasickKind::DFA) => {
debug!("forcefully chose DFA");
let dfa = self.dfa.build_from_noncontiguous(&nfa)?;
(Arc::new(dfa), AhoCorasickKind::DFA)
}
};
Ok(AhoCorasick { aut, kind, start_kind: self.start_kind })
}
/// Implements the automatic selection logic for the Aho-Corasick
/// implementation to use. Since all Aho-Corasick automatons are built
/// from a non-contiguous NFA, the caller is responsible for building
/// that first.
fn build_auto(
&self,
nfa: noncontiguous::NFA,
) -> (Arc<dyn AcAutomaton>, AhoCorasickKind) {
// We try to build a DFA if we have a very small number of patterns,
// otherwise the memory usage just gets too crazy. We also only do it
// when the start kind is unanchored or anchored, but not both, because
// both implies two full copies of the transition table.
let try_dfa = !matches!(self.start_kind, StartKind::Both)
&& nfa.patterns_len() <= 100;
if try_dfa {
match self.dfa.build_from_noncontiguous(&nfa) {
Ok(dfa) => {
debug!("chose a DFA");
return (Arc::new(dfa), AhoCorasickKind::DFA);
}
Err(_err) => {
debug!(
"failed to build DFA, trying something else: {}",
_err
);
}
}
}
// We basically always want a contiguous NFA if the limited
// circumstances in which we use a DFA are not true. It is quite fast
// and has excellent memory usage. The only way we don't use it is if
// there are so many states that it can't fit in a contiguous NFA.
// And the only way to know that is to try to build it. Building a
// contiguous NFA is mostly just reshuffling data from a noncontiguous
// NFA, so it isn't too expensive, especially relative to building a
// noncontiguous NFA in the first place.
match self.nfa_contiguous.build_from_noncontiguous(&nfa) {
Ok(nfa) => {
debug!("chose contiguous NFA");
return (Arc::new(nfa), AhoCorasickKind::ContiguousNFA);
}
#[allow(unused_variables)] // unused when 'logging' is disabled
Err(_err) => {
debug!(
"failed to build contiguous NFA, \
trying something else: {}",
_err
);
}
}
debug!("chose non-contiguous NFA");
(Arc::new(nfa), AhoCorasickKind::NoncontiguousNFA)
}
/// Set the desired match semantics.
///
/// The default is [`MatchKind::Standard`], which corresponds to the match
/// semantics supported by the standard textbook description of the
/// Aho-Corasick algorithm. Namely, matches are reported as soon as they
/// are found. Moreover, this is the only way to get overlapping matches
/// or do stream searching.
///
/// The other kinds of match semantics that are supported are
/// [`MatchKind::LeftmostFirst`] and [`MatchKind::LeftmostLongest`]. The
/// former corresponds to the match you would get if you were to try to
/// match each pattern at each position in the haystack in the same order
/// that you give to the automaton. That is, it returns the leftmost match
/// corresponding to the earliest pattern given to the automaton. The
/// latter corresponds to finding the longest possible match among all
/// leftmost matches.
///
/// For more details on match semantics, see the [documentation for
/// `MatchKind`](MatchKind).
///
/// Note that setting this to [`MatchKind::LeftmostFirst`] or
/// [`MatchKind::LeftmostLongest`] will cause some search routines on
/// [`AhoCorasick`] to return an error (or panic if you're using the
/// infallible API). Notably, this includes stream and overlapping
/// searches.
///
/// # Examples
///
/// In these examples, we demonstrate the differences between match
/// semantics for a particular set of patterns in a specific order:
/// `b`, `abc`, `abcd`.
///
/// Standard semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::Standard) // default, not necessary
/// .build(patterns)
/// .unwrap();
/// let mat = ac.find(haystack).expect("should have a match");
/// assert_eq!("b", &haystack[mat.start()..mat.end()]);
/// ```
///
/// Leftmost-first semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .build(patterns)
/// .unwrap();
/// let mat = ac.find(haystack).expect("should have a match");
/// assert_eq!("abc", &haystack[mat.start()..mat.end()]);
/// ```
///
/// Leftmost-longest semantics:
///
/// ```
/// use aho_corasick::{AhoCorasick, MatchKind};
///
/// let patterns = &["b", "abc", "abcd"];
/// let haystack = "abcd";
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostLongest)
/// .build(patterns)
/// .unwrap();
/// let mat = ac.find(haystack).expect("should have a match");
/// assert_eq!("abcd", &haystack[mat.start()..mat.end()]);
/// ```
pub fn match_kind(&mut self, kind: MatchKind) -> &mut AhoCorasickBuilder {
self.nfa_noncontiguous.match_kind(kind);
self.nfa_contiguous.match_kind(kind);
self.dfa.match_kind(kind);
self
}
/// Sets the starting state configuration for the automaton.
///
/// Every Aho-Corasick automaton is capable of having two start states: one
/// that is used for unanchored searches and one that is used for anchored
/// searches. Some automatons, like the NFAs, support this with almost zero
/// additional cost. Other automatons, like the DFA, require two copies of
/// the underlying transition table to support both simultaneously.
///
/// Because there may be an added non-trivial cost to supporting both, it
/// is possible to configure which starting state configuration is needed.
///
/// Indeed, since anchored searches tend to be somewhat more rare,
/// _only_ unanchored searches are supported by default. Thus,
/// [`StartKind::Unanchored`] is the default.
///
/// Note that when this is set to [`StartKind::Unanchored`], then
/// running an anchored search will result in an error (or a panic
/// if using the infallible APIs). Similarly, when this is set to
/// [`StartKind::Anchored`], then running an unanchored search will
/// result in an error (or a panic if using the infallible APIs). When
/// [`StartKind::Both`] is used, then both unanchored and anchored searches
/// are always supported.
///
/// Also note that even if an `AhoCorasick` searcher is using an NFA
/// internally (which always supports both unanchored and anchored
/// searches), an error will still be reported for a search that isn't
/// supported by the configuration set via this method. This means,
/// for example, that an error is never dependent on which internal
/// implementation of Aho-Corasick is used.
///
/// # Example: anchored search
///
/// This shows how to build a searcher that only supports anchored
/// searches:
///
/// ```
/// use aho_corasick::{
/// AhoCorasick, Anchored, Input, Match, MatchKind, StartKind,
/// };
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .start_kind(StartKind::Anchored)
/// .build(&["b", "abc", "abcd"])
/// .unwrap();
///
/// // An unanchored search is not supported! An error here is guaranteed
/// // given the configuration above regardless of which kind of
/// // Aho-Corasick implementation ends up being used internally.
/// let input = Input::new("foo abcd").anchored(Anchored::No);
/// assert!(ac.try_find(input).is_err());
///
/// let input = Input::new("foo abcd").anchored(Anchored::Yes);
/// assert_eq!(None, ac.try_find(input)?);
///
/// let input = Input::new("abcd").anchored(Anchored::Yes);
/// assert_eq!(Some(Match::must(1, 0..3)), ac.try_find(input)?);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
///
/// # Example: unanchored and anchored searches
///
/// This shows how to build a searcher that supports both unanchored and
/// anchored searches:
///
/// ```
/// use aho_corasick::{
/// AhoCorasick, Anchored, Input, Match, MatchKind, StartKind,
/// };
///
/// let ac = AhoCorasick::builder()
/// .match_kind(MatchKind::LeftmostFirst)
/// .start_kind(StartKind::Both)
/// .build(&["b", "abc", "abcd"])
/// .unwrap();
///
/// let input = Input::new("foo abcd").anchored(Anchored::No);
/// assert_eq!(Some(Match::must(1, 4..7)), ac.try_find(input)?);
///
/// let input = Input::new("foo abcd").anchored(Anchored::Yes);
/// assert_eq!(None, ac.try_find(input)?);
///
/// let input = Input::new("abcd").anchored(Anchored::Yes);
/// assert_eq!(Some(Match::must(1, 0..3)), ac.try_find(input)?);
///
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn start_kind(&mut self, kind: StartKind) -> &mut AhoCorasickBuilder {
self.dfa.start_kind(kind);
self.start_kind = kind;
self
}
/// Enable ASCII-aware case insensitive matching.
///
/// When this option is enabled, searching will be performed without
/// respect to case for ASCII letters (`a-z` and `A-Z`) only.
///
/// Enabling this option does not change the search algorithm, but it may
/// increase the size of the automaton.
///
/// **NOTE:** It is unlikely that support for Unicode case folding will
/// be added in the future. The ASCII case works via a simple hack to the
/// underlying automaton, but full Unicode handling requires a fair bit of
/// sophistication. If you do need Unicode handling, you might consider
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use aho_corasick::AhoCorasick;
///
/// let patterns = &["FOO", "bAr", "BaZ"];
/// let haystack = "foo bar baz";
///
/// let ac = AhoCorasick::builder()
/// .ascii_case_insensitive(true)
/// .build(patterns)
/// .unwrap();
/// assert_eq!(3, ac.find_iter(haystack).count());
/// ```
pub fn ascii_case_insensitive(
&mut self,
yes: bool,
) -> &mut AhoCorasickBuilder {
self.nfa_noncontiguous.ascii_case_insensitive(yes);
self.nfa_contiguous.ascii_case_insensitive(yes);
self.dfa.ascii_case_insensitive(yes);
self
}
/// Choose the type of underlying automaton to use.
///
/// Currently, there are four choices:
///
/// * [`AhoCorasickKind::NoncontiguousNFA`] instructs the searcher to
/// use a [`noncontiguous::NFA`]. A noncontiguous NFA is the fastest to
/// be built, has moderate memory usage and is typically the slowest to
/// execute a search.
/// * [`AhoCorasickKind::ContiguousNFA`] instructs the searcher to use a
/// [`contiguous::NFA`]. A contiguous NFA is a little slower to build than
/// a noncontiguous NFA, has excellent memory usage and is typically a
/// little slower than a DFA for a search.
/// * [`AhoCorasickKind::DFA`] instructs the searcher to use a
/// [`dfa::DFA`]. A DFA is very slow to build, uses exorbitant amounts of
/// memory, but will typically execute searches the fastest.
/// * `None` (the default) instructs the searcher to choose the "best"
/// Aho-Corasick implementation. This choice is typically based primarily
/// on the number of patterns.
///
/// Setting this configuration does not change the time complexity for
/// constructing the Aho-Corasick automaton (which is `O(p)` where `p`
/// is the total number of patterns being compiled). Setting this to
/// [`AhoCorasickKind::DFA`] does however reduce the time complexity of
/// non-overlapping searches from `O(n + p)` to `O(n)`, where `n` is the
/// length of the haystack.
///
/// In general, you should probably stick to the default unless you have
/// some kind of reason to use a specific Aho-Corasick implementation. For
/// example, you might choose `AhoCorasickKind::DFA` if you don't care
/// about memory usage and want the fastest possible search times.
///
/// Setting this guarantees that the searcher returned uses the chosen
/// implementation. If that implementation could not be constructed, then
/// an error will be returned. In contrast, when `None` is used, it is
/// possible for it to attempt to construct, for example, a contiguous
/// NFA and have it fail. In which case, it will fall back to using a
/// noncontiguous NFA.
///
/// If `None` is given, then one may use [`AhoCorasick::kind`] to determine
/// which Aho-Corasick implementation was chosen.
///
/// Note that the heuristics used for choosing which `AhoCorasickKind`
/// may be changed in a semver compatible release.
pub fn kind(
&mut self,
kind: Option<AhoCorasickKind>,
) -> &mut AhoCorasickBuilder {
self.kind = kind;
self
}
/// Enable heuristic prefilter optimizations.
///
/// When enabled, searching will attempt to quickly skip to match
/// candidates using specialized literal search routines. A prefilter
/// cannot always be used, and is generally treated as a heuristic. It
/// can be useful to disable this if the prefilter is observed to be
/// sub-optimal for a particular workload.
///
/// Currently, prefilters are typically only active when building searchers
/// with a small (less than 100) number of patterns.
///
/// This is enabled by default.
pub fn prefilter(&mut self, yes: bool) -> &mut AhoCorasickBuilder {
self.nfa_noncontiguous.prefilter(yes);
self.nfa_contiguous.prefilter(yes);
self.dfa.prefilter(yes);
self
}
/// Set the limit on how many states use a dense representation for their
/// transitions. Other states will generally use a sparse representation.
///
/// A dense representation uses more memory but is generally faster, since
/// the next transition in a dense representation can be computed in a
/// constant number of instructions. A sparse representation uses less
/// memory but is generally slower, since the next transition in a sparse
/// representation requires executing a variable number of instructions.
///
/// This setting is only used when an Aho-Corasick implementation is used
/// that supports the dense versus sparse representation trade off. Not all
/// do.
///
/// This limit is expressed in terms of the depth of a state, i.e., the
/// number of transitions from the starting state of the automaton. The
/// idea is that most of the time searching will be spent near the starting
/// state of the automaton, so states near the start state should use a
/// dense representation. States further away from the start state would
/// then use a sparse representation.
///
/// By default, this is set to a low but non-zero number. Setting this to
/// `0` is almost never what you want, since it is likely to make searches
/// very slow due to the start state itself being forced to use a sparse
/// representation. However, it is unlikely that increasing this number
/// will help things much, since the most active states have a small depth.
/// More to the point, the memory usage increases superlinearly as this
/// number increases.
pub fn dense_depth(&mut self, depth: usize) -> &mut AhoCorasickBuilder {
self.nfa_noncontiguous.dense_depth(depth);
self.nfa_contiguous.dense_depth(depth);
self
}
/// A debug settting for whether to attempt to shrink the size of the
/// automaton's alphabet or not.
///
/// This option is enabled by default and should never be disabled unless
/// one is debugging the underlying automaton.
///
/// When enabled, some (but not all) Aho-Corasick automatons will use a map
/// from all possible bytes to their corresponding equivalence class. Each
/// equivalence class represents a set of bytes that does not discriminate
/// between a match and a non-match in the automaton.
///
/// The advantage of this map is that the size of the transition table can
/// be reduced drastically from `#states * 256 * sizeof(u32)` to
/// `#states * k * sizeof(u32)` where `k` is the number of equivalence
/// classes (rounded up to the nearest power of 2). As a result, total
/// space usage can decrease substantially. Moreover, since a smaller
/// alphabet is used, automaton compilation becomes faster as well.
///
/// **WARNING:** This is only useful for debugging automatons. Disabling
/// this does not yield any speed advantages. Namely, even when this is
/// disabled, a byte class map is still used while searching. The only
/// difference is that every byte will be forced into its own distinct
/// equivalence class. This is useful for debugging the actual generated
/// transitions because it lets one see the transitions defined on actual
/// bytes instead of the equivalence classes.
pub fn byte_classes(&mut self, yes: bool) -> &mut AhoCorasickBuilder {
self.nfa_contiguous.byte_classes(yes);
self.dfa.byte_classes(yes);
self
}
}
/// The type of Aho-Corasick implementation to use in an [`AhoCorasick`]
/// searcher.
///
/// This is principally used as an input to the
/// [`AhoCorasickBuilder::start_kind`] method. Its documentation goes into more
/// detail about each choice.
#[non_exhaustive]
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum AhoCorasickKind {
/// Use a noncontiguous NFA.
NoncontiguousNFA,
/// Use a contiguous NFA.
ContiguousNFA,
/// Use a DFA. Warning: DFAs typically use a large amount of memory.
DFA,
}
/// A trait that effectively gives us practical dynamic dispatch over anything
/// that impls `Automaton`, but without needing to add a bunch of bounds to
/// the core `Automaton` trait. Basically, we provide all of the marker traits
/// that our automatons have, in addition to `Debug` impls and requiring that
/// there is no borrowed data. Without these, the main `AhoCorasick` type would
/// not be able to meaningfully impl `Debug` or the marker traits without also
/// requiring that all impls of `Automaton` do so, which would be not great.
trait AcAutomaton:
Automaton + Debug + Send + Sync + UnwindSafe + RefUnwindSafe + 'static
{
}
impl<A> AcAutomaton for A where
A: Automaton + Debug + Send + Sync + UnwindSafe + RefUnwindSafe + 'static
{
}
impl crate::automaton::private::Sealed for Arc<dyn AcAutomaton> {}
// I'm not sure why this trait impl shows up in the docs, as the AcAutomaton
// trait is not exported. So we forcefully hide it.
//
// SAFETY: This just defers to the underlying 'AcAutomaton' and thus inherits
// its safety properties.
#[doc(hidden)]
unsafe impl Automaton for Arc<dyn AcAutomaton> {
#[inline(always)]
fn start_state(&self, anchored: Anchored) -> Result<StateID, MatchError> {
(**self).start_state(anchored)
}
#[inline(always)]
fn next_state(
&self,
anchored: Anchored,
sid: StateID,
byte: u8,
) -> StateID {
(**self).next_state(anchored, sid, byte)
}
#[inline(always)]
fn is_special(&self, sid: StateID) -> bool {
(**self).is_special(sid)
}
#[inline(always)]
fn is_dead(&self, sid: StateID) -> bool {
(**self).is_dead(sid)
}
#[inline(always)]
fn is_match(&self, sid: StateID) -> bool {
(**self).is_match(sid)
}
#[inline(always)]
fn is_start(&self, sid: StateID) -> bool {
(**self).is_start(sid)
}
#[inline(always)]
fn match_kind(&self) -> MatchKind {
(**self).match_kind()
}
#[inline(always)]
fn match_len(&self, sid: StateID) -> usize {
(**self).match_len(sid)
}
#[inline(always)]
fn match_pattern(&self, sid: StateID, index: usize) -> PatternID {
(**self).match_pattern(sid, index)
}
#[inline(always)]
fn patterns_len(&self) -> usize {
(**self).patterns_len()
}
#[inline(always)]
fn pattern_len(&self, pid: PatternID) -> usize {
(**self).pattern_len(pid)
}
#[inline(always)]
fn min_pattern_len(&self) -> usize {
(**self).min_pattern_len()
}
#[inline(always)]
fn max_pattern_len(&self) -> usize {
(**self).max_pattern_len()
}
#[inline(always)]
fn memory_usage(&self) -> usize {
(**self).memory_usage()
}
#[inline(always)]
fn prefilter(&self) -> Option<&Prefilter> {
(**self).prefilter()
}
// Even though 'try_find' and 'try_find_overlapping' each have their
// own default impls, we explicitly define them here to fix a perf bug.
// Without these explicit definitions, the default impl will wind up using
// dynamic dispatch for all 'Automaton' method calls, including things like
// 'next_state' that absolutely must get inlined or else perf is trashed.
// Defining them explicitly here like this still requires dynamic dispatch
// to call 'try_find' itself, but all uses of 'Automaton' within 'try_find'
// are monomorphized.
//
// We don't need to explicitly impl any other methods, I think, because
// they are all implemented themselves in terms of 'try_find' and
// 'try_find_overlapping'. We still might wind up with an extra virtual
// call here or there, but that's okay since it's outside of any perf
// critical areas.
#[inline(always)]
fn try_find(
&self,
input: &Input<'_>,
) -> Result<Option<Match>, MatchError> {
(**self).try_find(input)
}
#[inline(always)]
fn try_find_overlapping(
&self,
input: &Input<'_>,
state: &mut OverlappingState,
) -> Result<(), MatchError> {
(**self).try_find_overlapping(input, state)
}
}
/// Returns an error if the start state configuration does not support the
/// desired search configuration. See the internal 'AhoCorasick::start_kind'
/// field docs for more details.
fn enforce_anchored_consistency(
have: StartKind,
want: Anchored,
) -> Result<(), MatchError> {
match have {
StartKind::Both => Ok(()),
StartKind::Unanchored if !want.is_anchored() => Ok(()),
StartKind::Unanchored => Err(MatchError::invalid_input_anchored()),
StartKind::Anchored if want.is_anchored() => Ok(()),
StartKind::Anchored => Err(MatchError::invalid_input_unanchored()),
}
}