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/*!
Provides packed multiple substring search, principally for a small number of
patterns.
This sub-module provides vectorized routines for quickly finding
matches of a small number of patterns. In general, users of this crate
shouldn't need to interface with this module directly, as the primary
[`AhoCorasick`](crate::AhoCorasick) searcher will use these routines
automatically as a prefilter when applicable. However, in some cases, callers
may want to bypass the Aho-Corasick machinery entirely and use this vectorized
searcher directly.
# Overview
The primary types in this sub-module are:
* [`Searcher`] executes the actual search algorithm to report matches in a
haystack.
* [`Builder`] accumulates patterns incrementally and can construct a
`Searcher`.
* [`Config`] permits tuning the searcher, and itself will produce a `Builder`
(which can then be used to build a `Searcher`). Currently, the only tuneable
knob are the match semantics, but this may be expanded in the future.
# Examples
This example shows how to create a searcher from an iterator of patterns.
By default, leftmost-first match semantics are used. (See the top-level
[`MatchKind`] type for more details about match semantics, which apply
similarly to packed substring search.)
```
use aho_corasick::{packed::{MatchKind, Searcher}, PatternID};
# fn example() -> Option<()> {
let searcher = Searcher::new(["foobar", "foo"].iter().cloned())?;
let matches: Vec<PatternID> = searcher
.find_iter("foobar")
.map(|mat| mat.pattern())
.collect();
assert_eq!(vec![PatternID::ZERO], matches);
# Some(()) }
# if cfg!(all(feature = "std", any(
# target_arch = "x86_64", target_arch = "aarch64",
# ))) {
# example().unwrap()
# } else {
# assert!(example().is_none());
# }
```
This example shows how to use [`Config`] to change the match semantics to
leftmost-longest:
```
use aho_corasick::{packed::{Config, MatchKind}, PatternID};
# fn example() -> Option<()> {
let searcher = Config::new()
.match_kind(MatchKind::LeftmostLongest)
.builder()
.add("foo")
.add("foobar")
.build()?;
let matches: Vec<PatternID> = searcher
.find_iter("foobar")
.map(|mat| mat.pattern())
.collect();
assert_eq!(vec![PatternID::must(1)], matches);
# Some(()) }
# if cfg!(all(feature = "std", any(
# target_arch = "x86_64", target_arch = "aarch64",
# ))) {
# example().unwrap()
# } else {
# assert!(example().is_none());
# }
```
# Packed substring searching
Packed substring searching refers to the use of SIMD (Single Instruction,
Multiple Data) to accelerate the detection of matches in a haystack. Unlike
conventional algorithms, such as Aho-Corasick, SIMD algorithms for substring
search tend to do better with a small number of patterns, where as Aho-Corasick
generally maintains reasonably consistent performance regardless of the number
of patterns you give it. Because of this, the vectorized searcher in this
sub-module cannot be used as a general purpose searcher, since building the
searcher may fail even when given a small number of patterns. However, in
exchange, when searching for a small number of patterns, searching can be quite
a bit faster than Aho-Corasick (sometimes by an order of magnitude).
The key take away here is that constructing a searcher from a list of patterns
is a fallible operation with no clear rules for when it will fail. While the
precise conditions under which building a searcher can fail is specifically an
implementation detail, here are some common reasons:
* Too many patterns were given. Typically, the limit is on the order of 100 or
so, but this limit may fluctuate based on available CPU features.
* The available packed algorithms require CPU features that aren't available.
For example, currently, this crate only provides packed algorithms for
`x86_64` and `aarch64`. Therefore, constructing a packed searcher on any
other target will always fail.
* Zero patterns were given, or one of the patterns given was empty. Packed
searchers require at least one pattern and that all patterns are non-empty.
* Something else about the nature of the patterns (typically based on
heuristics) suggests that a packed searcher would perform very poorly, so
no searcher is built.
*/
pub use crate::packed::api::{Builder, Config, FindIter, MatchKind, Searcher};
mod api;
mod ext;
mod pattern;
mod rabinkarp;
mod teddy;
#[cfg(all(feature = "std", test))]
mod tests;
mod vector;