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/*!
This module defines tests and test helpers for substring implementations.
*/
use alloc::{
boxed::Box,
format,
string::{String, ToString},
};
pub(crate) mod naive;
#[macro_use]
pub(crate) mod prop;
const SEEDS: &'static [Seed] = &[
Seed::new("", "", Some(0), Some(0)),
Seed::new("", "a", Some(0), Some(1)),
Seed::new("", "ab", Some(0), Some(2)),
Seed::new("", "abc", Some(0), Some(3)),
Seed::new("a", "", None, None),
Seed::new("a", "a", Some(0), Some(0)),
Seed::new("a", "aa", Some(0), Some(1)),
Seed::new("a", "ba", Some(1), Some(1)),
Seed::new("a", "bba", Some(2), Some(2)),
Seed::new("a", "bbba", Some(3), Some(3)),
Seed::new("a", "bbbab", Some(3), Some(3)),
Seed::new("a", "bbbabb", Some(3), Some(3)),
Seed::new("a", "bbbabbb", Some(3), Some(3)),
Seed::new("a", "bbbbbb", None, None),
Seed::new("ab", "", None, None),
Seed::new("ab", "a", None, None),
Seed::new("ab", "b", None, None),
Seed::new("ab", "ab", Some(0), Some(0)),
Seed::new("ab", "aab", Some(1), Some(1)),
Seed::new("ab", "aaab", Some(2), Some(2)),
Seed::new("ab", "abaab", Some(0), Some(3)),
Seed::new("ab", "baaab", Some(3), Some(3)),
Seed::new("ab", "acb", None, None),
Seed::new("ab", "abba", Some(0), Some(0)),
Seed::new("abc", "ab", None, None),
Seed::new("abc", "abc", Some(0), Some(0)),
Seed::new("abc", "abcz", Some(0), Some(0)),
Seed::new("abc", "abczz", Some(0), Some(0)),
Seed::new("abc", "zabc", Some(1), Some(1)),
Seed::new("abc", "zzabc", Some(2), Some(2)),
Seed::new("abc", "azbc", None, None),
Seed::new("abc", "abzc", None, None),
Seed::new("abczdef", "abczdefzzzzzzzzzzzzzzzzzzzz", Some(0), Some(0)),
Seed::new("abczdef", "zzzzzzzzzzzzzzzzzzzzabczdef", Some(20), Some(20)),
Seed::new(
"xyz",
"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaxyz",
Some(32),
Some(32),
),
Seed::new("\u{0}\u{15}", "\u{0}\u{15}\u{15}\u{0}", Some(0), Some(0)),
Seed::new("\u{0}\u{1e}", "\u{1e}\u{0}", None, None),
];
/// Runs a host of substring search tests.
///
/// This has support for "partial" substring search implementations only work
/// for a subset of needles/haystacks. For example, the "packed pair" substring
/// search implementation only works for haystacks of some minimum length based
/// of the pair of bytes selected and the size of the vector used.
pub(crate) struct Runner {
fwd: Option<
Box<dyn FnMut(&[u8], &[u8]) -> Option<Option<usize>> + 'static>,
>,
rev: Option<
Box<dyn FnMut(&[u8], &[u8]) -> Option<Option<usize>> + 'static>,
>,
}
impl Runner {
/// Create a new test runner for forward and reverse substring search
/// implementations.
pub(crate) fn new() -> Runner {
Runner { fwd: None, rev: None }
}
/// Run all tests. This panics on the first failure.
///
/// If the implementation being tested returns `None` for a particular
/// haystack/needle combination, then that test is skipped.
///
/// This runs tests on both the forward and reverse implementations given.
/// If either (or both) are missing, then tests for that implementation are
/// skipped.
pub(crate) fn run(self) {
if let Some(mut fwd) = self.fwd {
for seed in SEEDS.iter() {
for t in seed.generate() {
match fwd(t.haystack.as_bytes(), t.needle.as_bytes()) {
None => continue,
Some(result) => {
assert_eq!(
t.fwd, result,
"FORWARD, needle: {:?}, haystack: {:?}",
t.needle, t.haystack,
);
}
}
}
}
}
if let Some(mut rev) = self.rev {
for seed in SEEDS.iter() {
for t in seed.generate() {
match rev(t.haystack.as_bytes(), t.needle.as_bytes()) {
None => continue,
Some(result) => {
assert_eq!(
t.rev, result,
"REVERSE, needle: {:?}, haystack: {:?}",
t.needle, t.haystack,
);
}
}
}
}
}
}
/// Set the implementation for forward substring search.
///
/// If the closure returns `None`, then it is assumed that the given
/// test cannot be applied to the particular implementation and it is
/// skipped. For example, if a particular implementation only supports
/// needles or haystacks for some minimum length.
///
/// If this is not set, then forward substring search is not tested.
pub(crate) fn fwd(
mut self,
search: impl FnMut(&[u8], &[u8]) -> Option<Option<usize>> + 'static,
) -> Runner {
self.fwd = Some(Box::new(search));
self
}
/// Set the implementation for reverse substring search.
///
/// If the closure returns `None`, then it is assumed that the given
/// test cannot be applied to the particular implementation and it is
/// skipped. For example, if a particular implementation only supports
/// needles or haystacks for some minimum length.
///
/// If this is not set, then reverse substring search is not tested.
pub(crate) fn rev(
mut self,
search: impl FnMut(&[u8], &[u8]) -> Option<Option<usize>> + 'static,
) -> Runner {
self.rev = Some(Box::new(search));
self
}
}
/// A single substring test for forward and reverse searches.
#[derive(Clone, Debug)]
struct Test {
needle: String,
haystack: String,
fwd: Option<usize>,
rev: Option<usize>,
}
/// A single substring test for forward and reverse searches.
///
/// Each seed is valid on its own, but it also serves as a starting point
/// to generate more tests. Namely, we pad out the haystacks with other
/// characters so that we get more complete coverage. This is especially useful
/// for testing vector algorithms that tend to have weird special cases for
/// alignment and loop unrolling.
///
/// Padding works by assuming certain characters never otherwise appear in a
/// needle or a haystack. Neither should contain a `#` character.
#[derive(Clone, Copy, Debug)]
struct Seed {
needle: &'static str,
haystack: &'static str,
fwd: Option<usize>,
rev: Option<usize>,
}
impl Seed {
const MAX_PAD: usize = 34;
const fn new(
needle: &'static str,
haystack: &'static str,
fwd: Option<usize>,
rev: Option<usize>,
) -> Seed {
Seed { needle, haystack, fwd, rev }
}
fn generate(self) -> impl Iterator<Item = Test> {
assert!(!self.needle.contains('#'), "needle must not contain '#'");
assert!(!self.haystack.contains('#'), "haystack must not contain '#'");
(0..=Seed::MAX_PAD)
// Generate tests for padding at the beginning of haystack.
.map(move |pad| {
let needle = self.needle.to_string();
let prefix = "#".repeat(pad);
let haystack = format!("{}{}", prefix, self.haystack);
let fwd = if needle.is_empty() {
Some(0)
} else {
self.fwd.map(|i| pad + i)
};
let rev = if needle.is_empty() {
Some(haystack.len())
} else {
self.rev.map(|i| pad + i)
};
Test { needle, haystack, fwd, rev }
})
// Generate tests for padding at the end of haystack.
.chain((1..=Seed::MAX_PAD).map(move |pad| {
let needle = self.needle.to_string();
let suffix = "#".repeat(pad);
let haystack = format!("{}{}", self.haystack, suffix);
let fwd = if needle.is_empty() { Some(0) } else { self.fwd };
let rev = if needle.is_empty() {
Some(haystack.len())
} else {
self.rev
};
Test { needle, haystack, fwd, rev }
}))
}
}