Sindbad~EG File Manager
use core::cmp;
use crate::memmem::{prefilter::Pre, util};
/// Two-Way search in the forward direction.
#[derive(Clone, Copy, Debug)]
pub(crate) struct Forward(TwoWay);
/// Two-Way search in the reverse direction.
#[derive(Clone, Copy, Debug)]
pub(crate) struct Reverse(TwoWay);
/// An implementation of the TwoWay substring search algorithm, with heuristics
/// for accelerating search based on frequency analysis.
///
/// This searcher supports forward and reverse search, although not
/// simultaneously. It runs in O(n + m) time and O(1) space, where
/// `n ~ len(needle)` and `m ~ len(haystack)`.
///
/// The implementation here roughly matches that which was developed by
/// Crochemore and Perrin in their 1991 paper "Two-way string-matching." The
/// changes in this implementation are 1) the use of zero-based indices, 2) a
/// heuristic skip table based on the last byte (borrowed from Rust's standard
/// library) and 3) the addition of heuristics for a fast skip loop. That is,
/// (3) this will detect bytes that are believed to be rare in the needle and
/// use fast vectorized instructions to find their occurrences quickly. The
/// Two-Way algorithm is then used to confirm whether a match at that location
/// occurred.
///
/// The heuristic for fast skipping is automatically shut off if it's
/// detected to be ineffective at search time. Generally, this only occurs in
/// pathological cases. But this is generally necessary in order to preserve
/// a `O(n + m)` time bound.
///
/// The code below is fairly complex and not obviously correct at all. It's
/// likely necessary to read the Two-Way paper cited above in order to fully
/// grok this code. The essence of it is:
///
/// 1) Do something to detect a "critical" position in the needle.
/// 2) For the current position in the haystack, look if needle[critical..]
/// matches at that position.
/// 3) If so, look if needle[..critical] matches.
/// 4) If a mismatch occurs, shift the search by some amount based on the
/// critical position and a pre-computed shift.
///
/// This type is wrapped in Forward and Reverse types that expose consistent
/// forward or reverse APIs.
#[derive(Clone, Copy, Debug)]
struct TwoWay {
/// A small bitset used as a quick prefilter (in addition to the faster
/// SIMD based prefilter). Namely, a bit 'i' is set if and only if b%64==i
/// for any b in the needle.
///
/// When used as a prefilter, if the last byte at the current candidate
/// position is NOT in this set, then we can skip that entire candidate
/// position (the length of the needle). This is essentially the shift
/// trick found in Boyer-Moore, but only applied to bytes that don't appear
/// in the needle.
///
/// N.B. This trick was inspired by something similar in std's
/// implementation of Two-Way.
byteset: ApproximateByteSet,
/// A critical position in needle. Specifically, this position corresponds
/// to beginning of either the minimal or maximal suffix in needle. (N.B.
/// See SuffixType below for why "minimal" isn't quite the correct word
/// here.)
///
/// This is the position at which every search begins. Namely, search
/// starts by scanning text to the right of this position, and only if
/// there's a match does the text to the left of this position get scanned.
critical_pos: usize,
/// The amount we shift by in the Two-Way search algorithm. This
/// corresponds to the "small period" and "large period" cases.
shift: Shift,
}
impl Forward {
/// Create a searcher that uses the Two-Way algorithm by searching forwards
/// through any haystack.
pub(crate) fn new(needle: &[u8]) -> Forward {
if needle.is_empty() {
return Forward(TwoWay::empty());
}
let byteset = ApproximateByteSet::new(needle);
let min_suffix = Suffix::forward(needle, SuffixKind::Minimal);
let max_suffix = Suffix::forward(needle, SuffixKind::Maximal);
let (period_lower_bound, critical_pos) =
if min_suffix.pos > max_suffix.pos {
(min_suffix.period, min_suffix.pos)
} else {
(max_suffix.period, max_suffix.pos)
};
let shift = Shift::forward(needle, period_lower_bound, critical_pos);
Forward(TwoWay { byteset, critical_pos, shift })
}
/// Find the position of the first occurrence of this searcher's needle in
/// the given haystack. If one does not exist, then return None.
///
/// This accepts prefilter state that is useful when using the same
/// searcher multiple times, such as in an iterator.
///
/// Callers must guarantee that the needle is non-empty and its length is
/// <= the haystack's length.
#[inline(always)]
pub(crate) fn find(
&self,
pre: Option<&mut Pre<'_>>,
haystack: &[u8],
needle: &[u8],
) -> Option<usize> {
debug_assert!(!needle.is_empty(), "needle should not be empty");
debug_assert!(needle.len() <= haystack.len(), "haystack too short");
match self.0.shift {
Shift::Small { period } => {
self.find_small_imp(pre, haystack, needle, period)
}
Shift::Large { shift } => {
self.find_large_imp(pre, haystack, needle, shift)
}
}
}
/// Like find, but handles the degenerate substring test cases. This is
/// only useful for conveniently testing this substring implementation in
/// isolation.
#[cfg(test)]
fn find_general(
&self,
pre: Option<&mut Pre<'_>>,
haystack: &[u8],
needle: &[u8],
) -> Option<usize> {
if needle.is_empty() {
Some(0)
} else if haystack.len() < needle.len() {
None
} else {
self.find(pre, haystack, needle)
}
}
// Each of the two search implementations below can be accelerated by a
// prefilter, but it is not always enabled. To avoid its overhead when
// its disabled, we explicitly inline each search implementation based on
// whether a prefilter will be used or not. The decision on which to use
// is made in the parent meta searcher.
#[inline(always)]
fn find_small_imp(
&self,
mut pre: Option<&mut Pre<'_>>,
haystack: &[u8],
needle: &[u8],
period: usize,
) -> Option<usize> {
let last_byte = needle.len() - 1;
let mut pos = 0;
let mut shift = 0;
while pos + needle.len() <= haystack.len() {
let mut i = cmp::max(self.0.critical_pos, shift);
if let Some(pre) = pre.as_mut() {
if pre.should_call() {
pos += pre.call(&haystack[pos..], needle)?;
shift = 0;
i = self.0.critical_pos;
if pos + needle.len() > haystack.len() {
return None;
}
}
}
if !self.0.byteset.contains(haystack[pos + last_byte]) {
pos += needle.len();
shift = 0;
continue;
}
while i < needle.len() && needle[i] == haystack[pos + i] {
i += 1;
}
if i < needle.len() {
pos += i - self.0.critical_pos + 1;
shift = 0;
} else {
let mut j = self.0.critical_pos;
while j > shift && needle[j] == haystack[pos + j] {
j -= 1;
}
if j <= shift && needle[shift] == haystack[pos + shift] {
return Some(pos);
}
pos += period;
shift = needle.len() - period;
}
}
None
}
#[inline(always)]
fn find_large_imp(
&self,
mut pre: Option<&mut Pre<'_>>,
haystack: &[u8],
needle: &[u8],
shift: usize,
) -> Option<usize> {
let last_byte = needle.len() - 1;
let mut pos = 0;
'outer: while pos + needle.len() <= haystack.len() {
if let Some(pre) = pre.as_mut() {
if pre.should_call() {
pos += pre.call(&haystack[pos..], needle)?;
if pos + needle.len() > haystack.len() {
return None;
}
}
}
if !self.0.byteset.contains(haystack[pos + last_byte]) {
pos += needle.len();
continue;
}
let mut i = self.0.critical_pos;
while i < needle.len() && needle[i] == haystack[pos + i] {
i += 1;
}
if i < needle.len() {
pos += i - self.0.critical_pos + 1;
} else {
for j in (0..self.0.critical_pos).rev() {
if needle[j] != haystack[pos + j] {
pos += shift;
continue 'outer;
}
}
return Some(pos);
}
}
None
}
}
impl Reverse {
/// Create a searcher that uses the Two-Way algorithm by searching in
/// reverse through any haystack.
pub(crate) fn new(needle: &[u8]) -> Reverse {
if needle.is_empty() {
return Reverse(TwoWay::empty());
}
let byteset = ApproximateByteSet::new(needle);
let min_suffix = Suffix::reverse(needle, SuffixKind::Minimal);
let max_suffix = Suffix::reverse(needle, SuffixKind::Maximal);
let (period_lower_bound, critical_pos) =
if min_suffix.pos < max_suffix.pos {
(min_suffix.period, min_suffix.pos)
} else {
(max_suffix.period, max_suffix.pos)
};
// let critical_pos = needle.len() - critical_pos;
let shift = Shift::reverse(needle, period_lower_bound, critical_pos);
Reverse(TwoWay { byteset, critical_pos, shift })
}
/// Find the position of the last occurrence of this searcher's needle
/// in the given haystack. If one does not exist, then return None.
///
/// This will automatically initialize prefilter state. This should only
/// be used for one-off searches.
///
/// Callers must guarantee that the needle is non-empty and its length is
/// <= the haystack's length.
#[inline(always)]
pub(crate) fn rfind(
&self,
haystack: &[u8],
needle: &[u8],
) -> Option<usize> {
debug_assert!(!needle.is_empty(), "needle should not be empty");
debug_assert!(needle.len() <= haystack.len(), "haystack too short");
// For the reverse case, we don't use a prefilter. It's plausible that
// perhaps we should, but it's a lot of additional code to do it, and
// it's not clear that it's actually worth it. If you have a really
// compelling use case for this, please file an issue.
match self.0.shift {
Shift::Small { period } => {
self.rfind_small_imp(haystack, needle, period)
}
Shift::Large { shift } => {
self.rfind_large_imp(haystack, needle, shift)
}
}
}
/// Like rfind, but handles the degenerate substring test cases. This is
/// only useful for conveniently testing this substring implementation in
/// isolation.
#[cfg(test)]
fn rfind_general(&self, haystack: &[u8], needle: &[u8]) -> Option<usize> {
if needle.is_empty() {
Some(haystack.len())
} else if haystack.len() < needle.len() {
None
} else {
self.rfind(haystack, needle)
}
}
#[inline(always)]
fn rfind_small_imp(
&self,
haystack: &[u8],
needle: &[u8],
period: usize,
) -> Option<usize> {
let nlen = needle.len();
let mut pos = haystack.len();
let mut shift = nlen;
while pos >= nlen {
if !self.0.byteset.contains(haystack[pos - nlen]) {
pos -= nlen;
shift = nlen;
continue;
}
let mut i = cmp::min(self.0.critical_pos, shift);
while i > 0 && needle[i - 1] == haystack[pos - nlen + i - 1] {
i -= 1;
}
if i > 0 || needle[0] != haystack[pos - nlen] {
pos -= self.0.critical_pos - i + 1;
shift = nlen;
} else {
let mut j = self.0.critical_pos;
while j < shift && needle[j] == haystack[pos - nlen + j] {
j += 1;
}
if j >= shift {
return Some(pos - nlen);
}
pos -= period;
shift = period;
}
}
None
}
#[inline(always)]
fn rfind_large_imp(
&self,
haystack: &[u8],
needle: &[u8],
shift: usize,
) -> Option<usize> {
let nlen = needle.len();
let mut pos = haystack.len();
while pos >= nlen {
if !self.0.byteset.contains(haystack[pos - nlen]) {
pos -= nlen;
continue;
}
let mut i = self.0.critical_pos;
while i > 0 && needle[i - 1] == haystack[pos - nlen + i - 1] {
i -= 1;
}
if i > 0 || needle[0] != haystack[pos - nlen] {
pos -= self.0.critical_pos - i + 1;
} else {
let mut j = self.0.critical_pos;
while j < nlen && needle[j] == haystack[pos - nlen + j] {
j += 1;
}
if j == nlen {
return Some(pos - nlen);
}
pos -= shift;
}
}
None
}
}
impl TwoWay {
fn empty() -> TwoWay {
TwoWay {
byteset: ApproximateByteSet::new(b""),
critical_pos: 0,
shift: Shift::Large { shift: 0 },
}
}
}
/// A representation of the amount we're allowed to shift by during Two-Way
/// search.
///
/// When computing a critical factorization of the needle, we find the position
/// of the critical factorization by finding the needle's maximal (or minimal)
/// suffix, along with the period of that suffix. It turns out that the period
/// of that suffix is a lower bound on the period of the needle itself.
///
/// This lower bound is equivalent to the actual period of the needle in
/// some cases. To describe that case, we denote the needle as `x` where
/// `x = uv` and `v` is the lexicographic maximal suffix of `v`. The lower
/// bound given here is always the period of `v`, which is `<= period(x)`. The
/// case where `period(v) == period(x)` occurs when `len(u) < (len(x) / 2)` and
/// where `u` is a suffix of `v[0..period(v)]`.
///
/// This case is important because the search algorithm for when the
/// periods are equivalent is slightly different than the search algorithm
/// for when the periods are not equivalent. In particular, when they aren't
/// equivalent, we know that the period of the needle is no less than half its
/// length. In this case, we shift by an amount less than or equal to the
/// period of the needle (determined by the maximum length of the components
/// of the critical factorization of `x`, i.e., `max(len(u), len(v))`)..
///
/// The above two cases are represented by the variants below. Each entails
/// a different instantiation of the Two-Way search algorithm.
///
/// N.B. If we could find a way to compute the exact period in all cases,
/// then we could collapse this case analysis and simplify the algorithm. The
/// Two-Way paper suggests this is possible, but more reading is required to
/// grok why the authors didn't pursue that path.
#[derive(Clone, Copy, Debug)]
enum Shift {
Small { period: usize },
Large { shift: usize },
}
impl Shift {
/// Compute the shift for a given needle in the forward direction.
///
/// This requires a lower bound on the period and a critical position.
/// These can be computed by extracting both the minimal and maximal
/// lexicographic suffixes, and choosing the right-most starting position.
/// The lower bound on the period is then the period of the chosen suffix.
fn forward(
needle: &[u8],
period_lower_bound: usize,
critical_pos: usize,
) -> Shift {
let large = cmp::max(critical_pos, needle.len() - critical_pos);
if critical_pos * 2 >= needle.len() {
return Shift::Large { shift: large };
}
let (u, v) = needle.split_at(critical_pos);
if !util::is_suffix(&v[..period_lower_bound], u) {
return Shift::Large { shift: large };
}
Shift::Small { period: period_lower_bound }
}
/// Compute the shift for a given needle in the reverse direction.
///
/// This requires a lower bound on the period and a critical position.
/// These can be computed by extracting both the minimal and maximal
/// lexicographic suffixes, and choosing the left-most starting position.
/// The lower bound on the period is then the period of the chosen suffix.
fn reverse(
needle: &[u8],
period_lower_bound: usize,
critical_pos: usize,
) -> Shift {
let large = cmp::max(critical_pos, needle.len() - critical_pos);
if (needle.len() - critical_pos) * 2 >= needle.len() {
return Shift::Large { shift: large };
}
let (v, u) = needle.split_at(critical_pos);
if !util::is_prefix(&v[v.len() - period_lower_bound..], u) {
return Shift::Large { shift: large };
}
Shift::Small { period: period_lower_bound }
}
}
/// A suffix extracted from a needle along with its period.
#[derive(Debug)]
struct Suffix {
/// The starting position of this suffix.
///
/// If this is a forward suffix, then `&bytes[pos..]` can be used. If this
/// is a reverse suffix, then `&bytes[..pos]` can be used. That is, for
/// forward suffixes, this is an inclusive starting position, where as for
/// reverse suffixes, this is an exclusive ending position.
pos: usize,
/// The period of this suffix.
///
/// Note that this is NOT necessarily the period of the string from which
/// this suffix comes from. (It is always less than or equal to the period
/// of the original string.)
period: usize,
}
impl Suffix {
fn forward(needle: &[u8], kind: SuffixKind) -> Suffix {
debug_assert!(!needle.is_empty());
// suffix represents our maximal (or minimal) suffix, along with
// its period.
let mut suffix = Suffix { pos: 0, period: 1 };
// The start of a suffix in `needle` that we are considering as a
// more maximal (or minimal) suffix than what's in `suffix`.
let mut candidate_start = 1;
// The current offset of our suffixes that we're comparing.
//
// When the characters at this offset are the same, then we mush on
// to the next position since no decision is possible. When the
// candidate's character is greater (or lesser) than the corresponding
// character than our current maximal (or minimal) suffix, then the
// current suffix is changed over to the candidate and we restart our
// search. Otherwise, the candidate suffix is no good and we restart
// our search on the next candidate.
//
// The three cases above correspond to the three cases in the loop
// below.
let mut offset = 0;
while candidate_start + offset < needle.len() {
let current = needle[suffix.pos + offset];
let candidate = needle[candidate_start + offset];
match kind.cmp(current, candidate) {
SuffixOrdering::Accept => {
suffix = Suffix { pos: candidate_start, period: 1 };
candidate_start += 1;
offset = 0;
}
SuffixOrdering::Skip => {
candidate_start += offset + 1;
offset = 0;
suffix.period = candidate_start - suffix.pos;
}
SuffixOrdering::Push => {
if offset + 1 == suffix.period {
candidate_start += suffix.period;
offset = 0;
} else {
offset += 1;
}
}
}
}
suffix
}
fn reverse(needle: &[u8], kind: SuffixKind) -> Suffix {
debug_assert!(!needle.is_empty());
// See the comments in `forward` for how this works.
let mut suffix = Suffix { pos: needle.len(), period: 1 };
if needle.len() == 1 {
return suffix;
}
let mut candidate_start = needle.len() - 1;
let mut offset = 0;
while offset < candidate_start {
let current = needle[suffix.pos - offset - 1];
let candidate = needle[candidate_start - offset - 1];
match kind.cmp(current, candidate) {
SuffixOrdering::Accept => {
suffix = Suffix { pos: candidate_start, period: 1 };
candidate_start -= 1;
offset = 0;
}
SuffixOrdering::Skip => {
candidate_start -= offset + 1;
offset = 0;
suffix.period = suffix.pos - candidate_start;
}
SuffixOrdering::Push => {
if offset + 1 == suffix.period {
candidate_start -= suffix.period;
offset = 0;
} else {
offset += 1;
}
}
}
}
suffix
}
}
/// The kind of suffix to extract.
#[derive(Clone, Copy, Debug)]
enum SuffixKind {
/// Extract the smallest lexicographic suffix from a string.
///
/// Technically, this doesn't actually pick the smallest lexicographic
/// suffix. e.g., Given the choice between `a` and `aa`, this will choose
/// the latter over the former, even though `a < aa`. The reasoning for
/// this isn't clear from the paper, but it still smells like a minimal
/// suffix.
Minimal,
/// Extract the largest lexicographic suffix from a string.
///
/// Unlike `Minimal`, this really does pick the maximum suffix. e.g., Given
/// the choice between `z` and `zz`, this will choose the latter over the
/// former.
Maximal,
}
/// The result of comparing corresponding bytes between two suffixes.
#[derive(Clone, Copy, Debug)]
enum SuffixOrdering {
/// This occurs when the given candidate byte indicates that the candidate
/// suffix is better than the current maximal (or minimal) suffix. That is,
/// the current candidate suffix should supplant the current maximal (or
/// minimal) suffix.
Accept,
/// This occurs when the given candidate byte excludes the candidate suffix
/// from being better than the current maximal (or minimal) suffix. That
/// is, the current candidate suffix should be dropped and the next one
/// should be considered.
Skip,
/// This occurs when no decision to accept or skip the candidate suffix
/// can be made, e.g., when corresponding bytes are equivalent. In this
/// case, the next corresponding bytes should be compared.
Push,
}
impl SuffixKind {
/// Returns true if and only if the given candidate byte indicates that
/// it should replace the current suffix as the maximal (or minimal)
/// suffix.
fn cmp(self, current: u8, candidate: u8) -> SuffixOrdering {
use self::SuffixOrdering::*;
match self {
SuffixKind::Minimal if candidate < current => Accept,
SuffixKind::Minimal if candidate > current => Skip,
SuffixKind::Minimal => Push,
SuffixKind::Maximal if candidate > current => Accept,
SuffixKind::Maximal if candidate < current => Skip,
SuffixKind::Maximal => Push,
}
}
}
/// A bitset used to track whether a particular byte exists in a needle or not.
///
/// Namely, bit 'i' is set if and only if byte%64==i for any byte in the
/// needle. If a particular byte in the haystack is NOT in this set, then one
/// can conclude that it is also not in the needle, and thus, one can advance
/// in the haystack by needle.len() bytes.
#[derive(Clone, Copy, Debug)]
struct ApproximateByteSet(u64);
impl ApproximateByteSet {
/// Create a new set from the given needle.
fn new(needle: &[u8]) -> ApproximateByteSet {
let mut bits = 0;
for &b in needle {
bits |= 1 << (b % 64);
}
ApproximateByteSet(bits)
}
/// Return true if and only if the given byte might be in this set. This
/// may return a false positive, but will never return a false negative.
#[inline(always)]
fn contains(&self, byte: u8) -> bool {
self.0 & (1 << (byte % 64)) != 0
}
}
#[cfg(all(test, feature = "std", not(miri)))]
mod tests {
use quickcheck::quickcheck;
use super::*;
define_memmem_quickcheck_tests!(
super::simpletests::twoway_find,
super::simpletests::twoway_rfind
);
/// Convenience wrapper for computing the suffix as a byte string.
fn get_suffix_forward(needle: &[u8], kind: SuffixKind) -> (&[u8], usize) {
let s = Suffix::forward(needle, kind);
(&needle[s.pos..], s.period)
}
/// Convenience wrapper for computing the reverse suffix as a byte string.
fn get_suffix_reverse(needle: &[u8], kind: SuffixKind) -> (&[u8], usize) {
let s = Suffix::reverse(needle, kind);
(&needle[..s.pos], s.period)
}
/// Return all of the non-empty suffixes in the given byte string.
fn suffixes(bytes: &[u8]) -> Vec<&[u8]> {
(0..bytes.len()).map(|i| &bytes[i..]).collect()
}
/// Return the lexicographically maximal suffix of the given byte string.
fn naive_maximal_suffix_forward(needle: &[u8]) -> &[u8] {
let mut sufs = suffixes(needle);
sufs.sort();
sufs.pop().unwrap()
}
/// Return the lexicographically maximal suffix of the reverse of the given
/// byte string.
fn naive_maximal_suffix_reverse(needle: &[u8]) -> Vec<u8> {
let mut reversed = needle.to_vec();
reversed.reverse();
let mut got = naive_maximal_suffix_forward(&reversed).to_vec();
got.reverse();
got
}
#[test]
fn suffix_forward() {
macro_rules! assert_suffix_min {
($given:expr, $expected:expr, $period:expr) => {
let (got_suffix, got_period) =
get_suffix_forward($given.as_bytes(), SuffixKind::Minimal);
let got_suffix = std::str::from_utf8(got_suffix).unwrap();
assert_eq!(($expected, $period), (got_suffix, got_period));
};
}
macro_rules! assert_suffix_max {
($given:expr, $expected:expr, $period:expr) => {
let (got_suffix, got_period) =
get_suffix_forward($given.as_bytes(), SuffixKind::Maximal);
let got_suffix = std::str::from_utf8(got_suffix).unwrap();
assert_eq!(($expected, $period), (got_suffix, got_period));
};
}
assert_suffix_min!("a", "a", 1);
assert_suffix_max!("a", "a", 1);
assert_suffix_min!("ab", "ab", 2);
assert_suffix_max!("ab", "b", 1);
assert_suffix_min!("ba", "a", 1);
assert_suffix_max!("ba", "ba", 2);
assert_suffix_min!("abc", "abc", 3);
assert_suffix_max!("abc", "c", 1);
assert_suffix_min!("acb", "acb", 3);
assert_suffix_max!("acb", "cb", 2);
assert_suffix_min!("cba", "a", 1);
assert_suffix_max!("cba", "cba", 3);
assert_suffix_min!("abcabc", "abcabc", 3);
assert_suffix_max!("abcabc", "cabc", 3);
assert_suffix_min!("abcabcabc", "abcabcabc", 3);
assert_suffix_max!("abcabcabc", "cabcabc", 3);
assert_suffix_min!("abczz", "abczz", 5);
assert_suffix_max!("abczz", "zz", 1);
assert_suffix_min!("zzabc", "abc", 3);
assert_suffix_max!("zzabc", "zzabc", 5);
assert_suffix_min!("aaa", "aaa", 1);
assert_suffix_max!("aaa", "aaa", 1);
assert_suffix_min!("foobar", "ar", 2);
assert_suffix_max!("foobar", "r", 1);
}
#[test]
fn suffix_reverse() {
macro_rules! assert_suffix_min {
($given:expr, $expected:expr, $period:expr) => {
let (got_suffix, got_period) =
get_suffix_reverse($given.as_bytes(), SuffixKind::Minimal);
let got_suffix = std::str::from_utf8(got_suffix).unwrap();
assert_eq!(($expected, $period), (got_suffix, got_period));
};
}
macro_rules! assert_suffix_max {
($given:expr, $expected:expr, $period:expr) => {
let (got_suffix, got_period) =
get_suffix_reverse($given.as_bytes(), SuffixKind::Maximal);
let got_suffix = std::str::from_utf8(got_suffix).unwrap();
assert_eq!(($expected, $period), (got_suffix, got_period));
};
}
assert_suffix_min!("a", "a", 1);
assert_suffix_max!("a", "a", 1);
assert_suffix_min!("ab", "a", 1);
assert_suffix_max!("ab", "ab", 2);
assert_suffix_min!("ba", "ba", 2);
assert_suffix_max!("ba", "b", 1);
assert_suffix_min!("abc", "a", 1);
assert_suffix_max!("abc", "abc", 3);
assert_suffix_min!("acb", "a", 1);
assert_suffix_max!("acb", "ac", 2);
assert_suffix_min!("cba", "cba", 3);
assert_suffix_max!("cba", "c", 1);
assert_suffix_min!("abcabc", "abca", 3);
assert_suffix_max!("abcabc", "abcabc", 3);
assert_suffix_min!("abcabcabc", "abcabca", 3);
assert_suffix_max!("abcabcabc", "abcabcabc", 3);
assert_suffix_min!("abczz", "a", 1);
assert_suffix_max!("abczz", "abczz", 5);
assert_suffix_min!("zzabc", "zza", 3);
assert_suffix_max!("zzabc", "zz", 1);
assert_suffix_min!("aaa", "aaa", 1);
assert_suffix_max!("aaa", "aaa", 1);
}
quickcheck! {
fn qc_suffix_forward_maximal(bytes: Vec<u8>) -> bool {
if bytes.is_empty() {
return true;
}
let (got, _) = get_suffix_forward(&bytes, SuffixKind::Maximal);
let expected = naive_maximal_suffix_forward(&bytes);
got == expected
}
fn qc_suffix_reverse_maximal(bytes: Vec<u8>) -> bool {
if bytes.is_empty() {
return true;
}
let (got, _) = get_suffix_reverse(&bytes, SuffixKind::Maximal);
let expected = naive_maximal_suffix_reverse(&bytes);
expected == got
}
}
}
#[cfg(test)]
mod simpletests {
use super::*;
pub(crate) fn twoway_find(
haystack: &[u8],
needle: &[u8],
) -> Option<usize> {
Forward::new(needle).find_general(None, haystack, needle)
}
pub(crate) fn twoway_rfind(
haystack: &[u8],
needle: &[u8],
) -> Option<usize> {
Reverse::new(needle).rfind_general(haystack, needle)
}
define_memmem_simple_tests!(twoway_find, twoway_rfind);
// This is a regression test caught by quickcheck that exercised a bug in
// the reverse small period handling. The bug was that we were using 'if j
// == shift' to determine if a match occurred, but the correct guard is 'if
// j >= shift', which matches the corresponding guard in the forward impl.
#[test]
fn regression_rev_small_period() {
let rfind = super::simpletests::twoway_rfind;
let haystack = "ababaz";
let needle = "abab";
assert_eq!(Some(0), rfind(haystack.as_bytes(), needle.as_bytes()));
}
}
Sindbad File Manager Version 1.0, Coded By Sindbad EG ~ The Terrorists