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//! count occurrences of a given byte, or the number of UTF-8 code points, in a
//! byte slice, fast.
//!
//! This crate has the [`count`](fn.count.html) method to count byte
//! occurrences (for example newlines) in a larger `&[u8]` slice.
//!
//! For example:
//!
//! ```rust
//! assert_eq!(5, bytecount::count(b"Hello, this is the bytecount crate!", b' '));
//! ```
//!
//! Also there is a [`num_chars`](fn.num_chars.html) method to count
//! the number of UTF8 characters in a slice. It will work the same as
//! `str::chars().count()` for byte slices of correct UTF-8 character
//! sequences. The result will likely be off for invalid sequences,
//! although the result is guaranteed to be between `0` and
//! `[_]::len()`, inclusive.
//!
//! Example:
//!
//! ```rust
//! let sequence = "Wenn ich ein Vöglein wär, flög ich zu Dir!";
//! assert_eq!(sequence.chars().count(),
//! bytecount::num_chars(sequence.as_bytes()));
//! ```
//!
//! For completeness and easy comparison, the "naive" versions of both
//! count and num_chars are provided. Those are also faster if used on
//! predominantly small strings. The
//! [`naive_count_32`](fn.naive_count_32.html) method can be faster
//! still on small strings.
#![deny(missing_docs)]
#![cfg_attr(not(feature = "runtime-dispatch-simd"), no_std)]
#[cfg(not(feature = "runtime-dispatch-simd"))]
use core::mem;
#[cfg(feature = "runtime-dispatch-simd")]
use std::mem;
mod naive;
pub use naive::*;
mod integer_simd;
#[cfg(any(
all(feature = "runtime-dispatch-simd", any(target_arch = "x86", target_arch = "x86_64")),
feature = "generic-simd"
))]
mod simd;
/// Count occurrences of a byte in a slice of bytes, fast
///
/// # Examples
///
/// ```
/// let s = b"This is a Text with spaces";
/// let number_of_spaces = bytecount::count(s, b' ');
/// assert_eq!(number_of_spaces, 5);
/// ```
pub fn count(haystack: &[u8], needle: u8) -> usize {
if haystack.len() >= 32 {
#[cfg(all(feature = "runtime-dispatch-simd", target_arch = "x86_64"))]
{
if is_x86_feature_detected!("avx2") {
unsafe { return simd::x86_avx2::chunk_count(haystack, needle); }
}
}
#[cfg(feature = "generic-simd")]
return simd::generic::chunk_count(haystack, needle);
}
if haystack.len() >= 16 {
#[cfg(all(
feature = "runtime-dispatch-simd",
any(target_arch = "x86", target_arch = "x86_64"),
not(feature = "generic-simd")
))]
{
if is_x86_feature_detected!("sse2") {
unsafe { return simd::x86_sse2::chunk_count(haystack, needle); }
}
}
}
if haystack.len() >= mem::size_of::<usize>() {
return integer_simd::chunk_count(haystack, needle);
}
naive_count(haystack, needle)
}
/// Count the number of UTF-8 encoded Unicode codepoints in a slice of bytes, fast
///
/// This function is safe to use on any byte array, valid UTF-8 or not,
/// but the output is only meaningful for well-formed UTF-8.
///
/// # Example
///
/// ```
/// let swordfish = "メカジキ";
/// let char_count = bytecount::num_chars(swordfish.as_bytes());
/// assert_eq!(char_count, 4);
/// ```
pub fn num_chars(utf8_chars: &[u8]) -> usize {
if utf8_chars.len() >= 32 {
#[cfg(all(feature = "runtime-dispatch-simd", target_arch = "x86_64"))]
{
if is_x86_feature_detected!("avx2") {
unsafe { return simd::x86_avx2::chunk_num_chars(utf8_chars); }
}
}
#[cfg(feature = "generic-simd")]
return simd::generic::chunk_num_chars(utf8_chars);
}
if utf8_chars.len() >= 16 {
#[cfg(all(
feature = "runtime-dispatch-simd",
any(target_arch = "x86", target_arch = "x86_64"),
not(feature = "generic-simd")
))]
{
if is_x86_feature_detected!("sse2") {
unsafe { return simd::x86_sse2::chunk_num_chars(utf8_chars); }
}
}
}
if utf8_chars.len() >= mem::size_of::<usize>() {
return integer_simd::chunk_num_chars(utf8_chars);
}
naive_num_chars(utf8_chars)
}
|
