1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138

//! 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)
}