markup5ever\util/
smallcharset.rs

1// Copyright 2014-2017 The html5ever Project Developers. See the
2// COPYRIGHT file at the top-level directory of this distribution.
3//
4// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
5// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
7// option. This file may not be copied, modified, or distributed
8// except according to those terms.
9
10//! This module contains a single struct [`SmallCharSet`]. See its documentation for details.
11//!
12//! [`SmallCharSet`]: struct.SmallCharSet.html
13
14/// Represents a set of "small characters", those with Unicode scalar
15/// values less than 64.
16///
17/// This is stored as a bitmap, with 1 bit for each value.
18#[derive(Debug, Eq, PartialEq, Clone, Copy, Hash)]
19pub struct SmallCharSet {
20    pub bits: u64,
21}
22
23impl SmallCharSet {
24    /// Checks whether a character (u8 value below 64) is stored in the SmallCharSet.
25    ///
26    /// # Examples
27    ///
28    /// ```ignore
29    /// # use markup5ever::SmallCharSet;
30    /// let set = SmallCharSet {
31    ///     bits: 0b00000000_01000000_00000100_00000000_00000000_00000000_00010000_00000000
32    /// };
33    /// assert!(set.contains(64));
34    /// assert!(set.contains(b'6')); // `b'6'` is the same as 64u8
35    /// ```
36    #[inline]
37    fn contains(&self, n: u8) -> bool {
38        0 != (self.bits & (1 << (n as usize)))
39    }
40
41    /// Count the number of bytes of characters at the beginning of `buf` which are not in the set.
42    ///
43    /// This functionality is used in [`BufferQueue::pop_except_from`].
44    ///
45    /// # Examples
46    ///
47    /// ```
48    /// # #[macro_use] extern crate markup5ever;
49    /// # fn main() {
50    /// let set = small_char_set!(48 49 50); // '0' '1' '2'
51    /// // `test` is 4 chars, 😁 is 4 chars, then we meet a character in the set
52    /// let test_str = "test😁01232afd";
53    /// assert_eq!(set.nonmember_prefix_len(test_str), 8);
54    /// # }
55    /// ```
56    ///
57    /// [`BufferQueue::pop_except_from`]: buffer_queue/struct.BufferQueue.html#method.pop_except_from
58    pub fn nonmember_prefix_len(&self, buf: &str) -> u32 {
59        let mut n = 0;
60        for b in buf.bytes() {
61            if b >= 64 || !self.contains(b) {
62                n += 1;
63            } else {
64                break;
65            }
66        }
67        n
68    }
69}
70
71#[cfg(test)]
72mod test {
73    #[test]
74    fn nonmember_prefix() {
75        for &c in ['&', '\0'].iter() {
76            for x in 0..48u32 {
77                for y in 0..48u32 {
78                    let mut s = "x".repeat(x as usize);
79                    s.push(c);
80                    s.push_str(&"x".repeat(y as usize));
81                    let set = small_char_set!('&' '\0');
82
83                    assert_eq!(x, set.nonmember_prefix_len(&s));
84                }
85            }
86        }
87    }
88}
markup5ever\util/smallcharset.rs

markup5ever\util/
smallcharset.rs
