// Copyright 2014-2017 The html5ever Project Developers. See the

// COPYRIGHT file at the top-level directory of this distribution.

//

// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or

// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license

// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your

// option. This file may not be copied, modified, or distributed

// except according to those terms.

//! This module contains a single struct [`SmallCharSet`]. See its documentation for details.

//!

//! [`SmallCharSet`]: struct.SmallCharSet.html

/// Represents a set of "small characters", those with Unicode scalar

/// values less than 64.

///

/// This is stored as a bitmap, with 1 bit for each value.

#[derive(Debug, Eq, PartialEq, Clone, Copy, Hash)]

pub struct SmallCharSet {

    pub bits: u64,

}

impl SmallCharSet {

    /// Checks whether a character (u8 value below 64) is stored in the SmallCharSet.

    ///

    /// # Examples

    ///

    /// ```ignore

    /// # use markup5ever::SmallCharSet;

    /// let set = SmallCharSet {

    ///     bits: 0b00000000_01000000_00000100_00000000_00000000_00000000_00010000_00000000

    /// };

    /// assert!(set.contains(64));

    /// assert!(set.contains(b'6')); // `b'6'` is the same as 64u8

    /// ```

    #[inline]

    fn contains(&self, n: u8) -> bool {

        0 != (self.bits & (1 << (n as usize)))

    }

    /// Count the number of bytes of characters at the beginning of `buf` which are not in the set.

    ///

    /// This functionality is used in [`BufferQueue::pop_except_from`].

    ///

    /// # Examples

    ///

    /// ```

    /// # #[macro_use] extern crate markup5ever;

    /// # fn main() {

    /// let set = small_char_set!(48 49 50); // '0' '1' '2'

    /// // `test` is 4 chars, 😁 is 4 chars, then we meet a character in the set

    /// let test_str = "test😁01232afd";

    /// assert_eq!(set.nonmember_prefix_len(test_str), 8);

    /// # }

    /// ```

    ///

    /// [`BufferQueue::pop_except_from`]: buffer_queue/struct.BufferQueue.html#method.pop_except_from

    pub fn nonmember_prefix_len(&self, buf: &str) -> u32 {

        let mut n = 0;

        for b in buf.bytes() {

            if b >= 64 || !self.contains(b) {

                n += 1;

            } else {

                break;

            }

        }

        n

    }

}

#[cfg(test)]

mod test {

    #[test]

    fn nonmember_prefix() {

        for &c in ['&', '\0'].iter() {

            for x in 0..48u32 {

                for y in 0..48u32 {

                    let mut s = "x".repeat(x as usize);

                    s.push(c);

                    s.push_str(&"x".repeat(y as usize));

                    let set = small_char_set!('&' '\0');

                    assert_eq!(x, set.nonmember_prefix_len(&s));

                }

            }

        }

    }

}