// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// 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.

//! Operations on ASCII strings and characters.
//!
//! Most string operations in Rust act on UTF-8 strings. However, at times it
//! makes more sense to only consider the ASCII character set for a specific
//! operation.
//!
//! The [`escape_default`] function provides an iterator over the bytes of an
//! escaped version of the character given.
//!
//! [`escape_default`]: fn.escape_default.html

#![stable(feature = "rust1", since = "1.0.0")]

use fmt;
use ops::Range;
use iter::FusedIterator;

/// An iterator over the escaped version of a byte.
///
/// This `struct` is created by the [`escape_default`] function. See its
/// documentation for more.
///
/// [`escape_default`]: fn.escape_default.html
#[unstable(feature = "core_ascii", issue = "46409")]
pub struct EscapeDefault {
    range: Range<usize>,
    data: [u8; 4],
}

/// Returns an iterator that produces an escaped version of a `u8`.
///
/// The default is chosen with a bias toward producing literals that are
/// legal in a variety of languages, including C++11 and similar C-family
/// languages. The exact rules are:
///
/// * Tab is escaped as `\t`.
/// * Carriage return is escaped as `\r`.
/// * Line feed is escaped as `\n`.
/// * Single quote is escaped as `\'`.
/// * Double quote is escaped as `\"`.
/// * Backslash is escaped as `\\`.
/// * Any character in the 'printable ASCII' range `0x20` .. `0x7e`
///   inclusive is not escaped.
/// * Any other chars are given hex escapes of the form '\xNN'.
/// * Unicode escapes are never generated by this function.
///
/// # Examples
///
/// ```
/// #![no_std]
/// use core::ascii;
///
/// let escaped = ascii::escape_default(b'0').next().unwrap();
/// assert_eq!(b'0', escaped);
///
/// let mut escaped = ascii::escape_default(b'\t');
///
/// assert_eq!(b'\\', escaped.next().unwrap());
/// assert_eq!(b't', escaped.next().unwrap());
///
/// let mut escaped = ascii::escape_default(b'\r');
///
/// assert_eq!(b'\\', escaped.next().unwrap());
/// assert_eq!(b'r', escaped.next().unwrap());
///
/// let mut escaped = ascii::escape_default(b'\n');
///
/// assert_eq!(b'\\', escaped.next().unwrap());
/// assert_eq!(b'n', escaped.next().unwrap());
///
/// let mut escaped = ascii::escape_default(b'\'');
///
/// assert_eq!(b'\\', escaped.next().unwrap());
/// assert_eq!(b'\'', escaped.next().unwrap());
///
/// let mut escaped = ascii::escape_default(b'"');
///
/// assert_eq!(b'\\', escaped.next().unwrap());
/// assert_eq!(b'"', escaped.next().unwrap());
///
/// let mut escaped = ascii::escape_default(b'\\');
///
/// assert_eq!(b'\\', escaped.next().unwrap());
/// assert_eq!(b'\\', escaped.next().unwrap());
///
/// let mut escaped = ascii::escape_default(b'\x9d');
///
/// assert_eq!(b'\\', escaped.next().unwrap());
/// assert_eq!(b'x', escaped.next().unwrap());
/// assert_eq!(b'9', escaped.next().unwrap());
/// assert_eq!(b'd', escaped.next().unwrap());
/// ```
#[unstable(feature = "core_ascii", issue = "46409")]
pub fn escape_default(c: u8) -> EscapeDefault {
    let (data, len) = match c {
        b'\t' => ([b'\\', b't', 0, 0], 2),
        b'\r' => ([b'\\', b'r', 0, 0], 2),
        b'\n' => ([b'\\', b'n', 0, 0], 2),
        b'\\' => ([b'\\', b'\\', 0, 0], 2),
        b'\'' => ([b'\\', b'\'', 0, 0], 2),
        b'"' => ([b'\\', b'"', 0, 0], 2),
        b'\x20' ... b'\x7e' => ([c, 0, 0, 0], 1),
        _ => ([b'\\', b'x', hexify(c >> 4), hexify(c & 0xf)], 4),
    };

    return EscapeDefault { range: 0..len, data };

    fn hexify(b: u8) -> u8 {
        match b {
            0 ... 9 => b'0' + b,
            _ => b'a' + b - 10,
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Iterator for EscapeDefault {
    type Item = u8;
    fn next(&mut self) -> Option<u8> { self.range.next().map(|i| self.data[i]) }
    fn size_hint(&self) -> (usize, Option<usize>) { self.range.size_hint() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl DoubleEndedIterator for EscapeDefault {
    fn next_back(&mut self) -> Option<u8> {
        self.range.next_back().map(|i| self.data[i])
    }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl ExactSizeIterator for EscapeDefault {}
#[unstable(feature = "fused", issue = "35602")]
impl FusedIterator for EscapeDefault {}

#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for EscapeDefault {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.pad("EscapeDefault { .. }")
    }
}


#[cfg(test)]
mod tests {
    use char::from_u32;

    #[test]
    fn test_is_ascii() {
        assert!(b"".is_ascii());
        assert!(b"banana\0\x7F".is_ascii());
        assert!(b"banana\0\x7F".iter().all(|b| b.is_ascii()));
        assert!(!b"Vi\xe1\xbb\x87t Nam".is_ascii());
        assert!(!b"Vi\xe1\xbb\x87t Nam".iter().all(|b| b.is_ascii()));
        assert!(!b"\xe1\xbb\x87".iter().any(|b| b.is_ascii()));

        assert!("".is_ascii());
        assert!("banana\0\u{7F}".is_ascii());
        assert!("banana\0\u{7F}".chars().all(|c| c.is_ascii()));
        assert!(!"ประเทศไทย中华Việt Nam".chars().all(|c| c.is_ascii()));
        assert!(!"ประเทศไทย中华ệ ".chars().any(|c| c.is_ascii()));
    }

    #[test]
    fn test_to_ascii_uppercase() {
        assert_eq!("url()URL()uRl()ürl".to_ascii_uppercase(), "URL()URL()URL()üRL");
        assert_eq!("hıKß".to_ascii_uppercase(), "HıKß");

        for i in 0..501 {
            let upper = if 'a' as u32 <= i && i <= 'z' as u32 { i + 'A' as u32 - 'a' as u32 }
                        else { i };
            assert_eq!((from_u32(i).unwrap()).to_string().to_ascii_uppercase(),
                       (from_u32(upper).unwrap()).to_string());
        }
    }

    #[test]
    fn test_to_ascii_lowercase() {
        assert_eq!("url()URL()uRl()Ürl".to_ascii_lowercase(), "url()url()url()Ürl");
        // Dotted capital I, Kelvin sign, Sharp S.
        assert_eq!("HİKß".to_ascii_lowercase(), "hİKß");

        for i in 0..501 {
            let lower = if 'A' as u32 <= i && i <= 'Z' as u32 { i + 'a' as u32 - 'A' as u32 }
                        else { i };
            assert_eq!((from_u32(i).unwrap()).to_string().to_ascii_lowercase(),
                       (from_u32(lower).unwrap()).to_string());
        }
    }

    #[test]
    fn test_make_ascii_lower_case() {
        macro_rules! test {
            ($from: expr, $to: expr) => {
                {
                    let mut x = $from;
                    x.make_ascii_lowercase();
                    assert_eq!(x, $to);
                }
            }
        }
        test!(b'A', b'a');
        test!(b'a', b'a');
        test!(b'!', b'!');
        test!('A', 'a');
        test!('À', 'À');
        test!('a', 'a');
        test!('!', '!');
        test!(b"H\xc3\x89".to_vec(), b"h\xc3\x89");
        test!("HİKß".to_string(), "hİKß");
    }


    #[test]
    fn test_make_ascii_upper_case() {
        macro_rules! test {
            ($from: expr, $to: expr) => {
                {
                    let mut x = $from;
                    x.make_ascii_uppercase();
                    assert_eq!(x, $to);
                }
            }
        }
        test!(b'a', b'A');
        test!(b'A', b'A');
        test!(b'!', b'!');
        test!('a', 'A');
        test!('à', 'à');
        test!('A', 'A');
        test!('!', '!');
        test!(b"h\xc3\xa9".to_vec(), b"H\xc3\xa9");
        test!("hıKß".to_string(), "HıKß");

        let mut x = "Hello".to_string();
        x[..3].make_ascii_uppercase();  // Test IndexMut on String.
        assert_eq!(x, "HELlo")
    }

    #[test]
    fn test_eq_ignore_ascii_case() {
        assert!("url()URL()uRl()Ürl".eq_ignore_ascii_case("url()url()url()Ürl"));
        assert!(!"Ürl".eq_ignore_ascii_case("ürl"));
        // Dotted capital I, Kelvin sign, Sharp S.
        assert!("HİKß".eq_ignore_ascii_case("hİKß"));
        assert!(!"İ".eq_ignore_ascii_case("i"));
        assert!(!"K".eq_ignore_ascii_case("k"));
        assert!(!"ß".eq_ignore_ascii_case("s"));

        for i in 0..501 {
            let lower = if 'A' as u32 <= i && i <= 'Z' as u32 { i + 'a' as u32 - 'A' as u32 }
                        else { i };
            assert!((from_u32(i).unwrap()).to_string().eq_ignore_ascii_case(
                    &from_u32(lower).unwrap().to_string()));
        }
    }

    #[test]
    fn inference_works() {
        let x = "a".to_string();
        x.eq_ignore_ascii_case("A");
    }

    // Shorthands used by the is_ascii_* tests.
    macro_rules! assert_all {
        ($what:ident, $($str:tt),+) => {{
            $(
                for b in $str.chars() {
                    if !b.$what() {
                        panic!("expected {}({}) but it isn't",
                               stringify!($what), b);
                    }
                }
                for b in $str.as_bytes().iter() {
                    if !b.$what() {
                        panic!("expected {}(0x{:02x})) but it isn't",
                               stringify!($what), b);
                    }
                }
                assert!($str.$what());
                assert!($str.as_bytes().$what());
            )+
        }};
        ($what:ident, $($str:tt),+,) => (assert_all!($what,$($str),+))
    }
    macro_rules! assert_none {
        ($what:ident, $($str:tt),+) => {{
            $(
                for b in $str.chars() {
                    if b.$what() {
                        panic!("expected not-{}({}) but it is",
                               stringify!($what), b);
                    }
                }
                for b in $str.as_bytes().iter() {
                    if b.$what() {
                        panic!("expected not-{}(0x{:02x})) but it is",
                               stringify!($what), b);
                    }
                }
            )*
        }};
        ($what:ident, $($str:tt),+,) => (assert_none!($what,$($str),+))
    }

    #[test]
    fn test_is_ascii_alphabetic() {
        assert_all!(is_ascii_alphabetic,
            "",
            "abcdefghijklmnopqrstuvwxyz",
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
        );
        assert_none!(is_ascii_alphabetic,
            "0123456789",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
            " \t\n\x0c\r",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_uppercase() {
        assert_all!(is_ascii_uppercase,
            "",
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
        );
        assert_none!(is_ascii_uppercase,
            "abcdefghijklmnopqrstuvwxyz",
            "0123456789",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
            " \t\n\x0c\r",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_lowercase() {
        assert_all!(is_ascii_lowercase,
            "abcdefghijklmnopqrstuvwxyz",
        );
        assert_none!(is_ascii_lowercase,
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
            "0123456789",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
            " \t\n\x0c\r",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_alphanumeric() {
        assert_all!(is_ascii_alphanumeric,
            "",
            "abcdefghijklmnopqrstuvwxyz",
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
            "0123456789",
        );
        assert_none!(is_ascii_alphanumeric,
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
            " \t\n\x0c\r",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_digit() {
        assert_all!(is_ascii_digit,
            "",
            "0123456789",
        );
        assert_none!(is_ascii_digit,
            "abcdefghijklmnopqrstuvwxyz",
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
            " \t\n\x0c\r",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_hexdigit() {
        assert_all!(is_ascii_hexdigit,
            "",
            "0123456789",
            "abcdefABCDEF",
        );
        assert_none!(is_ascii_hexdigit,
            "ghijklmnopqrstuvwxyz",
            "GHIJKLMNOQPRSTUVWXYZ",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
            " \t\n\x0c\r",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_punctuation() {
        assert_all!(is_ascii_punctuation,
            "",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
        );
        assert_none!(is_ascii_punctuation,
            "abcdefghijklmnopqrstuvwxyz",
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
            "0123456789",
            " \t\n\x0c\r",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_graphic() {
        assert_all!(is_ascii_graphic,
            "",
            "abcdefghijklmnopqrstuvwxyz",
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
            "0123456789",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
        );
        assert_none!(is_ascii_graphic,
            " \t\n\x0c\r",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_whitespace() {
        assert_all!(is_ascii_whitespace,
            "",
            " \t\n\x0c\r",
        );
        assert_none!(is_ascii_whitespace,
            "abcdefghijklmnopqrstuvwxyz",
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
            "0123456789",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x0b\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
    }

    #[test]
    fn test_is_ascii_control() {
        assert_all!(is_ascii_control,
            "",
            "\x00\x01\x02\x03\x04\x05\x06\x07",
            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
            "\x10\x11\x12\x13\x14\x15\x16\x17",
            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
            "\x7f",
        );
        assert_none!(is_ascii_control,
            "abcdefghijklmnopqrstuvwxyz",
            "ABCDEFGHIJKLMNOQPRSTUVWXYZ",
            "0123456789",
            "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",
            " ",
        );
    }
}