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#![deny(missing_docs)]

//! This crate provides two owned iterators over String: OwnedChars and OwnedCharIndices. They have
//! the same output as Chars and CharIndices, but creating the iterator consumes the String as
//! opposed to borrowing.

/// Extension trait for String providing owned char and char-index iterators
pub trait OwnedCharsExt {
    /// Gets an owning iterator over the chars (see `chars()`)
    fn into_chars(self) -> OwnedChars;
    /// Gets an owning iterator over the chars and their indices (see `char_indices()`)
    fn into_char_indices(self) -> OwnedCharIndices;
}

impl OwnedCharsExt for String {
    fn into_chars(self) -> OwnedChars {
        OwnedChars { s: self, i: 0 }
    }

    fn into_char_indices(self) -> OwnedCharIndices {
        OwnedCharIndices { s: self, i: 0 }
    }
}

/// Iterator over the chars of a string (the string is owned by the iterator)
#[derive(Clone, Debug)]
pub struct OwnedChars {
    s: String,
    i: usize,
}

/// Iterator over the chars of a string and their indices (the string is owned by the iterator)
#[derive(Clone, Debug)]
pub struct OwnedCharIndices {
    s: String,
    i: usize,
}

impl Iterator for OwnedChars {
    type Item = char;
    
    fn next(&mut self) -> Option<char> {
        match self.s[self.i..].chars().next() {
            Some(c) => {
                self.i += c.len_utf8();
                Some(c)
            },
            None => None
        }
    }
}

impl Iterator for OwnedCharIndices {
    type Item = (usize, char);
    
    fn next(&mut self) -> Option<(usize, char)> {
        match self.s[self.i..].chars().next() {
            Some(c) => {
                let ret = Some((self.i, c));
                self.i += c.len_utf8();
                ret
            },
            None => None
        }
    }
}

#[test]
fn chars() {
    let s = String::from("héllo");
    assert_eq!(s.chars().collect::<Vec<_>>(),
               s.into_chars().collect::<Vec<_>>());
}

#[test]
fn char_indices() {
    let s = String::from("héllo");
    assert_eq!(s.char_indices().collect::<Vec<_>>(),
               s.into_char_indices().collect::<Vec<_>>());
}