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

use std::marker::PhantomData;

use parse::*;
use value32::*;
use value64::*;
use varint::*;

pub trait Packed<'a> {
    type Item;

    fn parse(&'a [u8]) -> ParseResult<(Self::Item, &'a [u8])>;
}

#[derive(Clone, Copy)]
pub struct PackedVarint;

impl<'a> Packed<'a> for PackedVarint {
    type Item = Varint;

    fn parse(data: &'a [u8]) -> ParseResult<(Varint, &'a [u8])> {
        parse_varint(data)
    }
}

#[derive(Clone, Copy)]
pub struct PackedValue32;

impl<'a> Packed<'a> for PackedValue32 {
    type Item = Value32<'a>;

    fn parse(data: &'a [u8]) -> ParseResult<(Value32<'a>, &'a [u8])> {
        parse_value32(data)
    }
}

#[derive(Clone, Copy)]
pub struct PackedValue64;

impl<'a> Packed<'a> for PackedValue64 {
    type Item = Value64<'a>;

    fn parse(data: &'a [u8]) -> ParseResult<(Value64<'a>, &'a [u8])> {
        parse_value64(data)
    }
}
                                                 

#[derive(Clone)]
pub struct PackedIter<'a, P, T> {
    data: &'a [u8],
    packed: PhantomData<P>,
    item: PhantomData<T>
}

impl<'a, P, T> PackedIter<'a, P, T> {
    pub fn new(data: &'a [u8]) -> Self {
        PackedIter {
            data: data,
            packed: PhantomData,
            item: PhantomData
        }
    }
}

impl<'a, P, T> From<ParseValue<'a>> for PackedIter<'a, P, T> {
    fn from(parse_value: ParseValue<'a>) -> Self {
        Self::new(parse_value.get_data())
    }
}

/// Type parameter P: Encoding
/// Type parameter T: Coercion target
impl<'a, P: Packed<'a>, T: From<<P as Packed<'a>>::Item>> Iterator for PackedIter<'a, P, T> {
    type Item = T;

    fn next(&mut self) -> Option<Self::Item> {
        if self.data.len() < 1 {
            return None
        }

        P::parse(self.data)
            .ok()
            .map(|(value, rest)| {
                self.data = rest;
                From::from(value)
            })
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        (0, Some(self.data.len()))
    }
}


#[cfg(test)]
mod tests {
    use super::*;

    const VARINTS_ENCODED: &'static [u8] = &[0x03, 0x8E, 0x02, 0x9E, 0xA7, 0x05];
    
    #[test]
    fn packed_varints() {
        let iter: PackedIter<'static, PackedVarint, u32> = PackedIter::new(VARINTS_ENCODED);
        assert_eq!(vec![3, 270, 86942], iter.collect::<Vec<u32>>());
    }
    
    const VALUE32S_ENCODED: &'static [u8] = &[
        1, 0, 0, 0,
        2, 0, 0, 0,
        3, 0, 0, 0
    ];

    #[test]
    fn packed_value32s() {
        let iter: PackedIter<'static, PackedValue32, u32> = PackedIter::new(VALUE32S_ENCODED);
        assert_eq!(vec![1, 2, 3], iter.collect::<Vec<u32>>());
    }
    
    const VALUE64S_ENCODED: &'static [u8] = &[
        1, 0, 0, 0, 0, 0, 0, 0,
        2, 0, 0, 0, 0, 0, 0, 0,
        3, 0, 0, 0, 0, 0, 0, 0,
    ];

    #[test]
    fn packed_value64s() {
        let iter: PackedIter<'static, PackedValue64, u32> = PackedIter::new(VALUE64S_ENCODED);
        assert_eq!(vec![1, 2, 3], iter.collect::<Vec<u32>>());
    }
}