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
131
132
133
134
135
136
137
138
139
140

use super::{Read, ReadError, Write, WriteError};
use alloc::vec::Vec;
use core::ops::Deref;

/// A stream of bytes
pub struct DataStream {
    /// TODO docs
    bytes: Vec<u8>,
    /// TODO docs
    pos: usize,
}

impl DataStream {
    /// Read something from the stream
    ///
    /// # Errors
    ///
    /// Will return `Err` if there was a problem reading the data.
    #[inline]
    pub fn read<T: Read>(&mut self) -> Result<T, ReadError> {
        T::read(&self.bytes, &mut self.pos)
    }

    /// Write something to the stream
    ///
    /// # Errors
    ///
    /// Will return `Err` if there was a problem writing the data.
    #[allow(clippy::needless_pass_by_value)]
    #[inline]
    pub fn write<T: Write>(&mut self, thing: T) -> Result<(), WriteError> {
        thing.write(&mut self.bytes, &mut self.pos)
    }

    /// Gets the remaining number of bytes
    #[inline]
    #[must_use]
    pub fn as_bytes(&self) -> &[u8] {
        &self.bytes
    }

    /// Gets remaining bytes as slice
    #[inline]
    #[must_use]
    pub fn as_remaining_bytes(&self) -> Option<&[u8]> {
        self.bytes.get(self.pos..)
    }

    /// Resets the data stream position
    #[inline]
    pub fn reset(&mut self) {
        self.pos = 0;
    }

    /// Get the current position
    #[inline]
    #[must_use]
    pub const fn position(&self) -> usize {
        self.pos
    }

    /// Gets the remaining number of bytes
    #[inline]
    #[must_use]
    pub fn remaining(&self) -> usize {
        self.bytes.len() - self.pos
    }
}

impl From<Vec<u8>> for DataStream {
    #[must_use]
    fn from(bytes: Vec<u8>) -> Self {
        Self { bytes, pos: 0 }
    }
}

impl From<&[u8]> for DataStream {
    #[must_use]
    fn from(bytes: &[u8]) -> Self {
        Self {
            bytes: bytes.to_vec(),
            pos: 0,
        }
    }
}

impl Deref for DataStream {
    type Target = [u8];

    #[must_use]
    fn deref(&self) -> &Self::Target {
        self.as_bytes()
    }
}

impl AsRef<[u8]> for DataStream {
    fn as_ref(&self) -> &[u8] {
        self.as_bytes()
    }
}

#[cfg(test)]
mod tests {
    use super::DataStream;
    use crate::{n, AccountName, Name};

    #[test]
    fn read_write() {
        let account = AccountName::from(n!("eosio.token"));
        let name = Name::from(n!("alice"));
        let mut ds1 = DataStream::from(vec![0; 16]);
        assert_eq!(ds1.position(), 0);
        assert_eq!(ds1.remaining(), 16);
        ds1.write(account).expect("failed to write account");
        assert_eq!(ds1.position(), 8);
        assert_eq!(ds1.remaining(), 8);
        assert_eq!(
            ds1.as_remaining_bytes()
                .expect("failed to get remaining bytes")
                .len(),
            8
        );
        ds1.write(name).expect("failed to write name");
        assert_eq!(ds1.position(), 16);
        assert_eq!(ds1.remaining(), 0);
        let bytes = ds1.as_bytes();
        let mut ds2 = DataStream::from(bytes);
        assert_eq!(ds2.position(), 0);
        assert_eq!(ds2.remaining(), 16);
        let account2 =
            ds2.read::<AccountName>().expect("failed to read account");
        assert_eq!(ds2.position(), 8);
        assert_eq!(ds2.remaining(), 8);
        let name2 = ds2.read::<Name>().expect("failed to read name");
        assert_eq!(ds2.position(), 16);
        assert_eq!(ds2.remaining(), 0);
        assert_eq!(account, account2);
        assert_eq!(name, name2);
    }
}