phoron_core 0.1.0

A serializer and deserializer for JVM bytecode
Documentation 
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//! A module for reading Java (JVM) types from a raw byte stream

use super::HasBeBytes;
use crate::error::ReadError;

use std::io::Read;

pub type ReadResult<T> = Result<T, ReadError>;

/// The `Reader` is used to read bytes off of a stream
/// over raw ``class` file objects.
pub struct Reader<R: Read> {
    reader: R,
}

impl<R: Read> Reader<R> {
    pub fn new(reader: R) -> Self {
        Reader { reader }
    }

    fn read_n<T: HasBeBytes<N>, const N: usize>(&mut self) -> ReadResult<T> {
        let mut buf = [0u8; N];
        self.reader.read_exact(&mut buf)?;
        Ok(T::from_be_bytes(buf))
    }

    /// Read an unsigned byte (8 bits) from the byte stream.
    pub fn read_unsigned_byte(&mut self) -> ReadResult<u8> {
        self.read_n::<u8, 1>()
    }

    /// Read an unsigned short (16 bits) from the byte stream.
    pub fn read_unsigned_short(&mut self) -> ReadResult<u16> {
        self.read_n::<u16, 2>()
    }

    /// Read an unsigned int (32 bits) from the byte stream.
    pub fn read_unsigned_int(&mut self) -> ReadResult<u32> {
        self.read_n::<u32, 4>()
    }

    /// Read an unsigned long (64 bits) from the byte stream.
    pub fn read_unsigned_long(&mut self) -> ReadResult<u64> {
        self.read_n::<u64, 8>()
    }
}

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

    #[test]
    fn test_read_unsigned_byte() {
        let bytes = [0xca, 0xfe, 0xba, 0xbe, 0x00, 0x01];
        let mut reader = Reader::new(Cursor::new(bytes));

        assert_eq!(reader.read_unsigned_byte().unwrap(), 0xca);
        assert_eq!(reader.read_unsigned_byte().unwrap(), 0xfe);
        assert_eq!(reader.read_unsigned_byte().unwrap(), 0xba);
        assert_eq!(reader.read_unsigned_byte().unwrap(), 0xbe);
    }

    #[test]
    fn test_read_unsigned_short() {
        let bytes = [0xca, 0xfe, 0xba, 0xbe, 0x00, 0x01];
        let mut reader = Reader::new(Cursor::new(bytes));

        assert_eq!(reader.read_unsigned_short().unwrap(), 0xcafe);
        assert_eq!(reader.read_unsigned_short().unwrap(), 0xbabe);
    }

    #[test]
    fn test_read_unsigned_int() {
        let bytes = [0xca, 0xfe, 0xba, 0xbe, 0x01, 0x00];
        let mut reader = Reader::new(Cursor::new(bytes));

        assert_eq!(reader.read_unsigned_int().unwrap(), 0xcafebabe);
    }

    #[test]
    fn test_read_unsigned_long() {
        let bytes = [0x00, 0x00, 0x00, 0x41, 0x00, 0x0f, 0x0a, 0x00, 0x00, 0x01];
        let mut reader = Reader::new(Cursor::new(bytes));

        assert_eq!(reader.read_unsigned_long().unwrap(), 0x00000041000f0a00);
    }
}