Trait object::read::ReadRef

pub trait ReadRef<'a>: Clone + Copy {
    // Required methods
    fn len(self) -> Result<u64, ()>;
    fn read_bytes_at(self, offset: u64, size: u64) -> Result<&'a [u8], ()>;
    fn read_bytes_at_until(
        self,
        range: Range<u64>,
        delimiter: u8
    ) -> Result<&'a [u8], ()>;

    // Provided methods
    fn read_bytes(self, offset: &mut u64, size: u64) -> Result<&'a [u8], ()> { ... }
    fn read<T: Pod>(self, offset: &mut u64) -> Result<&'a T, ()> { ... }
    fn read_at<T: Pod>(self, offset: u64) -> Result<&'a T, ()> { ... }
    fn read_slice<T: Pod>(
        self,
        offset: &mut u64,
        count: usize
    ) -> Result<&'a [T], ()> { ... }
    fn read_slice_at<T: Pod>(
        self,
        offset: u64,
        count: usize
    ) -> Result<&'a [T], ()> { ... }
}

A trait for reading references to Pod types from a block of data.

This allows parsers to handle both of these cases:

• the block of data exists in memory, and it is desirable to use references to this block instead of copying it,
• the block of data exists in storage, and it is desirable to read on demand to minimize I/O and memory usage.

The methods accept self by value because Self is expected to behave similar to a reference: it may be a reference with a lifetime of 'a, or it may be a wrapper of a reference.

The Clone and Copy bounds are for convenience, and since Self is expected to be similar to a reference, these are easily satisfied.

Object file parsers typically use offsets to locate the structures in the block, and will most commonly use the *_at methods to read a structure at a known offset.

Occasionally file parsers will need to treat the block as a stream, and so convenience methods are provided that update an offset with the size that was read.

Required Methods

fn len(self) -> Result<u64, ()>

The total size of the block of data.

fn read_bytes_at(self, offset: u64, size: u64) -> Result<&'a [u8], ()>

Get a reference to a u8 slice at the given offset.

Returns an error if offset or size are out of bounds.

fn read_bytes_at_until( self, range: Range<u64>, delimiter: u8 ) -> Result<&'a [u8], ()>

Get a reference to a delimited u8 slice which starts at range.start.

Does not include the delimiter.

Returns an error if the range is out of bounds or the delimiter is not found in the range.

Provided Methods

fn read_bytes(self, offset: &mut u64, size: u64) -> Result<&'a [u8], ()>

Get a reference to a u8 slice at the given offset, and update the offset.

Returns an error if offset or size are out of bounds.

fn read<T: Pod>(self, offset: &mut u64) -> Result<&'a T, ()>

Get a reference to a Pod type at the given offset, and update the offset.

Returns an error if offset or size are out of bounds.

The default implementation uses read_bytes, and returns an error if read_bytes does not return bytes with the correct alignment for T. Implementors may want to provide their own implementation that ensures the alignment can be satisfied. Alternatively, only use this method with types that do not need alignment (see the unaligned feature of this crate).

fn read_at<T: Pod>(self, offset: u64) -> Result<&'a T, ()>

Get a reference to a Pod type at the given offset.

Returns an error if offset or size are out of bounds.

Also see the read method for information regarding alignment of T.

fn read_slice<T: Pod>( self, offset: &mut u64, count: usize ) -> Result<&'a [T], ()>

Get a reference to a slice of a Pod type at the given offset, and update the offset.

Returns an error if offset or size are out of bounds.

Also see the read method for information regarding alignment of T.

fn read_slice_at<T: Pod>(self, offset: u64, count: usize) -> Result<&'a [T], ()>

Get a reference to a slice of a Pod type at the given offset.

Returns an error if offset or size are out of bounds.

Also see the read method for information regarding alignment of T.

Object Safety

This trait is not object safe.

Implementations on Foreign Types

impl<'a> ReadRef<'a> for &'a [u8]

fn len(self) -> Result<u64, ()>

fn read_bytes_at(self, offset: u64, size: u64) -> Result<&'a [u8], ()>

fn read_bytes_at_until( self, range: Range<u64>, delimiter: u8 ) -> Result<&'a [u8], ()>

Implementors