Struct Reader

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pub struct Reader<'a> { /* private fields */ }

Expand description

An incremental reader from a byte slice.

The main functions of interest are u32_le and the like, which read the relevant primitives from the slice. In these docs, they are abbreviated to a single function for simplicity.

Supported primitives are u8..=u128, i8..=i128, f32, f64.

The functions are suffixed with either _le or _be, for endianness. To use unsuffixed versions, import either the Le or Be trait.

Cloning a Reader is cheap, but it does not implement Copy for similar reasons as Range.

Implementations§

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impl<'a> Reader<'a>

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pub fn new(data: &'a [u8]) -> Reader<'a>

Constructs a new Reader.

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pub fn pos(&self) -> usize

Returns the read position of the reader.

To change the position, use seek or at.

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pub fn len(&self) -> usize

Returns the total length of the input.

Note that this is the total length, which does not change. See remaining for the number of bytes left that can be read.

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pub fn is_empty(&self) -> bool

Returns true if there are no more bytes left to read.

Note that unlike slices, this is based on remaining, not len.

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pub fn remaining(&self) -> &'a [u8] ⓘ

Returns the remaining data in the buffer.

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pub fn data(&self) -> &'a [u8] ⓘ

Returns the data being read from.

This is the full slice; for only the remainder, see remaining.

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pub fn T(&mut self) -> Result<T>

Read a primitive from the input.

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pub fn slice(&mut self, len: usize) -> Result<&'a [u8]>

Reads a slice of data from the input. No copying is done.

Returns an error if there is not enough data left, in which case the read position is unchanged.

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pub fn array<const N: usize>(&mut self) -> Result<[u8; N]>

Reads a fixed-size slice of data from the input.

Handles errors identically to slice.

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pub fn read_into(&mut self, buf: &mut [u8]) -> Result<()>

Reads a slice of data into a preexisting buffer.

Handles errors identically to slice.

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pub fn cstr(&mut self) -> Result<&'a CStr>

Reads data to and including the next null byte.

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pub fn seek(&mut self, pos: usize) -> Result<()>

Sets the read position.

Returns an error if the position is out of bounds.

See at for a version that returns a copy.

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pub fn at(&self, pos: usize) -> Result<Self>

Returns a copy of the reader at the specified position.

See also ptrN for a shorthand for the common pattern of f.clone().at(f.u32()? as usize)?.

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pub fn check(&mut self, v: &[u8]) -> Result<()>

Reads a number of bytes and returns an error if they are not as expected.

If it does not match, the read position is not affected.

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pub fn check_T(&mut self, v: T) -> Result<()>

Read a primitive from the input, giving an error if it is not as expected.

If it not match, the read position is not affected.

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pub fn ptrN(&mut self) -> Result<Self>

Read a uN primitive from the input, and return a new Reader at that position.

This is a shorthand for the common pattern of f.clone().at(f.uN()? as usize)?.

Note that no checking is made that the value actually fits inside a usize; the higher bits are simply discarded. This is primarily relevant with ptr128, and requires humongous amounts of memory to exhibit issues.

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