binary-layout 3.1.3

The binary-layout library allows type-safe, inplace, zero-copy access to structured binary data. You define a custom data layout and give it a slice of binary data, and it will allow you to read and write the fields defined in the layout from the binary data without having to copy any of the data. It's similar to transmuting to/from a `#[repr(packed)]` struct, but much safer.
Documentation 
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use core::marker::PhantomData;

use crate::{Field, FieldCopyAccess};

/// A field view represents the field metadata stored in a [Field] plus it stores the underlying
/// storage data it operates on, either as a reference to a slice `&[u8]`, `&mut [u8]`, or as
/// an owning [Vec<u8>].
///
/// Since this API remembers the underlying storage data in a view object, you don't have to pass it
/// in each time you're accessing a field. If you rather prefer an API that does not do that,
/// take a look at the [Field] API.
///
/// # Example:
/// ```
/// use binary_layout::prelude::*;
///
/// define_layout!(my_layout, LittleEndian, {
///   field_one: u16,
///   another_field: [u8; 16],
///   something_else: u32,
///   tail: [u8],
/// });
///
/// fn func(storage_data: &mut [u8]) {
///   let mut view = my_layout::View::new(storage_data);
///
///   // read some data
///   let format_version_header: u16 = view.field_one().read();
///   // equivalent: let format_version_header = u16::from_le_bytes((&storage_data[0..2]).try_into().unwrap());
///
///   // write some data
///   view.something_else_mut().write(10);
///   // equivalent: data_slice[18..22].copy_from_slice(&10u32.to_le_bytes());
///
///   // access a data region
///   let tail: &[u8] = view.tail();
///   // equivalent: let tail: &[u8] = &data_slice[22..];
///
///   // and modify it
///   view.tail_mut()[..5].copy_from_slice(&[1, 2, 3, 4, 5]);
///   // equivalent: data_slice[18..22].copy_from_slice(&[1, 2, 3, 4, 5]);
/// }
/// ```
pub struct FieldView<S, F: Field> {
    storage: S,
    _p: PhantomData<F>,
}

impl<S, F: Field> FieldView<S, F> {
    /// Create a new view for a field over a given storage.
    /// You probably shouldn't call this directly but should instead call
    /// `your_layout::View::new()`, which is generated by the
    /// [define_layout!](crate::define_layout!) macro for you.
    #[inline(always)]
    pub fn new(storage: S) -> Self {
        Self {
            storage,
            _p: PhantomData,
        }
    }
}
impl<S: AsRef<[u8]>, F: FieldCopyAccess> FieldView<S, F> {
    /// Read the field from a given data region, assuming the defined layout, using the [FieldView] API.
    ///
    /// # Example
    /// ```
    /// use binary_layout::prelude::*;
    ///
    /// define_layout!(my_layout, LittleEndian, {
    ///   //... other fields ...
    ///   some_integer_field: i8
    ///   //... other fields ...
    /// });
    ///
    /// fn func(storage_data: &[u8]) {
    ///   let view = my_layout::View::new(storage_data);
    ///   let read: i8 = view.some_integer_field().read();
    /// }
    /// ```
    #[inline(always)]
    pub fn read(&self) -> F::HighLevelType {
        F::read(self.storage.as_ref())
    }
}
impl<S: AsMut<[u8]>, F: FieldCopyAccess> FieldView<S, F> {
    /// Write the field to a given data region, assuming the defined layout, using the [FieldView] API.
    ///
    /// # Example
    /// ```
    /// use binary_layout::prelude::*;
    ///
    /// define_layout!(my_layout, LittleEndian, {
    ///   //... other fields ...
    ///   some_integer_field: i8
    ///   //... other fields ...
    /// });
    ///
    /// fn func(storage_data: &mut [u8]) {
    ///   let mut view = my_layout::View::new(storage_data);
    ///   view.some_integer_field_mut().write(10);
    /// }
    /// ```
    #[inline(always)]
    pub fn write(&mut self, v: F::HighLevelType) {
        F::write(self.storage.as_mut(), v)
    }
}