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use core::marker::PhantomData;
use crate::{Field, FieldCopyAccess, FieldReadExt, FieldWriteExt};
/// 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::*;
///
/// binary_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
/// [binary_layout!](crate::binary_layout!) macro for you.
#[inline(always)]
pub fn new(storage: S) -> Self {
Self {
storage,
_p: PhantomData,
}
}
}
impl<S: AsRef<[u8]>, F: FieldReadExt> FieldView<S, F> {
/// Read the field from a given data region, assuming the defined layout, using the [FieldView] API.
///
/// # Example
/// ```
/// use binary_layout::prelude::*;
///
/// binary_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: FieldWriteExt> FieldView<S, F> {
/// Write the field to a given data region, assuming the defined layout, using the [FieldView] API.
///
/// # Example
/// ```
/// use binary_layout::prelude::*;
///
/// binary_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)
}
}
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::*;
/// use core::num::NonZeroI8;
///
/// binary_layout!(my_layout, LittleEndian, {
/// //... other fields ...
/// some_integer_field: core::num::NonZeroI8,
/// //... other fields ...
/// });
///
/// fn func(storage_data: &[u8]) -> Result<NonZeroI8, NonZeroIsZeroError> {
/// let view = my_layout::View::new(storage_data);
/// let read: NonZeroI8 = view.some_integer_field().try_read()?;
/// Ok(read)
/// }
/// ```
#[inline(always)]
pub fn try_read(&self) -> Result<F::HighLevelType, F::ReadError> {
F::try_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::*;
/// use core::num::NonZeroI8;
/// use core::convert::Infallible;
///
/// binary_layout!(my_layout, LittleEndian, {
/// //... other fields ...
/// some_integer_field: core::num::NonZeroI8,
/// //... other fields ...
/// });
///
/// fn func(storage_data: &mut [u8]) -> Result<(), Infallible> {
/// let mut view = my_layout::View::new(storage_data);
/// let value = NonZeroI8::new(10).unwrap();
/// view.some_integer_field_mut().try_write(value)?;
/// Ok(())
/// }
/// ```
#[inline(always)]
pub fn try_write(&mut self, v: F::HighLevelType) -> Result<(), F::WriteError> {
F::try_write(self.storage.as_mut(), v)
}
}