/rust/registry/src/index.crates.io-1949cf8c6b5b557f/zerovec-0.11.4/src/ule/multi.rs

Source
// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).

use super::*;
use crate::varzerovec::lengthless::VarZeroLengthlessSlice;
use crate::vecs::VarZeroVecFormat;
use core::{fmt, mem};

/// This type is used by the custom derive to represent multiple [`VarULE`]
/// fields packed into a single end-of-struct field. It is not recommended
/// to use this type directly, use [`Tuple2VarULE`](crate::ule::tuplevar::Tuple2VarULE) etc instead.
///
/// Logically, consider it to be `(, , , ..)`
/// where `` etc are potentially different [`VarULE`] types.
///
/// Internally, it is represented by a VarZeroSlice without the length part.
#[derive(PartialEq, Eq)]
#[repr(transparent)]
pub struct MultiFieldsULE<const LEN: usize, Format: VarZeroVecFormat>(
    VarZeroLengthlessSlice<[u8], Format>,
);

impl<const LEN: usize, Format: VarZeroVecFormat> MultiFieldsULE<LEN, Format> {
    /// Compute the amount of bytes needed to support elements with lengths `lengths`
    #[inline]
    #[expect(clippy::expect_used)] // See #1410
    pub fn compute_encoded_len_for(lengths: [usize; LEN]) -> usize {
        let lengths = lengths.map(BlankSliceEncoder);
        crate::varzerovec::components::compute_serializable_len_without_length::<_, _, Format>(
            &lengths,
        )
        .expect("Too many bytes to encode") as usize
    }

    /// Construct a partially initialized MultiFieldsULE backed by a mutable byte buffer
    pub fn new_from_lengths_partially_initialized<'a>(
        lengths: [usize; LEN],
        output: &'a mut [u8],
    ) -> &'a mut Self {
        let lengths = lengths.map(BlankSliceEncoder);
        crate::varzerovec::components::write_serializable_bytes_without_length::<_, _, Format>(
            &lengths, output,
        );
        debug_assert!(
            <VarZeroLengthlessSlice<[u8], Format>>::parse_bytes(LEN as u32, output).is_ok(),
            "Encoded slice must be valid VarZeroSlice"
        );
        unsafe {
            // Safe since write_serializable_bytes produces a valid VarZeroLengthlessSlice buffer with the right format
            let slice = <VarZeroLengthlessSlice<[u8], Format>>::from_bytes_unchecked_mut(output);
            // safe since `Self` is transparent over VarZeroLengthlessSlice<[u8], Format>
            mem::transmute::<&mut VarZeroLengthlessSlice<[u8], Format>, &mut Self>(slice)
        }
    }

    /// Given a buffer of size obtained by [`Self::compute_encoded_len_for()`], write element A to index idx
    ///
    /// # Safety
    /// - `idx` must be in range
    /// - `T` must be the appropriate type expected by the custom derive in this usage of this type
    #[inline]
    pub unsafe fn set_field_at<T: VarULE + ?Sized, A: EncodeAsVarULE<T> + ?Sized>(
        &mut self,
        idx: usize,
        value: &A,
    ) {
        value.encode_var_ule_write(self.0.get_bytes_at_mut(LEN as u32, idx))
    }

    /// Validate field at `index` to see if it is a valid `T` VarULE type
    ///
    /// # Safety
    ///
    /// - `index` must be in range
    #[inline]
    pub unsafe fn validate_field<T: VarULE + ?Sized>(&self, index: usize) -> Result<(), UleError> {
        T::validate_bytes(self.0.get_unchecked(LEN as u32, index))
    }

    /// Get field at `index` as a value of type T
    ///
    /// # Safety
    ///
    /// - `index` must be in range
    /// - Element at `index` must have been created with the VarULE type T
    #[inline]
    pub unsafe fn get_field<T: VarULE + ?Sized>(&self, index: usize) -> &T {
        T::from_bytes_unchecked(self.0.get_unchecked(LEN as u32, index))
    }

    /// Construct from a byte slice
    ///
    /// # Safety
    /// - byte slice must be a valid VarZeroLengthlessSlice<[u8], Format> with length LEN
    #[inline]
    pub unsafe fn from_bytes_unchecked(bytes: &[u8]) -> &Self {
        // &Self is transparent over &VZS<..> with the right format
        mem::transmute(<VarZeroLengthlessSlice<[u8], Format>>::from_bytes_unchecked(bytes))
    }

    /// Get the bytes behind this value
    pub fn as_bytes(&self) -> &[u8] {
        self.0.as_bytes()
    }
}

impl<const LEN: usize, Format: VarZeroVecFormat> fmt::Debug for MultiFieldsULE<LEN, Format> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "MultiFieldsULE<{LEN}>({:?})", self.0.as_bytes())
    }
}
/// This lets us conveniently use the EncodeAsVarULE functionality to create
/// `VarZeroVec<[u8]>`s that have the right amount of space for elements
/// without having to duplicate any unsafe code
#[repr(transparent)]
struct BlankSliceEncoder(usize);

unsafe impl EncodeAsVarULE<[u8]> for BlankSliceEncoder {
    fn encode_var_ule_as_slices<R>(&self, _: impl FnOnce(&[&[u8]]) -> R) -> R {
        // unnecessary if the other two are implemented
        unreachable!()
    }

    #[inline]
    fn encode_var_ule_len(&self) -> usize {
        self.0
    }

    #[inline]
    fn encode_var_ule_write(&self, _dst: &mut [u8]) {
        // do nothing
    }
}

// Safety (based on the safety checklist on the VarULE trait):
//  1. MultiFieldsULE does not include any uninitialized or padding bytes (achieved by being transparent over a VarULE type)
//  2. MultiFieldsULE is aligned to 1 byte (achieved by being transparent over a VarULE type)
//  3. The impl of `validate_bytes()` returns an error if any byte is not valid.
//  4. The impl of `validate_bytes()` returns an error if the slice cannot be used in its entirety
//  5. The impl of `from_bytes_unchecked()` returns a reference to the same data.
//  6. All other methods are defaulted
//  7. `MultiFieldsULE` byte equality is semantic equality (achieved by being transparent over a VarULE type)
unsafe impl<const LEN: usize, Format: VarZeroVecFormat> VarULE for MultiFieldsULE<LEN, Format> {
    /// Note: MultiFieldsULE is usually used in cases where one should be calling .validate_field() directly for
    /// each field, rather than using the regular VarULE impl.
    ///
    /// This impl exists so that EncodeAsVarULE can work.
    #[inline]
    fn validate_bytes(slice: &[u8]) -> Result<(), UleError> {
        <VarZeroLengthlessSlice<[u8], Format>>::parse_bytes(LEN as u32, slice).map(|_| ())
    }

    #[inline]
    unsafe fn from_bytes_unchecked(bytes: &[u8]) -> &Self {
        // &Self is transparent over &VZS<..>
        mem::transmute(<VarZeroLengthlessSlice<[u8], Format>>::from_bytes_unchecked(bytes))
    }
}

Line	Count	Source
1		// This file is part of ICU4X. For terms of use, please see the file
2		// called LICENSE at the top level of the ICU4X source tree
3		// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
4
5		use super::*;
6		use crate::varzerovec::lengthless::VarZeroLengthlessSlice;
7		use crate::vecs::VarZeroVecFormat;
8		use core::{fmt, mem};
9
10		/// This type is used by the custom derive to represent multiple [`VarULE`]
11		/// fields packed into a single end-of-struct field. It is not recommended
12		/// to use this type directly, use [`Tuple2VarULE`](crate::ule::tuplevar::Tuple2VarULE) etc instead.
13		///
14		/// Logically, consider it to be `(, , , ..)`
15		/// where `` etc are potentially different [`VarULE`] types.
16		///
17		/// Internally, it is represented by a VarZeroSlice without the length part.
18		#[derive(PartialEq, Eq)]
19		#[repr(transparent)]
20		pub struct MultiFieldsULE<const LEN: usize, Format: VarZeroVecFormat>(
21		VarZeroLengthlessSlice<[u8], Format>,
22		);
23
24		impl<const LEN: usize, Format: VarZeroVecFormat> MultiFieldsULE<LEN, Format> {
25		/// Compute the amount of bytes needed to support elements with lengths `lengths`
26		#[inline]
27		#[expect(clippy::expect_used)] // See #1410
28	0	pub fn compute_encoded_len_for(lengths: [usize; LEN]) -> usize {
29	0	let lengths = lengths.map(BlankSliceEncoder);
30	0	crate::varzerovec::components::compute_serializable_len_without_length::<_, _, Format>(
31	0	&lengths,
32	0	)
33	0	.expect("Too many bytes to encode") as usize
34	0	} Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<2, zerovec::varzerovec::components::Index16>>::compute_encoded_len_for Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<_, _>>::compute_encoded_len_for
35
36		/// Construct a partially initialized MultiFieldsULE backed by a mutable byte buffer
37	0	pub fn new_from_lengths_partially_initialized<'a>(
38	0	lengths: [usize; LEN],
39	0	output: &'a mut [u8],
40	0	) -> &'a mut Self {
41	0	let lengths = lengths.map(BlankSliceEncoder);
42	0	crate::varzerovec::components::write_serializable_bytes_without_length::<_, _, Format>(
43	0	&lengths, output,
44		);
45	0	debug_assert!(
46	0	<VarZeroLengthlessSlice<[u8], Format>>::parse_bytes(LEN as u32, output).is_ok(),
47	0	"Encoded slice must be valid VarZeroSlice"
48		);
49	0	unsafe {
50	0	// Safe since write_serializable_bytes produces a valid VarZeroLengthlessSlice buffer with the right format
51	0	let slice = <VarZeroLengthlessSlice<[u8], Format>>::from_bytes_unchecked_mut(output);
52	0	// safe since `Self` is transparent over VarZeroLengthlessSlice<[u8], Format>
53	0	mem::transmute::<&mut VarZeroLengthlessSlice<[u8], Format>, &mut Self>(slice)
54	0	}
55	0	} Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<2, zerovec::varzerovec::components::Index16>>::new_from_lengths_partially_initialized Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<_, _>>::new_from_lengths_partially_initialized
56
57		/// Given a buffer of size obtained by [`Self::compute_encoded_len_for()`], write element A to index idx
58		///
59		/// # Safety
60		/// - `idx` must be in range
61		/// - `T` must be the appropriate type expected by the custom derive in this usage of this type
62		#[inline]
63	0	pub unsafe fn set_field_at<T: VarULE + ?Sized, A: EncodeAsVarULE<T> + ?Sized>(
64	0	&mut self,
65	0	idx: usize,
66	0	value: &A,
67	0	) {
68	0	value.encode_var_ule_write(self.0.get_bytes_at_mut(LEN as u32, idx))
69	0	} Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<2, zerovec::varzerovec::components::Index16>>::set_field_at::<zerovec::varzerovec::slice::VarZeroSlice<str>, zerovec::varzerovec::slice::VarZeroSlice<str>> Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<2, zerovec::varzerovec::components::Index16>>::set_field_at::<icu_collections::codepointinvlist::cpinvlist::CodePointInversionListULE, icu_collections::codepointinvlist::cpinvlist::CodePointInversionList> Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<_, _>>::set_field_at::<_, _>
70
71		/// Validate field at `index` to see if it is a valid `T` VarULE type
72		///
73		/// # Safety
74		///
75		/// - `index` must be in range
76		#[inline]
77	0	pub unsafe fn validate_field<T: VarULE + ?Sized>(&self, index: usize) -> Result<(), UleError> {
78	0	T::validate_bytes(self.0.get_unchecked(LEN as u32, index))
79	0	}
80
81		/// Get field at `index` as a value of type T
82		///
83		/// # Safety
84		///
85		/// - `index` must be in range
86		/// - Element at `index` must have been created with the VarULE type T
87		#[inline]
88	0	pub unsafe fn get_field<T: VarULE + ?Sized>(&self, index: usize) -> &T {
89	0	T::from_bytes_unchecked(self.0.get_unchecked(LEN as u32, index))
90	0	} Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<2, zerovec::varzerovec::components::Index16>>::get_field::<zerovec::varzerovec::slice::VarZeroSlice<str>> Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<2, zerovec::varzerovec::components::Index16>>::get_field::<icu_collections::codepointinvlist::cpinvlist::CodePointInversionListULE> Unexecuted instantiation: <zerovec::ule::multi::MultiFieldsULE<_, _>>::get_field::<_>
91
92		/// Construct from a byte slice
93		///
94		/// # Safety
95		/// - byte slice must be a valid VarZeroLengthlessSlice<[u8], Format> with length LEN
96		#[inline]
97	0	pub unsafe fn from_bytes_unchecked(bytes: &[u8]) -> &Self {
98		// &Self is transparent over &VZS<..> with the right format
99	0	mem::transmute(<VarZeroLengthlessSlice<[u8], Format>>::from_bytes_unchecked(bytes))
100	0	}
101
102		/// Get the bytes behind this value
103	0	pub fn as_bytes(&self) -> &[u8] {
104	0	self.0.as_bytes()
105	0	}
106		}
107
108		impl<const LEN: usize, Format: VarZeroVecFormat> fmt::Debug for MultiFieldsULE<LEN, Format> {
109	0	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
110	0	write!(f, "MultiFieldsULE<{LEN}>({:?})", self.0.as_bytes())
111	0	}
112		}
113		/// This lets us conveniently use the EncodeAsVarULE functionality to create
114		/// `VarZeroVec<[u8]>`s that have the right amount of space for elements
115		/// without having to duplicate any unsafe code
116		#[repr(transparent)]
117		struct BlankSliceEncoder(usize);
118
119		unsafe impl EncodeAsVarULE<[u8]> for BlankSliceEncoder {
120	0	fn encode_var_ule_as_slices<R>(&self, _: impl FnOnce(&[&[u8]]) -> R) -> R {
121		// unnecessary if the other two are implemented
122	0	unreachable!()
123		}
124
125		#[inline]
126	0	fn encode_var_ule_len(&self) -> usize {
127	0	self.0
128	0	} Unexecuted instantiation: <zerovec::ule::multi::BlankSliceEncoder as zerovec::ule::encode::EncodeAsVarULE<[u8]>>::encode_var_ule_len Unexecuted instantiation: <zerovec::ule::multi::BlankSliceEncoder as zerovec::ule::encode::EncodeAsVarULE<[u8]>>::encode_var_ule_len
129
130		#[inline]
131	0	fn encode_var_ule_write(&self, _dst: &mut [u8]) {
132		// do nothing
133	0	} Unexecuted instantiation: <zerovec::ule::multi::BlankSliceEncoder as zerovec::ule::encode::EncodeAsVarULE<[u8]>>::encode_var_ule_write Unexecuted instantiation: <zerovec::ule::multi::BlankSliceEncoder as zerovec::ule::encode::EncodeAsVarULE<[u8]>>::encode_var_ule_write
134		}
135
136		// Safety (based on the safety checklist on the VarULE trait):
137		// 1. MultiFieldsULE does not include any uninitialized or padding bytes (achieved by being transparent over a VarULE type)
138		// 2. MultiFieldsULE is aligned to 1 byte (achieved by being transparent over a VarULE type)
139		// 3. The impl of `validate_bytes()` returns an error if any byte is not valid.
140		// 4. The impl of `validate_bytes()` returns an error if the slice cannot be used in its entirety
141		// 5. The impl of `from_bytes_unchecked()` returns a reference to the same data.
142		// 6. All other methods are defaulted
143		// 7. `MultiFieldsULE` byte equality is semantic equality (achieved by being transparent over a VarULE type)
144		unsafe impl<const LEN: usize, Format: VarZeroVecFormat> VarULE for MultiFieldsULE<LEN, Format> {
145		/// Note: MultiFieldsULE is usually used in cases where one should be calling .validate_field() directly for
146		/// each field, rather than using the regular VarULE impl.
147		///
148		/// This impl exists so that EncodeAsVarULE can work.
149		#[inline]
150	0	fn validate_bytes(slice: &[u8]) -> Result<(), UleError> {
151	0	<VarZeroLengthlessSlice<[u8], Format>>::parse_bytes(LEN as u32, slice).map(\|_\| ())
152	0	}
153
154		#[inline]
155	0	unsafe fn from_bytes_unchecked(bytes: &[u8]) -> &Self {
156		// &Self is transparent over &VZS<..>
157	0	mem::transmute(<VarZeroLengthlessSlice<[u8], Format>>::from_bytes_unchecked(bytes))
158	0	}
159		}

Coverage Report

Created: 2025-09-27 06:43