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/src/array/partial_array.rs

/*
 * SPDX-FileCopyrightText: 2025 Sebastiano Vigna
 *
 * SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
 */

//! Immutable [partial array] implementations.
//!
//! [partial array]: PartialArray

use std::marker::PhantomData;

use mem_dbg::*;
use value_traits::slices::SliceByValue;

use crate::bits::{BitFieldVec, BitVec};
use crate::dict::EliasFanoBuilder;
use crate::dict::elias_fano::EliasFano;
use crate::panic_if_out_of_bounds;
use crate::rank_sel::{Rank9, SelectZeroAdaptConst};
use crate::traits::Backend;
use crate::traits::TryIntoUnaligned;
use crate::traits::Unaligned;
use crate::traits::{BitVecOps, BitVecOpsMut};
use crate::traits::{RankUnchecked, SuccUnchecked};

// Rank9 is inherently u64-based, so the dense index must use u64 backing
// regardless of usize.
type DenseIndex = Rank9<BitVec<Box<[u64]>>>;

/// An internal index for sparse partial arrays.
///
/// We cannot use directly an [Elias–Fano] structure because we need to
/// keep track of the first invalid position; and we need to keep track of
/// the first invalid position because we want to implement just
/// [`SuccUnchecked`] on the Elias–Fano structure, because it requires just
/// [`SelectZeroUnchecked`], whereas [`Succ`] would require
/// [`SelectUnchecked`] as well.
///
/// [Elias–Fano]: crate::dict::EliasFano
/// [`SuccUnchecked`]: crate::traits::SuccUnchecked
/// [`SelectZeroUnchecked`]: crate::traits::SelectZeroUnchecked
/// [`Succ`]: crate::traits::Succ
/// [`SelectUnchecked`]: crate::traits::SelectUnchecked
#[doc(hidden)]
#[derive(Debug, Clone, MemSize, MemDbg)]
#[cfg_attr(feature = "epserde", derive(epserde::Epserde))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct SparseIndex<D, L = BitFieldVec<Box<[u64]>>> {
    ef: EliasFano<u64, SelectZeroAdaptConst<BitVec<D>, Box<[usize]>, 12, 3>, L>,
    /// self.ef should not be queried for values >= self.first_invalid_position
    first_invalid_pos: usize,
}

/// Builder for creating an immutable partial array.
///
/// The builder allows you to specify the array length and then add
/// (position, value) pairs. Positions must be added in strictly
/// increasing order.
///
/// To get a builder you can use either [new_dense] or [new_sparse].
#[derive(Debug, Clone, MemSize, MemDbg)]
pub struct PartialArrayBuilder<T, B> {
    builder: B,
    values: Vec<T>,
    len: usize,
    min_next_pos: usize,
}

/// Creates a new builder for a dense partial array of the given length.
///
/// A dense partial array stores a bit vector of the given length to mark
/// which positions contain values, and uses ranking on this bit vector to
/// map positions to indices in a contiguous value array.
///
/// If your set of values is really sparse, consider using a
/// [sparse partial array].
///
/// # Examples
///
/// ```rust
/// # use sux::array::partial_array;
/// let mut builder = partial_array::new_dense(10);
/// builder.set(1, "foo");
/// builder.set(2, "hello");
/// builder.set(7, "world");
///
/// let array = builder.build();
/// assert_eq!(array.get(1), Some(&"foo"));
/// assert_eq!(array.get(2), Some(&"hello"));
/// assert_eq!(array.get(3), None);
/// assert_eq!(array.get(7), Some(&"world"));
/// ```
///
/// [sparse partial array]: new_sparse
pub fn new_dense<T>(len: usize) -> PartialArrayBuilder<T, BitVec<Box<[u64]>>> {
    let n_of_words = len.div_ceil(64);
    // SAFETY: the backing has exactly enough words for len bits
    let bit_vec = unsafe { BitVec::from_raw_parts(vec![0u64; n_of_words].into_boxed_slice(), len) };
    PartialArrayBuilder {
        builder: bit_vec,
        values: vec![],
        len,
        min_next_pos: 0,
    }
}

impl<T> PartialArrayBuilder<T, BitVec<Box<[u64]>>> {
    /// Sets a value at the given position.
    ///
    /// The provided position must be greater than the last position set.
    pub fn set(&mut self, position: usize, value: T) {
        if position < self.min_next_pos {
            panic!(
                "Positions must be set in increasing order: got {} after {}",
                position,
                self.min_next_pos - 1
            );
        }
        panic_if_out_of_bounds!(position, self.len);

        // SAFETY: position < len
        unsafe {
            self.builder.set_unchecked(position, true);
        }
        self.values.push(value);
        self.min_next_pos = position + 1;
    }

    /// Builds the immutable dense partial array.
    #[must_use]
    pub fn build(self) -> PartialArray<T, Rank9<BitVec<Box<[u64]>>>> {
        let (bit_vec, values) = (self.builder, self.values);
        let rank9 = Rank9::new(bit_vec);
        let values = values.into_boxed_slice();

        PartialArray {
            index: rank9,
            values,
            _marker: PhantomData,
        }
    }
}

/// Creates a new builder for a sparse partial array of the given length.
///
/// A sparse partial array stores the non-empty positions of the array in an
/// [Elias-Fano] structure.
///
/// [Elias-Fano]: crate::dict::EliasFano
/// [dense partial array]: new_dense
///
/// If your set of values is really dense, consider using a [dense partial array].
///
/// # Examples
///
/// ```rust
/// # use sux::array::partial_array;
/// let mut builder = partial_array::new_sparse(10, 3);
/// builder.set(1, "foo");
/// builder.set(2, "hello");
/// builder.set(7, "world");
///
/// let array = builder.build();
/// assert_eq!(array.get(1), Some(&"foo"));
/// assert_eq!(array.get(2), Some(&"hello"));
/// assert_eq!(array.get(3), None);
/// assert_eq!(array.get(7), Some(&"world"));
/// ```
///
/// Note that you must specify the number of values in advance.
pub fn new_sparse<T>(
    len: usize,
    num_values: usize,
) -> PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
    PartialArrayBuilder {
        builder: EliasFanoBuilder::<u64>::new(num_values, len as u64),
        values: vec![],
        len,
        min_next_pos: 0,
    }
}

impl<T> PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
    /// Sets a value at the given position.
    ///
    /// The provided position must be greater than the last position
    /// set.
    pub fn set(&mut self, position: usize, value: T) {
        if position < self.min_next_pos {
            panic!(
                "Positions must be set in increasing order: got {} after {}",
                position,
                self.min_next_pos - 1
            );
        }
        panic_if_out_of_bounds!(position, self.len);
        // SAFETY: conditions have been just checked
        unsafe { self.builder.push_unchecked(position as u64) };
        self.values.push(value);
        self.min_next_pos = position + 1;
    }

    /// Builds the immutable sparse partial array.
    #[must_use]
    pub fn build(self) -> PartialArray<T, SparseIndex<Box<[usize]>>> {
        let (builder, values) = (self.builder, self.values);
        let ef_dict = builder.build_with_dict();
        let values = values.into_boxed_slice();

        PartialArray {
            index: SparseIndex {
                ef: ef_dict,
                first_invalid_pos: self.min_next_pos,
            },
            values,
            _marker: PhantomData,
        }
    }
}

/// Extends the builder with an iterator of (position, value) pairs.
///
/// Position must be in strictly increasing order. The first returned
/// position must be greater than the last position set.
impl<T> Extend<(usize, T)> for PartialArrayBuilder<T, BitVec<Box<[u64]>>> {
    fn extend<I: IntoIterator<Item = (usize, T)>>(&mut self, iter: I) {
        for (pos, val) in iter {
            self.set(pos, val);
        }
    }
}

/// Extends the builder with an iterator of (position, value) pairs.
///
/// Position must be in strictly increasing order. The first returned
/// position must be greater than the last position set.
impl<T> Extend<(usize, T)> for PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
    fn extend<I: IntoIterator<Item = (usize, T)>>(&mut self, iter: I) {
        for (pos, val) in iter {
            self.set(pos, val);
        }
    }
}

/// An immutable partial array that supports efficient queries
/// in compacted storage.
///
/// This structure stores a *partial array*—an array in which only
/// some positions contain values. There is a [dense] and a [sparse]
/// implementation with different space/time trade-offs.
///
/// For convenience, this structure implements [`SliceByValue`].
///
/// When the index structure `P` supports it, this structure implements the
/// [`TryIntoUnaligned`] trait, allowing it
/// to be converted into (usually faster) structures using unaligned access.
///
/// See [`PartialArrayBuilder`] for details on how to create a partial array.
///
/// [dense]: new_dense
/// [sparse]: new_sparse
#[derive(Debug, Clone, MemSize, MemDbg)]
#[cfg_attr(feature = "epserde", derive(epserde::Epserde))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct PartialArray<T, P, V = Box<[T]>> {
    index: P,
    values: V,
    _marker: PhantomData<T>,
}

impl<T, P, V: AsRef<[T]>> PartialArray<T, P, V> {
    /// Returns the number of values stored in the array.
    #[inline(always)]
    pub fn num_values(&self) -> usize {
        self.values.as_ref().len()
    }
}

impl<T, V: AsRef<[T]>> PartialArray<T, DenseIndex, V> {
    /// Returns the total length of the array.
    ///
    /// This is the length that was specified when creating the builder,
    /// not the number of values actually stored.
    #[inline(always)]
    pub fn len(&self) -> usize {
        self.index.len()
    }

    /// Returns `true` if the array has no elements.
    #[inline(always)]
    pub fn is_empty(&self) -> bool {
        self.len() == 0
    }

    /// Gets a reference to the value at the given position.
    ///
    /// Returns `Some(&value)` if a value is present at the position,
    /// or `None` if no value was stored there.
    ///
    /// # Examples
    ///
    /// ```rust
    /// # use sux::array::partial_array;
    /// let mut builder = partial_array::new_dense(10);
    /// builder.set(5, 42);
    ///
    /// let array = builder.build();
    /// assert_eq!(array.get(5), Some(&42));
    /// assert_eq!(array.get(6), None);
    /// ```
    pub fn get(&self, position: usize) -> Option<&T> {
        panic_if_out_of_bounds!(position, self.len());

        // SAFETY: we just checked
        unsafe { self.get_unchecked(position) }
    }

    /// # Safety
    ///
    /// position < len()
    pub unsafe fn get_unchecked(&self, position: usize) -> Option<&T> {
        // Check if there's a value at this position
        // SAFETY: position < len() guaranteed by caller
        if !unsafe { self.index.get_unchecked(position) } {
            return None;
        }

        // Use ranking to find the index in the values array
        // SAFETY: position < len() guaranteed by caller
        let value_index = unsafe { self.index.rank_unchecked(position) };

        // SAFETY: necessarily value_index < num_values().
        Some(unsafe { self.values.as_ref().get_unchecked(value_index) })
    }
}

impl<T, D: Backend<Word = usize> + AsRef<[usize]>, L: SliceByValue<Value = u64>, V: AsRef<[T]>>
    PartialArray<T, SparseIndex<D, L>, V>
where
    for<'b> &'b L: crate::traits::IntoUncheckedIterator<Item = u64>,
{
    /// Returns the total length of the array.
    ///
    /// This is the length that was specified when creating the builder,
    /// not the number of values actually stored.
    #[inline(always)]
    pub fn len(&self) -> usize {
        self.index.ef.upper_bound() as usize
    }

    /// Returns `true` if the array has no elements.
    #[inline(always)]
    pub fn is_empty(&self) -> bool {
        self.index.ef.upper_bound() == 0
    }

    /// Gets a reference to the value at the given position.
    ///
    /// Returns `Some(&value)` if a value is present at the position,
    /// or `None` if no value was stored there.
    ///
    /// # Examples
    ///
    /// ```rust
    /// # use sux::array::partial_array;
    /// let mut builder = partial_array::new_sparse(10, 1);
    /// builder.set(5, 42);
    ///
    /// let array = builder.build();
    /// assert_eq!(array.get(5), Some(&42));
    /// assert_eq!(array.get(6), None);
    /// ```
    pub fn get(&self, position: usize) -> Option<&T> {
        panic_if_out_of_bounds!(position, self.len());

        // SAFETY: we just checked
        unsafe { self.get_unchecked(position) }
    }

    /// # Safety
    ///
    /// position < len()
    pub unsafe fn get_unchecked(&self, position: usize) -> Option<&T> {
        if position >= self.index.first_invalid_pos {
            return None;
        }
        // Check if there's a value at this position
        // SAFETY: position <= last set position
        let (index, pos) = unsafe { self.index.ef.succ_unchecked::<false>(position as u64) };

        if pos != position as u64 {
            None
        } else {
            // SAFETY: necessarily value_index < num values.
            Some(unsafe { self.values.as_ref().get_unchecked(index) })
        }
    }
}

/// Returns an option even when using `get_value_unchecked` because it should be safe to call
/// whenever `position < len()`.
impl<T: Clone, V: AsRef<[T]>> SliceByValue for PartialArray<T, DenseIndex, V> {
    type Value = Option<T>;

    fn len(&self) -> usize {
        self.len()
    }

    unsafe fn get_value_unchecked(&self, position: usize) -> Self::Value {
        // SAFETY: position < len() guaranteed by caller
        unsafe { self.get_unchecked(position) }.cloned()
    }
}

/// Returns an option even when using `get_value_unchecked` because it should be safe to call
/// whenever `position < len()`.
impl<
    T: Clone,
    D: Backend<Word = usize> + AsRef<[usize]>,
    L: SliceByValue<Value = u64>,
    V: AsRef<[T]>,
> SliceByValue for PartialArray<T, SparseIndex<D, L>, V>
where
    for<'b> &'b L: crate::traits::IntoUncheckedIterator<Item = u64>,
{
    type Value = Option<T>;

    fn len(&self) -> usize {
        self.len()
    }

    unsafe fn get_value_unchecked(&self, position: usize) -> Self::Value {
        // SAFETY: position < len() guaranteed by caller
        unsafe { self.get_unchecked(position) }.cloned()
    }
}

// ── Aligned ↔ Unaligned conversion ──────────────────────────────────

impl<D> TryIntoUnaligned for SparseIndex<D> {
    type Unaligned = SparseIndex<D, Unaligned<BitFieldVec<Box<[u64]>>>>;
    fn try_into_unaligned(
        self,
    ) -> Result<Self::Unaligned, crate::traits::UnalignedConversionError> {
        Ok(SparseIndex {
            ef: self.ef.try_into_unaligned()?,
            first_invalid_pos: self.first_invalid_pos,
        })
    }
}

impl<T, P: TryIntoUnaligned, V> TryIntoUnaligned for PartialArray<T, P, V> {
    type Unaligned = PartialArray<T, P::Unaligned, V>;
    fn try_into_unaligned(
        self,
    ) -> Result<Self::Unaligned, crate::traits::UnalignedConversionError> {
        Ok(PartialArray {
            index: self.index.try_into_unaligned()?,
            values: self.values,
            _marker: PhantomData,
        })
    }
}

1	/*
2	* SPDX-FileCopyrightText: 2025 Sebastiano Vigna
3	*
4	* SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
5	*/
6
7	//! Immutable [partial array] implementations.
8	//!
9	//! [partial array]: PartialArray
10
11	use std::marker::PhantomData;
12
13	use mem_dbg::*;
14	use value_traits::slices::SliceByValue;
15
16	use crate::bits::{BitFieldVec, BitVec};
17	use crate::dict::EliasFanoBuilder;
18	use crate::dict::elias_fano::EliasFano;
19	use crate::panic_if_out_of_bounds;
20	use crate::rank_sel::{Rank9, SelectZeroAdaptConst};
21	use crate::traits::Backend;
22	use crate::traits::TryIntoUnaligned;
23	use crate::traits::Unaligned;
24	use crate::traits::{BitVecOps, BitVecOpsMut};
25	use crate::traits::{RankUnchecked, SuccUnchecked};
26
27	// Rank9 is inherently u64-based, so the dense index must use u64 backing
28	// regardless of usize.
29	type DenseIndex = Rank9<BitVec<Box<[u64]>>>;
30
31	/// An internal index for sparse partial arrays.
32	///
33	/// We cannot use directly an [Elias–Fano] structure because we need to
34	/// keep track of the first invalid position; and we need to keep track of
35	/// the first invalid position because we want to implement just
36	/// [`SuccUnchecked`] on the Elias–Fano structure, because it requires just
37	/// [`SelectZeroUnchecked`], whereas [`Succ`] would require
38	/// [`SelectUnchecked`] as well.
39	///
40	/// [Elias–Fano]: crate::dict::EliasFano
41	/// [`SuccUnchecked`]: crate::traits::SuccUnchecked
42	/// [`SelectZeroUnchecked`]: crate::traits::SelectZeroUnchecked
43	/// [`Succ`]: crate::traits::Succ
44	/// [`SelectUnchecked`]: crate::traits::SelectUnchecked
45	#[doc(hidden)]
46	#[derive(Debug, Clone, MemSize, MemDbg)]
47	#[cfg_attr(feature = "epserde", derive(epserde::Epserde))]
48	#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
49	pub struct SparseIndex<D, L = BitFieldVec<Box<[u64]>>> {
50	ef: EliasFano<u64, SelectZeroAdaptConst<BitVec<D>, Box<[usize]>, 12, 3>, L>,
51	/// self.ef should not be queried for values >= self.first_invalid_position
52	first_invalid_pos: usize,
53	}
54
55	/// Builder for creating an immutable partial array.
56	///
57	/// The builder allows you to specify the array length and then add
58	/// (position, value) pairs. Positions must be added in strictly
59	/// increasing order.
60	///
61	/// To get a builder you can use either [new_dense] or [new_sparse].
62	#[derive(Debug, Clone, MemSize, MemDbg)]
63	pub struct PartialArrayBuilder<T, B> {
64	builder: B,
65	values: Vec<T>,
66	len: usize,
67	min_next_pos: usize,
68	}
69
70	/// Creates a new builder for a dense partial array of the given length.
71	///
72	/// A dense partial array stores a bit vector of the given length to mark
73	/// which positions contain values, and uses ranking on this bit vector to
74	/// map positions to indices in a contiguous value array.
75	///
76	/// If your set of values is really sparse, consider using a
77	/// [sparse partial array].
78	///
79	/// # Examples
80	///
81	/// ```rust
82	/// # use sux::array::partial_array;
83	/// let mut builder = partial_array::new_dense(10);
84	/// builder.set(1, "foo");
85	/// builder.set(2, "hello");
86	/// builder.set(7, "world");
87	///
88	/// let array = builder.build();
89	/// assert_eq!(array.get(1), Some(&"foo"));
90	/// assert_eq!(array.get(2), Some(&"hello"));
91	/// assert_eq!(array.get(3), None);
92	/// assert_eq!(array.get(7), Some(&"world"));
93	/// ```
94	///
95	/// [sparse partial array]: new_sparse
96	pub fn new_dense<T>(len: usize) -> PartialArrayBuilder<T, BitVec<Box<[u64]>>> {	8✔
97	let n_of_words = len.div_ceil(64);	24✔
98	// SAFETY: the backing has exactly enough words for len bits
99	let bit_vec = unsafe { BitVec::from_raw_parts(vec![0u64; n_of_words].into_boxed_slice(), len) };	48✔
100	PartialArrayBuilder {
101	builder: bit_vec,
102	values: vec![],	8✔
103	len,
104	min_next_pos: 0,
105	}
106	}
107
108	impl<T> PartialArrayBuilder<T, BitVec<Box<[u64]>>> {
109	/// Sets a value at the given position.
110	///
111	/// The provided position must be greater than the last position set.
112	pub fn set(&mut self, position: usize, value: T) {	13✔
113	if position < self.min_next_pos {	13✔
114	panic!(	1✔
115	"Positions must be set in increasing order: got {} after {}",	×
116	position,	×
117	self.min_next_pos - 1	1✔
118	);
119	}
120	panic_if_out_of_bounds!(position, self.len);	36✔
121
122	// SAFETY: position < len
123	unsafe {
124	self.builder.set_unchecked(position, true);	22✔
125	}
126	self.values.push(value);	33✔
127	self.min_next_pos = position + 1;	11✔
128	}
129
130	/// Builds the immutable dense partial array.
131	#[must_use]
132	pub fn build(self) -> PartialArray<T, Rank9<BitVec<Box<[u64]>>>> {	6✔
133	let (bit_vec, values) = (self.builder, self.values);	18✔
134	let rank9 = Rank9::new(bit_vec);	18✔
135	let values = values.into_boxed_slice();	18✔
136
137	PartialArray {
138	index: rank9,
139	values,
140	_marker: PhantomData,
141	}
142	}
143	}
144
145	/// Creates a new builder for a sparse partial array of the given length.
146	///
147	/// A sparse partial array stores the non-empty positions of the array in an
148	/// [Elias-Fano] structure.
149	///
150	/// [Elias-Fano]: crate::dict::EliasFano
151	/// [dense partial array]: new_dense
152	///
153	/// If your set of values is really dense, consider using a [dense partial array].
154	///
155	/// # Examples
156	///
157	/// ```rust
158	/// # use sux::array::partial_array;
159	/// let mut builder = partial_array::new_sparse(10, 3);
160	/// builder.set(1, "foo");
161	/// builder.set(2, "hello");
162	/// builder.set(7, "world");
163	///
164	/// let array = builder.build();
165	/// assert_eq!(array.get(1), Some(&"foo"));
166	/// assert_eq!(array.get(2), Some(&"hello"));
167	/// assert_eq!(array.get(3), None);
168	/// assert_eq!(array.get(7), Some(&"world"));
169	/// ```
170	///
171	/// Note that you must specify the number of values in advance.
172	pub fn new_sparse<T>(	9✔
173	len: usize,
174	num_values: usize,
175	) -> PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
176	PartialArrayBuilder {
177	builder: EliasFanoBuilder::<u64>::new(num_values, len as u64),	36✔
178	values: vec![],	9✔
179	len,
180	min_next_pos: 0,
181	}
182	}
183
184	impl<T> PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
185	/// Sets a value at the given position.
186	///
187	/// The provided position must be greater than the last position
188	/// set.
189	pub fn set(&mut self, position: usize, value: T) {	16✔
190	if position < self.min_next_pos {	16✔
191	panic!(	1✔
192	"Positions must be set in increasing order: got {} after {}",	×
UNCOV 193	position,	×
194	self.min_next_pos - 1	1✔
195	);
196	}
197	panic_if_out_of_bounds!(position, self.len);	45✔
198	// SAFETY: conditions have been just checked
199	unsafe { self.builder.push_unchecked(position as u64) };	42✔
200	self.values.push(value);	42✔
201	self.min_next_pos = position + 1;	14✔
202	}
203
204	/// Builds the immutable sparse partial array.
205	#[must_use]
206	pub fn build(self) -> PartialArray<T, SparseIndex<Box<[usize]>>> {	7✔
207	let (builder, values) = (self.builder, self.values);	21✔
208	let ef_dict = builder.build_with_dict();	21✔
209	let values = values.into_boxed_slice();	21✔
210
211	PartialArray {
212	index: SparseIndex {	14✔
213	ef: ef_dict,
214	first_invalid_pos: self.min_next_pos,
215	},
216	values,
217	_marker: PhantomData,
218	}
219	}
220	}
221
222	/// Extends the builder with an iterator of (position, value) pairs.
223	///
224	/// Position must be in strictly increasing order. The first returned
225	/// position must be greater than the last position set.
226	impl<T> Extend<(usize, T)> for PartialArrayBuilder<T, BitVec<Box<[u64]>>> {
227	fn extend<I: IntoIterator<Item = (usize, T)>>(&mut self, iter: I) {	×
UNCOV 228	for (pos, val) in iter {	×
UNCOV 229	self.set(pos, val);	×
230	}
231	}
232	}
233
234	/// Extends the builder with an iterator of (position, value) pairs.
235	///
236	/// Position must be in strictly increasing order. The first returned
237	/// position must be greater than the last position set.
238	impl<T> Extend<(usize, T)> for PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
239	fn extend<I: IntoIterator<Item = (usize, T)>>(&mut self, iter: I) {	×
UNCOV 240	for (pos, val) in iter {	×
UNCOV 241	self.set(pos, val);	×
242	}
243	}
244	}
245
246	/// An immutable partial array that supports efficient queries
247	/// in compacted storage.
248	///
249	/// This structure stores a partial array—an array in which only
250	/// some positions contain values. There is a [dense] and a [sparse]
251	/// implementation with different space/time trade-offs.
252	///
253	/// For convenience, this structure implements [`SliceByValue`].
254	///
255	/// When the index structure `P` supports it, this structure implements the
256	/// [`TryIntoUnaligned`] trait, allowing it
257	/// to be converted into (usually faster) structures using unaligned access.
258	///
259	/// See [`PartialArrayBuilder`] for details on how to create a partial array.
260	///
261	/// [dense]: new_dense
262	/// [sparse]: new_sparse
263	#[derive(Debug, Clone, MemSize, MemDbg)]
264	#[cfg_attr(feature = "epserde", derive(epserde::Epserde))]
265	#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
266	pub struct PartialArray<T, P, V = Box<[T]>> {
267	index: P,
268	values: V,
269	_marker: PhantomData<T>,
270	}
271
272	impl<T, P, V: AsRef<[T]>> PartialArray<T, P, V> {
273	/// Returns the number of values stored in the array.
274	#[inline(always)]
275	pub fn num_values(&self) -> usize {	14✔
276	self.values.as_ref().len()	28✔
277	}
278	}
279
280	impl<T, V: AsRef<[T]>> PartialArray<T, DenseIndex, V> {
281	/// Returns the total length of the array.
282	///
283	/// This is the length that was specified when creating the builder,
284	/// not the number of values actually stored.
285	#[inline(always)]
286	pub fn len(&self) -> usize {	9✔
287	self.index.len()	18✔
288	}
289
290	/// Returns `true` if the array has no elements.
291	#[inline(always)]
292	pub fn is_empty(&self) -> bool {	1✔
293	self.len() == 0	1✔
294	}
295
296	/// Gets a reference to the value at the given position.
297	///
298	/// Returns `Some(&value)` if a value is present at the position,
299	/// or `None` if no value was stored there.
300	///
301	/// # Examples
302	///
303	/// ```rust
304	/// # use sux::array::partial_array;
305	/// let mut builder = partial_array::new_dense(10);
306	/// builder.set(5, 42);
307	///
308	/// let array = builder.build();
309	/// assert_eq!(array.get(5), Some(&42));
310	/// assert_eq!(array.get(6), None);
311	/// ```
312	pub fn get(&self, position: usize) -> Option<&T> {	1,041✔
313	panic_if_out_of_bounds!(position, self.len());	2,084✔
314
315	// SAFETY: we just checked
316	unsafe { self.get_unchecked(position) }	3,120✔
317	}
318
319	/// # Safety
320	///
321	/// position < len()
322	pub unsafe fn get_unchecked(&self, position: usize) -> Option<&T> {	1,040✔
323	// Check if there's a value at this position
324	// SAFETY: position < len() guaranteed by caller
325	if !unsafe { self.index.get_unchecked(position) } {	2,080✔
326	return None;	1,027✔
327	}
328
329	// Use ranking to find the index in the values array
330	// SAFETY: position < len() guaranteed by caller
331	let value_index = unsafe { self.index.rank_unchecked(position) };	52✔
332
333	// SAFETY: necessarily value_index < num_values().
334	Some(unsafe { self.values.as_ref().get_unchecked(value_index) })	26✔
335	}
336	}
337
338	impl<T, D: Backend<Word = usize> + AsRef<[usize]>, L: SliceByValue<Value = u64>, V: AsRef<[T]>>
339	PartialArray<T, SparseIndex<D, L>, V>
340	where
341	for<'b> &'b L: crate::traits::IntoUncheckedIterator<Item = u64>,
342	{
343	/// Returns the total length of the array.
344	///
345	/// This is the length that was specified when creating the builder,
346	/// not the number of values actually stored.
347	#[inline(always)]
348	pub fn len(&self) -> usize {	10✔
349	self.index.ef.upper_bound() as usize	10✔
350	}
351
352	/// Returns `true` if the array has no elements.
353	#[inline(always)]
354	pub fn is_empty(&self) -> bool {	1✔
355	self.index.ef.upper_bound() == 0	1✔
356	}
357
358	/// Gets a reference to the value at the given position.
359	///
360	/// Returns `Some(&value)` if a value is present at the position,
361	/// or `None` if no value was stored there.
362	///
363	/// # Examples
364	///
365	/// ```rust
366	/// # use sux::array::partial_array;
367	/// let mut builder = partial_array::new_sparse(10, 1);
368	/// builder.set(5, 42);
369	///
370	/// let array = builder.build();
371	/// assert_eq!(array.get(5), Some(&42));
372	/// assert_eq!(array.get(6), None);
373	/// ```
374	pub fn get(&self, position: usize) -> Option<&T> {	1,061✔
375	panic_if_out_of_bounds!(position, self.len());	2,124✔
376
377	// SAFETY: we just checked
378	unsafe { self.get_unchecked(position) }	3,180✔
379	}
380
381	/// # Safety
382	///
383	/// position < len()
384	pub unsafe fn get_unchecked(&self, position: usize) -> Option<&T> {	1,060✔
385	if position >= self.index.first_invalid_pos {	1,060✔
386	return None;	505✔
387	}
388	// Check if there's a value at this position
389	// SAFETY: position <= last set position
390	let (index, pos) = unsafe { self.index.ef.succ_unchecked::<false>(position as u64) };	2,220✔
391
392	if pos != position as u64 {	555✔
393	None	536✔
394	} else {
395	// SAFETY: necessarily value_index < num values.
396	Some(unsafe { self.values.as_ref().get_unchecked(index) })	38✔
397	}
398	}
399	}
400
401	/// Returns an option even when using `get_value_unchecked` because it should be safe to call
402	/// whenever `position < len()`.
403	impl<T: Clone, V: AsRef<[T]>> SliceByValue for PartialArray<T, DenseIndex, V> {
404	type Value = Option<T>;
405
UNCOV 406	fn len(&self) -> usize {	×
UNCOV 407	self.len()	×
408	}
409
410	unsafe fn get_value_unchecked(&self, position: usize) -> Self::Value {	×
411	// SAFETY: position < len() guaranteed by caller
UNCOV 412	unsafe { self.get_unchecked(position) }.cloned()	×
413	}
414	}
415
416	/// Returns an option even when using `get_value_unchecked` because it should be safe to call
417	/// whenever `position < len()`.
418	impl<
419	T: Clone,
420	D: Backend<Word = usize> + AsRef<[usize]>,
421	L: SliceByValue<Value = u64>,
422	V: AsRef<[T]>,
423	> SliceByValue for PartialArray<T, SparseIndex<D, L>, V>
424	where
425	for<'b> &'b L: crate::traits::IntoUncheckedIterator<Item = u64>,
426	{
427	type Value = Option<T>;
428
UNCOV 429	fn len(&self) -> usize {	×
UNCOV 430	self.len()	×
431	}
432
433	unsafe fn get_value_unchecked(&self, position: usize) -> Self::Value {	×
434	// SAFETY: position < len() guaranteed by caller
UNCOV 435	unsafe { self.get_unchecked(position) }.cloned()	×
436	}
437	}
438
439	// ── Aligned ↔ Unaligned conversion ──────────────────────────────────
440
441	impl<D> TryIntoUnaligned for SparseIndex<D> {
442	type Unaligned = SparseIndex<D, Unaligned<BitFieldVec<Box<[u64]>>>>;
UNCOV 443	fn try_into_unaligned(	×
444	self,
445	) -> Result<Self::Unaligned, crate::traits::UnalignedConversionError> {
446	Ok(SparseIndex {	×
UNCOV 447	ef: self.ef.try_into_unaligned()?,	×
UNCOV 448	first_invalid_pos: self.first_invalid_pos,	×
449	})
450	}
451	}
452
453	impl<T, P: TryIntoUnaligned, V> TryIntoUnaligned for PartialArray<T, P, V> {
454	type Unaligned = PartialArray<T, P::Unaligned, V>;
UNCOV 455	fn try_into_unaligned(	×
456	self,
457	) -> Result<Self::Unaligned, crate::traits::UnalignedConversionError> {
458	Ok(PartialArray {	×
459	index: self.index.try_into_unaligned()?,	×
UNCOV 460	values: self.values,	×
UNCOV 461	_marker: PhantomData,	×
462	})
463	}
464	}

vigna / sux-rs / 24282745314

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