29757944694

Committed 20 Jul 2026 04:03PM UTC coverage: 72.617% (+1.5%) from 71.124%

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Fifth round of fixes

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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]>>, I = Box<[usize]>> {
    ef: EliasFano<u64, SelectZeroAdaptConst<BitVec<D>, I>, 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.
///
/// 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"));
/// ```
///
/// You must specify the number of values in advance.
///
/// # Panics
///
/// Panics if `num_values > len`, because strictly increasing in-bounds
/// positions cannot satisfy that capacity.
///
/// [Elias-Fano]: crate::dict::EliasFano
/// [dense partial array]: new_dense
pub fn new_sparse<T>(
    len: usize,
    num_values: usize,
) -> PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
    assert!(
        num_values <= len,
        "number of values ({num_values}) must not exceed array length ({len})"
    );
    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);
        // usize fits u64 on all supported targets, so this cast is lossless. The
        // checked push panics "Too many values" past the declared capacity,
        // upholding EliasFano's unchecked "at most n pushes" precondition.
        self.builder.push(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>,
    I: AsRef<[usize]>,
    V: AsRef<[T]>,
> PartialArray<T, SparseIndex<D, L, I>, 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>,
    I: AsRef<[usize]>,
    V: AsRef<[T]>,
> SliceByValue for PartialArray<T, SparseIndex<D, L, I>, 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]>>, I = Box<[usize]>> {
50	ef: EliasFano<u64, SelectZeroAdaptConst<BitVec<D>, I>, 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	/// If your set of values is really dense, consider using a [dense partial array].
151	///
152	/// # Examples
153	///
154	/// ```rust
155	/// # use sux::array::partial_array;
156	/// let mut builder = partial_array::new_sparse(10, 3);
157	/// builder.set(1, "foo");
158	/// builder.set(2, "hello");
159	/// builder.set(7, "world");
160	///
161	/// let array = builder.build();
162	/// assert_eq!(array.get(1), Some(&"foo"));
163	/// assert_eq!(array.get(2), Some(&"hello"));
164	/// assert_eq!(array.get(3), None);
165	/// assert_eq!(array.get(7), Some(&"world"));
166	/// ```
167	///
168	/// You must specify the number of values in advance.
169	///
170	/// # Panics
171	///
172	/// Panics if `num_values > len`, because strictly increasing in-bounds
173	/// positions cannot satisfy that capacity.
174	///
175	/// [Elias-Fano]: crate::dict::EliasFano
176	/// [dense partial array]: new_dense
177	pub fn new_sparse<T>(	12✔
178	len: usize,
179	num_values: usize,
180	) -> PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
181	assert!(	12✔
182	num_values <= len,	12✔
UNCOV 183	"number of values ({num_values}) must not exceed array length ({len})"	×
184	);
185	PartialArrayBuilder {
186	builder: EliasFanoBuilder::<u64>::new(num_values, len as u64),	44✔
187	values: vec![],	11✔
188	len,
189	min_next_pos: 0,
190	}
191	}
192
193	impl<T> PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
194	/// Sets a value at the given position.
195	///
196	/// The provided position must be greater than the last position
197	/// set.
198	pub fn set(&mut self, position: usize, value: T) {	19✔
199	if position < self.min_next_pos {	19✔
200	panic!(	1✔
UNCOV 201	"Positions must be set in increasing order: got {} after {}",	×
UNCOV 202	position,	×
203	self.min_next_pos - 1	1✔
204	);
205	}
206	panic_if_out_of_bounds!(position, self.len);	54✔
207	// usize fits u64 on all supported targets, so this cast is lossless. The
208	// checked push panics "Too many values" past the declared capacity,
209	// upholding EliasFano's unchecked "at most n pushes" precondition.
210	self.builder.push(position as u64);	51✔
211	self.values.push(value);	51✔
212	self.min_next_pos = position + 1;	17✔
213	}
214
215	/// Builds the immutable sparse partial array.
216	#[must_use]
217	pub fn build(self) -> PartialArray<T, SparseIndex<Box<[usize]>>> {	8✔
218	let (builder, values) = (self.builder, self.values);	24✔
219	let ef_dict = builder.build_with_dict();	24✔
220	let values = values.into_boxed_slice();	24✔
221
222	PartialArray {
223	index: SparseIndex {	16✔
224	ef: ef_dict,
225	first_invalid_pos: self.min_next_pos,
226	},
227	values,
228	_marker: PhantomData,
229	}
230	}
231	}
232
233	/// Extends the builder with an iterator of (position, value) pairs.
234	///
235	/// Position must be in strictly increasing order. The first returned
236	/// position must be greater than the last position set.
237	impl<T> Extend<(usize, T)> for PartialArrayBuilder<T, BitVec<Box<[u64]>>> {
UNCOV 238	fn extend<I: IntoIterator<Item = (usize, T)>>(&mut self, iter: I) {	×
239	for (pos, val) in iter {	×
240	self.set(pos, val);	×
241	}
242	}
243	}
244
245	/// Extends the builder with an iterator of (position, value) pairs.
246	///
247	/// Position must be in strictly increasing order. The first returned
248	/// position must be greater than the last position set.
249	impl<T> Extend<(usize, T)> for PartialArrayBuilder<T, EliasFanoBuilder<u64>> {
UNCOV 250	fn extend<I: IntoIterator<Item = (usize, T)>>(&mut self, iter: I) {	×
UNCOV 251	for (pos, val) in iter {	×
UNCOV 252	self.set(pos, val);	×
253	}
254	}
255	}
256
257	/// An immutable partial array that supports efficient queries
258	/// in compacted storage.
259	///
260	/// This structure stores a partial array, an array in which only
261	/// some positions contain values. There is a [dense] and a [sparse]
262	/// implementation with different space/time trade-offs.
263	///
264	/// For convenience, this structure implements [`SliceByValue`].
265	///
266	/// When the index structure `P` supports it, this structure implements the
267	/// [`TryIntoUnaligned`] trait, allowing it
268	/// to be converted into (usually faster) structures using unaligned access.
269	///
270	/// See [`PartialArrayBuilder`] for details on how to create a partial array.
271	///
272	/// [dense]: new_dense
273	/// [sparse]: new_sparse
274	#[derive(Debug, Clone, MemSize, MemDbg)]
275	#[cfg_attr(feature = "epserde", derive(epserde::Epserde))]
276	#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
277	pub struct PartialArray<T, P, V = Box<[T]>> {
278	index: P,
279	values: V,
280	_marker: PhantomData<T>,
281	}
282
283	impl<T, P, V: AsRef<[T]>> PartialArray<T, P, V> {
284	/// Returns the number of values stored in the array.
285	#[inline(always)]
286	pub fn num_values(&self) -> usize {	15✔
287	self.values.as_ref().len()	30✔
288	}
289	}
290
291	impl<T, V: AsRef<[T]>> PartialArray<T, DenseIndex, V> {
292	/// Returns the total length of the array.
293	///
294	/// This is the length that was specified when creating the builder,
295	/// not the number of values actually stored.
296	#[inline(always)]
297	pub fn len(&self) -> usize {	9✔
298	self.index.len()	18✔
299	}
300
301	/// Returns `true` if the array has no elements.
302	#[inline(always)]
303	pub fn is_empty(&self) -> bool {	1✔
304	self.len() == 0	1✔
305	}
306
307	/// Gets a reference to the value at the given position.
308	///
309	/// Returns `Some(&value)` if a value is present at the position,
310	/// or `None` if no value was stored there.
311	///
312	/// # Examples
313	///
314	/// ```rust
315	/// # use sux::array::partial_array;
316	/// let mut builder = partial_array::new_dense(10);
317	/// builder.set(5, 42);
318	///
319	/// let array = builder.build();
320	/// assert_eq!(array.get(5), Some(&42));
321	/// assert_eq!(array.get(6), None);
322	/// ```
323	pub fn get(&self, position: usize) -> Option<&T> {	1,041✔
324	panic_if_out_of_bounds!(position, self.len());	2,084✔
325
326	// SAFETY: we just checked
327	unsafe { self.get_unchecked(position) }	3,120✔
328	}
329
330	/// # Safety
331	///
332	/// position < len()
333	pub unsafe fn get_unchecked(&self, position: usize) -> Option<&T> {	1,040✔
334	// Check if there's a value at this position
335	// SAFETY: position < len() guaranteed by caller
336	if !unsafe { self.index.get_unchecked(position) } {	2,080✔
337	return None;	1,027✔
338	}
339
340	// Use ranking to find the index in the values array
341	// SAFETY: position < len() guaranteed by caller
342	let value_index = unsafe { self.index.rank_unchecked(position) };	52✔
343
344	// SAFETY: necessarily value_index < num_values().
345	Some(unsafe { self.values.as_ref().get_unchecked(value_index) })	26✔
346	}
347	}
348
349	impl<
350	T,
351	D: Backend<Word = usize> + AsRef<[usize]>,
352	L: SliceByValue<Value = u64>,
353	I: AsRef<[usize]>,
354	V: AsRef<[T]>,
355	> PartialArray<T, SparseIndex<D, L, I>, V>
356	where
357	for<'b> &'b L: crate::traits::IntoUncheckedIterator<Item = u64>,
358	{
359	/// Returns the total length of the array.
360	///
361	/// This is the length that was specified when creating the builder,
362	/// not the number of values actually stored.
363	#[inline(always)]
364	pub fn len(&self) -> usize {	11✔
365	self.index.ef.upper_bound() as usize	11✔
366	}
367
368	/// Returns `true` if the array has no elements.
369	#[inline(always)]
370	pub fn is_empty(&self) -> bool {	1✔
371	self.index.ef.upper_bound() == 0	1✔
372	}
373
374	/// Gets a reference to the value at the given position.
375	///
376	/// Returns `Some(&value)` if a value is present at the position,
377	/// or `None` if no value was stored there.
378	///
379	/// # Examples
380	///
381	/// ```rust
382	/// # use sux::array::partial_array;
383	/// let mut builder = partial_array::new_sparse(10, 1);
384	/// builder.set(5, 42);
385	///
386	/// let array = builder.build();
387	/// assert_eq!(array.get(5), Some(&42));
388	/// assert_eq!(array.get(6), None);
389	/// ```
390	pub fn get(&self, position: usize) -> Option<&T> {	1,063✔
391	panic_if_out_of_bounds!(position, self.len());	2,128✔
392
393	// SAFETY: we just checked
394	unsafe { self.get_unchecked(position) }	3,186✔
395	}
396
397	/// # Safety
398	///
399	/// position < len()
400	pub unsafe fn get_unchecked(&self, position: usize) -> Option<&T> {	1,062✔
401	if position >= self.index.first_invalid_pos {	1,062✔
402	return None;	506✔
403	}
404	// Check if there's a value at this position
405	// SAFETY: position <= last set position
406	let (index, pos) = unsafe { self.index.ef.succ_unchecked::<false>(position as u64) };	2,224✔
407
408	if pos != position as u64 {	556✔
409	None	536✔
410	} else {
411	// SAFETY: necessarily value_index < num values.
412	Some(unsafe { self.values.as_ref().get_unchecked(index) })	40✔
413	}
414	}
415	}
416
417	/// Returns an option even when using `get_value_unchecked` because it should be safe to call
418	/// whenever `position < len()`.
419	impl<T: Clone, V: AsRef<[T]>> SliceByValue for PartialArray<T, DenseIndex, V> {
420	type Value = Option<T>;
421
UNCOV 422	fn len(&self) -> usize {	×
UNCOV 423	self.len()	×
424	}
425
UNCOV 426	unsafe fn get_value_unchecked(&self, position: usize) -> Self::Value {	×
427	// SAFETY: position < len() guaranteed by caller
UNCOV 428	unsafe { self.get_unchecked(position) }.cloned()	×
429	}
430	}
431
432	/// Returns an option even when using `get_value_unchecked` because it should be safe to call
433	/// whenever `position < len()`.
434	impl<
435	T: Clone,
436	D: Backend<Word = usize> + AsRef<[usize]>,
437	L: SliceByValue<Value = u64>,
438	I: AsRef<[usize]>,
439	V: AsRef<[T]>,
440	> SliceByValue for PartialArray<T, SparseIndex<D, L, I>, V>
441	where
442	for<'b> &'b L: crate::traits::IntoUncheckedIterator<Item = u64>,
443	{
444	type Value = Option<T>;
445
446	fn len(&self) -> usize {	×
447	self.len()	×
448	}
449
UNCOV 450	unsafe fn get_value_unchecked(&self, position: usize) -> Self::Value {	×
451	// SAFETY: position < len() guaranteed by caller
UNCOV 452	unsafe { self.get_unchecked(position) }.cloned()	×
453	}
454	}
455
456	// ── Aligned ↔ Unaligned conversion ──────────────────────────────────
457
458	impl<D> TryIntoUnaligned for SparseIndex<D> {
459	type Unaligned = SparseIndex<D, Unaligned<BitFieldVec<Box<[u64]>>>>;
460	fn try_into_unaligned(	×
461	self,
462	) -> Result<Self::Unaligned, crate::traits::UnalignedConversionError> {
UNCOV 463	Ok(SparseIndex {	×
UNCOV 464	ef: self.ef.try_into_unaligned()?,	×
UNCOV 465	first_invalid_pos: self.first_invalid_pos,	×
466	})
467	}
468	}
469
470	impl<T, P: TryIntoUnaligned, V> TryIntoUnaligned for PartialArray<T, P, V> {
471	type Unaligned = PartialArray<T, P::Unaligned, V>;
UNCOV 472	fn try_into_unaligned(	×
473	self,
474	) -> Result<Self::Unaligned, crate::traits::UnalignedConversionError> {
UNCOV 475	Ok(PartialArray {	×
UNCOV 476	index: self.index.try_into_unaligned()?,	×
UNCOV 477	values: self.values,	×
UNCOV 478	_marker: PhantomData,	×
479	})
480	}
481	}

vigna / sux-rs / 29757944694

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