22649179319

Committed 04 Mar 2026 12:25AM UTC coverage: 71.445% (-0.06%) from 71.504%

Build # 22649179319

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github

Committed by

vigna

Commit Message

Deduplication support at codec level

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/webgraph/src/utils/batch_codec/gaps.rs

/*
 * SPDX-FileCopyrightText: 2023 Inria
 * SPDX-FileCopyrightText: 2023 Sebastiano Vigna
 * SPDX-FileCopyrightText: 2025 Tommaso Fontana
 *
 * SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
 */

use super::{BitReader, BitWriter};
use crate::traits::SortedIterator;
use crate::utils::{ArcMmapHelper, MmapHelper, Triple};
use crate::{
    traits::{BitDeserializer, BitSerializer},
    utils::{BatchCodec, humanize},
};

use std::sync::Arc;

use anyhow::{Context, Result};
use dsi_bitstream::prelude::*;
use mmap_rs::MmapFlags;
use rdst::*;

/// A codec for encoding and decoding batches of triples using gap compression.
///
/// This codec encodes triples of the form `(src, dst, label)` by encoding the
/// gaps between consecutive sources and destinations using a specified code.
///
/// # Type Parameters
///
/// - `S`: Serializer for the labels, implementing [`BitSerializer`] for the label type.
/// - `D`: Deserializer for the labels, implementing [`BitDeserializer`] for the label type.
/// - `SRC_CODE`: Code used for encoding source gaps (default: gamma).
/// - `DST_CODE`: Code used for encoding destination gaps (default: gamma).
///
/// # Encoding Format
///
/// 1. The batch length is written using delta coding.
/// 2. For each group of triples with the same source:
///     - The gap from the previous source is encoded.
///     - The gap from the previous destination is encoded.
///     - The label is serialized.
///
/// The bit deserializer must be [`Clone`] because we need one for each
/// [`GapsIter`], and there are possible scenarios in which the
/// deserializer might be stateful.
#[derive(Clone, Debug)]
pub struct GapsCodec<
    E: Endianness = NE,
    S: BitSerializer<E, BitWriter<E>> = (),
    D: BitDeserializer<E, BitReader<E>, DeserType = S::SerType> + Clone = (),
    const SRC_CODE: usize = { dsi_bitstream::dispatch::code_consts::GAMMA },
    const DST_CODE: usize = { dsi_bitstream::dispatch::code_consts::DELTA },
    const DEDUP: bool = false,
> where
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
    /// Serializer for the labels
    pub serializer: S,
    /// Deserializer for the labels
    pub deserializer: D,
    /// Marker for the endianness
    _marker: std::marker::PhantomData<E>,
}

impl<E, S, D, const SRC_CODE: usize, const DST_CODE: usize, const DEDUP: bool>
    GapsCodec<E, S, D, SRC_CODE, DST_CODE, DEDUP>
where
    E: Endianness,
    S: BitSerializer<E, BitWriter<E>> + Send + Sync,
    D: BitDeserializer<E, BitReader<E>, DeserType = S::SerType> + Send + Sync + Clone,
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
    /// Creates a new `GapsCodec` with the given serializer and deserializer.
    pub const fn new(serializer: S, deserializer: D) -> Self {
        Self {
            serializer,
            deserializer,
            _marker: std::marker::PhantomData,
        }
    }
}

impl<E, S: Default, D: Default, const SRC_CODE: usize, const DST_CODE: usize, const DEDUP: bool>
    core::default::Default for GapsCodec<E, S, D, SRC_CODE, DST_CODE, DEDUP>
where
    E: Endianness,
    S: BitSerializer<E, BitWriter<E>> + Send + Sync,
    D: BitDeserializer<E, BitReader<E>, DeserType = S::SerType> + Send + Sync + Clone,
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
    fn default() -> Self {
        Self::new(Default::default(), Default::default())
    }
}

/// Statistics about the encoding performed by [`GapsCodec`].
#[derive(Debug, Clone, Copy)]
pub struct GapsStats {
    /// Total number of triples encoded
    pub total_triples: usize,
    /// Number of bits used for source gaps
    pub src_bits: usize,
    /// Number of bits used for destination gaps
    pub dst_bits: usize,
    /// Number of bits used for labels
    pub labels_bits: usize,
}

impl core::fmt::Display for GapsStats {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        let total_bits = self.src_bits + self.dst_bits + self.labels_bits;
        write!(
            f,
            "src: {}B ({:.3} bits / arc), dst: {}B ({:.3} bits / arc), labels: {}B ({:.3} bits / arc), total: {}B ({:.3} bits / arc)",
            humanize(self.src_bits as f64 / 8.0),
            self.src_bits as f64 / self.total_triples as f64,
            humanize(self.dst_bits as f64 / 8.0),
            self.dst_bits as f64 / self.total_triples as f64,
            humanize(self.labels_bits as f64 / 8.0),
            self.labels_bits as f64 / self.total_triples as f64,
            humanize(total_bits as f64 / 8.0),
            total_bits as f64 / self.total_triples as f64,
        )
    }
}

impl<E, S, D, const SRC_CODE: usize, const DST_CODE: usize, const DEDUP: bool> BatchCodec
    for GapsCodec<E, S, D, SRC_CODE, DST_CODE, DEDUP>
where
    E: Endianness,
    S: BitSerializer<E, BitWriter<E>> + Send + Sync,
    D: BitDeserializer<E, BitReader<E>, DeserType = S::SerType> + Send + Sync + Clone,
    S::SerType: Send + Sync + Copy + 'static + core::fmt::Debug, // needed by radix sort
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
    type Label = S::SerType;
    type DecodedBatch = GapsIter<E, D, SRC_CODE, DST_CODE>;
    type EncodedBatchStats = GapsStats;

    fn encode_batch(
        &self,
        path: impl AsRef<std::path::Path>,
        batch: &mut [((usize, usize), Self::Label)],
    ) -> Result<(usize, Self::EncodedBatchStats)> {
        let start = std::time::Instant::now();
        Triple::cast_batch_mut(batch).radix_sort_unstable();
        log::debug!("Sorted {} arcs in {:?}", batch.len(), start.elapsed());
        self.encode_sorted_batch(path, batch)
    }

    fn encode_sorted_batch(
        &self,
        path: impl AsRef<std::path::Path>,
        batch: &[((usize, usize), Self::Label)],
    ) -> Result<(usize, Self::EncodedBatchStats)> {
        debug_assert!(Triple::cast_batch(batch).is_sorted());
        // create a bitstream to write to the file
        let file_path = path.as_ref();
        let mut stream = buf_bit_writer::from_path::<E, usize>(file_path).with_context(|| {
            format!(
                "Could not create BatchIterator temporary file {}",
                file_path.display()
            )
        })?;

        // Pre-count unique pairs for the length prefix when deduplicating
        let batch_len = if DEDUP {
            if batch.is_empty() {
                0
            } else {
                1 + batch.windows(2).filter(|w| w[0].0 != w[1].0).count()
            }
        } else {
            batch.len()
        };

        // prefix the stream with the length of the batch
        // we use a delta code since it'll be a big number most of the time
        stream
            .write_delta(batch_len as u64)
            .context("Could not write length")?;

        let mut stats = GapsStats {
            total_triples: batch_len,
            src_bits: 0,
            dst_bits: 0,
            labels_bits: 0,
        };
        // Dump the triples to the bitstream
        let (mut prev_src, mut prev_dst) = (0, 0);
        let mut prev_pair: Option<(usize, usize)> = None;
        for ((src, dst), label) in batch.iter() {
            if DEDUP {
                if prev_pair == Some((*src, *dst)) {
                    continue;
                }
                prev_pair = Some((*src, *dst));
            }
            // write the source gap as gamma
            stats.src_bits += ConstCode::<SRC_CODE>
                .write(&mut stream, (src - prev_src) as u64)
                .with_context(|| format!("Could not write {src} after {prev_src}"))?;
            if *src != prev_src {
                // Reset prev_y
                prev_dst = 0;
            }
            // write the destination gap as gamma
            stats.dst_bits += ConstCode::<DST_CODE>
                .write(&mut stream, (dst - prev_dst) as u64)
                .with_context(|| format!("Could not write {dst} after {prev_dst}"))?;
            // write the label
            stats.labels_bits += self
                .serializer
                .serialize(label, &mut stream)
                .context("Could not serialize label")?;
            (prev_src, prev_dst) = (*src, *dst);
        }
        // flush the stream and reset the buffer
        stream.flush().context("Could not flush stream")?;

        let total_bits = stats.src_bits + stats.dst_bits + stats.labels_bits;
        Ok((total_bits, stats))
    }

    fn decode_batch(&self, path: impl AsRef<std::path::Path>) -> Result<Self::DecodedBatch> {
        // open the file
        let mut stream = <BufBitReader<E, _>>::new(MemWordReader::new(ArcMmapHelper(Arc::new(
            MmapHelper::mmap(
                path.as_ref(),
                MmapFlags::TRANSPARENT_HUGE_PAGES | MmapFlags::SEQUENTIAL,
            )
            .with_context(|| format!("Could not mmap {}", path.as_ref().display()))?,
        ))));

        // read the length of the batch (first value in the stream)
        let len = stream.read_delta().context("Could not read length")? as usize;

        // create the iterator
        Ok(GapsIter {
            deserializer: self.deserializer.clone(),
            stream,
            len,
            current: 0,
            prev_src: 0,
            prev_dst: 0,
        })
    }
}

/// An iterator over triples encoded with gaps, this is returned by [`GapsCodec`].
#[derive(Clone, Debug)]
pub struct GapsIter<
    E: Endianness = NE,
    D: BitDeserializer<E, BitReader<E>> = (),
    const SRC_CODE: usize = { dsi_bitstream::dispatch::code_consts::GAMMA },
    const DST_CODE: usize = { dsi_bitstream::dispatch::code_consts::GAMMA },
> where
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
    /// Deserializer for the labels
    deserializer: D,
    /// Bitstream to read from
    stream: BitReader<E>,
    /// Length of the iterator (number of triples)
    len: usize,
    /// Current position in the iterator
    current: usize,
    /// Previous source node
    prev_src: usize,
    /// Previous destination node
    prev_dst: usize,
}

// SAFETY: gaps are decoded in non-decreasing (src, dst) order.
unsafe impl<
    E: Endianness,
    D: BitDeserializer<E, BitReader<E>>,
    const SRC_CODE: usize,
    const DST_CODE: usize,
> SortedIterator for GapsIter<E, D, SRC_CODE, DST_CODE>
where
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
}

impl<
    E: Endianness,
    D: BitDeserializer<E, BitReader<E>>,
    const SRC_CODE: usize,
    const DST_CODE: usize,
> Iterator for GapsIter<E, D, SRC_CODE, DST_CODE>
where
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
    type Item = ((usize, usize), D::DeserType);

    fn next(&mut self) -> Option<Self::Item> {
        if self.current >= self.len {
            return None;
        }
        let src_gap = ConstCode::<SRC_CODE>.read(&mut self.stream).ok()?;
        let dst_gap = ConstCode::<DST_CODE>.read(&mut self.stream).ok()?;
        let label = self.deserializer.deserialize(&mut self.stream).ok()?;
        self.prev_src += src_gap as usize;
        if src_gap != 0 {
            self.prev_dst = 0;
        }
        self.prev_dst += dst_gap as usize;
        self.current += 1;
        Some(((self.prev_src, self.prev_dst), label))
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        (self.len(), Some(self.len()))
    }

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

impl<
    E: Endianness,
    D: BitDeserializer<E, BitReader<E>>,
    const SRC_CODE: usize,
    const DST_CODE: usize,
> ExactSizeIterator for GapsIter<E, D, SRC_CODE, DST_CODE>
where
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
    fn len(&self) -> usize {
        self.len - self.current
    }
}

impl<
    E: Endianness,
    D: BitDeserializer<E, BitReader<E>>,
    const SRC_CODE: usize,
    const DST_CODE: usize,
> core::iter::FusedIterator for GapsIter<E, D, SRC_CODE, DST_CODE>
where
    BitReader<E>: BitRead<E> + CodesRead<E>,
    BitWriter<E>: BitWrite<E> + CodesWrite<E>,
{
}

1	/*
2	* SPDX-FileCopyrightText: 2023 Inria
3	* SPDX-FileCopyrightText: 2023 Sebastiano Vigna
4	* SPDX-FileCopyrightText: 2025 Tommaso Fontana
5	*
6	* SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
7	*/
8
9	use super::{BitReader, BitWriter};
10	use crate::traits::SortedIterator;
11	use crate::utils::{ArcMmapHelper, MmapHelper, Triple};
12	use crate::{
13	traits::{BitDeserializer, BitSerializer},
14	utils::{BatchCodec, humanize},
15	};
16
17	use std::sync::Arc;
18
19	use anyhow::{Context, Result};
20	use dsi_bitstream::prelude::*;
21	use mmap_rs::MmapFlags;
22	use rdst::*;
23
24	/// A codec for encoding and decoding batches of triples using gap compression.
25	///
26	/// This codec encodes triples of the form `(src, dst, label)` by encoding the
27	/// gaps between consecutive sources and destinations using a specified code.
28	///
29	/// # Type Parameters
30	///
31	/// - `S`: Serializer for the labels, implementing [`BitSerializer`] for the label type.
32	/// - `D`: Deserializer for the labels, implementing [`BitDeserializer`] for the label type.
33	/// - `SRC_CODE`: Code used for encoding source gaps (default: gamma).
34	/// - `DST_CODE`: Code used for encoding destination gaps (default: gamma).
35	///
36	/// # Encoding Format
37	///
38	/// 1. The batch length is written using delta coding.
39	/// 2. For each group of triples with the same source:
40	/// - The gap from the previous source is encoded.
41	/// - The gap from the previous destination is encoded.
42	/// - The label is serialized.
43	///
44	/// The bit deserializer must be [`Clone`] because we need one for each
45	/// [`GapsIter`], and there are possible scenarios in which the
46	/// deserializer might be stateful.
47	#[derive(Clone, Debug)]
48	pub struct GapsCodec<
49	E: Endianness = NE,
50	S: BitSerializer<E, BitWriter<E>> = (),
51	D: BitDeserializer<E, BitReader<E>, DeserType = S::SerType> + Clone = (),
52	const SRC_CODE: usize = { dsi_bitstream::dispatch::code_consts::GAMMA },
53	const DST_CODE: usize = { dsi_bitstream::dispatch::code_consts::DELTA },
54	const DEDUP: bool = false,
55	> where
56	BitReader<E>: BitRead<E> + CodesRead<E>,
57	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
58	{
59	/// Serializer for the labels
60	pub serializer: S,
61	/// Deserializer for the labels
62	pub deserializer: D,
63	/// Marker for the endianness
64	_marker: std::marker::PhantomData<E>,
65	}
66
67	impl<E, S, D, const SRC_CODE: usize, const DST_CODE: usize, const DEDUP: bool>
68	GapsCodec<E, S, D, SRC_CODE, DST_CODE, DEDUP>
69	where
70	E: Endianness,
71	S: BitSerializer<E, BitWriter<E>> + Send + Sync,
72	D: BitDeserializer<E, BitReader<E>, DeserType = S::SerType> + Send + Sync + Clone,
73	BitReader<E>: BitRead<E> + CodesRead<E>,
74	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
75	{
76	/// Creates a new `GapsCodec` with the given serializer and deserializer.
77	pub const fn new(serializer: S, deserializer: D) -> Self {	7✔
78	Self {
79	serializer,
80	deserializer,
81	_marker: std::marker::PhantomData,
82	}
83	}
84	}
85
86	impl<E, S: Default, D: Default, const SRC_CODE: usize, const DST_CODE: usize, const DEDUP: bool>
87	core::default::Default for GapsCodec<E, S, D, SRC_CODE, DST_CODE, DEDUP>
88	where
89	E: Endianness,
90	S: BitSerializer<E, BitWriter<E>> + Send + Sync,
91	D: BitDeserializer<E, BitReader<E>, DeserType = S::SerType> + Send + Sync + Clone,
92	BitReader<E>: BitRead<E> + CodesRead<E>,
93	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
94	{
95	fn default() -> Self {	5✔
96	Self::new(Default::default(), Default::default())	15✔
97	}
98	}
99
100	/// Statistics about the encoding performed by [`GapsCodec`].
101	#[derive(Debug, Clone, Copy)]
102	pub struct GapsStats {
103	/// Total number of triples encoded
104	pub total_triples: usize,
105	/// Number of bits used for source gaps
106	pub src_bits: usize,
107	/// Number of bits used for destination gaps
108	pub dst_bits: usize,
109	/// Number of bits used for labels
110	pub labels_bits: usize,
111	}
112
113	impl core::fmt::Display for GapsStats {
114	fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {	×
115	let total_bits = self.src_bits + self.dst_bits + self.labels_bits;	×
116	write!(	×
117	f,	×
118	"src: {}B ({:.3} bits / arc), dst: {}B ({:.3} bits / arc), labels: {}B ({:.3} bits / arc), total: {}B ({:.3} bits / arc)",
119	humanize(self.src_bits as f64 / 8.0),	×
120	self.src_bits as f64 / self.total_triples as f64,	×
121	humanize(self.dst_bits as f64 / 8.0),	×
122	self.dst_bits as f64 / self.total_triples as f64,	×
123	humanize(self.labels_bits as f64 / 8.0),	×
124	self.labels_bits as f64 / self.total_triples as f64,	×
125	humanize(total_bits as f64 / 8.0),	×
126	total_bits as f64 / self.total_triples as f64,	×
127	)
128	}
129	}
130
131	impl<E, S, D, const SRC_CODE: usize, const DST_CODE: usize, const DEDUP: bool> BatchCodec
132	for GapsCodec<E, S, D, SRC_CODE, DST_CODE, DEDUP>
133	where
134	E: Endianness,
135	S: BitSerializer<E, BitWriter<E>> + Send + Sync,
136	D: BitDeserializer<E, BitReader<E>, DeserType = S::SerType> + Send + Sync + Clone,
137	S::SerType: Send + Sync + Copy + 'static + core::fmt::Debug, // needed by radix sort
138	BitReader<E>: BitRead<E> + CodesRead<E>,
139	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
140	{
141	type Label = S::SerType;
142	type DecodedBatch = GapsIter<E, D, SRC_CODE, DST_CODE>;
143	type EncodedBatchStats = GapsStats;
144
145	fn encode_batch(	11✔
146	&self,
147	path: impl AsRef<std::path::Path>,
148	batch: &mut [((usize, usize), Self::Label)],
149	) -> Result<(usize, Self::EncodedBatchStats)> {
150	let start = std::time::Instant::now();	22✔
151	Triple::cast_batch_mut(batch).radix_sort_unstable();	22✔
152	log::debug!("Sorted {} arcs in {:?}", batch.len(), start.elapsed());	11✔
153	self.encode_sorted_batch(path, batch)	44✔
154	}
155
156	fn encode_sorted_batch(	12✔
157	&self,
158	path: impl AsRef<std::path::Path>,
159	batch: &[((usize, usize), Self::Label)],
160	) -> Result<(usize, Self::EncodedBatchStats)> {
161	debug_assert!(Triple::cast_batch(batch).is_sorted());	36✔
162	// create a bitstream to write to the file
163	let file_path = path.as_ref();	36✔
164	let mut stream = buf_bit_writer::from_path::<E, usize>(file_path).with_context(\|\| {	48✔
165	format!(	×
166	"Could not create BatchIterator temporary file {}",	×
167	file_path.display()	×
168	)
169	})?;
170
171	// Pre-count unique pairs for the length prefix when deduplicating
172	let batch_len = if DEDUP {	24✔
NEW 173	if batch.is_empty() {	×
NEW 174	0	×
175	} else {
NEW 176	1 + batch.windows(2).filter(\|w\| w[0].0 != w[1].0).count()	×
177	}
178	} else {
179	batch.len()	24✔
180	};
181
182	// prefix the stream with the length of the batch
183	// we use a delta code since it'll be a big number most of the time
184	stream	12✔
185	.write_delta(batch_len as u64)	24✔
186	.context("Could not write length")?;
187
188	let mut stats = GapsStats {
189	total_triples: batch_len,
190	src_bits: 0,
191	dst_bits: 0,
192	labels_bits: 0,
193	};
194	// Dump the triples to the bitstream
195	let (mut prev_src, mut prev_dst) = (0, 0);	36✔
196	let mut prev_pair: Option<(usize, usize)> = None;	36✔
197	for ((src, dst), label) in batch.iter() {	180✔
198	if DEDUP {	52✔
NEW 199	if prev_pair == Some((src, dst)) {	×
NEW 200	continue;	×
201	}
NEW 202	prev_pair = Some((src, dst));	×
203	}
204	// write the source gap as gamma
205	stats.src_bits += ConstCode::<SRC_CODE>	52✔
206	.write(&mut stream, (src - prev_src) as u64)	156✔
207	.with_context(\|\| format!("Could not write {src} after {prev_src}"))?;	52✔
208	if *src != prev_src {	94✔
209	// Reset prev_y
210	prev_dst = 0;	42✔
211	}
212	// write the destination gap as gamma
213	stats.dst_bits += ConstCode::<DST_CODE>	52✔
214	.write(&mut stream, (dst - prev_dst) as u64)	156✔
215	.with_context(\|\| format!("Could not write {dst} after {prev_dst}"))?;	52✔
216	// write the label
217	stats.labels_bits += self	52✔
218	.serializer	52✔
219	.serialize(label, &mut stream)	156✔
220	.context("Could not serialize label")?;	52✔
221	(prev_src, prev_dst) = (src, dst);	156✔
222	}
223	// flush the stream and reset the buffer
224	stream.flush().context("Could not flush stream")?;	36✔
225
226	let total_bits = stats.src_bits + stats.dst_bits + stats.labels_bits;	24✔
227	Ok((total_bits, stats))	12✔
228	}
229
230	fn decode_batch(&self, path: impl AsRef<std::path::Path>) -> Result<Self::DecodedBatch> {	12✔
231	// open the file
232	let mut stream = <BufBitReader<E, _>>::new(MemWordReader::new(ArcMmapHelper(Arc::new(	48✔
233	MmapHelper::mmap(	12✔
234	path.as_ref(),	24✔
235	MmapFlags::TRANSPARENT_HUGE_PAGES \| MmapFlags::SEQUENTIAL,	12✔
236	)
237	.with_context(\|\| format!("Could not mmap {}", path.as_ref().display()))?,	12✔
238	))));
239
240	// read the length of the batch (first value in the stream)
241	let len = stream.read_delta().context("Could not read length")? as usize;	48✔
242
243	// create the iterator
244	Ok(GapsIter {	12✔
245	deserializer: self.deserializer.clone(),	36✔
246	stream,	12✔
247	len,	12✔
248	current: 0,	12✔
249	prev_src: 0,	12✔
250	prev_dst: 0,	12✔
251	})
252	}
253	}
254
255	/// An iterator over triples encoded with gaps, this is returned by [`GapsCodec`].
256	#[derive(Clone, Debug)]
257	pub struct GapsIter<
258	E: Endianness = NE,
259	D: BitDeserializer<E, BitReader<E>> = (),
260	const SRC_CODE: usize = { dsi_bitstream::dispatch::code_consts::GAMMA },
261	const DST_CODE: usize = { dsi_bitstream::dispatch::code_consts::GAMMA },
262	> where
263	BitReader<E>: BitRead<E> + CodesRead<E>,
264	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
265	{
266	/// Deserializer for the labels
267	deserializer: D,
268	/// Bitstream to read from
269	stream: BitReader<E>,
270	/// Length of the iterator (number of triples)
271	len: usize,
272	/// Current position in the iterator
273	current: usize,
274	/// Previous source node
275	prev_src: usize,
276	/// Previous destination node
277	prev_dst: usize,
278	}
279
280	// SAFETY: gaps are decoded in non-decreasing (src, dst) order.
281	unsafe impl<
282	E: Endianness,
283	D: BitDeserializer<E, BitReader<E>>,
284	const SRC_CODE: usize,
285	const DST_CODE: usize,
286	> SortedIterator for GapsIter<E, D, SRC_CODE, DST_CODE>
287	where
288	BitReader<E>: BitRead<E> + CodesRead<E>,
289	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
290	{
291	}
292
293	impl<
294	E: Endianness,
295	D: BitDeserializer<E, BitReader<E>>,
296	const SRC_CODE: usize,
297	const DST_CODE: usize,
298	> Iterator for GapsIter<E, D, SRC_CODE, DST_CODE>
299	where
300	BitReader<E>: BitRead<E> + CodesRead<E>,
301	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
302	{
303	type Item = ((usize, usize), D::DeserType);
304
305	fn next(&mut self) -> Option<Self::Item> {	85✔
306	if self.current >= self.len {	85✔
307	return None;	14✔
308	}
309	let src_gap = ConstCode::<SRC_CODE>.read(&mut self.stream).ok()?;	355✔
310	let dst_gap = ConstCode::<DST_CODE>.read(&mut self.stream).ok()?;	355✔
311	let label = self.deserializer.deserialize(&mut self.stream).ok()?;	355✔
312	self.prev_src += src_gap as usize;	71✔
313	if src_gap != 0 {	133✔
314	self.prev_dst = 0;	62✔
315	}
316	self.prev_dst += dst_gap as usize;	71✔
317	self.current += 1;	71✔
318	Some(((self.prev_src, self.prev_dst), label))	71✔
319	}
320
321	fn size_hint(&self) -> (usize, Option<usize>) {	2✔
322	(self.len(), Some(self.len()))	6✔
323	}
324
325	fn count(self) -> usize {	×
326	self.len()	×
327	}
328	}
329
330	impl<
331	E: Endianness,
332	D: BitDeserializer<E, BitReader<E>>,
333	const SRC_CODE: usize,
334	const DST_CODE: usize,
335	> ExactSizeIterator for GapsIter<E, D, SRC_CODE, DST_CODE>
336	where
337	BitReader<E>: BitRead<E> + CodesRead<E>,
338	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
339	{
340	fn len(&self) -> usize {	5✔
341	self.len - self.current	5✔
342	}
343	}
344
345	impl<
346	E: Endianness,
347	D: BitDeserializer<E, BitReader<E>>,
348	const SRC_CODE: usize,
349	const DST_CODE: usize,
350	> core::iter::FusedIterator for GapsIter<E, D, SRC_CODE, DST_CODE>
351	where
352	BitReader<E>: BitRead<E> + CodesRead<E>,
353	BitWriter<E>: BitWrite<E> + CodesWrite<E>,
354	{
355	}

vigna / webgraph-rs / 22649179319

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