arrow_buffer/builder/
boolean.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use crate::{bit_mask, bit_util, BooleanBuffer, Buffer, MutableBuffer};
19use std::ops::Range;
20
21/// Builder for [`BooleanBuffer`]
22///
23/// # See Also
24///
25/// * [`NullBuffer`] for building [`BooleanBuffer`]s for representing nulls
26///
27/// [`NullBuffer`]: crate::NullBuffer
28#[derive(Debug)]
29pub struct BooleanBufferBuilder {
30    buffer: MutableBuffer,
31    len: usize,
32}
33
34impl BooleanBufferBuilder {
35    /// Creates a new `BooleanBufferBuilder` with sufficient space for
36    /// `capacity` bits (not bytes).
37    ///
38    /// The capacity is rounded up to the nearest multiple of 8 for the
39    /// allocation.
40    #[inline]
41    pub fn new(capacity: usize) -> Self {
42        let byte_capacity = bit_util::ceil(capacity, 8);
43        let buffer = MutableBuffer::new(byte_capacity);
44        Self { buffer, len: 0 }
45    }
46
47    /// Creates a new `BooleanBufferBuilder` from [`MutableBuffer`] of `len`
48    pub fn new_from_buffer(buffer: MutableBuffer, len: usize) -> Self {
49        assert!(len <= buffer.len() * 8);
50        let mut s = Self {
51            len: buffer.len() * 8,
52            buffer,
53        };
54        s.truncate(len);
55        s
56    }
57
58    /// Returns the length of the buffer
59    #[inline]
60    pub fn len(&self) -> usize {
61        self.len
62    }
63
64    /// Sets a bit in the buffer at `index`
65    #[inline]
66    pub fn set_bit(&mut self, index: usize, v: bool) {
67        if v {
68            bit_util::set_bit(self.buffer.as_mut(), index);
69        } else {
70            bit_util::unset_bit(self.buffer.as_mut(), index);
71        }
72    }
73
74    /// Gets a bit in the buffer at `index`
75    #[inline]
76    pub fn get_bit(&self, index: usize) -> bool {
77        bit_util::get_bit(self.buffer.as_slice(), index)
78    }
79
80    /// Returns true if empty
81    #[inline]
82    pub fn is_empty(&self) -> bool {
83        self.len == 0
84    }
85
86    /// Returns the capacity of the buffer, in bits (not bytes)
87    ///
88    /// Note this
89    ///
90    /// # Example
91    /// ```
92    /// # use arrow_buffer::builder::BooleanBufferBuilder;
93    /// // empty requires 0 bytes
94    /// let b = BooleanBufferBuilder::new(0);
95    /// assert_eq!(0, b.capacity());
96    /// // Creating space for 1 bit results in 64 bytes (space for 512 bits)
97    /// // (64 is the minimum allocation size for 64 bit architectures)
98    /// let mut b = BooleanBufferBuilder::new(1);
99    /// assert_eq!(512, b.capacity());
100    /// // 1000 bits requires 128 bytes (space for 1024 bits)
101    /// b.append_n(1000, true);
102    /// assert_eq!(1024, b.capacity());
103    /// ```
104    #[inline]
105    pub fn capacity(&self) -> usize {
106        self.buffer.capacity() * 8
107    }
108
109    /// Advances the buffer by `additional` bits
110    #[inline]
111    pub fn advance(&mut self, additional: usize) {
112        let new_len = self.len + additional;
113        let new_len_bytes = bit_util::ceil(new_len, 8);
114        if new_len_bytes > self.buffer.len() {
115            self.buffer.resize(new_len_bytes, 0);
116        }
117        self.len = new_len;
118    }
119
120    /// Truncates the builder to the given length
121    ///
122    /// If `len` is greater than the buffer's current length, this has no effect
123    #[inline]
124    pub fn truncate(&mut self, len: usize) {
125        if len > self.len {
126            return;
127        }
128
129        let new_len_bytes = bit_util::ceil(len, 8);
130        self.buffer.truncate(new_len_bytes);
131        self.len = len;
132
133        let remainder = self.len % 8;
134        if remainder != 0 {
135            let mask = (1_u8 << remainder).wrapping_sub(1);
136            *self.buffer.as_mut().last_mut().unwrap() &= mask;
137        }
138    }
139
140    /// Reserve space to at least `additional` new bits.
141    /// Capacity will be `>= self.len() + additional`.
142    /// New bytes are uninitialized and reading them is undefined behavior.
143    #[inline]
144    pub fn reserve(&mut self, additional: usize) {
145        let capacity = self.len + additional;
146        if capacity > self.capacity() {
147            // convert differential to bytes
148            let additional = bit_util::ceil(capacity, 8) - self.buffer.len();
149            self.buffer.reserve(additional);
150        }
151    }
152
153    /// Resizes the buffer, either truncating its contents (with no change in capacity), or
154    /// growing it (potentially reallocating it) and writing `false` in the newly available bits.
155    #[inline]
156    pub fn resize(&mut self, len: usize) {
157        match len.checked_sub(self.len) {
158            Some(delta) => self.advance(delta),
159            None => self.truncate(len),
160        }
161    }
162
163    /// Appends a boolean `v` into the buffer
164    #[inline]
165    pub fn append(&mut self, v: bool) {
166        self.advance(1);
167        if v {
168            unsafe { bit_util::set_bit_raw(self.buffer.as_mut_ptr(), self.len - 1) };
169        }
170    }
171
172    /// Appends n `additional` bits of value `v` into the buffer
173    #[inline]
174    pub fn append_n(&mut self, additional: usize, v: bool) {
175        match v {
176            true => {
177                let new_len = self.len + additional;
178                let new_len_bytes = bit_util::ceil(new_len, 8);
179                let cur_remainder = self.len % 8;
180                let new_remainder = new_len % 8;
181
182                if cur_remainder != 0 {
183                    // Pad last byte with 1s
184                    *self.buffer.as_slice_mut().last_mut().unwrap() |= !((1 << cur_remainder) - 1)
185                }
186                self.buffer.resize(new_len_bytes, 0xFF);
187                if new_remainder != 0 {
188                    // Clear remaining bits
189                    *self.buffer.as_slice_mut().last_mut().unwrap() &= (1 << new_remainder) - 1
190                }
191                self.len = new_len;
192            }
193            false => self.advance(additional),
194        }
195    }
196
197    /// Appends a slice of booleans into the buffer
198    #[inline]
199    pub fn append_slice(&mut self, slice: &[bool]) {
200        let additional = slice.len();
201        self.advance(additional);
202
203        let offset = self.len() - additional;
204        for (i, v) in slice.iter().enumerate() {
205            if *v {
206                unsafe { bit_util::set_bit_raw(self.buffer.as_mut_ptr(), offset + i) }
207            }
208        }
209    }
210
211    /// Append `range` bits from `to_set`
212    ///
213    /// `to_set` is a slice of bits packed LSB-first into `[u8]`
214    ///
215    /// # Panics
216    ///
217    /// Panics if `to_set` does not contain `ceil(range.end / 8)` bytes
218    pub fn append_packed_range(&mut self, range: Range<usize>, to_set: &[u8]) {
219        let offset_write = self.len;
220        let len = range.end - range.start;
221        self.advance(len);
222        bit_mask::set_bits(
223            self.buffer.as_slice_mut(),
224            to_set,
225            offset_write,
226            range.start,
227            len,
228        );
229    }
230
231    /// Append [`BooleanBuffer`] to this [`BooleanBufferBuilder`]
232    pub fn append_buffer(&mut self, buffer: &BooleanBuffer) {
233        let range = buffer.offset()..buffer.offset() + buffer.len();
234        self.append_packed_range(range, buffer.values())
235    }
236
237    /// Returns the packed bits
238    pub fn as_slice(&self) -> &[u8] {
239        self.buffer.as_slice()
240    }
241
242    /// Returns the packed bits
243    pub fn as_slice_mut(&mut self) -> &mut [u8] {
244        self.buffer.as_slice_mut()
245    }
246
247    /// Creates a [`BooleanBuffer`]
248    #[inline]
249    pub fn finish(&mut self) -> BooleanBuffer {
250        let buf = std::mem::replace(&mut self.buffer, MutableBuffer::new(0));
251        let len = std::mem::replace(&mut self.len, 0);
252        BooleanBuffer::new(buf.into(), 0, len)
253    }
254
255    /// Builds the [BooleanBuffer] without resetting the builder.
256    pub fn finish_cloned(&self) -> BooleanBuffer {
257        BooleanBuffer::new(Buffer::from_slice_ref(self.as_slice()), 0, self.len)
258    }
259}
260
261impl From<BooleanBufferBuilder> for Buffer {
262    #[inline]
263    fn from(builder: BooleanBufferBuilder) -> Self {
264        builder.buffer.into()
265    }
266}
267
268impl From<BooleanBufferBuilder> for BooleanBuffer {
269    #[inline]
270    fn from(builder: BooleanBufferBuilder) -> Self {
271        BooleanBuffer::new(builder.buffer.into(), 0, builder.len)
272    }
273}
274
275#[cfg(test)]
276mod tests {
277    use super::*;
278
279    #[test]
280    fn test_boolean_buffer_builder_write_bytes() {
281        let mut b = BooleanBufferBuilder::new(4);
282        b.append(false);
283        b.append(true);
284        b.append(false);
285        b.append(true);
286        assert_eq!(4, b.len());
287        assert_eq!(512, b.capacity());
288        let buffer = b.finish();
289        assert_eq!(4, buffer.len());
290
291        // Overallocate capacity
292        let mut b = BooleanBufferBuilder::new(8);
293        b.append_slice(&[false, true, false, true]);
294        assert_eq!(4, b.len());
295        assert_eq!(512, b.capacity());
296        let buffer = b.finish();
297        assert_eq!(4, buffer.len());
298    }
299
300    #[test]
301    fn test_boolean_buffer_builder_unset_first_bit() {
302        let mut buffer = BooleanBufferBuilder::new(4);
303        buffer.append(true);
304        buffer.append(true);
305        buffer.append(false);
306        buffer.append(true);
307        buffer.set_bit(0, false);
308        assert_eq!(buffer.len(), 4);
309        assert_eq!(buffer.finish().values(), &[0b1010_u8]);
310    }
311
312    #[test]
313    fn test_boolean_buffer_builder_unset_last_bit() {
314        let mut buffer = BooleanBufferBuilder::new(4);
315        buffer.append(true);
316        buffer.append(true);
317        buffer.append(false);
318        buffer.append(true);
319        buffer.set_bit(3, false);
320        assert_eq!(buffer.len(), 4);
321        assert_eq!(buffer.finish().values(), &[0b0011_u8]);
322    }
323
324    #[test]
325    fn test_boolean_buffer_builder_unset_an_inner_bit() {
326        let mut buffer = BooleanBufferBuilder::new(5);
327        buffer.append(true);
328        buffer.append(true);
329        buffer.append(false);
330        buffer.append(true);
331        buffer.set_bit(1, false);
332        assert_eq!(buffer.len(), 4);
333        assert_eq!(buffer.finish().values(), &[0b1001_u8]);
334    }
335
336    #[test]
337    fn test_boolean_buffer_builder_unset_several_bits() {
338        let mut buffer = BooleanBufferBuilder::new(5);
339        buffer.append(true);
340        buffer.append(true);
341        buffer.append(true);
342        buffer.append(false);
343        buffer.append(true);
344        buffer.set_bit(1, false);
345        buffer.set_bit(2, false);
346        assert_eq!(buffer.len(), 5);
347        assert_eq!(buffer.finish().values(), &[0b10001_u8]);
348    }
349
350    #[test]
351    fn test_boolean_buffer_builder_unset_several_bits_bigger_than_one_byte() {
352        let mut buffer = BooleanBufferBuilder::new(16);
353        buffer.append_n(10, true);
354        buffer.set_bit(0, false);
355        buffer.set_bit(3, false);
356        buffer.set_bit(9, false);
357        assert_eq!(buffer.len(), 10);
358        assert_eq!(buffer.finish().values(), &[0b11110110_u8, 0b01_u8]);
359    }
360
361    #[test]
362    fn test_boolean_buffer_builder_flip_several_bits_bigger_than_one_byte() {
363        let mut buffer = BooleanBufferBuilder::new(16);
364        buffer.append_n(5, true);
365        buffer.append_n(5, false);
366        buffer.append_n(5, true);
367        buffer.set_bit(0, false);
368        buffer.set_bit(3, false);
369        buffer.set_bit(9, false);
370        buffer.set_bit(6, true);
371        buffer.set_bit(14, true);
372        buffer.set_bit(13, false);
373        assert_eq!(buffer.len(), 15);
374        assert_eq!(buffer.finish().values(), &[0b01010110_u8, 0b1011100_u8]);
375    }
376
377    #[test]
378    fn test_bool_buffer_builder_get_first_bit() {
379        let mut buffer = BooleanBufferBuilder::new(16);
380        buffer.append_n(8, true);
381        buffer.append_n(8, false);
382        assert!(buffer.get_bit(0));
383    }
384
385    #[test]
386    fn test_bool_buffer_builder_get_first_bit_not_requires_mutability() {
387        let buffer = {
388            let mut buffer = BooleanBufferBuilder::new(16);
389            buffer.append_n(8, true);
390            buffer
391        };
392
393        assert!(buffer.get_bit(0));
394    }
395
396    #[test]
397    fn test_bool_buffer_builder_get_last_bit() {
398        let mut buffer = BooleanBufferBuilder::new(16);
399        buffer.append_n(8, true);
400        buffer.append_n(8, false);
401        assert!(!buffer.get_bit(15));
402    }
403
404    #[test]
405    fn test_bool_buffer_builder_get_an_inner_bit() {
406        let mut buffer = BooleanBufferBuilder::new(16);
407        buffer.append_n(4, false);
408        buffer.append_n(8, true);
409        buffer.append_n(4, false);
410        assert!(buffer.get_bit(11));
411    }
412
413    #[test]
414    fn test_bool_buffer_fuzz() {
415        use rand::prelude::*;
416
417        let mut buffer = BooleanBufferBuilder::new(12);
418        let mut all_bools = vec![];
419        let mut rng = rand::thread_rng();
420
421        let src_len = 32;
422        let (src, compacted_src) = {
423            let src: Vec<_> = std::iter::from_fn(|| Some(rng.next_u32() & 1 == 0))
424                .take(src_len)
425                .collect();
426
427            let mut compacted_src = BooleanBufferBuilder::new(src_len);
428            compacted_src.append_slice(&src);
429            (src, compacted_src.finish())
430        };
431
432        for _ in 0..100 {
433            let a = rng.next_u32() as usize % src_len;
434            let b = rng.next_u32() as usize % src_len;
435
436            let start = a.min(b);
437            let end = a.max(b);
438
439            buffer.append_packed_range(start..end, compacted_src.values());
440            all_bools.extend_from_slice(&src[start..end]);
441        }
442
443        let mut compacted = BooleanBufferBuilder::new(all_bools.len());
444        compacted.append_slice(&all_bools);
445
446        assert_eq!(buffer.finish(), compacted.finish())
447    }
448
449    #[test]
450    fn test_boolean_array_builder_resize() {
451        let mut builder = BooleanBufferBuilder::new(20);
452        builder.append_n(4, true);
453        builder.append_n(7, false);
454        builder.append_n(2, true);
455        builder.resize(20);
456
457        assert_eq!(builder.len(), 20);
458        assert_eq!(builder.as_slice(), &[0b00001111, 0b00011000, 0b00000000]);
459
460        builder.resize(5);
461        assert_eq!(builder.len(), 5);
462        assert_eq!(builder.as_slice(), &[0b00001111]);
463
464        builder.append_n(4, true);
465        assert_eq!(builder.len(), 9);
466        assert_eq!(builder.as_slice(), &[0b11101111, 0b00000001]);
467    }
468
469    #[test]
470    fn test_truncate() {
471        let b = MutableBuffer::from_iter([true, true, true, true]);
472        let mut builder = BooleanBufferBuilder::new_from_buffer(b, 2);
473        builder.advance(2);
474        let finished = builder.finish();
475        assert_eq!(finished.values(), &[0b00000011]);
476
477        let mut builder = BooleanBufferBuilder::new(10);
478        builder.append_n(5, true);
479        builder.resize(3);
480        builder.advance(2);
481        let finished = builder.finish();
482        assert_eq!(finished.values(), &[0b00000111]);
483
484        let mut builder = BooleanBufferBuilder::new(10);
485        builder.append_n(16, true);
486        assert_eq!(builder.as_slice(), &[0xFF, 0xFF]);
487        builder.truncate(20);
488        assert_eq!(builder.as_slice(), &[0xFF, 0xFF]);
489        builder.truncate(14);
490        assert_eq!(builder.as_slice(), &[0xFF, 0b00111111]);
491        builder.append(false);
492        builder.append(true);
493        assert_eq!(builder.as_slice(), &[0xFF, 0b10111111]);
494        builder.append_packed_range(0..3, &[0xFF]);
495        assert_eq!(builder.as_slice(), &[0xFF, 0b10111111, 0b00000111]);
496        builder.truncate(17);
497        assert_eq!(builder.as_slice(), &[0xFF, 0b10111111, 0b00000001]);
498        builder.append_packed_range(0..2, &[2]);
499        assert_eq!(builder.as_slice(), &[0xFF, 0b10111111, 0b0000101]);
500        builder.truncate(8);
501        assert_eq!(builder.as_slice(), &[0xFF]);
502        builder.resize(14);
503        assert_eq!(builder.as_slice(), &[0xFF, 0x00]);
504        builder.truncate(0);
505        assert_eq!(builder.as_slice(), &[]);
506    }
507
508    #[test]
509    fn test_boolean_builder_increases_buffer_len() {
510        // 00000010 01001000
511        let buf = Buffer::from([72_u8, 2_u8]);
512        let mut builder = BooleanBufferBuilder::new(8);
513
514        for i in 0..16 {
515            if i == 3 || i == 6 || i == 9 {
516                builder.append(true);
517            } else {
518                builder.append(false);
519            }
520        }
521        let buf2 = builder.finish();
522
523        assert_eq!(buf.len(), buf2.inner().len());
524        assert_eq!(buf.as_slice(), buf2.values());
525    }
526}
arrow_buffer/builder/boolean.rs

arrow_buffer/builder/
boolean.rs
