Module: collections.bitset

Source: ./collections/bitset.reef

Overview

collections/bitset - Efficient Bit Set Data Structure

Provides memory-efficient storage and manipulation of boolean flags. Uses 64-bit integers as storage (1 bit per flag vs 8 bits for bool).

Collections 0.9.2 / D12. BitSet stays a NON-GENERIC struct -- its width is fixed at create(n) and it holds bits, not values, so there is nothing to parameterise. It is method-based now; the free functions and their bit_ / _bit affixes are gone, because the receiver is already a BitSet.

Usage: import collections.bitset

let bs = bitset.create(256) // 256-bit bitset bs.set(10) bs.set(42)

if bs.test(10) println("Bit 10 is set") end if

print("Count: ") print_int(bs.count()) println("")

Renamed with the free functions (D12): set_bit -> set, clear_bit -> clear, toggle_bit -> toggle, test_bit -> test, count_set -> count, first_set_bit -> first_set, next_set_bit -> next_set, and the allocating bit_union / bit_intersection / bit_difference / bit_xor lose the bit_ prefix. The in-place *_into forms keep their names.

An out-of-range bit index remains a NO-OP rather than an error, which is the behaviour callers already relied on.

Use Cases:

• Compiler type qualifiers (const, volatile, etc.)
• Visited node tracking in graph traversal
• Sparse set membership testing
• Feature flag management

Types

BitSet

Fields:

Functions

fn bits_per_word(): int

Bits per word (using 32-bit for portability) Note: Reef's int is 64-bit but overflow occurs at 32 bits in multiplication

fn words_needed(n: int): int

Calculate number of words needed for n bits

fn create(size: int): BitSet

fn create_64(): BitSet

fn create_256(): BitSet

fn create_1024(): BitSet

fn word_index(n: int): int

Get word index for bit n

fn bit_position(n: int): int

Get bit position within word

fn bit_mask(pos: int): int

Create a mask with bit at position set Note: For 64-bit integers, positions 0-63 are valid

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