README.md

SwiftBitset

A bitset class in Swift for fast and concise set operations over integers. Works under both Linux and MacOS. It is engineered to be really fast, on par with portable C/C++ implementations.

It can be orders of magnitude faster than an IndexSet:

$ git clone https://github.com/lemire/SwiftBitsetBenchmark.git
$ cd SwiftBitsetBenchmark
$ swift build  -Xcc -march=native  --configuration release

$ $(swift build   --configuration release --show-bin-path)/SwiftBitsetBenchmark
testAddPerformance  10.693318  ms
testIndexSetAddPerformance  231.737616  ms

testCountPerformance  0.617098  ms
testIndexSetCountPerformance  0.007483  ms

testIteratorPerformance  5.503873  ms
testIndexSetIteratorPerformance  234.289692  ms

testIntersectionPerformance  3.157883  ms
testIndexSetIntersectionPerformance  2774.959423  ms

See https://github.com/lemire/SwiftBitsetBenchmark

Complete example for library users

Create a directory where you will create your application:

mkdir fun
cd fun
swift package init --type executable

Then edit Package.swift so that it reads something like this:

import PackageDescription

let package = Package(
    name: "fun",
    dependencies: [
   .package(url: "https://github.com/lemire/SwiftBitset.git",  from: "0.3.2")
    ],
    targets: [
        .target(
            name: "fun",
            dependencies: ["Bitset"]),
    ]
)

Edit main.swift (in Sources) so that it looks something like this :

import Bitset;

let b1 = Bitset (arrayLiteral: 1,4,10,1000,10000);
for i in b1 {
  print(i)
}

You can run your example as follows:

swift build  -Xcc -march=native  --configuration release
$(swift build   --configuration release  --show-bin-path)/fun

Code example

import Bitset;

let b1 = Bitset ();
b1.add(10000) // can add one
b1.addMany(1,4,10,1000,10000); // can add many
let b2 = Bitset ();
b2.addMany(1,3,10,1000);
let bexpected = Bitset (1,3,4,10,1000,10000); // can init with list
b2.union(b1)
print(b2.count() == 6) // print true
print(b2 == bexpected) // print true
bexpected.intersection(b1)
print(b1 == bexpected) // print true
for i in b1 {
  print(i)
}
// will print 1 4 10 1000 10000
b1.remove(4) // can remove values
let d1 = b1 & b2;// intersection
let d2 = b1 | b2;// union
let d3 = b1 - b2;// difference
let d4 = b1 ^ b2;// symmetric difference
b1 &= b2;// inplace intersection
b1 |= b2;// inplace union
b1 -= b2;// inplace difference
b1 ^= b2;// inplace symmetric difference

Usage for contributors

swift build -Xcc -march=native --configuration release
swift test # optional

To dissamble a function...

swift build -Xcc -march=native --configuration release
lldb ./.build/release/Bitset.build/Bitset.swift.o
disassemble -n intersectionCount

To benchmark from the command line:

swift test -Xswiftc -Ounchecked -s BitsetTests.BitsetTests/testForEachPerformance

For interactive use:

$ swift build -Xcc -march=native --configuration release
$ swift -I .build/release -L .build/release -lBitsetDynamic
  1> import Bitset
  2> let b1 = Bitset ()
  3> print(b1)

For Xcode users (Mac Only)

$ swift package generate-xcodeproj
generated: ./Bitset.xcodeproj
$ open ./SwiftBitset.xcodeproj

Licensing

Apache 2.0