mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-12-27 08:42:14 +01:00
97 lines
3.1 KiB
Markdown
97 lines
3.1 KiB
Markdown
|
# bitset
|
||
|
|
|
||
|
|
*Go language library to map between non-negative integers and boolean values*
|
||
|
|
|
||
|
|
[](https://travis-ci.org/willf/bitset?branch=master)
|
||
|
|
[](https://coveralls.io/github/willf/bitset?branch=master)
|
||
|
|
[](https://goreportcard.com/report/github.com/willf/bitset)
|
||
|
|
[](http://godoc.org/github.com/willf/bitset)
|
||
|
|
|
||
|
|
|
||
|
|
## Description
|
||
|
|
|
||
|
|
Package bitset implements bitsets, a mapping between non-negative integers and boolean values.
|
||
|
|
It should be more efficient than map[uint] bool.
|
||
|
|
|
||
|
|
It provides methods for setting, clearing, flipping, and testing individual integers.
|
||
|
|
|
||
|
|
But it also provides set intersection, union, difference, complement, and symmetric operations, as well as tests to check whether any, all, or no bits are set, and querying a bitset's current length and number of positive bits.
|
||
|
|
|
||
|
|
BitSets are expanded to the size of the largest set bit; the memory allocation is approximately Max bits, where Max is the largest set bit. BitSets are never shrunk. On creation, a hint can be given for the number of bits that will be used.
|
||
|
|
|
||
|
|
Many of the methods, including Set, Clear, and Flip, return a BitSet pointer, which allows for chaining.
|
||
|
|
|
||
|
|
### Example use:
|
||
|
|
|
||
|
|
```go
|
||
|
|
package main
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"math/rand"
|
||
|
|
|
||
|
|
"github.com/willf/bitset"
|
||
|
|
)
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
fmt.Printf("Hello from BitSet!\n")
|
||
|
|
var b bitset.BitSet
|
||
|
|
// play some Go Fish
|
||
|
|
for i := 0; i < 100; i++ {
|
||
|
|
card1 := uint(rand.Intn(52))
|
||
|
|
card2 := uint(rand.Intn(52))
|
||
|
|
b.Set(card1)
|
||
|
|
if b.Test(card2) {
|
||
|
|
fmt.Println("Go Fish!")
|
||
|
|
}
|
||
|
|
b.Clear(card1)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Chaining
|
||
|
|
b.Set(10).Set(11)
|
||
|
|
|
||
|
|
for i, e := b.NextSet(0); e; i, e = b.NextSet(i + 1) {
|
||
|
|
fmt.Println("The following bit is set:", i)
|
||
|
|
}
|
||
|
|
if b.Intersection(bitset.New(100).Set(10)).Count() == 1 {
|
||
|
|
fmt.Println("Intersection works.")
|
||
|
|
} else {
|
||
|
|
fmt.Println("Intersection doesn't work???")
|
||
|
|
}
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
As an alternative to BitSets, one should check out the 'big' package, which provides a (less set-theoretical) view of bitsets.
|
||
|
|
|
||
|
|
Godoc documentation is at: https://godoc.org/github.com/willf/bitset
|
||
|
|
|
||
|
|
|
||
|
|
## Implementation Note
|
||
|
|
|
||
|
|
Go 1.9 introduced a native `math/bits` library. We provide backward compatibility to Go 1.7, which might be removed.
|
||
|
|
|
||
|
|
It is possible that a later version will match the `math/bits` return signature for counts (which is `int`, rather than our library's `unit64`). If so, the version will be bumped.
|
||
|
|
|
||
|
|
## Installation
|
||
|
|
|
||
|
|
```bash
|
||
|
|
go get github.com/willf/bitset
|
||
|
|
```
|
||
|
|
|
||
|
|
## Contributing
|
||
|
|
|
||
|
|
If you wish to contribute to this project, please branch and issue a pull request against master ("[GitHub Flow](https://guides.github.com/introduction/flow/)")
|
||
|
|
|
||
|
|
This project include a Makefile that allows you to test and build the project with simple commands.
|
||
|
|
To see all available options:
|
||
|
|
```bash
|
||
|
|
make help
|
||
|
|
```
|
||
|
|
|
||
|
|
## Running all tests
|
||
|
|
|
||
|
|
Before committing the code, please check if it passes all tests using (note: this will install some dependencies):
|
||
|
|
```bash
|
||
|
|
make qa
|
||
|
|
```
|