README
¶
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 postive 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:
import "bitset"
var b BitSet
b.Set(10).Set(11)
if b.Test(1000) {
b.Clear(1000)
}
for i,e := v.NextSet(0); e; i,e = v.NextSet(i + 1) {
frmt.Println("The following bit is set:",i);
}
if B.Intersection(bitset.New(100).Set(10)).Count() > 1 {
fmt.Println("Intersection works.")
}
As an alternative to BitSets, one should check out the 'big' package, which provides a (less set-theoretical) view of bitsets.
Discussions golang-nuts Google Group:
Godoc documentation is at: https://godoc.org/github.com/willf/bitset
Documentation
¶
Overview ¶
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 postive 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:
import "bitset"
var b BitSet
b.Set(10).Set(11)
if b.Test(1000) {
b.Clear(1000)
}
if B.Intersection(bitset.New(100).Set(10)).Count() > 1 {
fmt.Println("Intersection works.")
}
As an alternative to BitSets, one should check out the 'big' package,
which provides a (less set-theoretical) view of bitsets.
Index ¶
- func Cap() uint
- type BitSet
- func (b *BitSet) All() bool
- func (b *BitSet) Any() bool
- func (b *BitSet) BinaryStorageSize() int
- func (b *BitSet) Clear(i uint) *BitSet
- func (b *BitSet) ClearAll() *BitSet
- func (b *BitSet) Clone() *BitSet
- func (b *BitSet) Complement() (result *BitSet)
- func (b *BitSet) Copy(c *BitSet) (count uint)
- func (b *BitSet) Count() uint
- func (b *BitSet) Difference(compare *BitSet) (result *BitSet)
- func (b *BitSet) DifferenceCardinality(compare *BitSet) uint
- func (b *BitSet) DumpAsBits() string
- func (b *BitSet) Equal(c *BitSet) bool
- func (b *BitSet) Flip(i uint) *BitSet
- func (b *BitSet) InPlaceDifference(compare *BitSet)
- func (b *BitSet) InPlaceIntersection(compare *BitSet)
- func (b *BitSet) InPlaceSymmetricDifference(compare *BitSet)
- func (b *BitSet) InPlaceUnion(compare *BitSet)
- func (b *BitSet) Intersection(compare *BitSet) (result *BitSet)
- func (b *BitSet) IntersectionCardinality(compare *BitSet) uint
- func (b *BitSet) Len() uint
- func (b *BitSet) MarshalJSON() ([]byte, error)
- func (b *BitSet) NextClear(i uint) (uint, bool)
- func (b *BitSet) NextSet(i uint) (uint, bool)
- func (b *BitSet) None() bool
- func (b *BitSet) ReadFrom(stream io.Reader) (int64, error)
- func (b *BitSet) Set(i uint) *BitSet
- func (b *BitSet) SetTo(i uint, value bool) *BitSet
- func (b *BitSet) SymmetricDifference(compare *BitSet) (result *BitSet)
- func (b *BitSet) SymmetricDifferenceCardinality(compare *BitSet) uint
- func (b *BitSet) Test(i uint) bool
- func (b *BitSet) Union(compare *BitSet) (result *BitSet)
- func (b *BitSet) UnionCardinality(compare *BitSet) uint
- func (b *BitSet) UnmarshalJSON(data []byte) error
- func (b *BitSet) WriteTo(stream io.Writer) (int64, error)
- type BitSetError
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type BitSet ¶
type BitSet struct {
// contains filtered or unexported fields
}
The zero value of a BitSet is an empty set of length 0.
func (*BitSet) BinaryStorageSize ¶
func (*BitSet) Complement ¶
Return the (local) Complement of a biset (up to length bits)
func (*BitSet) Copy ¶
Copy this BitSet into a destination BitSet Returning the size of the destination BitSet like array copy
func (*BitSet) Difference ¶
Difference of base set and other set This is the BitSet equivalent of &^ (and not)
func (*BitSet) DifferenceCardinality ¶
computes the cardinality of the differnce
func (*BitSet) Equal ¶
Test the equvalence of two BitSets. False if they are of different sizes, otherwise true only if all the same bits are set
func (*BitSet) InPlaceDifference ¶
Difference of base set and other set This is the BitSet equivalent of &^ (and not)
func (*BitSet) InPlaceIntersection ¶
Intersection of base set and other set This is the BitSet equivalent of & (and)
func (*BitSet) InPlaceSymmetricDifference ¶
SymmetricDifference of base set and other set This is the BitSet equivalent of ^ (xor)
func (*BitSet) InPlaceUnion ¶
Union of base set and other set This is the BitSet equivalent of | (or)
func (*BitSet) Intersection ¶
Intersection of base set and other set This is the BitSet equivalent of & (and)
func (*BitSet) IntersectionCardinality ¶
Computes the cardinality of the union
func (*BitSet) MarshalJSON ¶
func (*BitSet) NextClear ¶
return the next clear bit from the specified index, including possibly the current index along with an error code (true = valid, false = no bit found i.e. all bits are set)
func (*BitSet) NextSet ¶
return the next bit set from the specified index, including possibly the current index along with an error code (true = valid, false = no set bit found) for i,e := v.NextSet(0); e; i,e = v.NextSet(i + 1) {...}
func (*BitSet) SymmetricDifference ¶
SymmetricDifference of base set and other set This is the BitSet equivalent of ^ (xor)
func (*BitSet) SymmetricDifferenceCardinality ¶
computes the cardinality of the symmetric difference
func (*BitSet) UnionCardinality ¶
func (*BitSet) UnmarshalJSON ¶
type BitSetError ¶
type BitSetError string
Source Files