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intset.go
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intset.go
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package frozen
import (
"fmt"
"math/bits"
"golang.org/x/exp/constraints"
"github.com/arr-ai/hash"
"github.com/arr-ai/frozen/internal/pkg/fu"
"github.com/arr-ai/frozen/internal/pkg/iterator"
)
type IntSet[I constraints.Integer] struct {
data Map[I, cellMask]
count int
}
type cellMask uint64
const (
cellShift = 6
cellBits = 1 << cellShift
)
func locateCell[I constraints.Integer](i I) (cell I, bitMask cellMask) {
return i >> cellShift, cellMask(1) << uint(i%cellBits)
}
// NewIntSet returns an IntSet with the values provided.
func NewIntSet[I constraints.Integer](is ...I) IntSet[I] {
m := map[I]cellMask{}
for _, i := range is {
cellIndex, bitMask := locateCell(i)
m[cellIndex] = m[cellIndex] | bitMask
}
b := NewMapBuilder[I, cellMask](len(m))
count := 0
for cellIndex, cell := range m {
b.Put(cellIndex, cell)
count += cell.count()
}
return IntSet[I]{data: b.Finish(), count: count}
}
// IsEmpty returns true if there is no values in s and false otherwise.
func (s IntSet[I]) IsEmpty() bool {
return s.data.IsEmpty()
}
// Count returns the number of elements in IntSet.
func (s IntSet[I]) Count() int {
return s.count
}
// Range returns the iterator for IntSet.
func (s IntSet[I]) Range() iterator.Iterator[I] {
return &intSetIterator[I]{
cellIter: s.data.Range(),
cell: 1,
}
}
// Elements returns all the values of IntSet.
func (s IntSet[I]) Elements() []I {
result := make([]I, 0, s.Count())
for i := s.Range(); i.Next(); {
result = append(result, i.Value())
}
return result
}
// func (s IntSet[I]) OrderedElements(less Less) []I {}
// Any returns a random value from s.
func (s IntSet[I]) Any() I {
cellIndex, cell := s.data.Any()
bit := iterator.BitIterator(cell).Index()
return cellIndex<<cellShift + I(bit)
}
// func (s IntSet[I]) AnyN(n I) IntSet {}
// func (s IntSet[I]) OrderedFirstN(n I, less Less) []I {}
// func (s IntSet[I]) First(less Less) I {}
// func (s IntSet[I]) FirstN(n I, less Less) IntSet {}
// String returns a string representation of IntSet.
func (s IntSet[I]) String() string {
return fu.String(s)
}
// Format formats IntSet.
func (s IntSet[I]) Format(f fmt.State, verb rune) {
if verb == 'v' && f.Flag('+') {
fu.Fprint(f, s.data)
return
}
fu.WriteString(f, "[")
for i, r := 0, s.Range(); r.Next(); i++ {
fu.Comma(f, i)
fu.Format(r.Value(), f, verb)
}
fu.WriteString(f, "]")
}
func (s IntSet[I]) Hash(seed uintptr) uintptr {
for i := s.Range(); i.Next(); {
seed ^= hash.Interface(i.Value(), 0)
}
return seed
}
// EqualSet is deprecated. Use Equal instead.
func (s IntSet[I]) EqualSet(t IntSet[I]) bool {
return s.Equal(t)
}
// Equal returns true if both IntSets are equal.
func (s IntSet[I]) Equal(t IntSet[I]) bool {
return s.data.Equal(t.data)
}
// Equal returns true if t is an IntSet and a and b are equal.
func (s IntSet[I]) Same(t any) bool {
if t, is := t.(IntSet[I]); is {
return s.Equal(t)
}
return false
}
// IsSubsetOf returns true if s is a subset of t and false otherwise.
func (s IntSet[I]) IsSubsetOf(t IntSet[I]) bool {
for r := s.data.Range(); r.Next(); {
sCell := r.Value()
if tCell, has := t.data.Get(r.Key()); !has || sCell&^tCell != 0 {
return false
}
}
return true
}
// Has returns true if value exists in the IntSet and false otherwise.
func (s IntSet[I]) Has(val I) bool {
cell, _, bitMask := s.locate(val)
return cell&bitMask != 0
}
// With returns a new IntSet with the values of s and the provided values.
func (s IntSet[I]) With(i I) IntSet[I] {
if cell, cellIndex, bitMask := s.locate(i); cell&bitMask == 0 {
s.data = s.data.With(cellIndex, cell|bitMask)
s.count++
}
return s
}
// Without returns an IntSet without the provided values.
func (s IntSet[I]) Without(i I) IntSet[I] {
if cell, cellIndex, bitMask := s.locate(i); cell&bitMask != 0 {
if cell &^= bitMask; cell != 0 {
// TODO: optimize this so it doesn't do With many times
s.data = s.data.With(cellIndex, cell)
} else {
s.data = s.data.Without(cellIndex)
}
s.count--
}
return s
}
// Where returns an IntSet whose values fulfill the provided condition.
func (s IntSet[I]) Where(pred func(elem I) bool) IntSet[I] {
// TODO: find a way that works more on block level or maybe make IntSetBuilder?
var b MapBuilder[I, cellMask]
count := 0
for r := s.data.Range(); r.Next(); {
cellIndex, cell := r.Entry()
cellOffset := cellIndex * cellBits
var newCell cellMask
for cell != 0 {
maskIndex := I(cell.index())
if pred(cellOffset + maskIndex) {
newCell |= cellMask(1) << maskIndex
}
cell &= (cell - 1)
}
if newCell != 0 {
b.Put(cellIndex, newCell)
count += newCell.count()
}
}
return IntSet[I]{data: b.Finish(), count: count}
}
// Map returns an IntSet with whose values are mapped from s.
func (s IntSet[I]) Map(f func(elem I) I) IntSet[I] {
arr := make([]I, 0, s.count)
for i := s.Range(); i.Next(); {
arr = append(arr, f(i.Value()))
}
return NewIntSet(arr...)
}
// func (s IntSet[I]) Reduce(reduce func(elems ...I) I) I {}
// func (s IntSet[I]) Reduce2(reduce func(a, b I) I) I {}
// Intersection returns an IntSet whose values exists in s and t.
func (s IntSet[I]) Intersection(t IntSet[I]) IntSet[I] {
var intersectMap MapBuilder[I, cellMask]
count := 0
for tCell := t.data.Range(); tCell.Next(); {
if sCell, has := s.data.Get(tCell.Key()); has {
if iCell := sCell & tCell.Value(); iCell != 0 {
intersectMap.Put(tCell.Key(), iCell)
count += iCell.count()
}
}
}
return IntSet[I]{data: intersectMap.Finish(), count: count}
}
// Union returns an integer set that is a union of s and t.
func (s IntSet[I]) Union(t IntSet[I]) IntSet[I] {
unionMap := s.data
count := s.count
var unionCell cellMask
for tCell := t.data.Range(); tCell.Next(); {
if sCell, has := s.data.Get(tCell.Key()); has {
unionCell = sCell | tCell.Value()
count += unionCell.diffCount(sCell)
} else {
unionCell = tCell.Value()
count += unionCell.count()
}
unionMap = unionMap.With(tCell.Key(), unionCell)
}
return IntSet[I]{data: unionMap, count: count}
}
// func (s IntSet[I]) Difference(t IntSet) IntSet {}
// func (s IntSet[I]) SymmetricDifference(t IntSet) IntSet {}
// func (s IntSet[I]) Powerset() IntSet {}
// func (s IntSet[I]) GroupBy(key func(el int) int) Map {}
func (s IntSet[I]) locate(i I) (cell cellMask, cellIndex I, bitMask cellMask) {
cellIndex, bitMask = locateCell(i)
cell, _ = s.data.Get(cellIndex)
return
}
func (c cellMask) diffCount(c2 cellMask) int {
return (c ^ c2).count()
}
func (c cellMask) count() int {
return bits.OnesCount64(uint64(c))
}
func (c cellMask) index() int {
return bits.TrailingZeros64(uint64(c))
}
func (c cellMask) next() cellMask {
return c & (c - 1)
}