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field_set.go
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field_set.go
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package pggen
// field_set.go defines a bitset used for specifying subsets of fields
import (
"github.com/willf/bitset"
)
// A bitset to use to select a subset of fields. FieldSets are reference
// types like slices or maps, so if you want to copy one, use the Clone method.
type FieldSet struct {
b *bitset.BitSet
}
// Create a new field set with a hint that length bits will be needed.
func NewFieldSet(lengthHint int) FieldSet {
return FieldSet{b: bitset.New(uint(lengthHint))}
}
// Create a new field set with the first `length` bits set
func NewFieldSetFilled(length int) FieldSet {
fs := NewFieldSet(length)
for i := 0; i < length; i++ {
fs.Set(i, true)
}
return fs
}
// Deep copy the field set.
func (fs FieldSet) Clone() FieldSet {
if fs.b == nil {
return FieldSet{}
}
return FieldSet{b: fs.b.Clone()}
}
// Set the bit at position `bit` to `value`. Can be chained.
func (fs FieldSet) Set(bit int, value bool) FieldSet {
if fs.b == nil {
fs.b = &bitset.BitSet{}
}
fs.b.SetTo(uint(bit), value)
return fs
}
// Return the value of the given bit
func (fs FieldSet) Test(bit int) bool {
if fs.b == nil {
return false
}
return fs.b.Test(uint(bit))
}
// Return the number of bits set to 1
func (fs FieldSet) CountSetBits() int {
if fs.b == nil {
return 0
}
return int(fs.b.Count())
}
// Return the intersection of the two field sets. Equivalent of bitwise AND.
func (fs FieldSet) Intersection(rhs FieldSet) FieldSet {
if fs.b == nil || rhs.b == nil {
return FieldSet{}
}
return FieldSet{b: fs.b.Intersection(rhs.b)}
}