106 lines
1.9 KiB
Go
106 lines
1.9 KiB
Go
package dag
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// Set is a set data structure.
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type Set map[interface{}]interface{}
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// Hashable is the interface used by set to get the hash code of a value.
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// If this isn't given, then the value of the item being added to the set
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// itself is used as the comparison value.
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type Hashable interface {
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Hashcode() interface{}
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}
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// hashcode returns the hashcode used for set elements.
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func hashcode(v interface{}) interface{} {
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if h, ok := v.(Hashable); ok {
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return h.Hashcode()
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}
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return v
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}
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// Add adds an item to the set
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func (s Set) Add(v interface{}) {
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s[hashcode(v)] = v
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}
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// Delete removes an item from the set.
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func (s Set) Delete(v interface{}) {
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delete(s, hashcode(v))
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}
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// Include returns true/false of whether a value is in the set.
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func (s Set) Include(v interface{}) bool {
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_, ok := s[hashcode(v)]
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return ok
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}
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// Intersection computes the set intersection with other.
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func (s Set) Intersection(other Set) Set {
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result := make(Set)
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if s == nil {
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return result
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}
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if other != nil {
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for _, v := range s {
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if other.Include(v) {
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result.Add(v)
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}
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}
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}
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return result
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}
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// Difference returns a set with the elements that s has but
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// other doesn't.
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func (s Set) Difference(other Set) Set {
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result := make(Set)
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if s != nil {
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for k, v := range s {
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var ok bool
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if other != nil {
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_, ok = other[k]
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}
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if !ok {
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result.Add(v)
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}
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}
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}
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return result
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}
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// Filter returns a set that contains the elements from the receiver
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// where the given callback returns true.
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func (s Set) Filter(cb func(interface{}) bool) Set {
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result := make(Set)
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for _, v := range s {
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if cb(v) {
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result.Add(v)
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}
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}
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return result
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}
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// Len is the number of items in the set.
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func (s Set) Len() int {
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return len(s)
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}
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// List returns the list of set elements.
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func (s Set) List() []interface{} {
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if s == nil {
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return nil
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}
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r := make([]interface{}, 0, len(s))
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for _, v := range s {
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r = append(r, v)
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}
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return r
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}
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