120 lines
2.3 KiB
Go
120 lines
2.3 KiB
Go
package schema
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import (
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"sort"
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"sync"
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)
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// Set is a set data structure that is returned for elements of type
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// TypeSet.
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type Set struct {
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F SchemaSetFunc
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m map[int]interface{}
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once sync.Once
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}
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// Add adds an item to the set if it isn't already in the set.
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func (s *Set) Add(item interface{}) {
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s.add(item)
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}
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// Contains checks if the set has the given item.
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func (s *Set) Contains(item interface{}) bool {
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_, ok := s.m[s.F(item)]
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return ok
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}
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// Len returns the amount of items in the set.
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func (s *Set) Len() int {
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return len(s.m)
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}
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// List returns the elements of this set in slice format.
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//
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// The order of the returned elements is deterministic. Given the same
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// set, the order of this will always be the same.
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func (s *Set) List() []interface{} {
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result := make([]interface{}, len(s.m))
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for i, k := range s.listCode() {
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result[i] = s.m[k]
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}
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return result
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}
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// Differences performs a set difference of the two sets, returning
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// a new third set that has only the elements unique to this set.
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func (s *Set) Difference(other *Set) *Set {
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result := &Set{F: s.F}
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result.init()
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for k, v := range s.m {
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if _, ok := other.m[k]; !ok {
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result.m[k] = v
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}
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}
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return result
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}
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// Intersection performs the set intersection of the two sets
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// and returns a new third set.
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func (s *Set) Intersection(other *Set) *Set {
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result := &Set{F: s.F}
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result.init()
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for k, v := range s.m {
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if _, ok := other.m[k]; ok {
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result.m[k] = v
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}
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}
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return result
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}
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// Union performs the set union of the two sets and returns a new third
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// set.
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func (s *Set) Union(other *Set) *Set {
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result := &Set{F: s.F}
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result.init()
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for k, v := range s.m {
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result.m[k] = v
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}
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for k, v := range other.m {
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result.m[k] = v
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}
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return result
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}
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func (s *Set) init() {
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s.m = make(map[int]interface{})
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}
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func (s *Set) add(item interface{}) int {
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s.once.Do(s.init)
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code := s.F(item)
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if _, ok := s.m[code]; !ok {
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s.m[code] = item
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}
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return code
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}
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func (s *Set) index(item interface{}) int {
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return sort.SearchInts(s.listCode(), s.F(item))
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}
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func (s *Set) listCode() []int {
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// Sort the hash codes so the order of the list is deterministic
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keys := make([]int, 0, len(s.m))
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for k, _ := range s.m {
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keys = append(keys, k)
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}
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sort.Sort(sort.IntSlice(keys))
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return keys
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}
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