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187 lines
4.1 KiB
187 lines
4.1 KiB
package sets |
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import ( |
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"reflect" |
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"sort" |
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) |
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type Empty struct{} |
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// sets.String is a set of strings, implemented via map[string]struct{} for minimal memory consumption. |
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type String map[string]Empty |
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// NewString creates a String from a list of values. |
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func NewString(items ...string) String { |
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ss := String{} |
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ss.Insert(items...) |
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return ss |
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} |
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// StringKeySet creates a String from a keys of a map[string](? extends interface{}). |
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// If the value passed in is not actually a map, this will panic. |
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func StringKeySet(theMap interface{}) String { |
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v := reflect.ValueOf(theMap) |
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ret := String{} |
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for _, keyValue := range v.MapKeys() { |
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ret.Insert(keyValue.Interface().(string)) |
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} |
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return ret |
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} |
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// Insert adds items to the set. |
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func (s String) Insert(items ...string) { |
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for _, item := range items { |
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s[item] = Empty{} |
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} |
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} |
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// Delete removes all items from the set. |
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func (s String) Delete(items ...string) { |
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for _, item := range items { |
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delete(s, item) |
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} |
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} |
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// Has returns true if and only if item is contained in the set. |
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func (s String) Has(item string) bool { |
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_, contained := s[item] |
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return contained |
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} |
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// HasAll returns true if and only if all items are contained in the set. |
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func (s String) HasAll(items ...string) bool { |
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for _, item := range items { |
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if !s.Has(item) { |
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return false |
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} |
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} |
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return true |
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} |
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// HasAny returns true if any items are contained in the set. |
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func (s String) HasAny(items ...string) bool { |
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for _, item := range items { |
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if s.Has(item) { |
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return true |
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} |
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} |
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return false |
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} |
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// Difference returns a set of objects that are not in s2 |
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// For example: |
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// s1 = {a1, a2, a3} |
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// s2 = {a1, a2, a4, a5} |
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// s1.Difference(s2) = {a3} |
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// s2.Difference(s1) = {a4, a5} |
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func (s String) Difference(s2 String) String { |
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result := NewString() |
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for key := range s { |
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if !s2.Has(key) { |
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result.Insert(key) |
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} |
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} |
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return result |
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} |
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// Union returns a new set which includes items in either s1 or s2. |
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// For example: |
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// s1 = {a1, a2} |
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// s2 = {a3, a4} |
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// s1.Union(s2) = {a1, a2, a3, a4} |
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// s2.Union(s1) = {a1, a2, a3, a4} |
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func (s1 String) Union(s2 String) String { |
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result := NewString() |
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for key := range s1 { |
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result.Insert(key) |
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} |
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for key := range s2 { |
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result.Insert(key) |
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} |
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return result |
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} |
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// Intersection returns a new set which includes the item in BOTH s1 and s2 |
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// For example: |
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// s1 = {a1, a2} |
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// s2 = {a2, a3} |
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// s1.Intersection(s2) = {a2} |
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func (s1 String) Intersection(s2 String) String { |
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var walk, other String |
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result := NewString() |
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if s1.Len() < s2.Len() { |
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walk = s1 |
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other = s2 |
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} else { |
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walk = s2 |
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other = s1 |
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} |
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for key := range walk { |
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if other.Has(key) { |
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result.Insert(key) |
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} |
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} |
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return result |
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} |
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// IsSuperset returns true if and only if s1 is a superset of s2. |
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func (s1 String) IsSuperset(s2 String) bool { |
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for item := range s2 { |
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if !s1.Has(item) { |
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return false |
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} |
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} |
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return true |
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} |
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// Equal returns true if and only if s1 is equal (as a set) to s2. |
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// Two sets are equal if their membership is identical. |
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// (In practice, this means same elements, order doesn't matter) |
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func (s1 String) Equal(s2 String) bool { |
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return len(s1) == len(s2) && s1.IsSuperset(s2) |
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} |
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type sortableSliceOfString []string |
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func (s sortableSliceOfString) Len() int { return len(s) } |
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func (s sortableSliceOfString) Less(i, j int) bool { return lessString(s[i], s[j]) } |
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func (s sortableSliceOfString) Swap(i, j int) { s[i], s[j] = s[j], s[i] } |
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// List returns the contents as a sorted string slice. |
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func (s String) List() []string { |
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res := make(sortableSliceOfString, 0, len(s)) |
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for key := range s { |
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res = append(res, key) |
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} |
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sort.Sort(res) |
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return []string(res) |
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} |
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// UnsortedList returns the slice with contents in random order. |
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func (s String) UnsortedList() []string { |
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res := make([]string, 0, len(s)) |
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for key := range s { |
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res = append(res, key) |
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} |
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return res |
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} |
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// Returns a single element from the set. |
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func (s String) PopAny() (string, bool) { |
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for key := range s { |
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s.Delete(key) |
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return key, true |
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} |
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var zeroValue string |
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return zeroValue, false |
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} |
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// Len returns the size of the set. |
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func (s String) Len() int { |
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return len(s) |
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} |
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func lessString(lhs, rhs string) bool { |
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return lhs < rhs |
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}
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