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// Copyright 2013 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package set
import (
"sort"
)
// Strings represents the classic "set" data structure, and contains strings.
type Strings map[string]bool
// NewStrings creates and initializes a Strings and populates it with
// initial values as specified in the parameters.
func NewStrings(initial ...string) Strings {
result := make(Strings)
for _, value := range initial {
result.Add(value)
}
return result
}
// Size returns the number of elements in the set.
func (s Strings) Size() int {
return len(s)
}
// IsEmpty is true for empty or uninitialized sets.
func (s Strings) IsEmpty() bool {
return len(s) == 0
}
// Add puts a value into the set.
func (s Strings) Add(value string) {
if s == nil {
panic("uninitalised set")
}
s[value] = true
}
// Remove takes a value out of the set. If value wasn't in the set to start
// with, this method silently succeeds.
func (s Strings) Remove(value string) {
delete(s, value)
}
// Contains returns true if the value is in the set, and false otherwise.
func (s Strings) Contains(value string) bool {
_, exists := s[value]
return exists
}
// Values returns an unordered slice containing all the values in the set.
func (s Strings) Values() []string {
result := make([]string, len(s))
i := 0
for key := range s {
result[i] = key
i++
}
return result
}
// SortedValues returns an ordered slice containing all the values in the set.
func (s Strings) SortedValues() []string {
values := s.Values()
sort.Strings(values)
return values
}
// Union returns a new Strings representing a union of the elments in the
// method target and the parameter.
func (s Strings) Union(other Strings) Strings {
result := make(Strings)
// Use the internal map rather than going through the friendlier functions
// to avoid extra allocation of slices.
for value := range s {
result[value] = true
}
for value := range other {
result[value] = true
}
return result
}
// Intersection returns a new Strings representing a intersection of the elments in the
// method target and the parameter.
func (s Strings) Intersection(other Strings) Strings {
result := make(Strings)
// Use the internal map rather than going through the friendlier functions
// to avoid extra allocation of slices.
for value := range s {
if other.Contains(value) {
result[value] = true
}
}
return result
}
// Difference returns a new Strings representing all the values in the
// target that are not in the parameter.
func (s Strings) Difference(other Strings) Strings {
result := make(Strings)
// Use the internal map rather than going through the friendlier functions
// to avoid extra allocation of slices.
for value := range s {
if !other.Contains(value) {
result[value] = true
}
}
return result
}
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