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103 lines
2.9 KiB
Go
103 lines
2.9 KiB
Go
// Copyright (c) 2015, Emir Pasic. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package hashbidimap implements a bidirectional map backed by two hashmaps.
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//
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// A bidirectional map, or hash bag, is an associative data structure in which the (key,value) pairs form a one-to-one correspondence.
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// Thus the binary relation is functional in each direction: value can also act as a key to key.
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// A pair (a,b) thus provides a unique coupling between 'a' and 'b' so that 'b' can be found when 'a' is used as a key and 'a' can be found when 'b' is used as a key.
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//
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// Elements are unordered in the map.
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//
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// Structure is not thread safe.
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//
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// Reference: https://en.wikipedia.org/wiki/Bidirectional_map
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package hashbidimap
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import (
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"fmt"
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"github.com/emirpasic/gods/maps"
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"github.com/emirpasic/gods/maps/hashmap"
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)
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func assertMapImplementation() {
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var _ maps.BidiMap = (*Map)(nil)
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}
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// Map holds the elements in two hashmaps.
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type Map struct {
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forwardMap hashmap.Map
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inverseMap hashmap.Map
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}
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// New instantiates a bidirectional map.
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func New() *Map {
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return &Map{*hashmap.New(), *hashmap.New()}
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}
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// Put inserts element into the map.
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func (m *Map) Put(key interface{}, value interface{}) {
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if valueByKey, ok := m.forwardMap.Get(key); ok {
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m.inverseMap.Remove(valueByKey)
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}
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if keyByValue, ok := m.inverseMap.Get(value); ok {
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m.forwardMap.Remove(keyByValue)
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}
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m.forwardMap.Put(key, value)
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m.inverseMap.Put(value, key)
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}
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// Get searches the element in the map by key and returns its value or nil if key is not found in map.
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// Second return parameter is true if key was found, otherwise false.
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func (m *Map) Get(key interface{}) (value interface{}, found bool) {
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return m.forwardMap.Get(key)
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}
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// GetKey searches the element in the map by value and returns its key or nil if value is not found in map.
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// Second return parameter is true if value was found, otherwise false.
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func (m *Map) GetKey(value interface{}) (key interface{}, found bool) {
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return m.inverseMap.Get(value)
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}
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// Remove removes the element from the map by key.
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func (m *Map) Remove(key interface{}) {
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if value, found := m.forwardMap.Get(key); found {
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m.forwardMap.Remove(key)
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m.inverseMap.Remove(value)
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}
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}
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// Empty returns true if map does not contain any elements
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func (m *Map) Empty() bool {
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return m.Size() == 0
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}
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// Size returns number of elements in the map.
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func (m *Map) Size() int {
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return m.forwardMap.Size()
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}
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// Keys returns all keys (random order).
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func (m *Map) Keys() []interface{} {
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return m.forwardMap.Keys()
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}
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// Values returns all values (random order).
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func (m *Map) Values() []interface{} {
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return m.inverseMap.Keys()
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}
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// Clear removes all elements from the map.
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func (m *Map) Clear() {
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m.forwardMap.Clear()
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m.inverseMap.Clear()
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}
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// String returns a string representation of container
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func (m *Map) String() string {
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str := "HashBidiMap\n"
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str += fmt.Sprintf("%v", m.forwardMap)
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return str
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}
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