mirror of https://github.com/emirpasic/gods
Merge pull request #23 from emirpasic/bidi_map
- bidimap implemention as dual hashmap bidirectional mappull/29/head v1.3.0
Emir Pasic
8 years ago
committed by
GitHub
commit
16fd6c0e09
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// 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 examples
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import "github.com/emirpasic/gods/maps/hashbidimap"
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// HashBidiMapExample to demonstrate basic usage of HashMap
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func HashBidiMapExample() {
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m := hashbidimap.New() // empty
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m.Put(1, "x") // 1->x
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m.Put(3, "b") // 1->x, 3->b (random order)
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m.Put(1, "a") // 1->a, 3->b (random order)
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m.Put(2, "b") // 1->a, 2->b (random order)
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_, _ = m.GetKey("a") // 1, true
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_, _ = m.Get(2) // b, true
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_, _ = m.Get(3) // nil, false
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_ = m.Values() // []interface {}{"a", "b"} (random order)
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_ = m.Keys() // []interface {}{1, 2} (random order)
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m.Remove(1) // 2->b
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m.Clear() // empty
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m.Empty() // true
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m.Size() // 0
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}
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// 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 := "HashMap\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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@ -0,0 +1,182 @@
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// 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
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import (
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"fmt"
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"testing"
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)
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func TestMapPut(t *testing.T) {
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m := New()
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m.Put(5, "e")
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m.Put(6, "f")
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m.Put(7, "g")
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m.Put(3, "c")
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m.Put(4, "d")
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m.Put(1, "x")
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m.Put(2, "b")
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m.Put(1, "a") //overwrite
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if actualValue := m.Size(); actualValue != 7 {
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t.Errorf("Got %v expected %v", actualValue, 7)
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}
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if actualValue, expectedValue := m.Keys(), []interface{}{1, 2, 3, 4, 5, 6, 7}; !sameElements(actualValue, expectedValue) {
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t.Errorf("Got %v expected %v", actualValue, expectedValue)
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}
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if actualValue, expectedValue := m.Values(), []interface{}{"a", "b", "c", "d", "e", "f", "g"}; !sameElements(actualValue, expectedValue) {
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t.Errorf("Got %v expected %v", actualValue, expectedValue)
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}
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// key,expectedValue,expectedFound
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tests1 := [][]interface{}{
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{1, "a", true},
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{2, "b", true},
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{3, "c", true},
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{4, "d", true},
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{5, "e", true},
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{6, "f", true},
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{7, "g", true},
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{8, nil, false},
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}
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for _, test := range tests1 {
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// retrievals
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actualValue, actualFound := m.Get(test[0])
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if actualValue != test[1] || actualFound != test[2] {
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t.Errorf("Got %v expected %v", actualValue, test[1])
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}
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}
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}
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func TestMapRemove(t *testing.T) {
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m := New()
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m.Put(5, "e")
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m.Put(6, "f")
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m.Put(7, "g")
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m.Put(3, "c")
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m.Put(4, "d")
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m.Put(1, "x")
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m.Put(2, "b")
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m.Put(1, "a") //overwrite
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m.Remove(5)
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m.Remove(6)
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m.Remove(7)
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m.Remove(8)
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m.Remove(5)
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if actualValue, expectedValue := m.Keys(), []interface{}{1, 2, 3, 4}; !sameElements(actualValue, expectedValue) {
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t.Errorf("Got %v expected %v", actualValue, expectedValue)
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}
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if actualValue, expectedValue := m.Values(), []interface{}{"a", "b", "c", "d"}; !sameElements(actualValue, expectedValue) {
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t.Errorf("Got %v expected %v", actualValue, expectedValue)
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}
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if actualValue := m.Size(); actualValue != 4 {
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t.Errorf("Got %v expected %v", actualValue, 4)
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}
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tests2 := [][]interface{}{
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{1, "a", true},
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{2, "b", true},
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{3, "c", true},
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{4, "d", true},
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{5, nil, false},
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{6, nil, false},
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{7, nil, false},
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{8, nil, false},
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}
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for _, test := range tests2 {
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actualValue, actualFound := m.Get(test[0])
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if actualValue != test[1] || actualFound != test[2] {
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t.Errorf("Got %v expected %v", actualValue, test[1])
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}
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}
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m.Remove(1)
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m.Remove(4)
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m.Remove(2)
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m.Remove(3)
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m.Remove(2)
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m.Remove(2)
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if actualValue, expectedValue := fmt.Sprintf("%s", m.Keys()), "[]"; actualValue != expectedValue {
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t.Errorf("Got %v expected %v", actualValue, expectedValue)
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}
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if actualValue, expectedValue := fmt.Sprintf("%s", m.Values()), "[]"; actualValue != expectedValue {
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t.Errorf("Got %v expected %v", actualValue, expectedValue)
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}
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if actualValue := m.Size(); actualValue != 0 {
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t.Errorf("Got %v expected %v", actualValue, 0)
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}
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if actualValue := m.Empty(); actualValue != true {
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t.Errorf("Got %v expected %v", actualValue, true)
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}
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}
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func TestMapGetKey(t *testing.T) {
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m := New()
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m.Put(5, "e")
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m.Put(6, "f")
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m.Put(7, "g")
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m.Put(3, "c")
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m.Put(4, "d")
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m.Put(1, "x")
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m.Put(2, "b")
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m.Put(1, "a") //overwrite
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// key,expectedValue,expectedFound
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tests1 := [][]interface{}{
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{1, "a", true},
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{2, "b", true},
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{3, "c", true},
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{4, "d", true},
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{5, "e", true},
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{6, "f", true},
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{7, "g", true},
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{nil, "x", false},
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}
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for _, test := range tests1 {
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// retrievals
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actualValue, actualFound := m.GetKey(test[1])
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if actualValue != test[0] || actualFound != test[2] {
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t.Errorf("Got %v expected %v", actualValue, test[0])
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}
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}
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}
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func sameElements(a []interface{}, b []interface{}) bool {
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if len(a) != len(b) {
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return false
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}
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for _, av := range a {
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found := false
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for _, bv := range b {
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if av == bv {
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found = true
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break
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}
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}
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if !found {
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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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func BenchmarkMap(b *testing.B) {
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for i := 0; i < b.N; i++ {
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m := New()
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for n := 0; n < 1000; n++ {
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m.Put(n, n)
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}
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for n := 0; n < 1000; n++ {
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m.Remove(n)
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}
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}
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}
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