Go數據結構：字典

Go中Dictionary數據結構的分析與實現

詞典商店[key, value]對。 Go通過內置的字典提供了非常方便的字典實現map類型。

在本文中，我將豐富map內置類型，並通過一些方便的操作來獲取其中的信息並更改其內容。

我將創建一個ItemDictionary泛型類型，並發安全，可以為任何類型生成字典。通過運行genny該代碼將創建一個特定於類型的Dictionary實現，並封裝實際的map包含數據。

目標

該字典是使用以下方法創建的dict := ValueDictionary{}並提供以下導出方法集：

  • Set()
  • Delete()
  • Has()
  • Get()
  • Clear()
  • Size()
  • Keys()
  • Values()

執行

// Package dictionary creates a ValueDictionary data structure for the Item type
package dictionary

import (
“sync”


<span style="color:#e6db74">"github.com/cheekybits/genny/generic"</span>

)


// Key the key of the dictionary
type Key generic.Type


// Value the content of the dictionary
type Value generic.Type


// ValueDictionary the set of Items
type ValueDictionary struct {
items map[Key]Value
lock  sync.RWMutex
}


// Set adds a new item to the dictionary
func (d *ValueDictionary) Set(k Key, v Value) {
d.lock.Lock()
defer d.lock.Unlock()
if d.items == nil {
d.items = make(map[Key]Value)
}
d.items[k] = v
}


// Delete removes a value from the dictionary, given its key
func (d *ValueDictionary) Delete(k Key) bool {
d.lock.Lock()
defer d.lock.Unlock()
_, ok := d.items[k]
if ok {
delete(d.items, k)
}
return ok
}


// Has returns true if the key exists in the dictionary
func (d *ValueDictionary) Has(k Key) bool {
d.lock.RLock()
defer d.lock.RUnlock()
_, ok := d.items[k]
return ok
}


// Get returns the value associated with the key
func (d *ValueDictionary) Get(k Key) Value {
d.lock.RLock()
defer d.lock.RUnlock()
return d.items[k]
}


// Clear removes all the items from the dictionary
func (d *ValueDictionary) Clear() {
d.lock.Lock()
defer d.lock.Unlock()
d.items = make(map[Key]Value)
}


// Size returns the amount of elements in the dictionary
func (d *ValueDictionary) Size() int {
d.lock.RLock()
defer d.lock.RUnlock()
return len(d.items)
}


// Keys returns a slice of all the keys present
func (d *ValueDictionary) Keys() []Key {
d.lock.RLock()
defer d.lock.RUnlock()
keys := []Key{}
for i := range d.items {
keys = append(keys, i)
}
return keys
}


// Values returns a slice of all the values present
func (d *ValueDictionary) Values() []Value {
d.lock.RLock()
defer d.lock.RUnlock()
values := []Value{}
for i := range d.items {
values = append(values, d.items[i])
}
return values
}

測驗

這些測試描述了上述實現的用法。請注意，我們從不與基礎互動map類型，如果只有Go尚未為我們提供地圖類型，則也可以通過其他方式實現。

package dictionary

import (
“fmt”
“testing”
)


func populateDictionary(count int, start int) *ValueDictionary {
dict := ValueDictionary{}
for i := start; i < (start + count); i++ {
dict.Set(fmt.Sprintf(“key%d”, i), fmt.Sprintf(“value%d”, i))
}
return &dict
}


func TestSet(t *testing.T) {
dict := populateDictionary(3, 0)
if size := dict.Size(); size != 3 {
t.Errorf(“wrong count, expected 3 and got %d”, size)
}
dict.Set(“key1”, “value1”) //should not add a new one, just change the existing one
    if size := dict.Size(); size != 3 {
t.Errorf(“wrong count, expected 3 and got %d”, size)
}
dict.Set(“key4”, “value4”) //should add it
    if size := dict.Size(); size != 4 {
t.Errorf(“wrong count, expected 4 and got %d”, size)
}
}


func TestDelete(t *testing.T) {
dict := populateDictionary(3, 0)
dict.Delete(“key2”)
if size := dict.Size(); size != 2 {
t.Errorf(“wrong count, expected 2 and got %d”, size)
}
}


func TestClear(t *testing.T) {
dict := populateDictionary(3, 0)
dict.Clear()
if size := dict.Size(); size != 0 {
t.Errorf(“wrong count, expected 0 and got %d”, size)
}
}


func TestHas(t *testing.T) {
dict := populateDictionary(3, 0)
has := dict.Has(“key2”)
if !has {
t.Errorf(“expected key2 to be there”)
}
dict.Delete(“key2”)
has = dict.Has(“key2”)
if has {
t.Errorf(“expected key2 to be removed”)
}
dict.Delete(“key1”)
has = dict.Has(“key1”)
if has {
t.Errorf(“expected key1 to be removed”)
}
}


func TestKeys(t *testing.T) {
dict := populateDictionary(3, 0)
items := dict.Keys()
if len(items) != 3 {
t.Errorf(“wrong count, expected 3 and got %d”, len(items))
}
dict = populateDictionary(520, 0)
items = dict.Keys()
if len(items) != 520 {
t.Errorf(“wrong count, expected 520 and got %d”, len(items))
}
}


func TestValues(t *testing.T) {
dict := populateDictionary(3, 0)
items := dict.Values()
if len(items) != 3 {
t.Errorf(“wrong count, expected 3 and got %d”, len(items))
}
dict = populateDictionary(520, 0)
items = dict.Values()
if len(items) != 520 {
t.Errorf(“wrong count, expected 520 and got %d”, len(items))
}
}


func TestSize(t *testing.T) {
dict := populateDictionary(3, 0)
items := dict.Values()
if len(items) != dict.Size() {
t.Errorf(“wrong count, expected %d and got %d”, dict.Size(), len(items))
}
dict = populateDictionary(0, 0)
items = dict.Values()
if len(items) != dict.Size() {
t.Errorf(“wrong count, expected %d and got %d”, dict.Size(), len(items))
}
dict = populateDictionary(10000, 0)
items = dict.Values()
if len(items) != dict.Size() {
t.Errorf(“wrong count, expected %d and got %d”, dict.Size(), len(items))
}
}

創建具體的字典數據結構

您可以使用以下通用實現來生成特定於類型的字典，方法是：

//generate a `IntDictionary` dictionary of `string` keys associated to `int` values
genny -in dictionary.go -out dictionary-string-int.go gen "Key=string Value=int"

//generate a </span>StringDictionary<span style="color:#e6db74"> dictionary of </span>string<span style="color:#e6db74"> keys associated to </span>string<span style="color:#e6db74"> values
genny -in dictionary.go -out dictionary-string-string.go gen “Key=string Value=string”


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