Using LRU Cache instead of the old backingStore

Author: antoninkriz

src/LRUCache.js

@@ -9,138 +9,139 @@ function LRULinkListEntry(hash, obj) {
  this._next = null
 }
 
-// My favorite so far.
-function LRUCacheByLinkList(length) {
- this.maxLength = length
- this.reset()
-}
-
-LRUCacheByLinkList.prototype.reset = () => {
- this.length = 0
- this._top = null
- this._bottom = null
- this._keyVals = {}
-}
-
-LRUCacheByLinkList.prototype.detachElement = entry => {
- const prev = entry._prev
- const next = entry._next
-
- if (prev !== null) {
- prev._next = next
+class LRUCacheByLinkList {
+ constructor(length) {
+ this.maxLength = length
+ this.reset()
  }
 
- if (next !== null) {
- next._prev = prev
+ reset = () => {
+ this.length = 0
+ this._top = null
+ this._bottom = null
+ this._keyVals = {}
  }
 
- if (entry === this._top) {
- this._top = next
- }
+ detachElement = entry => {
+ const prev = entry._prev
+  const next = entry._next
 
- if (entry === this._bottom) {
- this._bottom = prev
- }
+  if (prev !== null) {
+  prev._next = next
+  }
 
- this.length--
- return entry
-}
+  if (next !== null) {
+  next._prev = prev
+ }
 
-LRUCacheByLinkList.prototype.removeElement = entry => {
- this.detachElement(entry)
- delete this._keyVals[entry._hash]
- return entry._datum
-}
+ if (entry === this._top) {
+ this._top = next
+ }
+
+ if (entry === this._bottom) {
+ this._bottom = prev
+ }
 
-LRUCacheByLinkList.prototype.insertAtTop = entry => {
- if (this._top !== null) {
- this._top._prev = entry
- entry._next = this._top
+ this.length--
+ return entry
  }
 
- if (this._bottom === null) {
- this._bottom = entry
+ removeElement = entry => {
+ this.detachElement(entry)
+ delete this._keyVals[entry._hash]
+ return entry._datum
  }
 
- this._top = entry
- this.length++
-}
+ insertAtTop = entry => {
+ if (this._top !== null) {
+ this._top._prev = entry
+ entry._next = this._top
+ }
+
+ if (this._bottom === null) {
+ this._bottom = entry
+ }
 
-LRUCacheByLinkList.prototype.insertAtBottom = value => {
- if (this._bottom !== null) {
- this._bottom._next = value
- value._prev = this._bottom
+ this._top = entry
+ this.length++
  }
 
- if (this._top === null) {
- this._top = value
+ insertAtBottom = value => {
+ if (this._bottom !== null) {
+ this._bottom._next = value
+ value._prev = this._bottom
+ }
+
+ if (this._top === null) {
+ this._top = value
+ }
+
+ this._bottom = value
+ this.length++
  }
 
- this._bottom = value
- this.length++
-}
+ set = (key, value) => {
+ const existinEl = this._keyVals[key]
 
-LRUCacheByLinkList.prototype.set = (key, value) => {
- const existinEl = this._keyVals[key]
+ // Handling for dups
+ if (existinEl) {
+ if (existinEl._datum === value) {
+ // Don't change anything
+ return
+ }
 
- // Handling for dups
- if (existinEl) {
- if (existinEl._datum === value) {
- // Don't change anything
- return
+ // hardest part of code.
+ this.removeElement(existinEl)
  }
 
- // hardest part of code.
- this.removeElement(existinEl)
- }
+ value = new LRULinkListEntry(key, value)
+ this._keyVals[key] = value
 
- value = new LRULinkListEntry(key, value)
- this._keyVals[key] = value
+  // Most likely it will only be equal
+  // to purge the least used
 
- // Most likely it will only be equal
- // to purge the least used
+ if (this.length === this.maxLength) {
+ this.removeLeastUsed()
+ }
 
- if (this.length === this.maxLength) {
- this.removeLeastUsed()
+ this.insertAtTop(value)
  }
 
- this.insertAtTop(value)
-}
+ removeLeastUsed = () => {
+ // Buhahah this is easy.
+ return this.removeElement(this._bottom)
+ }
 
-LRUCacheByLinkList.prototype.removeLeastUsed = () => {
- // Buhahah this is easy.
- return this.removeElement(this._bottom)
-}
+ get = key => {
+ const value = this._keyVals[key]
 
-LRUCacheByLinkList.prototype.get = key => {
- const value = this._keyVals[key]
+ if (value !== undefined) {
+ // Promote this as it got used
+ this.promote(value)
+ return value._datum
+ }
 
- if (value !== undefined) {
- // Promote this as it got used
- this.promote(value)
- return value._datum
+ return null
  }
 
- return null
-}
+ // Remove the element
+ // and push it from the front
+ // so least recently used objects will end up at the end.
+ promote = el => {
+ // No need to promote
+ if (el === this.top) {
+ return
+ }
 
-// Remove the element
-// and push it from the front
-// so least recently used objects will end up at the end.
-LRUCacheByLinkList.prototype.promote = el => {
- // No need to promote
- if (el === this.top) {
- return
+ // seriously do we need to remove it ?
+ this.detachElement(el)
+ this.insertAtTop(el)
  }
 
- // seriously do we need to remove it ?
- this.detachElement(el)
- this.insertAtTop(el)
-}
-
-// Call this method
-LRUCacheByLinkList.prototype.forEach = cb => {
- Object.keys(this._keyVals).forEach(entry => cb(entry._datum))
+ // Call this method
+ forEach = cb => {
+ Object.keys(this._keyVals).forEach(entry => cb(entry._datum))
+ }
 }
 
 module.exports = LRUCacheByLinkList