Add rentries, rkeys, rvalues

Same as entries/keys/values, but in order from oldest to newest instead of newest to oldest.
isaacs · Mar 14, 2022 · 7eb6368 · 7eb6368
1 parent bb01e26
commit 7eb6368
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Showing 4 changed files with 196 additions and 5 deletions.
diff --git a/README.md b/README.md
@@ -336,15 +336,33 @@ If you put more stuff in it, then items will fall out.
 
 * `keys()`
 
-    Return a generator yielding the keys in the cache.
+    Return a generator yielding the keys in the cache, in order from most
+    recently used to least recently used.
+
+* `rkeys()`
+
+    Return a generator yielding the keys in the cache, in order from least
+    recently used to most recently used.
 
 * `values()`
 
-    Return a generator yielding the values in the cache.
+    Return a generator yielding the values in the cache, in order from most
+    recently used to least recently used.
+
+* `rvalues()`
+
+    Return a generator yielding the values in the cache, in order from
+    least recently used to most recently used.
 
 * `entries()`
 
-    Return a generator yielding `[key, value]` pairs.
+    Return a generator yielding `[key, value]` pairs, in order from most
+    recently used to least recently used.
+
+* `rentries()`
+
+    Return a generator yielding `[key, value]` pairs, in order from least
+    recently used to most recently used.
 
 * `find(fn, [getOptions])`
 

diff --git a/index.js b/index.js
@@ -243,24 +243,29 @@ class LRUCache {
 
   *indexes ({ allowStale = this.allowStale } = {}) {
     if (this.size) {
-      for (let i = this.tail; true; i = this.prev[i]) {
+      for (let i = this.tail, j; true; ) {
         if (allowStale || !this.isStale(i)) {
           yield i
         }
         if (i === this.head) {
           break
+        } else {
+          i = this.prev[i]
         }
       }
     }
   }
+
   *rindexes ({ allowStale = this.allowStale } = {}) {
     if (this.size) {
-      for (let i = this.head; true; i = this.next[i]) {
+      for (let i = this.head, j; true; ) {
         if (allowStale || !this.isStale(i)) {
           yield i
         }
         if (i === this.tail) {
           break
+        } else {
+          i = this.next[i]
         }
       }
     }
@@ -271,18 +276,33 @@ class LRUCache {
       yield [this.keyList[i], this.valList[i]]
     }
   }
+  *rentries () {
+    for (const i of this.rindexes()) {
+      yield [this.keyList[i], this.valList[i]]
+    }
+  }
 
   *keys () {
     for (const i of this.indexes()) {
       yield this.keyList[i]
     }
   }
+  *rkeys () {
+    for (const i of this.rindexes()) {
+      yield this.keyList[i]
+    }
+  }
 
   *values () {
     for (const i of this.indexes()) {
       yield this.valList[i]
     }
   }
+  *rvalues () {
+    for (const i of this.rindexes()) {
+      yield this.valList[i]
+    }
+  }
 
   [Symbol.iterator] () {
     return this.entries()

diff --git a/tap-snapshots/test/map-like.js.test.cjs b/tap-snapshots/test/map-like.js.test.cjs
@@ -134,6 +134,18 @@ exports[`test/map-like.js TAP > empty, keys 1`] = `
 Generator []
 `
 
+exports[`test/map-like.js TAP > empty, rentries 1`] = `
+Generator []
+`
+
+exports[`test/map-like.js TAP > empty, rkeys 1`] = `
+Generator []
+`
+
+exports[`test/map-like.js TAP > empty, rvalues 1`] = `
+Generator []
+`
+
 exports[`test/map-like.js TAP > empty, values 1`] = `
 Generator []
 `
@@ -325,6 +337,77 @@ Generator [
 ]
 `
 
+exports[`test/map-like.js TAP > rentries 1`] = `
+Generator [
+  Array [
+    3,
+    "3",
+  ],
+  Array [
+    4,
+    "4",
+  ],
+  Array [
+    5,
+    "5",
+  ],
+  Array [
+    6,
+    "6",
+  ],
+  Array [
+    7,
+    "7",
+  ],
+]
+`
+
+exports[`test/map-like.js TAP > rentries, 7 stale 1`] = `
+Generator [
+  Array [
+    3,
+    "3",
+  ],
+  Array [
+    5,
+    "5",
+  ],
+  Array [
+    6,
+    "6",
+  ],
+  Array [
+    4,
+    "new value 4",
+  ],
+]
+`
+
+exports[`test/map-like.js TAP > rentries, new value 4 1`] = `
+Generator [
+  Array [
+    3,
+    "3",
+  ],
+  Array [
+    5,
+    "5",
+  ],
+  Array [
+    6,
+    "6",
+  ],
+  Array [
+    7,
+    "7",
+  ],
+  Array [
+    4,
+    "new value 4",
+  ],
+]
+`
+
 exports[`test/map-like.js TAP > rforEach, no thisp 1`] = `
 Array [
   Array [
@@ -346,6 +429,64 @@ Array [
 ]
 `
 
+exports[`test/map-like.js TAP > rkeys 1`] = `
+Generator [
+  3,
+  4,
+  5,
+  6,
+  7,
+]
+`
+
+exports[`test/map-like.js TAP > rkeys, 7 stale 1`] = `
+Generator [
+  3,
+  5,
+  6,
+  4,
+]
+`
+
+exports[`test/map-like.js TAP > rkeys, new value 4 1`] = `
+Generator [
+  3,
+  5,
+  6,
+  7,
+  4,
+]
+`
+
+exports[`test/map-like.js TAP > rvalues 1`] = `
+Generator [
+  "3",
+  "4",
+  "5",
+  "6",
+  "7",
+]
+`
+
+exports[`test/map-like.js TAP > rvalues, 7 stale 1`] = `
+Generator [
+  "3",
+  "5",
+  "6",
+  "new value 4",
+]
+`
+
+exports[`test/map-like.js TAP > rvalues, new value 4 1`] = `
+Generator [
+  "3",
+  "5",
+  "6",
+  "7",
+  "new value 4",
+]
+`
+
 exports[`test/map-like.js TAP > values 1`] = `
 Generator [
   "7",

diff --git a/test/map-like.js b/test/map-like.js
@@ -10,6 +10,9 @@ const c = new LRU({ max: 5, maxSize: 5 })
 t.matchSnapshot(c.keys(), 'empty, keys')
 t.matchSnapshot(c.values(), 'empty, values')
 t.matchSnapshot(c.entries(), 'empty, entries')
+t.matchSnapshot(c.rkeys(), 'empty, rkeys')
+t.matchSnapshot(c.rvalues(), 'empty, rvalues')
+t.matchSnapshot(c.rentries(), 'empty, rentries')
 t.matchSnapshot(c.dump(), 'empty, dump')
 
 for (let i = 0; i < 8; i++) {
@@ -29,12 +32,18 @@ const e = i => ({
 t.matchSnapshot(c.keys(), 'keys')
 t.matchSnapshot(c.values(), 'values')
 t.matchSnapshot(c.entries(), 'entries')
+t.matchSnapshot(c.rkeys(), 'rkeys')
+t.matchSnapshot(c.rvalues(), 'rvalues')
+t.matchSnapshot(c.rentries(), 'rentries')
 t.matchSnapshot(c.dump(), 'dump')
 
 c.set(4, 'new value 4')
 t.matchSnapshot(c.keys(), 'keys, new value 4')
 t.matchSnapshot(c.values(), 'values, new value 4')
 t.matchSnapshot(c.entries(), 'entries, new value 4')
+t.matchSnapshot(c.rkeys(), 'rkeys, new value 4')
+t.matchSnapshot(c.rvalues(), 'rvalues, new value 4')
+t.matchSnapshot(c.rentries(), 'rentries, new value 4')
 t.matchSnapshot(c.dump(), 'dump, new value 4')
 
 // pretend an entry is stale for some reason
@@ -59,6 +68,9 @@ for (const i of c.rindexes()) {
 t.matchSnapshot(c.keys(), 'keys, 7 stale')
 t.matchSnapshot(c.values(), 'values, 7 stale')
 t.matchSnapshot(c.entries(), 'entries, 7 stale')
+t.matchSnapshot(c.rkeys(), 'rkeys, 7 stale')
+t.matchSnapshot(c.rvalues(), 'rvalues, 7 stale')
+t.matchSnapshot(c.rentries(), 'rentries, 7 stale')
 t.matchSnapshot(c.dump(), 'dump, 7 stale')
 
 const feArr = []