fix(genfun): make internal properties private

zkat · Apr 16, 2017 · e855c72 · e855c72
1 parent 74abcc2
commit e855c72
Showing 1 changed file with 26 additions and 32 deletions.
diff --git a/lib/genfun.js b/lib/genfun.js
@@ -4,23 +4,17 @@ const Method = require('./method')
 const Role = require('./role')
 const util = require('./util')
 
-/**
- * Creates generic functions capable of multiple dispatch across several
- * arguments. The generic function returned by this constructor is
- * functionally identical to a standard function: it can be called,
- * applied, and receives the expected binding for `this` when appropriate.
- *
- * @constructor
- * @param {object} [opts] - Options used when initializing the genfun.
- * @returns {function} New generic function.
- */
+const kDefaultMethod = Symbol('defaultMethod')
+const kMethods = Symbol('methods')
+const kCache = Symbol('cache')
+
 module.exports = function genfun () {
   function gf () {
     return gf.applyGenfun(this, arguments)
   }
   Object.setPrototypeOf(gf, Genfun.prototype)
-  gf.methods = []
-  gf.cache = {key: [], methods: [], state: STATES.UNINITIALIZED}
+  gf[kMethods] = []
+  gf[kCache] = {key: [], methods: [], state: STATES.UNINITIALIZED}
   return gf
 }
 
@@ -51,12 +45,12 @@ Genfun.prototype.add = function addMethod (selector, func) {
       selector[i] = Object.prototype
     }
   }
-  this.cache = {key: [], methods: [], state: STATES.UNINITIALIZED}
+  this[kCache] = {key: [], methods: [], state: STATES.UNINITIALIZED}
   let method = new Method(this, selector, func)
   if (selector.length) {
-    this.methods.push(method)
+    this[kMethods].push(method)
   } else {
-    this.defaultMethod = method
+    this[kDefaultMethod] = method
   }
   return this
 }
@@ -187,8 +181,8 @@ Genfun.prototype.applyGenfun = function applyGenfun (newThis, args) {
 }
 
 Genfun.prototype.getApplicableMethods = function getApplicableMethods (args) {
-  if (!args.length || !this.methods.length) {
-    return this.defaultMethod ? [this.defaultMethod] : []
+  if (!args.length || !this[kMethods].length) {
+    return this[kDefaultMethod] ? [this[kDefaultMethod]] : []
   }
   let applicableMethods
   let maybeMethods = cachedMethods(this, args)
@@ -202,7 +196,7 @@ Genfun.prototype.getApplicableMethods = function getApplicableMethods (args) {
 }
 
 function cacheArgs (genfun, args, methods) {
-  if (genfun.cache.state === STATES.MEGAMORPHIC) { return }
+  if (genfun[kCache].state === STATES.MEGAMORPHIC) { return }
   var key = []
   var proto
   for (var i = 0; i < args.length; i++) {
@@ -213,14 +207,14 @@ function cacheArgs (genfun, args, methods) {
       return null
     }
   }
-  genfun.cache.key.unshift(key)
-  genfun.cache.methods.unshift(methods)
-  if (genfun.cache.key.length === 1) {
-    genfun.cache.state = STATES.MONOMORPHIC
-  } else if (genfun.cache.key.length < MAX_CACHE_SIZE) {
-    genfun.cache.state = STATES.POLYMORPHIC
+  genfun[kCache].key.unshift(key)
+  genfun[kCache].methods.unshift(methods)
+  if (genfun[kCache].key.length === 1) {
+    genfun[kCache].state = STATES.MONOMORPHIC
+  } else if (genfun[kCache].key.length < MAX_CACHE_SIZE) {
+    genfun[kCache].state = STATES.POLYMORPHIC
   } else {
-    genfun.cache.state = STATES.MEGAMORPHIC
+    genfun[kCache].state = STATES.MEGAMORPHIC
   }
 }
 
@@ -238,8 +232,8 @@ function cacheableProto (genfun, arg) {
 }
 
 function cachedMethods (genfun, args) {
-  if (genfun.cache.state === STATES.UNINITIALIZED ||
-      genfun.cache.state === STATES.MEGAMORPHIC) {
+  if (genfun[kCache].state === STATES.UNINITIALIZED ||
+      genfun[kCache].state === STATES.MEGAMORPHIC) {
     return null
   }
   var protos = []
@@ -252,9 +246,9 @@ function cachedMethods (genfun, args) {
       return
     }
   }
-  for (i = 0; i < genfun.cache.key.length; i++) {
-    if (matchCachedMethods(genfun.cache.key[i], protos)) {
-      return genfun.cache.methods[i]
+  for (i = 0; i < genfun[kCache].key.length; i++) {
+    if (matchCachedMethods(genfun[kCache].key[i], protos)) {
+      return genfun[kCache].methods[i]
     }
   }
 }
@@ -307,8 +301,8 @@ function computeApplicableMethods (genfun, args) {
             Method.isFullySpecified(method))
   })
   applicableMethods.sort((a, b) => Method.score(a) - Method.score(b))
-  if (genfun.defaultMethod) {
-    applicableMethods.push(genfun.defaultMethod)
+  if (genfun[kDefaultMethod]) {
+    applicableMethods.push(genfun[kDefaultMethod])
   }
   return applicableMethods
 }