Editing Comparison of memoization implementations

This edit will create a new revision.

Your details (optional)

Name

Email (won’t be displayed; might be used for Gravatar)

URL

Test case details

Title *

Published (uncheck if you want to fiddle around before making the page public)

Description (in case you feel further explanation is needed)(Markdown syntax is allowed)

Are you a spammer? (just answer the question)

Preparation code

Preparation code HTML (this will be inserted in the <body> of a valid HTML5 document in standards mode) (useful when testing DOM operations or including libraries)

Function.prototype.cached7 = function(){
    "use strict";
    var self = this, cache7 = {};
    return function(arg){
        if(cache7[arg] !== undefined) {
            //console.log('Cache hit for '+arg);
            return cache7[arg];
        } else {
            //console.log('Cache miss for '+arg);
            return cache7[arg] = self(arg);
        }
    };
}
  
  
  //memo1
  //underscore.js implem
  
  function memoize1(func, hasher) {
      var memo = {};
      hasher || (hasher = function(value){
        return value; //^this could be done better..surely..
      });
      return function() {
        var key = hasher.apply(this, arguments);
        return hasOwnProperty.call(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
      };
    };
  
  
  //memo2 - another variation with changes by @addyosmani
  //based on initial work by thejit
  //note: I'm aware of the perils of hanging the implem off
  //fn, just want to find out if this version performs much better
    function memoize2(fn) {
      return function () {
          var args = Array.prototype.slice.call(arguments),
              hash = "",
              i  = args.length;
          while(i--){
            hash += (Object.prototype.toString.call({}) == Object.prototype.toString.call(args[i])) ? JSON.stringify(args[i]) : args[i];
            fn.memoize = fn.memoize || {};
        } 
          return (hash in fn.memoize) ? fn.memoize[hash] : fn.memoize[hash] = fn.apply(this, args);
      };
  }
  
  //memo3 - unscriptables implem.
  function memoize3(func, context) {
      function memoizeArg (argPos) {
          var cache = {};
          return function () {
              if (argPos == 0) {
                  if (!(arguments[argPos] in cache)) {
                      cache[arguments[argPos]] = func.apply(context, arguments);
                  }
                  return cache[arguments[argPos]];
              }
              else {
                  if (!(arguments[argPos] in cache)) {
                      cache[arguments[argPos]] = memoizeArg(argPos - 1);
                  }
                  return cache[arguments[argPos]].apply(this, arguments);
              }
          }
      }
      // JScript doesn't grok the arity property, but uses length instead
      var arity = func.arity || func.length;
      return memoizeArg(arity - 1);
  }
  
  //memo4 - by stevenlevithan
  function memoize4(functor, expiration) {
  	var memo = {};
  	return function () {
  		var key = Array.prototype.join.call(arguments, "§");
  		if (key in memo)
  			return memo[key];
  		if (expiration)
  			setTimeout(function () {delete memo[key];}, expiration);
  		return memo[key] = functor.apply(this, arguments);
  	};
  }
  
  
  //memo5 - @gbradley
  
  function memoize5(fn){
  var lookup={};
  return function(){
  	var args=[].slice.call(arguments);
  	var key=JSON.stringify(args);
  	var result=lookup[key];
  	if (!result){
  		result=fn.apply(this,args);
  		lookup[key]=result;
  		}
  	return result;
  	};
  }

// Redefine to prevent any unknown special inlines...
  function fib7(x) {
      if(x<2) return 1; else return fib7(x-1) + fib7(x-2);
  }
  
var fibTest1 = memoize1(fib);
var fibTest2 = memoize2(fib);
var fibTest3 = memoize3(fib);
var fibTest4 = memoize4(fib,1000);
var fibTest5 = memoize5(fib);
var fibTest6 = fib.cached();
var fibTest7 = memoize7(fib);
var fibTest7c = fib7.cached7();

</script>

Title

Async (check if this is an asynchronous test)

Code

fibTest7c(20);
fibTest7c(20);