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creating_an_algorithm [2012/10/28 18:59]
creating_an_algorithm [2015/02/02 08:28] (current)
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 ====== Creating algorithms ====== ====== Creating algorithms ======
 ===== Including an algorithm in a page ===== ===== Including an algorithm in a page =====
-An algorithm is stored in a single page in the Algorithm namespace. Different variants ​require ​different pages. For +An algorithm is stored in a single page in the Algorithm namespace. Different variants ​of the same algorithm are stored on different pages. For 
 example Factorial recursive and Factorial iterative. example Factorial recursive and Factorial iterative.
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 ===== Creating an algorithm page ===== ===== Creating an algorithm page =====
-An algorithm page is split into three sections: ​algorithmsupport, and visualisation. Each of these sections contains code wrapped ​in %%<​syntax>​%% tags.+An algorithm page is split into five sections: ​SourceSupport, Unit Tests, Options, and Visualisation. Each section is editable ​in a tabbed code editor at the bottom of the algorithm page.
-The basic outline of an algorithm page should look like this: +{{ :editor-tabs.png?nolink |}}
-<​code>​ +
-[algorithm my-algorithm] +
- +
-====== Algorithm ====== +
-<syntax js> +
-</​syntax>​ +
- +
-====== Support ====== +
-<syntax js> +
-</​syntax>​ +
- +
-====== Visualisation ====== +
-<syntax html> +
-</​syntax>​ +
-</​code>​ +
- +
-The algorithm page should include itself, so that you can easily preview how your changes will work.+
 ==== Algorithm ==== ==== Algorithm ====
-The 1st section contains the algorithm. This is the code that the user sees in the interactive environment. +The 1st section contains the algorithm. This is the code that the user sees in the interactive environment. For example, this is the code for the Fisher-Yates shuffle algorithm
-<syntax js>+<code>
 function shuffle(a) { function shuffle(a) {
     for (var i=a.length-1;​ i>0; i--) {     for (var i=a.length-1;​ i>0; i--) {
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     return a;     return a;
 } }
 ==== Support ==== ==== Support ====
-The 2nd section contains the support code. This is support ​code, such as functions ​that the main algorithm ​uses. If it also includes a run() function this function is called when running the algorithm. +The 2nd section contains the support code. This is code that the main algorithm ​makes use of, for example utility functions. If the support code also includes a ''​run()'' ​function ​then this function is called when running the algorithm, instead of running the algorithm code from line 1
-<syntax js>+<code>
 function swap(a, i, j) { function swap(a, i, j) {
     var t = a[i]; a[i] = a[j]; a[j] = t;     var t = a[i]; a[i] = a[j]; a[j] = t;
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     return shuffle(a);     return shuffle(a);
 } }
-==== Visualisation ​==== +==== Unit Tests ==== 
-The 3rd section ​contains ​the visualisation code. This code is a self contained webpage, it is embedded ​in an i-frame when displayed alongside ​the code.+The unit tests section ​should contain unit tests to ensure ​the algorithm ​is correct. Each function ​in this section whose name has a '​test'​ prefix will be run on a web-worker thread. If there is any exception thrown during running the function ​the test fails.
-The webpage must provide a global update() function, which is called at each new line when running the algorithm. The update function takes two arguments, the current node in the AST and an execution context.+==== Options ==== 
 +The 4rd section contains options ​in JSON formatAvailable options are
-Two other functions are optional: globals() and args(). If the visualisation contains a function args() then the return value of calling ​that function ​will be passed into the run support ​functionThis allows ​the visualisation ​to supply the input to the algorithmIf a globals function ​is provided then it returns ​an object whose keys are added to the globals of the interpreter.+  * ''​title''​ -- The title algorithm. 
 +  * ''​height''​ -- The height of the transcluded algorithm. 
 +  * ''​preRunSource''​ -- If true, the algorithm source will be run at load time and the debugger buttons will initially be disabled. The debug controls enable when ''​runScript("​..."​)''​ is called from the visualisation. For an example ​of this in use see [[algorithm:​linked-list]]. 
 +  * ''​persistentGlobals''​ -- This is an array of strings referring to global variables. These are passed to web-workers each time ''​runScript''​ is called. 
 +  * ''​import''​ -- An array of strings of algorithm pages that will be imported as support ​code 
 +A simple example is: 
 +    "​title":"​Fisher-Yates shuffle",​ 
 +    "​height":"​270px"​ 
 +For a more complex example see [[algorithm:​hash_set-open_hashing|λ Hash set open-hashing]]. 
 +==== Visualisation ==== 
 +The 4th section contains ​the visualisation ​codeThis code is a self contained webpage, ​it is embedded in an iframe when displayed alongside ​the code.
-<syntax html> +The webpage must provide a global ''​update()'' ​function, which is called at each new line when running the algorithm. The update ​function ​takes several arguments,  
-<​html>​ +  * ''​n''​ the current node in the AST (This should be used very rarely
-  <​head>​ +  * ''​x''​ the execution context
-    <script type="​text/​javascript">​ +  * ''​isRunning''​ is the debugger in the middle of running code? 
-        function globals() +  * ''​duration''​ if the visualisation animates, how long it should takeIf ''​duration''​ is below 0 then visualising can be skipped ​if the update function is stateless
-            return {}; +  * ''​prev''​ the prev continuation, ​if the visualisation is undo-able it should return ​new prev continuation that calls this.
-        } +
-        ​function ​args() { +
-            return null; +
-        } +
-        ​function ​update(nx) { +
-            var element = document.getElementById("​container"​); +
-            var i = x.lookupInScope("​i"​);​ +
-            var j = x.lookupInScope("​j"​);​ +
-            var a = x.lookupInScope("​a"​);​ +
-            var xValue = x.lookupInScope("​x"​);​ +
-            ​if (i) { +
-               var arrayString = "​[";​ +
-               for (var k=0; k<a.length;k++) { +
-                   arrayString += i===k? "<​span style=\"​color:​red\">"​+a[k] +
-                     ​+"</​span>"​ : j===k? "<​span style=\"​color:​blue\">"​+a[k] +
-                     ​+"</​span>"​ : a[k]; +
-                   if (k < a.length-1) arrayString += ", "; +
-               } +
-               ​arrayString += "​]";​ +
-               ​element.innerHTML = "a = " + arrayString + "<​br>"​+"​i = "+i; +
-           } +
-        } +
-    </​script>​ +
-  </​head>​ +
-  <​body>​ +
-  <pre id="​container"></​pre>​ +
-  </​body>​ +
-</​html>​ +
-If the body tag has height style attribute ​that size is used to size the visualisation.+Two other functions are optional: ''​globals()''​ and ''​args()''​. ​If the visualisation contains ​global function ''​args()''​ then the return value of calling ​that function will be passed into the ''​run()''​ support function. This allows the visualisation to supply the input to the algorithm. If a ''​globals()''​ function ​is provided then it returns an object whose keys are added to the globals of the interpreter.
creating_an_algorithm.1351475950.txt.gz · Last modified: 2015/02/02 08:24 (external edit)