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creating_an_algorithm [2012/09/30 18:04]
creating_an_algorithm [2015/02/02 08:28] (current)
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-====== Including an algorithm in a page ====== +====== Creating algorithms ====== 
-An algorithm is stored in a single page in the Algorithm namespace. Different variants ​require ​different pages. For +===== Including an algorithm in a page ===== 
 +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: +An algorithm page is split into five sections: ​Source, ​Support, Unit Tests, Options, and Visualisation. Each section is editable in a tabbed ​code editor at the bottom of the algorithm page.
-<​code>​ +
-====== Algorithm ====== +
-====== ​Support ​====== +
-====== ​Visualisation ​====== +
-Each of these sections contains code wrapped in %%<​syntax>​%% tags.+{{ :​editor-tabs.png?nolink |}}
-===== 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);
 } }
 +==== Unit Tests ==== 
 +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. 
 +==== Options ==== 
 +The 4rd section contains options in JSON format. Available options are 
 +  * ''​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 code. This code is a self contained webpage, it is embedded in an iframe when displayed alongside the code. 
 +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,  
 +  * ''​n''​ the current node in the AST (This should be used very rarely) 
 +  * ''​x''​ the execution context. 
 +  * ''​isRunning''​ is the debugger in the middle of running code? 
 +  * ''​duration''​ if the visualisation animates, how long it should take. If ''​duration''​ is below 0 then visualising can be skipped if the update function is stateless. 
 +  * ''​prev''​ the prev continuation,​ if the visualisation is undo-able it should return a new prev continuation that calls this.
-===== 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 functionThis allows the visualisation to supply the input to the algorithmIf ''​globals()''​ function is provided then it returns an object whose keys are added to the globals of the interpreter.
-The 3rd section contains ​the visualisation ​code. This is complete webpage that contains an update() function, which is called for every new line when running ​the algorithm. The update ​function ​takes two arguments, ​the current node in the AST and an execution context. +
-<syntax html> +
-<​html>​ +
-  <​head>​ +
-    <script type="​text/​javascript">​ +
-        function update(n, x+
-            var element = document.getElementById("​container"​);​ +
-            var i = x.lookupInScope("​i"​);​ +
-            var j = x.lookupInScope("​j"​);​ +
-            var = 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>​ +
creating_an_algorithm.1349053477.txt.gz · Last modified: 2015/02/02 08:24 (external edit)