some bug fixes for demo site and renaming of priority queue stuff and…

… addition docs

HuffmanCoding/Demo.html

@@ -179,12 +179,17 @@ <h2>Efficiency:</h2>
           currNode = currNode.left;
         } else if (currBit === "1") {
           currNode = currNode.right;
+        } else {
+          throw new Error("String to decode must consist of only 0s and 1s.");
         }
         if (currNode.val.length === 1) {
           output += currNode.val[0];
           currNode = huffman;
         }
       }
+      if (currNode !== huffman) {
+        throw new Error("String cannot be decoded - make sure you aren't missing any bits!");
+      }
       return output;
     };
 
@@ -230,7 +235,7 @@ <h2>Efficiency:</h2>
       var pairs = Object
         .keys(dictionary)
         .sort(function(a, b) {
-          return dictionary[a].length - dictionary[b].length;
+          return a < b ? -1 : 1;
         })
         .forEach(function(key) {
           var li = $("<li></li>");
@@ -250,11 +255,16 @@ <h2>Efficiency:</h2>
     };
 
     var triggerEncode = function() {
+      $("textarea.decode").val('');
       if (!huffman) {
         $(".error").text("Please enter a corpus and create an encoding scheme first.")
         return;
       };
       var input = $('textarea.encode').val();
+      if (!input) {
+        $(".error").text("Please enter some text to encode.")
+        return;
+      }
       var output;
       try {
         output = encodeString(input, huffman);
@@ -274,11 +284,16 @@ <h2>Efficiency:</h2>
 
     var triggerDecode = function() {
       $(".efficiency").hide();
+      $("textarea.encode").val('');
       if (!huffman) {
         $(".error").text("Please enter a corpus and create an encoding scheme first.")
         return;
       };
       var input = $('textarea.decode').val();
+      if (!input) {
+        $(".error").text("Please enter some text to decode.")
+        return;
+      }
       var output;
       try {
         output = decodeString(input, huffman);

HuffmanCoding/src/huffman.js

@@ -12,8 +12,15 @@ var decodeString = function(input, huffmanTree) {
 
 // Given a corpus of text, return a Huffman tree that represents the
 // frequencies of characters in the corpus.
-// You may use the `Tree` class that is provided in the file `misc.js`
-// A sample corpus is also included as the variable `lorumIpsum`.
+//
+// You should use the `PriorityQueue` class that is provided in the
+// file `priorityQueue.js`.  The relevant methods are .insert(key, val),
+// which inserts a value with the given key into the queue, and
+// .extract(), which returns the {key: key, val: val} pair with the lowest
+// key priority.
+//
+// You may also use the `Tree` class that is provided in the file `misc.js`
+// Some corpuses are included as the variables `lorumIpsum` and `declaration`.
 var makeHuffmanTree = function(corpus) {
   return new Tree();
 };

HuffmanCoding/src/priorityQueue.js

@@ -50,7 +50,6 @@ PriorityQueue.prototype.insert = function(key, val) {
     var working = parent !== undefined;
 
     while (working && current > 0) {
-        console.log(this._key(parent), this._key(current));
         if (this._key(parent) > this._key(current)) {
             this._swap(current, parent);
             current = parent;