rewrote prototype inhertence

pdf.js

@@ -345,8 +345,9 @@ var FlateStream = (function() {
         DecodeStream.call(this);
     }
 
-    constructor.prototype = {
-        getBits: function(bits) {
+    constructor.prototype = Object.create(DecodeStream.prototype);
+
+    constructor.prototype.getBits = function(bits) {
         var codeSize = this.codeSize;
         var codeBuf = this.codeBuf;
         var bytes = this.bytes;
@@ -364,8 +365,8 @@ var FlateStream = (function() {
         this.codeSize = codeSize -= bits;
         this.bytesPos = bytesPos;
         return b;
-        },
-        getCode: function(table) {
+    };
+    constructor.prototype.getCode = function(table) {
         var codes = table[0];
         var maxLen = table[1];
         var codeSize = this.codeSize;
@@ -389,8 +390,8 @@ var FlateStream = (function() {
             this.codeSize = (codeSize - codeLen);
             this.bytesPos = bytesPos;
             return codeVal;
-        },
-        generateHuffmanTable: function(lengths) {
+    };
+    constructor.prototype.generateHuffmanTable = function(lengths) {
         var n = lengths.length;
 
         // find max code length
@@ -426,8 +427,8 @@ var FlateStream = (function() {
         }
 
         return [codes, maxLen];
-        },
-        readBlock: function() {
+    };
+    constructor.prototype.readBlock = function() {
         function repeat(stream, array, len, offset, what) {
             var repeat = stream.getBits(len) + offset;
             while (repeat-- > 0)
@@ -507,10 +508,10 @@ var FlateStream = (function() {
                 }
             }
 
-                litCodeTable = this.generateHuffmanTable(
-                        codeLengths.slice(0, numLitCodes));
-                distCodeTable = this.generateHuffmanTable(
-                        codeLengths.slice(numLitCodes, codes));
+            litCodeTable =
+                this.generateHuffmanTable(codeLengths.slice(0, numLitCodes));
+            distCodeTable =
+                this.generateHuffmanTable(codeLengths.slice(numLitCodes, codes));
         } else {
             error("Unknown block type in flate stream");
         }
@@ -543,16 +544,8 @@ var FlateStream = (function() {
                     buffer[pos] = buffer[pos - dist];
             }
         }
-        }
     };
 
-    var thisPrototype = constructor.prototype;
-    var superPrototype = DecodeStream.prototype;
-    for (var i in superPrototype) {
-        if (!thisPrototype[i])
-            thisPrototype[i] = superPrototype[i];
-    }
-
     return constructor;
 })();
 
@@ -586,8 +579,9 @@ var PredictorStream = (function() {
         DecodeStream.call(this);
     }
 
-    constructor.prototype = {
-        readBlockTiff : function() {
+    constructor.prototype = Object.create(DecodeStream.prototype);
+
+    constructor.prototype.readBlockTiff = function() {
         var buffer = this.buffer;
         var pos = this.pos;
 
@@ -651,8 +645,8 @@ var PredictorStream = (function() {
             }
         }
         this.bufferLength += rowBytes;
-        },
-        readBlockPng : function() {
+    };
+    constructor.prototype.readBlockPng = function() {
         var buffer = this.buffer;
         var pos = this.pos;
 
@@ -726,16 +720,8 @@ var PredictorStream = (function() {
             break;
         }
         this.bufferLength += rowBytes;
-        },
     };
 
-    var thisPrototype = constructor.prototype;
-    var superPrototype = DecodeStream.prototype;
-    for (var i in superPrototype) {
-        if (!thisPrototype[i])
-            thisPrototype[i] = superPrototype[i];
-    }
-
     return constructor;
 })();