root / trunk / web / dojo / dojox / encoding / compression / splay.js
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1 | 9 | andrej.cim | /*
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2 | Copyright (c) 2004-2010, The Dojo Foundation All Rights Reserved.
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3 | Available via Academic Free License >= 2.1 OR the modified BSD license.
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4 | see: http://dojotoolkit.org/license for details
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5 | */
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6 | |||
7 | |||
8 | if(!dojo._hasResource["dojox.encoding.compression.splay"]){ |
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9 | dojo._hasResource["dojox.encoding.compression.splay"]=true; |
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10 | dojo.provide("dojox.encoding.compression.splay");
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11 | dojo.require("dojox.encoding.bits");
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12 | dojox.encoding.compression.Splay=function(n){ |
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13 | this.up=new Array(2*n+1); |
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14 | this.left=new Array(n); |
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15 | this.right=new Array(n); |
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16 | this.reset();
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17 | }; |
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18 | dojo.extend(dojox.encoding.compression.Splay,{reset:function(){ |
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19 | for(var i=1;i<this.up.length;this.up[i]=Math.floor((i-1)/2),++i){ |
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20 | } |
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21 | for(var i=0;i<this.left.length;this.left[i]=2*i+1,this.right[i]=2*i+2,++i){ |
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22 | } |
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23 | },splay:function(i){ |
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24 | var a=i+this.left.length; |
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25 | do{
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26 | var c=this.up[a]; |
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27 | if(c){
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28 | var d=this.up[c]; |
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29 | var b=this.left[d]; |
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30 | if(c==b){
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31 | b=this.right[d];
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32 | this.right[d]=a;
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33 | }else{
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34 | this.left[d]=a;
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35 | } |
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36 | this[a==this.left[c]?"left":"right"][c]=b; |
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37 | this.up[a]=d;
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38 | this.up[b]=c;
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39 | a=d; |
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40 | }else{
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41 | a=c; |
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42 | } |
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43 | }while(a);
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44 | },encode:function(_1,_2){ |
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45 | var s=[],a=_1+this.left.length; |
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46 | do{
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47 | s.push(this.right[this.up[a]]==a); |
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48 | a=this.up[a];
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49 | }while(a);
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50 | this.splay(_1);
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51 | var l=s.length;
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52 | while(s.length){
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53 | _2.putBits(s.pop()?1:0,1); |
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54 | } |
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55 | return l;
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56 | },decode:function(_3){ |
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57 | var a=0; |
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58 | do{
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59 | a=this[_3.getBits(1)?"right":"left"][a]; |
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60 | }while(a<this.left.length); |
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61 | a-=this.left.length;
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62 | this.splay(a);
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63 | return a;
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64 | }}); |
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65 | } |