js实现的哈夫曼编码

修改版

function Huffman(str) {    // 需要编码的字符串    this.str = str;    // 键和频率映射表    this.keyCountMap = null;    // 编码和键的映射表    this.codeKeyMap = {};    // 键和编码的映射表    this.keyCodeMap = {};       // 哈夫曼树节点列表    this.nodeList = null;    // 哈夫曼树根节点    this.root = null;    // 哈夫曼编码后的01序列    this.code = null;}Huffman.prototype.cal =  function cal() {    str = this.str;    var map = {};    var i = 0;    while(str[i]) {        map[str[i]] ? map[str[i]]++ : (map[str[i]] = 1);        i++;    }    this.keyCountMap = map;}Huffman.prototype.sort = function sort() {    map = this.keyCountMap;    var result = [];    for (key in map) {        if(map.hasOwnProperty(key)) {            var obj = {                key: key,                val: map[key]            };            result.push(new Node(null, null, obj));        }    }    this.nodeList = result.sort(function(x,y){return x.data.val > y.data.val});}function Node(left, right, data) {    this.left = left;    this.right = right;    this.data = data;}Huffman.prototype.makeTree = function makeTree() {    var i = 0;    var len = this.nodeList.length;    var node1;    var node2;    var parentNode;    var table = this.nodeList;    while(table.length > 1) {        parentNode = new Node(table[i], table[i+1], {key: null, val: table[i]['data'].val + table[i+1]['data'].val});        table.splice(i,2);        table.unshift(parentNode);        table.sort(function(x,y){return x.data.val > y.data.val});    }    this.root = table[0] || new Node();    return this.root;}Huffman.prototype.traversal = function traversal(tree, code) {    if (tree.left !== null) {        traversal.call(this,tree.left, code + '0');    } else {        this.keyCodeMap[tree.data.key] = code;    }    if (tree.right !== null) {        traversal.call(this, tree.right,code + '1');    } else {        this.keyCodeMap[tree.data.key] = code;    }}Huffman.prototype.encode = function encode() {    this.cal();    this.sort();    var root = this.makeTree();    this.traversal(root, '');    var ret = this.keyCodeMap;    var i = 0;    var result = '';    var str = this.str;    while(str[i]) {        result += ret[str[i++]];    }    this.code = result;    console.log('encode:' + result);    return result}Huffman.prototype.reverseMap = function reverseMap() {    var ret = this.keyCodeMap;    var result = {};    for (key in ret) {        if(ret.hasOwnProperty(key)) {            result[ret[key]] = key;        }    }    this.codeKeyMap = result;    return result;}Huffman.prototype.decode = function decode() {    var i = 0;    var result = '';    var data = '';      var map = this.reverseMap();        var str = this.code;    while(str) {        result += str[i++];        if (result in map) {            data += map[result];            str = str.replace(new RegExp("^"+result),'');            result = '';            i = 0;        }    }    console.log("decode:" + data)}Huffman.prototype.encodeBase64 = function() {    try {        var base64 = btoa(this.code);        return base64;    } catch(e) {        return '';    }}var str = 'ew qew qd ef 24 gf ewr getElementsByTagName';var huffman = new Huffman(str)huffman.encode(str)huffman.decode();huffman.encodeBase64();

原始版

function cal(str) {    if (typeof str !== 'string' || str.length < 1) {        return;    }    var map = {};    var i = 0;    while(str[i]) {        map[str[i]] ? map[str[i]]++ : (map[str[i]] = 1);        i++;    }    return map;}function sort(map) {    map = map || {};    var result = [];    for (key in map) {        if(map.hasOwnProperty(key)) {            var obj = {                key: key,                val: map[key]            };            result.push(new Node(null, null, obj));        }    }    return result.sort(function(x,y){return x.data.val > y.data.val});}function Node(left, right, data) {    this.left = left;    this.right = right;    this.data = data;}function makeTree(table) {    var i = 0;    var len = table.length;    var node1;    var node2;    var parentNode;    while(table.length > 1) {        parentNode = new Node(table[i], table[i+1], {key: null, val: table[i]['data'].val + table[i+1]['data'].val});        table.splice(i,2);        table.unshift(parentNode);        table.sort(function(x,y){return x.data.val > y.data.val});    }    return table;}function encode(str, ret) {    if (typeof str !== 'string' || str.length < 1) {        return;    }    var i = 0;    var result = '';    while(str[i]) {        result += ret[str[i++]];    }    return result}function reverseRet(ret) {    var result = {};    for (key in ret) {        if(ret.hasOwnProperty(key)) {            result[ret[key]] = key;        }    }    return result;}function decode(str, ret) {    var i = 0;    var result = '';    var data = '';    var map = reverseRet(ret);    while(str) {        result += str[i++];        if (result in map) {            data += map[result];            str = str.replace(new RegExp("^"+result),'');            result = '';            i = 0;        }    }    console.log(data)}function traversal(tree, code, ret) {    if (tree.left !== null) {        traversal(tree.left, code + '0', ret);    } else {        ret[tree.data.key] = code;    }    if (tree.right !== null) {        traversal(tree.right,code + '1', ret);    } else {        ret[tree.data.key] = code;    }}var ret = {};var str = 'ew qew qd ef 24 gf ewr getElementsByTagName';traversal(makeTree(sort(cal(str)))[0],'', ret)decode(encode(str, ret), ret)btoa(encode(str,ret))