basant307/AI_Governance_Project

1/**2 * @preserve3 * JS Implementation of incremental MurmurHash3 (r150) (as of May 10, 2013)4 *5 * @author <a href="mailto:jensyt@gmail.com">Jens Taylor</a>6 * @see http://github.com/homebrewing/brauhaus-diff7 * @author <a href="mailto:gary.court@gmail.com">Gary Court</a>8 * @see http://github.com/garycourt/murmurhash-js9 * @author <a href="mailto:aappleby@gmail.com">Austin Appleby</a>10 * @see http://sites.google.com/site/murmurhash/11 */12(function(){13    var cache;14 15    // Call this function without `new` to use the cached object (good for16    // single-threaded environments), or with `new` to create a new object.17    //18    // @param {string} key A UTF-16 or ASCII string19    // @param {number} seed An optional positive integer20    // @return {object} A MurmurHash3 object for incremental hashing21    function MurmurHash3(key, seed) {22        var m = this instanceof MurmurHash3 ? this : cache;23        m.reset(seed)24        if (typeof key === 'string' && key.length > 0) {25            m.hash(key);26        }27 28        if (m !== this) {29            return m;30        }31    };32 33    // Incrementally add a string to this hash34    //35    // @param {string} key A UTF-16 or ASCII string36    // @return {object} this37    MurmurHash3.prototype.hash = function(key) {38        var h1, k1, i, top, len;39 40        len = key.length;41        this.len += len;42 43        k1 = this.k1;44        i = 0;45        switch (this.rem) {46            case 0: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) : 0;47            case 1: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) << 8 : 0;48            case 2: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) << 16 : 0;49            case 3:50                k1 ^= len > i ? (key.charCodeAt(i) & 0xff) << 24 : 0;51                k1 ^= len > i ? (key.charCodeAt(i++) & 0xff00) >> 8 : 0;52        }53 54        this.rem = (len + this.rem) & 3; // & 3 is same as % 455        len -= this.rem;56        if (len > 0) {57            h1 = this.h1;58            while (1) {59                k1 = (k1 * 0x2d51 + (k1 & 0xffff) * 0xcc9e0000) & 0xffffffff;60                k1 = (k1 << 15) | (k1 >>> 17);61                k1 = (k1 * 0x3593 + (k1 & 0xffff) * 0x1b870000) & 0xffffffff;62 63                h1 ^= k1;64                h1 = (h1 << 13) | (h1 >>> 19);65                h1 = (h1 * 5 + 0xe6546b64) & 0xffffffff;66 67                if (i >= len) {68                    break;69                }70 71                k1 = ((key.charCodeAt(i++) & 0xffff)) ^72                     ((key.charCodeAt(i++) & 0xffff) << 8) ^73                     ((key.charCodeAt(i++) & 0xffff) << 16);74                top = key.charCodeAt(i++);75                k1 ^= ((top & 0xff) << 24) ^76                      ((top & 0xff00) >> 8);77            }78 79            k1 = 0;80            switch (this.rem) {81                case 3: k1 ^= (key.charCodeAt(i + 2) & 0xffff) << 16;82                case 2: k1 ^= (key.charCodeAt(i + 1) & 0xffff) << 8;83                case 1: k1 ^= (key.charCodeAt(i) & 0xffff);84            }85 86            this.h1 = h1;87        }88 89        this.k1 = k1;90        return this;91    };92 93    // Get the result of this hash94    //95    // @return {number} The 32-bit hash96    MurmurHash3.prototype.result = function() {97        var k1, h1;98        99        k1 = this.k1;100        h1 = this.h1;101 102        if (k1 > 0) {103            k1 = (k1 * 0x2d51 + (k1 & 0xffff) * 0xcc9e0000) & 0xffffffff;104            k1 = (k1 << 15) | (k1 >>> 17);105            k1 = (k1 * 0x3593 + (k1 & 0xffff) * 0x1b870000) & 0xffffffff;106            h1 ^= k1;107        }108 109        h1 ^= this.len;110 111        h1 ^= h1 >>> 16;112        h1 = (h1 * 0xca6b + (h1 & 0xffff) * 0x85eb0000) & 0xffffffff;113        h1 ^= h1 >>> 13;114        h1 = (h1 * 0xae35 + (h1 & 0xffff) * 0xc2b20000) & 0xffffffff;115        h1 ^= h1 >>> 16;116 117        return h1 >>> 0;118    };119 120    // Reset the hash object for reuse121    //122    // @param {number} seed An optional positive integer123    MurmurHash3.prototype.reset = function(seed) {124        this.h1 = typeof seed === 'number' ? seed : 0;125        this.rem = this.k1 = this.len = 0;126        return this;127    };128 129    // A cached object to use. This can be safely used if you're in a single-130    // threaded environment, otherwise you need to create new hashes to use.131    cache = new MurmurHash3();132 133    if (typeof(module) != 'undefined') {134        module.exports = MurmurHash3;135    } else {136        this.MurmurHash3 = MurmurHash3;137    }138}());139