'use strict';
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function pad (hash, len) {
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while (hash.length < len) {
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hash = '0' + hash;
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}
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return hash;
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}
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function fold (hash, text) {
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var i;
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var chr;
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var len;
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if (text.length === 0) {
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return hash;
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}
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for (i = 0, len = text.length; i < len; i++) {
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chr = text.charCodeAt(i);
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hash = ((hash << 5) - hash) + chr;
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hash |= 0;
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}
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return hash < 0 ? hash * -2 : hash;
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}
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function foldObject (hash, o, seen) {
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return Object.keys(o).sort().reduce(foldKey, hash);
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function foldKey (hash, key) {
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return foldValue(hash, o[key], key, seen);
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}
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}
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function foldValue (input, value, key, seen) {
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var hash = fold(fold(fold(input, key), toString(value)), typeof value);
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if (value === null) {
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return fold(hash, 'null');
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}
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if (value === undefined) {
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return fold(hash, 'undefined');
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}
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if (typeof value === 'object' || typeof value === 'function') {
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if (seen.indexOf(value) !== -1) {
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return fold(hash, '[Circular]' + key);
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}
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seen.push(value);
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var objHash = foldObject(hash, value, seen)
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if (!('valueOf' in value) || typeof value.valueOf !== 'function') {
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return objHash;
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}
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try {
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return fold(objHash, String(value.valueOf()))
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} catch (err) {
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return fold(objHash, '[valueOf exception]' + (err.stack || err.message))
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}
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}
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return fold(hash, value.toString());
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}
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function toString (o) {
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return Object.prototype.toString.call(o);
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}
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function sum (o) {
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return pad(foldValue(0, o, '', []).toString(16), 8);
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}
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module.exports = sum;
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