79 lines
2.4 KiB
JavaScript
79 lines
2.4 KiB
JavaScript
// Copyright (c) Vitaliy Filippov, 2019+
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// License: MIT
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function stableStringify(obj, opts)
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{
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if (!opts)
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opts = {};
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if (typeof opts === 'function')
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opts = { cmp: opts };
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let space = opts.space || '';
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if (typeof space === 'number')
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space = Array(space+1).join(' ');
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const cycles = (typeof opts.cycles === 'boolean') ? opts.cycles : false;
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const cmp = opts.cmp && (function (f)
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{
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return function (node)
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{
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return function (a, b)
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{
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let aobj = { key: a, value: node[a] };
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let bobj = { key: b, value: node[b] };
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return f(aobj, bobj);
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};
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};
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})(opts.cmp);
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const seen = new Map();
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return (function stringify (parent, key, node, level)
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{
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const indent = space ? ('\n' + new Array(level + 1).join(space)) : '';
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const colonSeparator = space ? ': ' : ':';
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if (node === undefined)
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{
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return;
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}
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if (typeof node !== 'object' || node === null)
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{
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return JSON.stringify(node);
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}
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if (node instanceof Array)
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{
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const out = [];
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for (let i = 0; i < node.length; i++)
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{
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const item = stringify(node, i, node[i], level+1) || JSON.stringify(null);
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out.push(indent + space + item);
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}
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return '[' + out.join(',') + indent + ']';
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}
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else
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{
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if (seen.has(node))
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{
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if (cycles)
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return JSON.stringify('__cycle__');
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throw new TypeError('Converting circular structure to JSON');
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}
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else
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seen.set(node, true);
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const keys = Object.keys(node).sort(cmp && cmp(node));
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const out = [];
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for (let i = 0; i < keys.length; i++)
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{
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const key = keys[i];
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const value = stringify(node, key, node[key], level+1);
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if (!value)
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continue;
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const keyValue = JSON.stringify(key)
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+ colonSeparator
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+ value;
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out.push(indent + space + keyValue);
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}
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seen.delete(node);
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return '{' + out.join(',') + indent + '}';
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}
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})({ '': obj }, '', obj, 0);
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}
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module.exports = stableStringify;
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