65 lines
2 KiB
JavaScript
65 lines
2 KiB
JavaScript
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const COMMA = ',';
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const COLON = ':';
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const LEFT_SQUARE_BRACKET = '[';
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const RIGHT_SQUARE_BRACKET = ']';
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const LEFT_CURLY_BRACKET = '{';
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const RIGHT_CURLY_BRACKET = '}';
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// Recursively encodes the supplied object according to the canonical JSON form
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// as specified at http://wiki.laptop.org/go/Canonical_JSON. It's a restricted
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// dialect of JSON in which keys are lexically sorted, floats are not allowed,
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// and only double quotes and backslashes are escaped.
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function canonicalize(object) {
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const buffer = [];
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if (typeof object === 'string') {
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buffer.push(canonicalizeString(object));
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} else if (typeof object === 'boolean') {
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buffer.push(JSON.stringify(object));
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} else if (Number.isInteger(object)) {
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buffer.push(JSON.stringify(object));
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} else if (object === null) {
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buffer.push(JSON.stringify(object));
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} else if (Array.isArray(object)) {
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buffer.push(LEFT_SQUARE_BRACKET);
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let first = true;
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object.forEach((element) => {
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if (!first) {
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buffer.push(COMMA);
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}
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first = false;
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buffer.push(canonicalize(element));
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});
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buffer.push(RIGHT_SQUARE_BRACKET);
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} else if (typeof object === 'object') {
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buffer.push(LEFT_CURLY_BRACKET);
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let first = true;
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Object.keys(object)
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.sort()
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.forEach((property) => {
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if (!first) {
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buffer.push(COMMA);
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}
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first = false;
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buffer.push(canonicalizeString(property));
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buffer.push(COLON);
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buffer.push(canonicalize(object[property]));
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});
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buffer.push(RIGHT_CURLY_BRACKET);
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} else {
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throw new TypeError('cannot encode ' + object.toString());
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}
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return buffer.join('');
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}
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// String canonicalization consists of escaping backslash (\) and double
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// quote (") characters and wrapping the resulting string in double quotes.
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function canonicalizeString(string) {
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const escapedString = string.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
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return '"' + escapedString + '"';
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}
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module.exports = {
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canonicalize,
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};
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