|
| 1 | +const COMMA = ','; |
| 2 | +const COLON = ':'; |
| 3 | +const LEFT_SQUARE_BRACKET = '['; |
| 4 | +const RIGHT_SQUARE_BRACKET = ']'; |
| 5 | +const LEFT_CURLY_BRACKET = '{'; |
| 6 | +const RIGHT_CURLY_BRACKET = '}'; |
| 7 | + |
| 8 | +// Recursively encodes the supplied object according to the canonical JSON form |
| 9 | +// as specified at http://wiki.laptop.org/go/Canonical_JSON. It's a restricted |
| 10 | +// dialect of JSON in which keys are lexically sorted, floats are not allowed, |
| 11 | +// and only double quotes and backslashes are escaped. |
| 12 | +function canonicalize(object) { |
| 13 | + const buffer = []; |
| 14 | + if (typeof object === 'string') { |
| 15 | + buffer.push(canonicalizeString(object)); |
| 16 | + } else if (typeof object === 'boolean') { |
| 17 | + buffer.push(JSON.stringify(object)); |
| 18 | + } else if (Number.isInteger(object)) { |
| 19 | + buffer.push(JSON.stringify(object)); |
| 20 | + } else if (object === null) { |
| 21 | + buffer.push(JSON.stringify(object)); |
| 22 | + } else if (Array.isArray(object)) { |
| 23 | + buffer.push(LEFT_SQUARE_BRACKET); |
| 24 | + let first = true; |
| 25 | + object.forEach((element) => { |
| 26 | + if (!first) { |
| 27 | + buffer.push(COMMA); |
| 28 | + } |
| 29 | + first = false; |
| 30 | + buffer.push(canonicalize(element)); |
| 31 | + }); |
| 32 | + buffer.push(RIGHT_SQUARE_BRACKET); |
| 33 | + } else if (typeof object === 'object') { |
| 34 | + buffer.push(LEFT_CURLY_BRACKET); |
| 35 | + let first = true; |
| 36 | + Object.keys(object) |
| 37 | + .sort() |
| 38 | + .forEach((property) => { |
| 39 | + if (!first) { |
| 40 | + buffer.push(COMMA); |
| 41 | + } |
| 42 | + first = false; |
| 43 | + buffer.push(canonicalizeString(property)); |
| 44 | + buffer.push(COLON); |
| 45 | + buffer.push(canonicalize(object[property])); |
| 46 | + }); |
| 47 | + buffer.push(RIGHT_CURLY_BRACKET); |
| 48 | + } else { |
| 49 | + throw new TypeError('cannot encode ' + object.toString()); |
| 50 | + } |
| 51 | + |
| 52 | + return buffer.join(''); |
| 53 | +} |
| 54 | + |
| 55 | +// String canonicalization consists of escaping backslash (\) and double |
| 56 | +// quote (") characters and wrapping the resulting string in double quotes. |
| 57 | +function canonicalizeString(string) { |
| 58 | + const escapedString = string.replace(/\\/g, '\\\\').replace(/"/g, '\\"'); |
| 59 | + return '"' + escapedString + '"'; |
| 60 | +} |
| 61 | + |
| 62 | +module.exports = { |
| 63 | + canonicalize, |
| 64 | +}; |
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