* Decodes a MessagePack value starting at the given offset. * Returns an object with the decoded value and the new offset.
(data, offset)
| 51 | * Returns an object with the decoded value and the new offset. |
| 52 | */ |
| 53 | function decodeMessagePack(data, offset) { |
| 54 | if (offset >= data.length) |
| 55 | return { value: null, offset: offset }; |
| 56 | |
| 57 | var byte = data[offset]; |
| 58 | offset++; |
| 59 | |
| 60 | // Positive fixint (0x00 - 0x7f) |
| 61 | if (byte <= 0x7f) |
| 62 | return { value: byte, offset: offset }; |
| 63 | |
| 64 | // Fixmap (0x80 - 0x8f) |
| 65 | if (byte >= 0x80 && byte <= 0x8f) { |
| 66 | var size = byte & 0x0f; |
| 67 | var map = {}; |
| 68 | for (var i = 0; i < size; i++) { |
| 69 | var keyResult = decodeMessagePack(data, offset); |
| 70 | offset = keyResult.offset; |
| 71 | var valueResult = decodeMessagePack(data, offset); |
| 72 | offset = valueResult.offset; |
| 73 | map[keyResult.value] = valueResult.value; |
| 74 | } |
| 75 | return { value: map, offset: offset }; |
| 76 | } |
| 77 | |
| 78 | // Fixarray (0x90 - 0x9f) |
| 79 | if (byte >= 0x90 && byte <= 0x9f) { |
| 80 | var size = byte & 0x0f; |
| 81 | var array = []; |
| 82 | for (var i = 0; i < size; i++) { |
| 83 | var result = decodeMessagePack(data, offset); |
| 84 | offset = result.offset; |
| 85 | array.push(result.value); |
| 86 | } |
| 87 | return { value: array, offset: offset }; |
| 88 | } |
| 89 | |
| 90 | // Fixstr (0xa0 - 0xbf) |
| 91 | if (byte >= 0xa0 && byte <= 0xbf) { |
| 92 | var length = byte & 0x1f; |
| 93 | var str = ""; |
| 94 | for (var i = 0; i < length && offset < data.length; i++) |
| 95 | str += String.fromCharCode(data[offset++]); |
| 96 | return { value: str, offset: offset }; |
| 97 | } |
| 98 | |
| 99 | // Negative fixint (0xe0 - 0xff) |
| 100 | if (byte >= 0xe0) |
| 101 | return { value: byte - 256, offset: offset }; |
| 102 | |
| 103 | // Other types |
| 104 | switch (byte) { |
| 105 | case 0xc0: |
| 106 | return { value: null, offset: offset }; |
| 107 | |
| 108 | case 0xc2: |
| 109 | return { value: false, offset: offset }; |
| 110 |