@substrate-system/bencode
Version:
Bencode de/encoder
8 lines (7 loc) • 8.17 kB
Source Map (JSON)
{
"version": 3,
"sources": ["../src/decode.ts"],
"sourcesContent": ["import { arr2text, text2arr, arr2hex } from '@substrate-system/uint8-util'\n\nconst INTEGER_START = 0x69 // 'i'\nconst STRING_DELIM = 0x3A // ':'\nconst DICTIONARY_START = 0x64 // 'd'\nconst LIST_START = 0x6C // 'l'\nconst END_OF_TYPE = 0x65 // 'e'\n\nexport type Decoded =\n | Record<string, any>\n | Array<any>\n | string\n | number;\n\nexport interface Decoder {\n (data:Uint8Array|string):Decoded|null\n (data:Uint8Array|string, encoding:string):Decoded|null\n (data:Uint8Array|string, start:number, encoding:string):Decoded|null\n (data:Uint8Array|string, start:number, end:number, encoding:string):Decoded|null\n data:Uint8Array|null;\n bytes:number;\n position:number;\n encoding:string|null;\n next:()=>Record<string, any>|Array<any>|Uint8Array|string|number|null;\n dictionary:()=>Record<string, any>|null;\n list:()=>any[];\n buffer:()=>Uint8Array|string;\n find:(ch:number)=>number|null;\n integer:()=>number;\n}\n\n/**\n * Decode bencoded data.\n *\n * @param {Uint8Array|string} data The buffer to decode\n * @param {number} [start] Optional start index\n * @param {number} [end] Optional end index\n * @param {string} [encoding] Optional encoding type (utf8, etc)\n * @return {Decoded}\n */\nconst decode:Decoder = function decode (\n data:Uint8Array|string,\n start?:number|string,\n end?:number|string,\n encoding?:string\n):Decoded|null {\n if (!data || data.length === 0) {\n throw new Error('Missing data to decode.')\n }\n\n if (typeof start !== 'number' && encoding == null) {\n encoding = start\n start = undefined\n }\n\n if (typeof end !== 'number' && encoding == null) {\n encoding = end\n end = undefined\n }\n\n decode.position = 0\n decode.encoding = encoding || null\n\n decode.data = !(ArrayBuffer.isView(data)) ?\n text2arr(data) :\n new Uint8Array(data.slice(\n start as number|undefined,\n end as number|undefined)\n )\n\n decode.bytes = decode.data.length\n\n return decode.next()\n}\n\ndecode.bytes = 0\ndecode.position = 0\ndecode.data = null\ndecode.encoding = null\n\ndecode.next = function ():Record<string, any>|Array<any>|Uint8Array|string|number|null {\n switch (decode.data![decode.position]) {\n case DICTIONARY_START:\n return decode.dictionary()\n case LIST_START:\n return decode.list()\n case INTEGER_START:\n return decode.integer()\n default:\n return decode.buffer()\n }\n}\n\ndecode.find = function (chr:number):number|null {\n if (!decode.data?.length) return null\n let i = decode.position\n const c = decode.data.length\n const d = decode.data\n\n while (i < c) {\n if (d[i] === chr) return i\n i++\n }\n\n throw new Error(\n 'Invalid data: Missing delimiter \"' +\n String.fromCharCode(chr) + '\" [0x' +\n chr.toString(16) + ']'\n )\n}\n\ndecode.dictionary = function ():Record<string, any>|null {\n if (!decode.data) return null\n decode.position++\n\n const dict = {}\n\n while (decode.data[decode.position] !== END_OF_TYPE) {\n const buffer = decode.buffer()\n if (typeof buffer === 'string') {\n dict[buffer] = decode.next()\n continue\n }\n let key = arr2text(buffer)\n if (key.includes('\\uFFFD')) key = arr2hex(buffer)\n dict[key] = decode.next()\n }\n\n decode.position++\n\n return dict\n}\n\ndecode.list = function ():any[] {\n decode.position++\n\n const lst:any[] = []\n\n while (decode.data![decode.position] !== END_OF_TYPE) {\n lst.push(decode.next())\n }\n\n decode.position++\n\n return lst\n}\n\ndecode.integer = function () {\n const end = decode.find(END_OF_TYPE)\n const number = getIntFromBuffer(decode.data, decode.position + 1, end)\n if (!end) throw new Error('not end')\n\n decode.position += end + 1 - decode.position\n\n return number\n}\n\ndecode.buffer = function ():Uint8Array|string {\n const sep = decode.find(STRING_DELIM)\n const newIndex = (sep || 0) + 1\n const length = getIntFromBuffer(decode.data, decode.position, sep)\n const end = newIndex + length\n\n decode.position = end\n\n return decode.encoding ?\n arr2text(decode.data!.slice(newIndex, end)) :\n decode.data!.slice(newIndex, end)\n}\n\nexport default decode\n\n/**\n * replaces parseInt(buffer.toString('ascii', start, end)).\n * For strings with less then ~30 charachters, this is actually a lot faster.\n *\n * @param {Uint8Array} data\n * @param {Number} start\n * @param {Number} end\n * @return {Number} calculated number\n */\nfunction getIntFromBuffer (buffer, start, end) {\n let sum = 0\n let sign = 1\n\n for (let i = start; i < end; i++) {\n const num = buffer[i]\n\n if (num < 58 && num >= 48) {\n sum = sum * 10 + (num - 48)\n continue\n }\n\n if (i === start && num === 43) { // +\n continue\n }\n\n if (i === start && num === 45) { // -\n sign = -1\n continue\n }\n\n if (num === 46) { // .\n // its a float. break here.\n break\n }\n\n throw new Error('not a number: buffer[' + i + '] = ' + num)\n }\n\n return sum * sign\n}\n"],
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"names": ["decode"]
}