444 lines
14 KiB
JavaScript
444 lines
14 KiB
JavaScript
export const Types = {
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BERT_START: 131,
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SMALL_ATOM: 115,
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ATOM: 100,
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BINARY: 109,
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SMALL_INTEGER: 97,
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INTEGER: 98,
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SMALL_BIG: 110,
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LARGE_BIG: 111,
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FLOAT: 99,
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STRING: 107,
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LIST: 108,
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SMALL_TUPLE: 104,
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LARGE_TUPLE: 105, // TODO: Implement.
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MAP: 116,
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NIL: 106,
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NEW_FLOAT: 70,
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ZERO: 0,
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};
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export const Lang = {
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ELIXIR: 0,
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ERLANG: 1,
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};
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export class Bert {
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allBinariesAsString;
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mapKeyAsAtom;
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decodeUndefinedValues;
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convention;
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outputBuffer;
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constructor(allBinariesAsString = false, mapKeyAsAtom = true, decodeUndefinedValues = true, convention = Lang.ELIXIR) {
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this.allBinariesAsString = allBinariesAsString;
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this.mapKeyAsAtom = mapKeyAsAtom;
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this.decodeUndefinedValues = decodeUndefinedValues;
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this.convention = convention;
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this.outputBuffer = Buffer.alloc(10000000);
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this.outputBuffer[0] = Types.BERT_START;
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}
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toAtom = toAtom;
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toTuple = toTuple;
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#encode = (obj, buffer) => this[`encode_${typeof obj}`](obj, buffer);
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encode = (obj, copy = true) => {
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const tailBuffer = this.#encode(obj, this.outputBuffer.subarray(1));
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process.stderr.write(`tailbuffer length: ${tailBuffer.length}\n`);
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if (tailBuffer.length === 0) {
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throw new Error("Bert encode a too big term, encoding buffer overflow");
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}
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else if (copy) {
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const ret = Buffer.alloc(tailBuffer.length + 1);
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this.outputBuffer.copy(ret, 0, 0, ret.length + 1);
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return ret;
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}
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else {
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return this.outputBuffer.subarray(0, tailBuffer.length + 1);
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}
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};
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#decode = (buffer) => {
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const t = buffer[0];
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buffer = buffer.subarray(1);
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switch (t) {
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case Types.SMALL_ATOM:
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return this.decode_atom(buffer, 1);
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case Types.ATOM:
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return this.decode_atom(buffer, 2);
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case Types.BINARY:
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return this.decode_binary(buffer);
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case Types.SMALL_INTEGER:
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return this.decode_integer(buffer, 1, true);
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case Types.INTEGER:
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return this.decode_integer(buffer, 4);
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case Types.SMALL_BIG:
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return this.decode_big(buffer, 1);
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case Types.LARGE_BIG:
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return this.decode_big(buffer, 4);
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case Types.FLOAT:
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return this.decode_float(buffer);
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case Types.NEW_FLOAT:
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return this.decode_new_float(buffer);
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case Types.STRING:
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return this.decode_string(buffer);
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case Types.LIST:
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return this.decode_list(buffer);
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case Types.SMALL_TUPLE:
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return this.decode_tuple(buffer, 1);
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// case Types.LARGE_TUPLE:
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// return this.decode_large_tuple(buffer, 4)
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case Types.NIL:
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return this.decode_nil(buffer);
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case Types.MAP:
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return this.decode_map(buffer);
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default:
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throw new Error(`Unexpected BERT type: ${t}`);
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}
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};
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decode = (buffer) => {
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if (buffer[0] !== Types.BERT_START) {
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throw new Error("Not a valid BERT");
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}
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const obj = this.#decode(buffer.subarray(1));
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if (obj.rest.length !== 0) {
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throw new Error("Invalid BERT");
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}
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return obj.value;
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};
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encode_string = (obj, buffer) => {
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if (this.convention === Lang.ELIXIR) {
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process.stderr.write(`encode string as elixir\n`);
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return this.encode_binary(Buffer.from(obj), buffer);
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}
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else {
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buffer[0] = Types.STRING;
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buffer.writeUInt16BE(Buffer.byteLength(obj, "utf-8"), 1);
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const len = buffer.write(obj, 3);
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return buffer.subarray(0, 3 + len);
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}
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};
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encode_boolean = (obj, buffer) => {
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if (obj) {
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return this.#encode(this.toAtom("true"), buffer);
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}
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else {
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return this.#encode(this.toAtom("false"), buffer);
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}
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};
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encode_number = (obj, buffer) => {
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const isInteger = obj % 1 === 0;
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// Handle floats...
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if (!isInteger) {
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return this.encode_float(obj, buffer);
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}
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// Small int...
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if (isInteger && obj >= 0 && obj < 256) {
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buffer[0] = Types.SMALL_INTEGER;
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buffer.writeUInt8(obj, 1);
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return buffer.subarray(0, 2);
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}
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// 4 byte int...
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if (isInteger && obj >= -134217728 && obj <= 134217727) {
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buffer[0] = Types.INTEGER;
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buffer.writeInt32BE(obj, 1);
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return buffer.subarray(0, 5);
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}
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// Bignum...
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const numBuffer = Buffer.alloc(buffer.length);
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if (obj < 0) {
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obj *= -1;
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numBuffer[0] = 1;
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}
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else {
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numBuffer[0] = 0;
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}
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let offset = 1;
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while (obj !== 0) {
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numBuffer[offset] = obj % 256;
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obj = Math.floor(obj / 256);
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offset++;
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}
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if (offset < 256) {
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buffer[0] = Types.SMALL_BIG;
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buffer.writeUInt8(offset - 1, 1);
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numBuffer.copy(buffer, 2, 0, offset);
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return buffer.subarray(0, 2 + offset);
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}
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else {
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buffer[0] = Types.LARGE_BIG;
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buffer.writeUInt32BE(offset - 1, 1);
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numBuffer.copy(buffer, 5, 0, offset);
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return buffer.subarray(0, 5 + offset);
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}
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};
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encode_float = (obj, buffer) => {
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// float...
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buffer[0] = Types.NEW_FLOAT;
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buffer.writeDoubleBE(obj, 1);
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return buffer.subarray(0, 9);
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};
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encode_object = (obj, buffer) => {
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// Check if it's an atom, binary, or tuple...
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if (obj === null) {
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const undefinedAtom = this.convention === Lang.ELIXIR ? "nil" : "undefined";
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return this.#encode(this.toAtom(undefinedAtom), buffer);
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}
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if (Buffer.isBuffer(obj)) {
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return this.encode_binary(obj, buffer);
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}
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if (Array.isArray(obj)) {
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return this.encode_array(obj, buffer);
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}
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if (obj.type === "Atom") {
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return this.encode_atom(obj, buffer);
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}
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if (obj.type === "Tuple") {
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return this.encode_tuple(obj, buffer);
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}
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// Treat the object as an associative array...
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return this.encode_map(obj, buffer);
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};
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encode_atom = (obj, buffer) => {
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buffer[0] = Types.ATOM;
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buffer.writeUInt16BE(obj.value.length, 1);
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const len = buffer.write(obj.value, 3);
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return buffer.subarray(0, 3 + len);
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};
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encode_binary = (obj, buffer) => {
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process.stderr.write(`encode binary\n`);
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buffer[0] = Types.BINARY;
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buffer.writeUInt32BE(obj.length, 1);
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const len = obj.copy(buffer, 5);
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return buffer.subarray(0, 5 + len);
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};
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encode_undefined = (_obj, buffer) => {
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return this.#encode(null, buffer);
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};
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encode_tuple = (obj, buffer) => {
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if (obj.length < 256) {
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buffer[0] = Types.SMALL_TUPLE;
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buffer.writeUInt8(obj.length, 1);
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buffer = buffer.subarray(0, 2);
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}
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else {
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buffer[0] = Types.LARGE_TUPLE;
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buffer.writeUInt32BE(obj.length, 1);
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buffer = buffer.subarray(0, 5);
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}
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for (let i = 0; i < obj.length; ++i) {
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buffer = this.#encode(obj[i], buffer);
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}
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return buffer;
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};
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encode_array = (obj, buffer) => {
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if (obj.length === 0) {
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buffer[0] = Types.NIL;
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return buffer.subarray(0, 1);
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}
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buffer[0] = Types.LIST;
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buffer.writeUInt32BE(obj.length, 1);
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buffer = buffer.subarray(0, 5);
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for (let i = 0; i < obj.length; ++i) {
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buffer = this.#encode(obj[i], buffer);
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}
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buffer[0] = Types.NIL;
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return buffer.subarray(0, 1);
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};
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encode_map = (obj, buffer) => {
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const keys = Object.keys(obj);
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buffer[0] = Types.MAP;
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buffer.writeUInt32BE(keys.length, 1);
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buffer = buffer.subarray(0, 5);
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for (let i = 0; i < keys.length; ++i) {
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const key = this.mapKeyAsAtom ? this.toAtom(keys[i]) : keys[i];
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buffer = this.#encode(key, buffer);
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buffer = this.#encode(obj[keys[i]], buffer);
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}
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return buffer;
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};
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decode_atom = (buffer, count) => {
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const size = this.bytesToInt(buffer, count, true);
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buffer = Buffer.from(buffer, count);
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let value = buffer.toString("utf8", 0, size);
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if (value === "true") {
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value = true;
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}
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else if (value === "false") {
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value = false;
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}
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else if (this.decodeUndefinedValues &&
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this.convention === Lang.ELIXIR &&
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value === "nil") {
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value = null;
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}
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else if (this.decodeUndefinedValues &&
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this.convention === Lang.ERLANG &&
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value === "undefined") {
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value = null;
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}
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else {
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value = this.toAtom(value);
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}
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return {
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value,
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rest: buffer.subarray(size),
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};
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};
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decode_binary = (buffer) => {
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const size = this.bytesToInt(buffer, 4, true);
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buffer = Buffer.from(buffer, 4);
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const bin = Buffer.alloc(size);
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buffer.copy(bin, 0, 0, size);
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return {
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value: this.convention === Lang.ELIXIR && this.allBinariesAsString
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? bin.toString()
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: bin,
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rest: buffer.subarray(size),
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};
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};
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decode_integer = (buffer, count, unsigned = false) => {
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return {
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value: this.bytesToInt(buffer, count, unsigned),
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rest: buffer.subarray(count),
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};
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};
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decode_big = (buffer, count) => {
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const size = this.bytesToInt(buffer, count, false);
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buffer = buffer.subarray(count);
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let num = 0;
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const isNegative = buffer[0] === 1;
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buffer = buffer.subarray(1);
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for (let i = size - 1; i >= 0; --i) {
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const n = buffer[i];
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if (num === 0) {
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num = n;
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}
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else {
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num = num * 256 + n;
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}
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}
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if (isNegative) {
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num = num * -1;
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}
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return {
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value: num,
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rest: buffer.subarray(size),
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};
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};
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decode_float = (buffer) => {
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const size = 31;
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return {
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value: parseFloat(buffer.toString("utf8", 0, size)),
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rest: buffer.subarray(size),
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};
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};
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decode_new_float = (buffer) => {
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return {
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value: buffer.readDoubleBE(0),
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rest: buffer.subarray(8),
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};
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};
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decode_string = (buffer) => {
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const size = this.bytesToInt(buffer, 2, true);
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buffer = buffer.subarray(2);
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return {
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value: buffer.toString("utf8", 0, size),
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rest: buffer.subarray(size),
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};
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};
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decode_list = (buffer) => {
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const arr = [];
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const size = this.bytesToInt(buffer, 4, true);
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buffer = Buffer.from(buffer, 4);
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for (let i = 0; i < size; ++i) {
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const el = this.#decode(buffer);
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arr.push(el.value);
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buffer = el.rest;
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}
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const lastChar = buffer[0];
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if (lastChar !== Types.NIL) {
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throw new Error("List does not end with NIL");
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}
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buffer = buffer.subarray(1);
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return {
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value: arr,
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rest: buffer,
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};
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};
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decode_map = (buffer) => {
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const map = {};
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const size = this.bytesToInt(buffer, 4, true);
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buffer = buffer.subarray(4);
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for (let i = 0; i < size; ++i) {
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let el = this.#decode(buffer);
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const key = el.value;
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el = this.#decode(el.rest);
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const value = el.value;
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map[key] = value;
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buffer = el.rest;
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}
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return {
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value: map,
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rest: buffer,
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};
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};
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decode_tuple = (buffer, count) => {
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const arr = [];
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const size = this.bytesToInt(buffer, count, true);
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buffer = buffer.subarray(count);
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for (let i = 0; i < size; ++i) {
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const el = this.#decode(buffer);
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arr.push(el.value);
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buffer = el.rest;
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}
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return {
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value: this.toTuple(arr),
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rest: buffer,
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};
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};
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decode_nil = (buffer) => {
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// nil is an empty list
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return {
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value: [],
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rest: buffer,
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};
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};
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bytesToInt = (buffer, length, unsigned) => {
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switch (length) {
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case 1:
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return unsigned ? buffer.readUInt8(0) : buffer.readInt8(0);
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case 2:
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return unsigned ? buffer.readUInt16BE(0) : buffer.readInt16BE(0);
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case 4:
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return unsigned ? buffer.readUInt32BE(0) : buffer.readInt32BE(0);
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}
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};
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binary_to_list = (str) => {
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const ret = [];
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for (let i = 0; i < str.length; ++i)
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ret.push(str[i]);
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return ret;
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};
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}
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/**
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* Convert object to atom.
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*
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*/
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export const toAtom = (str) => ({
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type: "Atom",
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value: str,
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toString: () => str,
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});
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/**
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* Convert array of items to tuple.
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*
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*/
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export const toTuple = (arr) => ({
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...arr,
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type: "Tuple",
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length: arr.length,
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value: arr,
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toString: () => "{" +
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arr
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.filter((i) => i !== "")
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.map((i) => i.toString())
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.join(", ") +
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"}",
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});
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