All files / json-crdt-patch/codec/binary Decoder.ts

96.55% Statements 112/116
87.8% Branches 36/41
100% Functions 7/7
99.03% Lines 103/104

Press n or j to go to the next uncovered block, b, p or k for the previous block.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187183x 183x                 183x 183x 183x 183x         183x                   183x                   52520x 52520x       52520x 52520x 52520x 52520x 52520x 52520x 52520x 52520x 52520x 52520x 52520x       225936x 225936x 225936x       60218x 60218x 60218x       52520x 52520x 113670x       113670x 113670x 113670x 113670x 113670x   11867x 11867x 11867x     810x 810x     10182x 10182x     2x 2x     6654x 6654x     2466x 2466x     2524x 2524x     1787x 1787x 1787x 1787x     17154x 17154x 17154x 17154x 31513x 31513x 31513x 31513x   17154x 17154x     1x 1x 1x 1x 1x 1x 1x 1x   1x 1x     40799x 40799x 40799x 40799x 40799x 40799x     6589x 6589x 6589x 6589x 6589x 6589x 6589x     1895x 1895x 1895x 1895x 4532x 1895x 1895x     10373x 10373x 10373x 60218x 10373x 10373x     567x 567x 567x                
import {CrdtReader} from '../../util/binary/CrdtReader';
import {
  interval,
  type ITimespanStruct,
  type ITimestampStruct,
  ClockVector,
  ServerClockVector,
  Timestamp,
} from '../../clock';
import type {Patch} from '../../Patch';
import {PatchBuilder} from '../../PatchBuilder';
import {SESSION} from '../../constants';
import {CborDecoder} from '@jsonjoy.com/json-pack/lib/cbor/CborDecoder';
import {JsonCrdtPatchOpcode} from '../../constants';
 
/**
 * JSON CRDT Patch "binary" codec decoder.
 */
export class Decoder extends CborDecoder<CrdtReader> {
  protected builder!: PatchBuilder;
  private patchSid?: number;
 
  /**
   * Creates a new JSON CRDT patch decoder.
   *
   * @param reader An optional custom implementation of a CRDT decoder.
   */
  constructor(reader: CrdtReader = new CrdtReader()) {
    super(reader);
  }
 
  /**
   * Decodes a JSON CRDT patch from a binary blob.
   *
   * @param data Binary data to decode.
   * @returns A JSON CRDT patch.
   */
  public decode(data: Uint8Array): Patch {
    this.reader.reset(data);
    return this.readPatch();
  }
 
  public readPatch(): Patch {
    const reader = this.reader;
    const sid = reader.vu57();
    const time = reader.vu57();
    const isServerClock = sid === SESSION.SERVER;
    const clock = isServerClock ? new ServerClockVector(SESSION.SERVER, time) : new ClockVector(sid, time);
    this.patchSid = clock.sid;
    const builder = (this.builder = new PatchBuilder(clock));
    const map = this.val();
    if (map instanceof Array) builder.patch.meta = map[0];
    this.decodeOperations();
    return builder.patch;
  }
 
  protected decodeId(): ITimestampStruct {
    const reader = this.reader;
    const [isSessionDifferent, x] = reader.b1vu56();
    return isSessionDifferent ? new Timestamp(reader.vu57(), x) : new Timestamp(this.patchSid!, x);
  }
 
  protected decodeTss(): ITimespanStruct {
    const id = this.decodeId();
    const span = this.reader.vu57();
    return interval(id, 0, span);
  }
 
  protected decodeOperations(): void {
    const reader = this.reader;
    const length = reader.vu57();
    for (let i = 0; i < length; i++) this.decodeOperation();
  }
 
  protected decodeOperation(): void {
    const builder = this.builder;
    const reader = this.reader;
    const octet = reader.u8();
    const opcode = octet >> 3;
    switch (opcode) {
      case JsonCrdtPatchOpcode.new_con: {
        const length = octet & 0b111;
        builder.const(!length ? this.val() : this.decodeId());
        break;
      }
      case JsonCrdtPatchOpcode.new_val: {
        builder.val();
        break;
      }
      case JsonCrdtPatchOpcode.new_obj: {
        builder.obj();
        break;
      }
      case JsonCrdtPatchOpcode.new_vec: {
        builder.vec();
        break;
      }
      case JsonCrdtPatchOpcode.new_str: {
        builder.str();
        break;
      }
      case JsonCrdtPatchOpcode.new_bin: {
        builder.bin();
        break;
      }
      case JsonCrdtPatchOpcode.new_arr: {
        builder.arr();
        break;
      }
      case JsonCrdtPatchOpcode.ins_val: {
        const obj = this.decodeId();
        const val = this.decodeId();
        builder.setVal(obj, val);
        break;
      }
      case JsonCrdtPatchOpcode.ins_obj: {
        const length = octet & 0b111 || reader.vu57();
        const obj = this.decodeId();
        const tuples: [key: string, value: ITimestampStruct][] = [];
        for (let i = 0; i < length; i++) {
          const key = this.val();
          Iif (typeof key !== 'string') continue;
          const value = this.decodeId();
          tuples.push([key, value]);
        }
        builder.insObj(obj, tuples);
        break;
      }
      case JsonCrdtPatchOpcode.ins_vec: {
        const length = octet & 0b111 || reader.vu57();
        const obj = this.decodeId();
        const tuples: [index: number, value: ITimestampStruct][] = [];
        for (let i = 0; i < length; i++) {
          const index = this.val();
          Iif (typeof index !== 'number') continue;
          const value = this.decodeId();
          tuples.push([index, value]);
        }
        builder.insVec(obj, tuples);
        break;
      }
      case JsonCrdtPatchOpcode.ins_str: {
        const length = octet & 0b111 || reader.vu57();
        const obj = this.decodeId();
        const after = this.decodeId();
        const str = reader.utf8(length);
        builder.insStr(obj, after, str);
        break;
      }
      case JsonCrdtPatchOpcode.ins_bin: {
        const length = octet & 0b111 || reader.vu57();
        const obj = this.decodeId();
        const after = this.decodeId();
        const buf = reader.buf(length);
        Iif (!(buf instanceof Uint8Array)) return;
        builder.insBin(obj, after, buf);
        break;
      }
      case JsonCrdtPatchOpcode.ins_arr: {
        const length = octet & 0b111 || reader.vu57();
        const obj = this.decodeId();
        const after = this.decodeId();
        const elements: ITimestampStruct[] = [];
        for (let i = 0; i < length; i++) elements.push(this.decodeId());
        builder.insArr(obj, after, elements);
        break;
      }
      case JsonCrdtPatchOpcode.del: {
        const length = octet & 0b111 || reader.vu57();
        const obj = this.decodeId();
        const what: ITimespanStruct[] = [];
        for (let i = 0; i < length; i++) what.push(this.decodeTss());
        builder.del(obj, what);
        break;
      }
      case JsonCrdtPatchOpcode.nop: {
        const length = octet & 0b111 || reader.vu57();
        builder.nop(length);
        break;
      }
      default: {
        throw new Error('UNKNOWN_OP');
      }
    }
  }
}