12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485
import { Codec, createCodec, metadata } from "../common/mod.ts"import { compact } from "./compact.ts"import { u32 } from "./int.ts"
const compactU32 = compact(u32)
export class BitSequence {  readonly data;
  [index: number]: boolean
  constructor(readonly length = 0, data?: Uint8Array) {    const byteLength = Math.ceil(length / 8)    data ??= new Uint8Array(byteLength)    if (data.length !== byteLength) {      throw new Error("Incorrectly sized Uint8Array passed to BitSequence constructor")    }    this.data = data  }
  static from(array: (boolean | 0 | 1)[]) {    const sequence = new BitSequence(array.length)    for (let i = 0; i < array.length; i++) {      sequence._setBit(i, array[i]!)    }    return sequence  }
  get byteLength() {    return this.data.length  }
  _hasBit(index: number): boolean {    return 0 <= index && index < this.length && index === Math.floor(index)  }
  _getBit(index: number): boolean | undefined {    if (!this._hasBit(index)) return undefined    const i = Math.floor(index / 8)    const j = 7 - index % 8    return !!(this.data[i]! & (1 << j))  }
  _setBit(index: number, bit: boolean | 0 | 1): boolean {    if (!this._hasBit(index)) return false    const i = Math.floor(index / 8)    const j = 7 - index % 8    this.data[i] = this.data[i]! & ~(1 << j) | (+!!bit << j)    return true  }}
Object.setPrototypeOf(  BitSequence.prototype,  new Proxy(Object.prototype, {    get: (target, k, receiver) => {      const i = typeof k === "string" ? +k : NaN      if (isNaN(i)) return Reflect.get(target, k, receiver)      return (receiver as BitSequence)._getBit(i)    },    set: (target, k, v, receiver) => {      const i = typeof k === "string" ? +k : NaN      if (isNaN(i)) return Reflect.set(target, k, v, receiver)      return (receiver as BitSequence)._setBit(i, v)    },  }),)
export const bitSequence: Codec<BitSequence> = createCodec({  _metadata: metadata("$.bitSequence"),  _staticSize: compactU32._staticSize,  _encode(buffer, value) {    compactU32._encode(buffer, value.length)    buffer.insertArray(value.data)  },  _decode(buffer) {    const length = compactU32._decode(buffer)    const byteLength = Math.ceil(length / 8)    return new BitSequence(length, buffer.array.subarray(buffer.index, buffer.index += byteLength))  },  _assert(assert) {    assert.instanceof(this, BitSequence)  },})