Method read

javascript/packages/core/lib/gen/decimal.ts:57–90

(accessor: (expr: string) => string)

  }

  read(accessor: (expr: string) => string): string {
    const codec = this.builder.getExternal(DecimalCodec.name);
    const decimal = this.builder.getExternal(Decimal.name);
    const scale = this.scope.uniqueName("decimal_scale");
    const header = this.scope.uniqueName("decimal_header");
    const meta = this.scope.uniqueName("decimal_meta");
    const length = this.scope.uniqueName("decimal_length");
    const magnitudeBytes = this.scope.uniqueName("decimal_magnitude_bytes");
    const magnitude = this.scope.uniqueName("decimal_magnitude");
    const unscaled = this.scope.uniqueName("decimal_unscaled");
    return `
      const ${scale} = ${this.builder.reader.readVarInt32()};
      const ${header} = ${this.builder.reader.readVarUInt64()};
      if ((${header} & 1n) === 0n) {
        ${accessor(`new ${decimal}(${codec}.decodeZigZag64(${header} >> 1n), ${scale})`)}
      } else {
        const ${meta} = ${header} >> 1n;
        const ${length} = Number(${meta} >> 1n);
        if (${length} <= 0 || ${length} > 0x7fffffff) {
          throw new Error(\`Invalid decimal magnitude length \${${length}}.\`);
        }
        const ${magnitudeBytes} = ${this.builder.reader.buffer(length)};
        if (${magnitudeBytes}[${length} - 1] === 0) {
          throw new Error("Non-canonical decimal magnitude bytes: trailing zero byte.");
        }
        const ${magnitude} = ${codec}.fromCanonicalLittleEndianMagnitude(${magnitudeBytes});
        if (${magnitude} === 0n) {
          throw new Error("Big decimal encoding must not represent zero.");
        }
        const ${unscaled} = ((${meta} & 1n) === 0n) ? ${magnitude} : -${magnitude};
        ${accessor(`new ${decimal}(${unscaled}, ${scale})`)}
      }
    `;
  }

  getFixedSize(): number {
    return 20;