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Text file src/github.com/google/flatbuffers/ts/flexbuffers/reference-util.ts

Documentation: github.com/google/flatbuffers/ts/flexbuffers

     1import { BitWidth } from './bit-width.js'
     2import { toByteWidth, fromByteWidth } from './bit-width-util.js'
     3import { toUTF8Array, fromUTF8Array } from './flexbuffers-util.js'
     4
     5export function validateOffset(dataView: DataView, offset: number, width: number): void {
     6  if (dataView.byteLength <= offset + width || (offset & (toByteWidth(width) - 1)) !== 0) {
     7    throw "Bad offset: " + offset + ", width: " + width;
     8  }
     9}
    10
    11export function readInt(dataView: DataView, offset: number, width: number): number | bigint {
    12  if (width < 2) {
    13    if (width < 1) {
    14      return dataView.getInt8(offset);
    15    } else {
    16      return dataView.getInt16(offset, true);
    17    }
    18  } else {
    19    if (width < 3) {
    20      return dataView.getInt32(offset, true)
    21    } else {
    22      if (dataView.setBigInt64 === undefined) {
    23        return BigInt(dataView.getUint32(offset, true)) + (BigInt(dataView.getUint32(offset + 4, true)) << BigInt(32));
    24      }
    25      return dataView.getBigInt64(offset, true)
    26    }
    27  }
    28}
    29
    30export function readUInt(dataView: DataView, offset: number, width: number): number | bigint {
    31  if (width < 2) {
    32    if (width < 1) {
    33      return dataView.getUint8(offset);
    34    } else {
    35      return dataView.getUint16(offset, true);
    36    }
    37  } else {
    38    if (width < 3) {
    39      return dataView.getUint32(offset, true)
    40    } else {
    41      if (dataView.getBigUint64 === undefined) {
    42        return BigInt(dataView.getUint32(offset, true)) + (BigInt(dataView.getUint32(offset + 4, true)) << BigInt(32));
    43      }
    44      return dataView.getBigUint64(offset, true)
    45    }
    46  }
    47}
    48
    49export function readFloat(dataView: DataView, offset: number, width: number): number {
    50  if (width < BitWidth.WIDTH32) {
    51    throw "Bad width: " + width;
    52  }
    53  if (width === BitWidth.WIDTH32) {
    54    return dataView.getFloat32(offset, true);
    55  }
    56  return dataView.getFloat64(offset, true);
    57}
    58
    59export function indirect(dataView: DataView, offset: number, width: number): number {
    60  const step = readUInt(dataView, offset, width) as number;
    61  return offset - step;
    62}
    63
    64export function keyIndex(key: string, dataView: DataView, offset: number, parentWidth: number, byteWidth: number, length: number): number | null {
    65  const input = toUTF8Array(key);
    66  const keysVectorOffset = indirect(dataView, offset, parentWidth) - byteWidth * 3;
    67  const bitWidth = fromByteWidth(byteWidth);
    68  const indirectOffset = keysVectorOffset - Number(readUInt(dataView, keysVectorOffset, bitWidth));
    69  const _byteWidth = Number(readUInt(dataView, keysVectorOffset + byteWidth, bitWidth));
    70  let low = 0;
    71  let high = length - 1;
    72  while (low <= high) {
    73    const mid = (high + low) >> 1;
    74    const dif = diffKeys(input, mid, dataView, indirectOffset, _byteWidth);
    75    if (dif === 0) return mid;
    76    if (dif < 0) {
    77      high = mid - 1;
    78    } else {
    79      low = mid + 1;
    80    }
    81  }
    82  return null;
    83}
    84
    85export function diffKeys(input: Uint8Array, index: number, dataView: DataView, offset: number, width: number): number {
    86  const keyOffset = offset + index * width;
    87  const keyIndirectOffset = keyOffset - Number(readUInt(dataView, keyOffset, fromByteWidth(width)));
    88  for (let i = 0; i < input.length; i++) {
    89    const dif = input[i] - dataView.getUint8(keyIndirectOffset + i);
    90    if (dif !== 0) {
    91      return dif;
    92    }
    93  }
    94  return dataView.getUint8(keyIndirectOffset + input.length) === 0 ? 0 : -1;
    95}
    96
    97export function keyForIndex(index: number, dataView: DataView, offset: number, parentWidth: number, byteWidth: number): string {
    98  const keysVectorOffset = indirect(dataView, offset, parentWidth) - byteWidth * 3;
    99  const bitWidth = fromByteWidth(byteWidth);
   100  const indirectOffset = keysVectorOffset - Number(readUInt(dataView, keysVectorOffset, bitWidth));
   101  const _byteWidth = Number(readUInt(dataView, keysVectorOffset + byteWidth, bitWidth));
   102  const keyOffset = indirectOffset + index * _byteWidth;
   103  const keyIndirectOffset = keyOffset - Number(readUInt(dataView, keyOffset, fromByteWidth(_byteWidth)));
   104  let length = 0;
   105  while (dataView.getUint8(keyIndirectOffset + length) !== 0) {
   106    length++;
   107  }
   108  return fromUTF8Array(new Uint8Array(dataView.buffer, keyIndirectOffset, length));
   109}

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