118 lines
4.5 KiB
JavaScript
118 lines
4.5 KiB
JavaScript
import { BitWidth } from './bit-width';
|
|
import { toByteWidth, fromByteWidth } from './bit-width-util';
|
|
import { toUTF8Array, fromUTF8Array } from './flexbuffers-util';
|
|
import { Reference } from './reference';
|
|
import { Long } from '../long';
|
|
export function validateOffset(dataView, offset, width) {
|
|
if (dataView.byteLength <= offset + width || (offset & (toByteWidth(width) - 1)) !== 0) {
|
|
throw "Bad offset: " + offset + ", width: " + width;
|
|
}
|
|
}
|
|
export function readInt(dataView, offset, width) {
|
|
if (width < 2) {
|
|
if (width < 1) {
|
|
return dataView.getInt8(offset);
|
|
}
|
|
else {
|
|
return dataView.getInt16(offset, true);
|
|
}
|
|
}
|
|
else {
|
|
if (width < 3) {
|
|
return dataView.getInt32(offset, true);
|
|
}
|
|
else {
|
|
if (dataView.setBigInt64 === undefined) {
|
|
return new Long(dataView.getUint32(offset, true), dataView.getUint32(offset + 4, true));
|
|
}
|
|
return dataView.getBigInt64(offset, true);
|
|
}
|
|
}
|
|
}
|
|
export function readUInt(dataView, offset, width) {
|
|
if (width < 2) {
|
|
if (width < 1) {
|
|
return dataView.getUint8(offset);
|
|
}
|
|
else {
|
|
return dataView.getUint16(offset, true);
|
|
}
|
|
}
|
|
else {
|
|
if (width < 3) {
|
|
return dataView.getUint32(offset, true);
|
|
}
|
|
else {
|
|
if (dataView.getBigUint64 === undefined) {
|
|
return new Long(dataView.getUint32(offset, true), dataView.getUint32(offset + 4, true));
|
|
}
|
|
return dataView.getBigUint64(offset, true);
|
|
}
|
|
}
|
|
}
|
|
export function readFloat(dataView, offset, width) {
|
|
if (width < BitWidth.WIDTH32) {
|
|
throw "Bad width: " + width;
|
|
}
|
|
if (width === BitWidth.WIDTH32) {
|
|
return dataView.getFloat32(offset, true);
|
|
}
|
|
return dataView.getFloat64(offset, true);
|
|
}
|
|
export function indirect(dataView, offset, width) {
|
|
const step = readUInt(dataView, offset, width);
|
|
return offset - step;
|
|
}
|
|
export function keyIndex(key, dataView, offset, parentWidth, byteWidth, length) {
|
|
const input = toUTF8Array(key);
|
|
const keysVectorOffset = indirect(dataView, offset, parentWidth) - byteWidth * 3;
|
|
const bitWidth = fromByteWidth(byteWidth);
|
|
const indirectOffset = keysVectorOffset - readUInt(dataView, keysVectorOffset, bitWidth);
|
|
const _byteWidth = readUInt(dataView, keysVectorOffset + byteWidth, bitWidth);
|
|
let low = 0;
|
|
let high = length - 1;
|
|
while (low <= high) {
|
|
const mid = (high + low) >> 1;
|
|
const dif = diffKeys(input, mid, dataView, indirectOffset, _byteWidth);
|
|
if (dif === 0)
|
|
return mid;
|
|
if (dif < 0) {
|
|
high = mid - 1;
|
|
}
|
|
else {
|
|
low = mid + 1;
|
|
}
|
|
}
|
|
return null;
|
|
}
|
|
export function diffKeys(input, index, dataView, offset, width) {
|
|
const keyOffset = offset + index * width;
|
|
const keyIndirectOffset = keyOffset - readUInt(dataView, keyOffset, fromByteWidth(width));
|
|
for (let i = 0; i < input.length; i++) {
|
|
const dif = input[i] - dataView.getUint8(keyIndirectOffset + i);
|
|
if (dif !== 0) {
|
|
return dif;
|
|
}
|
|
}
|
|
return dataView.getUint8(keyIndirectOffset + input.length) === 0 ? 0 : -1;
|
|
}
|
|
export function valueForIndexWithKey(index, key, dataView, offset, parentWidth, byteWidth, length, path) {
|
|
const _indirect = indirect(dataView, offset, parentWidth);
|
|
const elementOffset = _indirect + index * byteWidth;
|
|
const packedType = dataView.getUint8(_indirect + length * byteWidth + index);
|
|
return new Reference(dataView, elementOffset, fromByteWidth(byteWidth), packedType, `${path}/${key}`);
|
|
}
|
|
export function keyForIndex(index, dataView, offset, parentWidth, byteWidth) {
|
|
const keysVectorOffset = indirect(dataView, offset, parentWidth) - byteWidth * 3;
|
|
const bitWidth = fromByteWidth(byteWidth);
|
|
const indirectOffset = keysVectorOffset - readUInt(dataView, keysVectorOffset, bitWidth);
|
|
const _byteWidth = readUInt(dataView, keysVectorOffset + byteWidth, bitWidth);
|
|
const keyOffset = indirectOffset + index * _byteWidth;
|
|
const keyIndirectOffset = keyOffset - readUInt(dataView, keyOffset, fromByteWidth(_byteWidth));
|
|
let length = 0;
|
|
while (dataView.getUint8(keyIndirectOffset + length) !== 0) {
|
|
length++;
|
|
}
|
|
return fromUTF8Array(new Uint8Array(dataView.buffer, keyIndirectOffset, length));
|
|
}
|