File size: 3,592 Bytes
9ae1216 | 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 | /**
* @import {DataReader, ThriftObject, ThriftType} from '../src/types.js'
*/
// TCompactProtocol types
const STOP = 0
const TRUE = 1
const FALSE = 2
const BYTE = 3
const I16 = 4
const I32 = 5
const I64 = 6
const DOUBLE = 7
const BINARY = 8
const LIST = 9
const STRUCT = 12
/**
* Parse TCompactProtocol
*
* @param {DataReader} reader
* @returns {{ [key: `field_${number}`]: any }}
*/
export function deserializeTCompactProtocol(reader) {
/** @type {ThriftObject} */
const value = {}
let fid = 0
while (reader.offset < reader.view.byteLength) {
// Parse each field based on its type and add to the result object
const byte = reader.view.getUint8(reader.offset++)
const type = byte & 0x0f
if (type === STOP) break
const delta = byte >> 4
fid = delta ? fid + delta : readZigZag(reader)
value[`field_${fid}`] = readElement(reader, type)
}
return value
}
/**
* Read a single element based on its type
*
* @param {DataReader} reader
* @param {number} type
* @returns {ThriftType}
*/
function readElement(reader, type) {
switch (type) {
case TRUE:
return true
case FALSE:
return false
case BYTE:
return reader.view.getInt8(reader.offset++)
case I16:
case I32:
return readZigZag(reader)
case I64:
return readZigZagBigInt(reader)
case DOUBLE: {
const value = reader.view.getFloat64(reader.offset, true)
reader.offset += 8
return value
}
case BINARY: {
const stringLength = readVarInt(reader)
const strBytes = new Uint8Array(reader.view.buffer, reader.view.byteOffset + reader.offset, stringLength)
reader.offset += stringLength
return strBytes
}
case LIST: {
const byte = reader.view.getUint8(reader.offset++)
const elemType = byte & 0x0f
let listSize = byte >> 4
if (listSize === 15) {
listSize = readVarInt(reader)
}
const boolType = elemType === TRUE || elemType === FALSE
const values = new Array(listSize)
for (let i = 0; i < listSize; i++) {
values[i] = boolType ? readElement(reader, BYTE) === 1 : readElement(reader, elemType)
}
return values
}
case STRUCT:
// main function handles struct parsing
return deserializeTCompactProtocol(reader)
default:
// MAP, SET, UUID not used by parquet
throw new Error(`thrift unhandled type: ${type}`)
}
}
/**
* Read varint aka Unsigned LEB128.
*
* @param {DataReader} reader
* @returns {number}
*/
export function readVarInt(reader) {
let result = 0
let shift = 0
while (true) {
// Read groups of 7 low bits until high bit is 0
const byte = reader.view.getUint8(reader.offset++)
result |= (byte & 0x7f) << shift
if (!(byte & 0x80)) {
return result
}
shift += 7
}
}
/**
* Read a varint as a bigint.
*
* @param {DataReader} reader
* @returns {bigint}
*/
function readVarBigInt(reader) {
let result = 0n
let shift = 0n
while (true) {
const byte = reader.view.getUint8(reader.offset++)
result |= BigInt(byte & 0x7f) << shift
if (!(byte & 0x80)) {
return result
}
shift += 7n
}
}
/**
* Read a zigzag number.
* Zigzag folds positive and negative numbers into the positive number space.
*
* @param {DataReader} reader
* @returns {number}
*/
export function readZigZag(reader) {
const zigzag = readVarInt(reader)
return zigzag >>> 1 ^ -(zigzag & 1)
}
/**
* Read a zigzag bigint.
*
* @param {DataReader} reader
* @returns {bigint}
*/
export function readZigZagBigInt(reader) {
const zigzag = readVarBigInt(reader)
return zigzag >> 1n ^ -(zigzag & 1n)
}
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