function decodeDocumentHeader()

in backend/columnar.js [1006:1038]

• 30 lines of code
• 9 McCabe index (conditional complexity)

function decodeDocumentHeader(buffer) {
  const documentDecoder = new Decoder(buffer)
  const header = decodeContainerHeader(documentDecoder, true)
  const decoder = new Decoder(header.chunkData)
  if (!documentDecoder.done) throw new RangeError('Encoded document has trailing data')
  if (header.chunkType !== CHUNK_TYPE_DOCUMENT) throw new RangeError(`Unexpected chunk type: ${header.chunkType}`)

  const actorIds = [], numActors = decoder.readUint53()
  for (let i = 0; i < numActors; i++) {
    actorIds.push(decoder.readHexString())
  }
  const heads = [], headsIndexes = [], numHeads = decoder.readUint53()
  for (let i = 0; i < numHeads; i++) {
    heads.push(bytesToHexString(decoder.readRawBytes(32)))
  }

  const changesColumns = decodeColumnInfo(decoder)
  const opsColumns = decodeColumnInfo(decoder)
  for (let i = 0; i < changesColumns.length; i++) {
    changesColumns[i].buffer = decoder.readRawBytes(changesColumns[i].bufferLen)
    inflateColumn(changesColumns[i])
  }
  for (let i = 0; i < opsColumns.length; i++) {
    opsColumns[i].buffer = decoder.readRawBytes(opsColumns[i].bufferLen)
    inflateColumn(opsColumns[i])
  }
  if (!decoder.done) {
    for (let i = 0; i < numHeads; i++) headsIndexes.push(decoder.readUint53())
  }

  const extraBytes = decoder.readRawBytes(decoder.buf.byteLength - decoder.offset)
  return { changesColumns, opsColumns, actorIds, heads, headsIndexes, extraBytes }
}