def manifest.read.loop

mylsm-lsm-store@0.6.0.1 · src/legacy/ManifestIo.bend:151

import Base
import mylsm-lsm-store@0.6.0.1/src/Fs.bend as Fs
import bend-kit-bytes@0.3.2.0/bytes.bend as Bytes

151def manifest.read.loop(fuel: Nat, state: ManifestReadState) -> IO(File & Result<&1, &1, U32 & String, Bytes.Bytes>):
152  match fuel:
153    case 0n:
154      match state:
155        case ManifestNeed{file, +remaining, chunks}:
156          match remaining:
157            case 0n:
158              IO.pure(File & Result<&1, &1, U32 & String, Bytes.Bytes>, (file, Done{Bytes.concat(List.reverse(&1, Bytes.Bytes, chunks))}))
159            case 1n+_:
160              IO.pure(File & Result<&1, &1, U32 & String, Bytes.Bytes>, (file, Fail{(U32.from_nat(7n), "bounded manifest read exhausted")}))
161        case ManifestGot{pair, _, _}:
162          match pair:
163            case (file, Fail{error}):
164              IO.pure(File & Result<&1, &1, U32 & String, Bytes.Bytes>, (file, Fail{error}))
165            case (file, Done{_}):
166              IO.pure(File & Result<&1, &1, U32 & String, Bytes.Bytes>, (file, Fail{(U32.from_nat(7n), "bounded manifest read exhausted")}))
167    case 1n+rest:
168      match state:
169        case ManifestNeed{file, +remaining, chunks}:
170          match remaining:
171            case 0n:
172              IO.pure(File & Result<&1, &1, U32 & String, Bytes.Bytes>, (file, Done{Bytes.concat(List.reverse(&1, Bytes.Bytes, chunks))}))
173            case 1n+_:
174              do IO<File & Result<&1, &1, U32 & String, Bytes.Bytes>>:
175                pair : File & Result<&1, &1, U32 & String, Bytes.Bytes> <- Fs.read_bytes(file, U32.from_nat(remaining))
176                manifest.read.loop(rest, ManifestGot{pair, remaining, chunks})
177        case ManifestGot{pair, +remaining, chunks}:
178          match pair:
179            case (file, Fail{error}):
180              IO.pure(File & Result<&1, &1, U32 & String, Bytes.Bytes>, (file, Fail{error}))
181            case (file, Done{Bytes.Bytes{0, _}}):
182              IO.pure(File & Result<&1, &1, U32 & String, Bytes.Bytes>, (file, Fail{(U32.from_nat(8n), "truncated manifest file")}))
183            case (file, Done{Bytes.Bytes{+len, buf}}):
184              manifest.read.loop(rest, ManifestNeed{file, Nat.sub(remaining, U32.to_nat(len)), Con{Bytes.Bytes{len, buf}, chunks}})