Function tail

packages/opencode/src/tool/shell.ts:225–255

(text: string, maxLines: number, maxBytes: number)

}

function tail(text: string, maxLines: number, maxBytes: number) {
  const lines = text.split("\n")
  if (lines.length <= maxLines && Buffer.byteLength(text, "utf-8") <= maxBytes) {
    return {
      text,
      cut: false,
    }
  }

  const out: string[] = []
  let bytes = 0
  for (let i = lines.length - 1; i >= 0 && out.length < maxLines; i--) {
    const size = Buffer.byteLength(lines[i], "utf-8") + (out.length > 0 ? 1 : 0)
    if (bytes + size > maxBytes) {
      if (out.length === 0) {
        const buf = Buffer.from(lines[i], "utf-8")
        let start = buf.length - maxBytes
        if (start < 0) start = 0
        while (start < buf.length && (buf[start] & 0xc0) === 0x80) start++
        out.unshift(buf.subarray(start).toString("utf-8"))
      }
      break
    }
    out.unshift(lines[i])
    bytes += size
  }
  return {
    text: out.join("\n"),
    cut: true,
  }
}

const parse = Effect.fn("ShellTool.parse")(function* (command: string, ps: boolean) {
  const tree = yield* Effect.promise(() => parser().then((p) => (ps ? p.ps : p.bash).parse(command)))