class DBCError extends Error {
}

class CheckError extends DBCError {}
class SentinelError extends DBCError {}
class PreCondError extends DBCError {}
class PostCondError extends DBCError {}

export const check = (test, msg, err=CheckError) => {
  if(!test) {
    console.trace(msg);
    throw new err(msg);
  }
}

export const sentinel = (test) => {
  check(test, "SENTINEL ERROR", SentinelError);
}

export const pre = (test_cb, msg) => {
  check(test_cb(), `PRECOND ERROR: ${msg}`, PreCondError);
}

export const post = (test_cb, msg) => {
  check(test_cb(), `POSTCOND ERROR: ${msg}`, PostCondError);
}


export default {
  check, sentinel, pre, post,
  CheckError, SentinelError, PreCondError,
  PostCondError,
}