// a persistent map using a clever combination of persisting and logging
// and with case-insensitive keys
// (well, only logging as of now)
// Note: don't put in static initializer (programID not set yet)
static class PersistentCIMap<B> extends AbstractMap<S, B> {
  new Map<S, B> m;
  File file;
  
  PersistentCIMap(S fileName) {
    this(getProgramFile(fileName));
  }
  
  PersistentCIMap(S progID, S fileName) {
    this(getProgramFile(progID, fileName));
  }
  
  *(File *file) {
    for (S s : scanLog(file)) pcall {
      L l = cast unstructure(s);
      if (eq(l.get(0), "add"))
        m.put(toLowerCase((S) l.get(1)), (B) l.get(2));
      else if (eq(l.get(0), "remove"))
        m.remove(toLowerCase((S) l.get(1)));
      else
        print("Unknown command in log: " + l.get(0));
    }
  }
  
  // just delegates
  
  public int size() {
    ret m.size();
  }
  
  public B get(O a) {
    ret m.get(toLowerCase((S) a));
  }
  
  public boolean containsKey(O a) {
    ret m.containsKey(toLowerCase((S) a));
  }
  
  // TODO: calling remove() in the iterator will have unpersisted
  // effects.
  public Set<Map.Entry<S, B>> entrySet() {
    ret m.entrySet();
  }
  
  // delegates with logging

  public B put(S a, B b) {
    a = toLowerCase(a);
    B c = m.get(a);
    if (neq(b, c)) {
      m.put(a, b);
      logQuoted(file, structure(litlist("add", a, b)));
    }
    ret c;
  }
  
  public B remove(O a) {
    a = toLowerCase((S) a);
    B result = m.remove(a);
    logQuoted(file, structure(litlist("remove", a)));
    ret result;
  }
}

Began life as a copy of #1002063