| 1 | package dolda.jsvc; |
| 2 | |
| 3 | import java.util.*; |
| 4 | |
| 5 | public class SvcConfig { |
| 6 | public static class Param<T> { |
| 7 | private T value; |
| 8 | private final Object id = new Object(); |
| 9 | |
| 10 | public Param(T def) { |
| 11 | this.value = def; |
| 12 | } |
| 13 | |
| 14 | @SuppressWarnings("unchecked") |
| 15 | public T get() { |
| 16 | if(Thread.currentThread() instanceof RequestThread) { |
| 17 | Map<Object, Object> props = RequestThread.request().props(); |
| 18 | if(props.containsKey(id)) { |
| 19 | /* This can very well actually be set to something |
| 20 | * of the wrong type, but since the result would, |
| 21 | * obviously, be a ClassCastException either way, |
| 22 | * this way is at least the more convenient. */ |
| 23 | return((T)props.get(id)); |
| 24 | } |
| 25 | } |
| 26 | return(value); |
| 27 | } |
| 28 | } |
| 29 | |
| 30 | public static Responder let(final Responder next, Object... params) { |
| 31 | final Map<Param, Object> values = new HashMap<Param, Object>(); |
| 32 | if((params.length % 2) != 0) |
| 33 | throw(new IllegalArgumentException("SvcConfig.let takes only an even number of parameters")); |
| 34 | for(int i = 0; i < params.length; i += 2) |
| 35 | values.put((Param)params[i], params[i + 1]); |
| 36 | return(new Responder() { |
| 37 | public void respond(Request req) { |
| 38 | final Map<Param, Object> old = new HashMap<Param, Object>(); |
| 39 | { |
| 40 | Map<Object, Object> props = req.props(); |
| 41 | for(Map.Entry<Param, Object> val : values.entrySet()) { |
| 42 | Param p = val.getKey(); |
| 43 | if(props.containsKey(p.id)) |
| 44 | old.put(p, props.get(p.id)); |
| 45 | props.put(p.id, val.getValue()); |
| 46 | } |
| 47 | } |
| 48 | try { |
| 49 | next.respond(req); |
| 50 | } finally { |
| 51 | Map<Object, Object> props = req.props(); |
| 52 | for(Map.Entry<Param, Object> val : values.entrySet()) { |
| 53 | Param p = val.getKey(); |
| 54 | if(old.containsKey(p)) { |
| 55 | props.put(p.id, old.get(p)); |
| 56 | } else { |
| 57 | props.remove(p.id); |
| 58 | } |
| 59 | } |
| 60 | } |
| 61 | } |
| 62 | }); |
| 63 | } |
| 64 | } |