From 1c868f4eeb5afebdcf631441985d5ba17fcbd6b2 Mon Sep 17 00:00:00 2001
From: Fredrik Tolf <fredrik@dolda2000.com>
Date: Tue, 13 Oct 2009 01:36:16 +0200
Subject: [PATCH] Added a configuration manager with support for LET-like
 constructs.

---
 src/dolda/jsvc/Request.java          |  2 +-
 src/dolda/jsvc/SvcConfig.java        | 64 ++++++++++++++++++++++++++++++++++++
 src/dolda/jsvc/j2ee/J2eeRequest.java |  4 +--
 3 files changed, 67 insertions(+), 3 deletions(-)
 create mode 100644 src/dolda/jsvc/SvcConfig.java

diff --git a/src/dolda/jsvc/Request.java b/src/dolda/jsvc/Request.java
index 6c779ac..8de008a 100644
--- a/src/dolda/jsvc/Request.java
+++ b/src/dolda/jsvc/Request.java
@@ -21,7 +21,7 @@ public interface Request {
     public MultiMap<String, String> outheaders();
     
     /* Misc. */
-    public Map<?, ?> props();
+    public Map<Object, Object> props();
     public ServerContext ctx();
     public SocketAddress remoteaddr();
     public SocketAddress localaddr();
diff --git a/src/dolda/jsvc/SvcConfig.java b/src/dolda/jsvc/SvcConfig.java
new file mode 100644
index 0000000..d200aa3
--- /dev/null
+++ b/src/dolda/jsvc/SvcConfig.java
@@ -0,0 +1,64 @@
+package dolda.jsvc;
+
+import java.util.*;
+
+public class SvcConfig {
+    public static class Param<T> {
+	private T value;
+	private final Object id = new Object();
+	
+	public Param(T def) {
+	    this.value = def;
+	}
+	
+	@SuppressWarnings("unchecked")
+	public T get() {
+	    if(Thread.currentThread() instanceof RequestThread) {
+		Map<Object, Object> props = RequestThread.request().props();
+		if(props.containsKey(id)) {
+		    /* This can very well actually be set to something
+		     * of the wrong type, but since the result would,
+		     * obviously, be a ClassCastException either way,
+		     * this way is at least the more convenient. */
+		    return((T)props.get(id));
+		}
+	    }
+	    return(value);
+	}
+    }
+    
+    public static Responder let(final Responder next, Object... params) {
+	final Map<Param, Object> values = new HashMap<Param, Object>();
+	if((params.length % 2) != 0)
+	    throw(new IllegalArgumentException("SvcConfig.let takes only an even number of parameters"));
+	for(int i = 0; i < params.length; i += 2)
+	    values.put((Param)params[i], params[i + 1]);
+	return(new Responder() {
+		public void respond(Request req) {
+		    final Map<Param, Object> old = new HashMap<Param, Object>();
+		    {
+			Map<Object, Object> props = req.props();
+			for(Map.Entry<Param, Object> val : values.entrySet()) {
+			    Param p = val.getKey();
+			    if(props.containsKey(p.id))
+				old.put(p, props.get(p.id));
+			    props.put(p.id, val.getValue());
+			}
+		    }
+		    try {
+			next.respond(req);
+		    } finally {
+			Map<Object, Object> props = req.props();
+			for(Map.Entry<Param, Object> val : values.entrySet()) {
+			    Param p = val.getKey();
+			    if(old.containsKey(p)) {
+				props.put(p.id, old.get(p));
+			    } else {
+				props.remove(p.id);
+			    }
+			}
+		    }
+		}
+	    });
+    }
+}
diff --git a/src/dolda/jsvc/j2ee/J2eeRequest.java b/src/dolda/jsvc/j2ee/J2eeRequest.java
index f394653..9beddf5 100644
--- a/src/dolda/jsvc/j2ee/J2eeRequest.java
+++ b/src/dolda/jsvc/j2ee/J2eeRequest.java
@@ -14,7 +14,7 @@ public class J2eeRequest extends ResponseBuffer {
     private HttpServletResponse resp;
     private String method, path;
     private URL url;
-    private Map<?, ?> props = new HashMap();
+    private Map<Object, Object> props = new HashMap<Object, Object>();
     
     public J2eeRequest(ServletConfig cfg, HttpServletRequest req, HttpServletResponse resp) {
 	this.cfg = cfg;
@@ -69,7 +69,7 @@ public class J2eeRequest extends ResponseBuffer {
 	    path = path.substring(1);
     }
     
-    public Map<?, ?> props() {
+    public Map<Object, Object> props() {
 	return(props);
     }
     
-- 
2.11.0