Created a utility function for easily looking up methods.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@238 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/presents/util/ClassUtil.java

@@ -1,18 +1,21 @@
 //
-// $Id: ClassUtil.java,v 1.1 2001/07/19 07:09:16 mdb Exp $
+// $Id: ClassUtil.java,v 1.2 2001/08/14 06:48:08 mdb Exp $
 
 package com.threerings.cocktail.cher.util;
 
 import java.lang.reflect.Method;
 import java.util.HashMap;
 
+import com.samskivert.Log;
+import com.samskivert.util.StringUtil;
+
 /**
  * Class related utility functions.
  */
 public class ClassUtil
 {
     /**
-     * Locates and returns teh first method in the supplied class whose
+     * Locates and returns the first method in the supplied class whose
      * name is equal to the specified name. If a method is located, it
      * will be cached in the supplied cache so that subsequent requests
      * will immediately return the method from the cache rather than
@@ -37,6 +40,60 @@ public class ClassUtil
         return method;
     }
 
+    /**
+     * Looks up the method on the specified object that has a signature
+     * that matches the supplied arguments array. This has to create an
+     * array of class objects correspnding to the types of all of the
+     * arguments in the args array, so none of them are allowed to be
+     * null. This is very expensive, so you shouldn't be doing this for
+     * something that happens frequently.
+     *
+     * <p><em>Note:</em> primitive types for arguments are preferred. What
+     * this means is that if an element of the <code>args</code> array is
+     * an instance of <code>Integer</code>, for example, then this code
+     * assumes that it is intended for that to be unwrapped into an
+     * <code>int</code> in calling the actual function. The reason this is
+     * necessary is that method lookup isn't smart about first checking
+     * for a method taking the primitive argument and then falling back to
+     * one taking an <code>Integer</code> object. So we insist that all
+     * arguments that <em>can</em> be unwrapped, <em>are</em> unwrapped.
+     * Why would you want to pass <code>Integer</code> objects as
+     * arguments to your function anyway?
+     *
+     * @return the best matching method with the specified name that
+     * accepts the supplied arguments, or null if no method could be
+     * found.
+     */
+    public static Method getMethod (String name, Object target, Object[] args)
+    {
+        // grab a whole crapload of class objects
+        Class tclass = target.getClass();
+        Class[] aclasses = new Class[args.length];
+        for (int i = 0; i < aclasses.length; i++) {
+            Class aclass = args[i].getClass();
+            Class mclass = (Class)_classMap.get(aclass);
+            // use the massaged class if there is one
+            aclasses[i] = (mclass == null) ? aclass : mclass;
+        }
+
+        // now look up the method
+        Method meth = null;
+        try {
+            meth = tclass.getMethod(name, aclasses);
+        } catch (NoSuchMethodException nsme) {
+            // nothing to do here but fall through and return null
+            Log.info("No such method [name=" + name +
+                     ", tclass=" + tclass.getName() + 
+                     ", args=" + StringUtil.toString(aclasses) + "].");
+
+        } catch (SecurityException se) {
+            Log.warning("Unable to look up method? " +
+                        "[tclass=" + tclass.getName() +
+                        ", mname=" + name + "].");
+        }
+        return meth;
+    }
+
     /**
      * Locates and returns the first method in the supplied class whose
      * name is equal to the specified name.
@@ -54,4 +111,17 @@ public class ClassUtil
         }
         return null;
     }
+
+    /** Used when massaging arguments into their primitive type. */
+    protected static HashMap _classMap = new HashMap();
+    static {
+        _classMap.put(Boolean.class, Boolean.TYPE);
+        _classMap.put(Byte.class, Byte.TYPE);
+        _classMap.put(Character.class, Character.TYPE);
+        _classMap.put(Short.class, Short.TYPE);
+        _classMap.put(Integer.class, Integer.TYPE);
+        _classMap.put(Long.class, Long.TYPE);
+        _classMap.put(Float.class, Float.TYPE);
+        _classMap.put(Double.class, Double.TYPE);
+    }
 }