Added support for case tags.

3 files changed, 24 insertions, 1 deletions

diff --git a/sources/scala/Object.java b/sources/scala/Object.java
index e0144b1cae..4a44ad0caa 100644
--- a/sources/scala/Object.java
+++ b/sources/scala/Object.java
@@ -14,4 +14,11 @@ package scala;
 /** @meta class extends scala.AnyRef;
  */
 public class Object {
+
+    /** This method is needed for optimizing pattern matching expressions
+     *  which match on constructors of case classes.
+     */
+    public int $tag() {
+    	return 0;
+    }
 }
diff --git a/sources/scalac/symtab/Symbol.java b/sources/scalac/symtab/Symbol.java
index c3da3e15d9..28772e6bc5 100644
--- a/sources/scalac/symtab/Symbol.java
+++ b/sources/scalac/symtab/Symbol.java
@@ -1051,6 +1051,13 @@ public abstract class Symbol implements Modifiers, Kinds {
 	this.infos = TypeIntervalList.EMPTY;
 	this.setInfo(completer);
     }
+
+    /** return a tag which (in the ideal case) uniquely identifies
+     *  class symbols
+     */
+  	public int tag() {
+  		return name.toString().hashCode();
+  	}
 }
 
 /** A class for term symbols
diff --git a/sources/scalac/typechecker/RefCheck.java b/sources/scalac/typechecker/RefCheck.java
index 460e98abeb..d25c547e20 100644
--- a/sources/scalac/typechecker/RefCheck.java
+++ b/sources/scalac/typechecker/RefCheck.java
@@ -588,7 +588,6 @@ public class RefCheck extends Transformer implements Modifiers, Kinds {
 		testtp = testtp.subst(tparams, targs);
 	    }
 	}
-
 	// if (that is C) {...
 	Tree cond = gen.TypeApply(
 	    gen.Select(
@@ -639,6 +638,15 @@ public class RefCheck extends Transformer implements Modifiers, Kinds {
 	    return gen.Select(qual, clazz.caseFieldAccessor(i));
 	}
 
+	private Tree tagMethod(ClassSymbol clazz) {
+        Symbol tagSym = new TermSymbol(
+            clazz.pos, Names.tag, clazz,
+            clazz.isSubClass(defs.OBJECT_CLASS) ? OVERRIDE : 0)
+            .setInfo(Type.MethodType(Symbol.EMPTY_ARRAY, defs.INT_TYPE));
+        clazz.info().members().enter(tagSym);
+        return gen.DefDef(clazz.pos, tagSym, gen.mkIntLit(clazz.pos, clazz.tag()));
+	}
+
     private Tree hashCodeMethod(ClassSymbol clazz) {
 	Symbol hashCodeSym = new TermSymbol(
 	    clazz.pos, Names.hashCode, clazz, OVERRIDE)
@@ -693,6 +701,7 @@ public class RefCheck extends Transformer implements Modifiers, Kinds {
 	    ts.append(equalsMethod(clazz));
 	if (!hasImplementation(clazz, Names.hashCode))
 	    ts.append(hashCodeMethod(clazz));
+	ts.append(tagMethod(clazz));
 	if (ts.length() > 0) {
 	    Tree[] stats1 = new Tree[stats.length + ts.length()];
 	    System.arraycopy(stats, 0, stats1, 0, stats.length);