keyword interning, identity equality

3 files changed, 13 insertions, 30 deletions

diff --git a/src/jvm/clojure/lang/Keyword.java b/src/jvm/clojure/lang/Keyword.java
index ccdca37d..1576a20d 100644
--- a/src/jvm/clojure/lang/Keyword.java
+++ b/src/jvm/clojure/lang/Keyword.java
@@ -12,45 +12,28 @@
 
 package clojure.lang;
 
-
-public class Keyword implements IFn{
+import java.util.concurrent.ConcurrentHashMap;
 
 
-/**
- * Used by intern()
- *
- * @param name
- */
+public class Keyword implements IFn{
 
+private static ConcurrentHashMap<Symbol, Keyword> table = new ConcurrentHashMap();
 public final Symbol sym;
-final int hash;
 
-public Keyword(Symbol sym){
-	this.sym = sym;
-	this.hash = RT.hashCombine(":".hashCode(), sym.hashCode());
+public static Keyword intern(Symbol sym){
+	Keyword k = new Keyword(sym);
+	Keyword existingk = table.putIfAbsent(sym, k);
+	return existingk == null ? k : existingk;
 }
 
-public Keyword(String ns, String name){
-	this(Symbol.intern(ns, name));
+public static Keyword intern(String ns, String name){
+	return intern(Symbol.intern(ns, name));
 }
 
-public boolean equals(Object o){
-	if(this == o)
-		return true;
-	if(o == null || !(o instanceof Keyword))
-		return false;
-
-	Keyword keyword = (Keyword) o;
-
-	//identity compares intended, names are interned
-	return sym.equals(keyword.sym);
-}
-
-public int hashCode(){
-	return hash;
+private Keyword(Symbol sym){
+	this.sym = sym;
 }
 
-
 public String toString(){
 	return ":" + sym;
 }
diff --git a/src/jvm/clojure/lang/LispReader.java b/src/jvm/clojure/lang/LispReader.java
index 3556fbe9..01614c78 100644
--- a/src/jvm/clojure/lang/LispReader.java
+++ b/src/jvm/clojure/lang/LispReader.java
@@ -268,7 +268,7 @@ private static Object matchSymbol(String s){
 		boolean isKeyword = s.charAt(0) == ':';

 		Symbol sym = Symbol.intern(s.substring(isKeyword ? 1 : 0));

 		if(isKeyword)

-			return new Keyword(sym);

+			return Keyword.intern(sym);

 		return sym;

 		}

 	return null;

diff --git a/src/jvm/clojure/lang/RT.java b/src/jvm/clojure/lang/RT.java
index 94451504..0069ffd7 100644
--- a/src/jvm/clojure/lang/RT.java
+++ b/src/jvm/clojure/lang/RT.java
@@ -21,7 +21,7 @@ public class RT{
 static public Symbol T = Symbol.create(null, "t");
 final static public DynamicVar OUT =
 		DynamicVar.intern(Symbol.create("clojure", "out"), new OutputStreamWriter(System.out));
-final static Keyword TAG_KEY = new Keyword("clojure", "tag");
+final static Keyword TAG_KEY = Keyword.intern("clojure", "tag");
 
 final static public DynamicVar CURRENT_MODULE = DynamicVar.intern(Symbol.create("clojure", "current-module"),
                                                                   Module.findOrCreateModule("clojure/user"));