jsstring caching

darcs-hash:20040706104249-24bed-bbff3a3b5232fc7709897a7f856f997512350722.gz

diff --git a/src/org/ibex/js/JS.java b/src/org/ibex/js/JS.java
index d8d0f33..04d7edd 100644 (file)
--- a/src/org/ibex/js/JS.java
+++ b/src/org/ibex/js/JS.java
@@ -209,7 +209,15 @@ public abstract class JS {
     public static final JS B(boolean b) { return b ? T : F; }
     public static final JS B(int i) { return i==0 ? F : T; }
     
-    public static final JS S(String s) { return new JSString(s); }
+    private static final int CACHE_SIZE = 65536 / 4; // must be a power of two
+    private static final JSString[] stringCache = new JSString[CACHE_SIZE];
+    public static final JS S(String s)  {
+        if(s == null) return null;
+        int slot = s.hashCode()&(CACHE_SIZE-1);
+        JSString ret = stringCache[slot];
+        if(ret == null || !ret.s.equals(s)) stringCache[slot] = ret = new JSString(s);
+        return ret;
+    }
 
     public static final JS N(double d) { return new JSNumber.D(d); }
     public static final JS N(long l) { return new JSNumber.L(l); }
@@ -220,20 +228,20 @@ public abstract class JS {
         return N(n.doubleValue());
     }
 
-    private static final JSNumber.I[] smallIntCache = new JSNumber.I[65535 / 4];
-    private static final JSNumber.I[] largeIntCache = new JSNumber.I[65535 / 4];
+    private static final JSNumber.I[] smallIntCache = new JSNumber.I[CACHE_SIZE];
+    private static final JSNumber.I[] largeIntCache = new JSNumber.I[CACHE_SIZE];
     public static final JS N(int i) {
         JSNumber.I ret = null;
         int idx = i + smallIntCache.length / 2;
-        if (idx < smallIntCache.length && idx > 0) {
+        if (idx < CACHE_SIZE && idx > 0) {
             ret = smallIntCache[idx];
             if (ret != null) return ret;
         }
-        else ret = largeIntCache[Math.abs(idx % largeIntCache.length)];
+        else ret = largeIntCache[Math.abs(idx % CACHE_SIZE)];
         if (ret == null || ret.i != i) {
             ret = new JSNumber.I(i);
             if (idx < smallIntCache.length && idx > 0) smallIntCache[idx] = ret;
-            else largeIntCache[Math.abs(idx % largeIntCache.length)] = ret;
+            else largeIntCache[Math.abs(idx % CACHE_SIZE)] = ret;
         }
         return ret;
     }