better enumeration, no need for SWAP(n>1)

[org.ibex.core.git] / src / org / ibex / js / Interpreter.java

diff --git a/src/org/ibex/js/Interpreter.java b/src/org/ibex/js/Interpreter.java
index c17fcc3..6c8736b 100644 (file)
--- a/src/org/ibex/js/Interpreter.java
+++ b/src/org/ibex/js/Interpreter.java
@@ -86,14 +86,7 @@ class Interpreter implements ByteCodes, Tokens {
             case JF: if (!JS.toBoolean(stack.pop())) pc += JS.toInt((JS)arg) - 1; break;
             case JMP: pc += JS.toInt((JS)arg) - 1; break;
             case POP: stack.pop(); break;
-            case SWAP: {
-                int depth = (arg == null ? 1 : JS.toInt((JS)arg));
-                JS save = stack.elementAt(stack.size() - 1);
-                for(int i=stack.size() - 1; i > stack.size() - 1 - depth; i--)
-                    stack.setElementAt(stack.elementAt(i-1), i);
-                stack.setElementAt(save, stack.size() - depth - 1);
-                break;
-            }
+            case SWAP: stack.swap(); break;
             case DUP: stack.push(stack.peek()); break;
             case NEWSCOPE: scope = new JSScope(scope); break;
             case OLDSCOPE: scope = scope.getParentScope(); break;
@@ -120,11 +113,7 @@ class Interpreter implements ByteCodes, Tokens {
 
             case PUSHKEYS: {
                 JS o = stack.peek();
-                Enumeration e = o.keys();
-                JSArray a = new JSArray();
-                // FEATURE: Take advantage of the Enumeration, don't create a JSArray
-                while(e.hasMoreElements()) a.addElement((JS)e.nextElement());
-                stack.push(a);
+                stack.push(o == null ? null : o.keys());
                 break;
             }
 
@@ -135,7 +124,7 @@ class Interpreter implements ByteCodes, Tokens {
 
             case BREAK:
             case CONTINUE:
-                while(stack.size() > 0) {
+                while(!stack.empty()) {
                     JS o = stack.pop();
                     if (o instanceof CallMarker) je("break or continue not within a loop");
                     if (o instanceof TryMarker) {
@@ -169,7 +158,7 @@ class Interpreter implements ByteCodes, Tokens {
 
             case RETURN: {
                 JS retval = stack.pop();
-                while(stack.size() > 0) {
+                while(!stack.empty()) {
                     Object o = stack.pop();
                     if (o instanceof TryMarker) {
                         if(((TryMarker)o).finallyLoc < 0) continue;
@@ -220,10 +209,7 @@ class Interpreter implements ByteCodes, Tokens {
                 Trap t = null;
                 TrapMarker tm = null;
                 if(target instanceof JSScope && key.jsequals(CASCADE)) {
-                    Object o=null;
-                    int i;
-                    for(i=stack.size()-1;i>=0;i--) if((o = stack.elementAt(i)) instanceof CallMarker) break;
-                    if(i==0) throw new Error("didn't find a call marker while doing cascade");
+                    CallMarker o = stack.findCall();
                     if(o instanceof TrapMarker) {
                         tm = (TrapMarker) o;
                         target = tm.trapee;
@@ -274,10 +260,7 @@ class Interpreter implements ByteCodes, Tokens {
                 Trap t = null;
                 TrapMarker tm = null;
                 if(target instanceof JSScope && key.jsequals(CASCADE)) {
-                    JS o=null;
-                    int i;
-                    for(i=stack.size()-1;i>=0;i--) if((o = stack.elementAt(i)) instanceof CallMarker) break;
-                    if(i==0) throw new Error("didn't find a call marker while doing cascade");
+                    CallMarker o = stack.findCall();
                     if(o instanceof TrapMarker) {
                         tm = (TrapMarker) o;
                         target = tm.trapee;
@@ -355,7 +338,7 @@ class Interpreter implements ByteCodes, Tokens {
             }
 
             case THROW:
-                throw new JSExn(stack.pop(), stack, f, pc, scope);
+                throw new JSExn(stack.pop(), this);
 
                 /* FIXME GRAMMAR
             case MAKE_GRAMMAR: {
@@ -501,7 +484,7 @@ class Interpreter implements ByteCodes, Tokens {
         if a handler is not found the exception is thrown
     */
     void catchException(JSExn e) throws JSExn {
-        while(stack.size() > 0) {
+        while(!stack.empty()) {
             JS o = stack.pop();
             if (o instanceof CatchMarker || o instanceof TryMarker) {
                 boolean inCatch = o instanceof CatchMarker;
@@ -664,27 +647,38 @@ class Interpreter implements ByteCodes, Tokens {
         private static final int MAX_STACK_SIZE = 512;
         private JS[] stack = new JS[64];
         private int sp = 0;
-        public final void push(JS o) throws JSExn {
-            if(sp == stack.length) grow();
-            stack[sp++] = o;
-        }
-        public final JS peek() {
-            if(sp == 0) throw new RuntimeException("Stack underflow");
-            return stack[sp-1];
+        
+        boolean empty() { return sp == 0; }
+        void push(JS o) throws JSExn { if(sp == stack.length) grow(); stack[sp++] = o; }
+        JS peek() { if(sp == 0) throw new RuntimeException("Stack underflow"); return stack[sp-1]; }
+        final JS pop() { if(sp == 0) throw new RuntimeException("Stack underflow"); return stack[--sp]; }
+        void swap() throws JSExn {
+            if(sp < 2) throw new JSExn("stack overflow");
+            JS tmp = stack[sp-2];
+            stack[sp-2] = stack[sp-1];
+            stack[sp-1] = tmp;
         }
-        public final JS pop() {
-            if(sp == 0) throw new RuntimeException("Stack underflow");
-            return stack[--sp];
+        CallMarker findCall() {
+            for(int i=sp-1;i>=0;i--) if(stack[i] instanceof CallMarker) return (CallMarker) stack[i];
+            return null;
         }
-        private void grow() throws JSExn {
+        void grow() throws JSExn {
             if(stack.length >= MAX_STACK_SIZE) throw new JSExn("Stack overflow");
             JS[] stack2 = new JS[stack.length * 2];
             System.arraycopy(stack,0,stack2,0,stack.length);
-        }
-        public int size() { return sp; }
-        public JS elementAt(int i) { return stack[i]; }
+        }       
         
-        // FIXME: Eliminate all uses of SWAP n>1 so we don't need this
-        public void setElementAt(JS o, int i) { stack[i] = o; }
+        void backtrace(JSExn e) {
+            for(int i=sp-1;i>=0;i--) {
+                if (stack[i] instanceof CallMarker) {
+                    CallMarker cm = (CallMarker)stack[i];
+                    if(cm.f == null) break;
+                    String s = cm.f.sourceName + ":" + cm.f.line[cm.pc-1];
+                    if(cm instanceof Interpreter.TrapMarker) 
+                        s += " (trap on " + JS.debugToString(((Interpreter.TrapMarker)cm).key) + ")";
+                    e.addBacktrace(s);
+                }
+            }
+        }
     }
 }