+// Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
+
+package org.xwt.js;
+import org.xwt.util.*;
+import java.io.*;
+import java.util.*;
+
+/** A JavaScript Scope */
+class ScopeImpl extends JS.Obj {
+ private JS.Scope parentScope;
+ private static Object NULL = new Object();
+ public ScopeImpl(JS.Scope parentScope) { this(parentScope, false); }
+ public ScopeImpl(JS.Scope parentScope, boolean sealed) {
+ super(sealed);
+ if (parentScope == this) throw new Error("can't make a scope its own parent!");
+ this.parentScope = parentScope;
+ }
+ public JS.Scope getParentScope() { return parentScope; }
+
+ // transparent scopes are not returned by THIS
+ public boolean isTransparent() { return false; }
+
+ public boolean has(Object key) { return super.get(key) != null; }
+ public Object get(Object key) {
+ if (!has(key)) return parentScope == null ? null : getParentScope().get(key);
+ Object ret = super.get(key); return ret == NULL ? null : ret;
+ }
+ public void put(Object key, Object val) {
+ if (!has(key) && parentScope != null) getParentScope().put(key, val);
+ else super.put(key, val == null ? NULL : val);
+ }
+ public Object[] keys() { throw new Error("you can't enumerate the properties of a Scope"); }
+ public void declare(String s) {
+ if (isTransparent()) getParentScope().declare(s);
+ else super.put(s, NULL);
+ }
+}