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src/FESI/Interpreter/ScopeChain.java

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+// ScopeChain.java
+// FESI Copyright (c) Jean-Marc Lugrin, 1999
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 2 of the License, or (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+package FESI.Interpreter;
+
+import FESI.Exceptions.*;
+import FESI.Data.*;
+
+/**
+ * The scope chaine has established by WITH statements. Used to 
+ * lookup values by name.
+ */
+public class ScopeChain {
+    private ScopeChain previousElement;
+    private ESObject thisElement;
+    
+    /**
+     * CReate a new scope chain linked to a previous one (which
+     * is null only for the topmost chain)
+     * @param thisElement Object to look at at this level
+     * @param previousElement previous object in scope chain
+     */
+    ScopeChain(ESObject thisElement, ScopeChain previousElement) {
+        this.previousElement = previousElement;
+        this.thisElement = thisElement;
+    }
+    
+    /** 
+     * Return the previous element in scope chain
+     * @return The previous element
+     */
+    ScopeChain previousScope() {
+        return previousElement;
+    }
+    
+
+    /**
+     * Return a reference to an object in the scope chain, so that the value
+     * can be accessed or modified.
+     *
+     * @param   identifier  The name of the object
+     * @return  an ESReference object    
+     * @exception  EcmaScriptException Not thrown 
+     */
+    public ESReference getReference(String identifier) throws EcmaScriptException {
+      return getReference(identifier, identifier.hashCode());
+   } 
+
+    /**
+     * Return a reference to an object in the scope chain, so that the value
+     * can be accessed or modified.
+     *
+     * @param   identifier  The name of the object
+     * @param   hash The hashCode of this identifier
+     * @return  an ESReference object    
+     * @exception   EcmaScriptException  Not thrown
+     */
+    public ESReference getReference(String identifier, int hash) throws EcmaScriptException {
+          ScopeChain theChain = this;
+          do {
+              if (theChain.thisElement.hasProperty(identifier, hash)) {
+                  return new ESReference(theChain.thisElement, identifier, hash);
+              }
+              theChain = theChain.previousElement;
+          } while (theChain != null);
+      return new ESReference(null, identifier, hash);
+   } 
+    
+
+    /**
+     * Return a value for an object in the scope chain.
+     * return ESUndefined for undefined properties of existing objects,
+     * but generate an error for unexistent object.
+     * <P>A variant of getProperty is used, which will call recursively
+     * this routine and the getProperty in a previous scope until all
+     * scopes have been examined or a value is returned. This avoid the
+     * call of hasProperty followed by a second call to getProperty to
+     * get the property value.
+     *
+     * @param   identifier  The name of the object
+     * @return  The value of the object, possibly ESUndefined
+     * @exception   EcmaScriptException  if no global object has that value
+     */
+   public ESValue getValue(String identifier) throws EcmaScriptException {
+       return getValue(identifier, identifier.hashCode());
+   }
+
+
+    /**
+     * Return a value for an object in the scope chain.
+     * return ESUndefined for undefined properties of existing objects,
+     * but generate an error for unexistent object.
+     * <P>A variant of getProperty is used, which will call recursively
+     * this routine and the getProperty in a previous scope until all
+     * scopes have been examined or a value is returned. This avoid the
+     * call of hasProperty followed by a second call to getProperty to
+     * get the property value.
+     *
+     * @param   identifier  The name of the object
+     * @param hash The hash code of the element (for optimization)
+     * @return  The value of the object, possibly ESUndefined
+     * @exception   EcmaScriptException  if no global object has that value
+     */
+   public ESValue getValue(String identifier, int hash) throws EcmaScriptException {
+       return thisElement.getPropertyInScope(identifier, previousElement, hash);
+   }
+    
+    
+    /**
+     * Call a function defined by name in the scope chain.
+     * <P>A variant of doCall is used, which will call recursively
+     * this routine and the doCall in a previous scope until all
+     * scopes have been examined or a value is returned. This avoid the
+     * call of hasProperty followed by a second call to getProperty to
+     * get the property value.
+     *
+     * @param   evaluator  The evaluator doing the call
+     * @param   thisObject  The 'this' object of the call
+     * @param   functionName  The name of the function to call
+     * @param hash The hash code of the function name (for optimization)
+     * @param arguments The parameters of the call
+     * @return  The result of the call, possibly NULL
+     * @exception   EcmaScriptException  for any error
+     */
+   public ESValue doIndirectCall(Evaluator evaluator,
+                                ESObject thisObject, 
+                                String functionName,
+                                int hash, 
+                                ESValue[] arguments) throws EcmaScriptException {
+       return thisElement.doIndirectCallInScope(evaluator, previousElement, thisObject, functionName, hash, arguments);
+   }
+
+}