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From ra...@apache.org
Subject svn commit: r307370 - /jakarta/commons/sandbox/scxml/trunk/src/main/java/org/apache/commons/scxml/env/faces/ShaleDialogELEvaluator.java
Date Sun, 09 Oct 2005 05:42:25 GMT
Author: rahul
Date: Sat Oct  8 22:42:23 2005
New Revision: 307370

URL: http://svn.apache.org/viewcvs?rev=307370&view=rev
Log:
Exploring use of SCXML documents for describing Shale dialogs.

Added:
    jakarta/commons/sandbox/scxml/trunk/src/main/java/org/apache/commons/scxml/env/faces/ShaleDialogELEvaluator.java
  (with props)

Added: jakarta/commons/sandbox/scxml/trunk/src/main/java/org/apache/commons/scxml/env/faces/ShaleDialogELEvaluator.java
URL: http://svn.apache.org/viewcvs/jakarta/commons/sandbox/scxml/trunk/src/main/java/org/apache/commons/scxml/env/faces/ShaleDialogELEvaluator.java?rev=307370&view=auto
==============================================================================
--- jakarta/commons/sandbox/scxml/trunk/src/main/java/org/apache/commons/scxml/env/faces/ShaleDialogELEvaluator.java
(added)
+++ jakarta/commons/sandbox/scxml/trunk/src/main/java/org/apache/commons/scxml/env/faces/ShaleDialogELEvaluator.java
Sat Oct  8 22:42:23 2005
@@ -0,0 +1,154 @@
+/*
+ *
+ *   Copyright 2005 The Apache Software Foundation.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ */
+package org.apache.commons.scxml.env.faces;
+
+import java.util.regex.Pattern;
+
+import javax.faces.context.FacesContext;
+import javax.faces.el.EvaluationException;
+import javax.faces.el.MethodBinding;
+import javax.faces.el.MethodNotFoundException;
+import javax.faces.el.ReferenceSyntaxException;
+
+import org.apache.commons.scxml.Context;
+import org.apache.commons.scxml.Evaluator;
+import org.apache.commons.scxml.SCXMLExpressionException;
+import org.apache.commons.scxml.env.jsp.ELEvaluator;
+
+/**
+ * <p>EL evaluator, for evaluating the expressions in SCXML documents used
+ * to specify Shale dialogs.</p>
+ *
+ * <p>This evaluator uses the following premises for evaluation:
+ *   <ol>
+ *     <li>JSF method binding expressions will take the form:
+ *         #{...}
+ *         These will return a <code>java.lang.String</code> object as
+ *         required by the methods associated with
+ *         <code>org.apache.shale.dialog.ActionState</code></li>
+ *     <li>JSP 2.0 EL expressions will take the form:
+ *         ${...}</li>
+ *   </ol>
+ * </p>
+ *
+ * <p>This evaluator delegates to the following expression evaluators:
+ *   <ol>
+ *     <li>JSF method binding expressions get delegated to the JSF
+ *         implementation (Ex: Apache MyFaces).</li>
+ *     <li>JSP expressions get delegated to the Apache Jakarta Commons
+ *         EL ExpressionEvaluator implementation. This evaluator adds
+ *         ability to evaluate special predicates defined by SCXML.</li>
+ *   </ol>
+ * </p>
+ */
+public class ShaleDialogELEvaluator extends ELEvaluator {
+
+    /**
+     * Shale ActionState method parameters.
+     *
+     * @see org.apache.shale.dialog.faces.DialogNavigationHandler.PARAMETERS
+     */
+    private static final Object[] PARAMETERS = new Object[0];
+    /**
+     * Shale ActionState method signature.
+     *
+     * @see org.apache.shale.dialog.faces.DialogNavigationHandler.SIGNATURE
+     */
+    private static final Class[] SIGNATURE = new Class[0];
+
+    // We do not have the privilege of having specific element attributes
+    // associated with specific types of expressions
+    /** Pattern for recognizing the method / value binding expression. */
+    private static Pattern jsfBindingExpr =
+        Pattern.compile("^\\s*#\\{.*\\}\\s*$");
+    /** FacesContext for this request. */
+    private FacesContext context;
+
+    /**
+     * Constructor.
+     */
+    public ShaleDialogELEvaluator() {
+        super();
+    }
+
+    /**
+     * Set per request context.
+     *
+     * @param context The FacesContext for this request.
+     */
+    public void setFacesContext(final FacesContext context) {
+        this.context = context;
+    }
+
+    /**
+     * Evaluate an expression.
+     *
+     * @param ctx variable context
+     * @param expr expression
+     * @return Object The result of the evaluation
+     * @throws SCXMLExpressionException For a malformed expression
+     * @see Evaluator#eval(Context, String)
+     */
+    public Object eval(final Context ctx, final String expr)
+    throws SCXMLExpressionException {
+        if (jsfBindingExpr.matcher(expr).matches()) {
+            return invokeShaleActionStateMethod(expr);
+        }
+        return super.eval(ctx, expr);
+    }
+
+    /**
+     * Evaluate a boolean expression.
+     *
+     * @param ctx variable context
+     * @param expr expression
+     * @return Boolean The result of the evaluation
+     * @throws SCXMLExpressionException For a malformed expression
+     * @see Evaluator#evalCond(Context, String)
+     */
+    public Boolean evalCond(final Context ctx, final String expr)
+    throws SCXMLExpressionException {
+        return super.evalCond(ctx, expr);
+    }
+
+    /**
+     * Invoke method binding expression for Shale <code>ActionState</code>.
+     * Shale requires return type to be a <code>java.lang.String</code>.
+     *
+     * @param expr Method binding expression
+     * @return String Method return value
+     * @throws SCXMLExpressionException Re-throw potential Faces
+     *                  exceptions as a SCXMLExpressionException.
+     */
+    private String invokeShaleActionStateMethod(final String expr)
+    throws SCXMLExpressionException {
+        try {
+            MethodBinding mb = context.getApplication().
+                createMethodBinding(expr, SIGNATURE);
+            return (String) mb.invoke(context, PARAMETERS);
+        } catch (ReferenceSyntaxException rse) {
+            throw new SCXMLExpressionException(rse);
+        } catch (MethodNotFoundException mnfe) {
+            throw new SCXMLExpressionException(mnfe);
+        } catch (EvaluationException ee) {
+            throw new SCXMLExpressionException(ee);
+        }
+    }
+
+}
+

Propchange: jakarta/commons/sandbox/scxml/trunk/src/main/java/org/apache/commons/scxml/env/faces/ShaleDialogELEvaluator.java
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Propchange: jakarta/commons/sandbox/scxml/trunk/src/main/java/org/apache/commons/scxml/env/faces/ShaleDialogELEvaluator.java
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    svn:keywords = Date Author Id Revision HeadURL



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