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java/org/apache/tomcat/util/digester/FactoryCreateRule.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.tomcat.util.digester;
+
+import org.xml.sax.Attributes;
+
+
+/**
+ * <p>Rule implementation that uses an {@link ObjectCreationFactory} to create
+ * a new object which it pushes onto the object stack.  When the element is
+ * complete, the object will be popped.</p>
+ *
+ * <p>This rule is intended in situations where the element's attributes are
+ * needed before the object can be created.  A common scenario is for the
+ * ObjectCreationFactory implementation to use the attributes  as parameters
+ * in a call to either a factory method or to a non-empty constructor.
+ */
+
+public class FactoryCreateRule extends Rule {
+
+    // ----------------------------------------------------------- Fields
+
+    /** Should exceptions thrown by the factory be ignored? */
+    private boolean ignoreCreateExceptions;
+    /** Stock to manage */
+    private ArrayStack<Boolean> exceptionIgnoredStack;
+
+
+    // ----------------------------------------------------------- Constructors
+
+    /**
+     * Construct a factory create rule using the given, already instantiated,
+     * {@link ObjectCreationFactory}.
+     *
+     * @param creationFactory called on to create the object.
+     * @param ignoreCreateExceptions if true, exceptions thrown by the object
+     *  creation factory will be ignored.
+     */
+    public FactoryCreateRule(
+                            ObjectCreationFactory creationFactory,
+                            boolean ignoreCreateExceptions) {
+
+        this.creationFactory = creationFactory;
+        this.ignoreCreateExceptions = ignoreCreateExceptions;
+    }
+
+
+    // ----------------------------------------------------- Instance Variables
+
+    /**
+     * The object creation factory we will use to instantiate objects
+     * as required based on the attributes specified in the matched XML
+     * element.
+     */
+    protected ObjectCreationFactory creationFactory = null;
+
+
+    // --------------------------------------------------------- Public Methods
+
+
+    /**
+     * Process the beginning of this element.
+     *
+     * @param attributes The attribute list of this element
+     */
+    @Override
+    public void begin(String namespace, String name, Attributes attributes) throws Exception {
+
+        if (ignoreCreateExceptions) {
+
+            if (exceptionIgnoredStack == null) {
+                exceptionIgnoredStack = new ArrayStack<>();
+            }
+
+            try {
+                Object instance = creationFactory.createObject(attributes);
+
+                if (digester.log.isDebugEnabled()) {
+                    digester.log.debug("[FactoryCreateRule]{" + digester.match +
+                            "} New " + instance.getClass().getName());
+                }
+                digester.push(instance);
+                exceptionIgnoredStack.push(Boolean.FALSE);
+
+            } catch (Exception e) {
+                // log message and error
+                if (digester.log.isInfoEnabled()) {
+                    digester.log.info("[FactoryCreateRule] Create exception ignored: " +
+                        ((e.getMessage() == null) ? e.getClass().getName() : e.getMessage()));
+                    if (digester.log.isDebugEnabled()) {
+                        digester.log.debug("[FactoryCreateRule] Ignored exception:", e);
+                    }
+                }
+                exceptionIgnoredStack.push(Boolean.TRUE);
+            }
+
+        } else {
+            Object instance = creationFactory.createObject(attributes);
+
+            if (digester.log.isDebugEnabled()) {
+                digester.log.debug("[FactoryCreateRule]{" + digester.match +
+                        "} New " + instance.getClass().getName());
+            }
+            digester.push(instance);
+        }
+    }
+
+
+    /**
+     * Process the end of this element.
+     */
+    @Override
+    public void end(String namespace, String name) throws Exception {
+
+        // check if object was created
+        // this only happens if an exception was thrown and we're ignoring them
+        if (
+                ignoreCreateExceptions &&
+                exceptionIgnoredStack != null &&
+                !(exceptionIgnoredStack.empty())) {
+
+            if ((exceptionIgnoredStack.pop()).booleanValue()) {
+                // creation exception was ignored
+                // nothing was put onto the stack
+                if (digester.log.isTraceEnabled()) {
+                    digester.log.trace("[FactoryCreateRule] No creation so no push so no pop");
+                }
+                return;
+            }
+        }
+
+        Object top = digester.pop();
+        if (digester.log.isDebugEnabled()) {
+            digester.log.debug("[FactoryCreateRule]{" + digester.match +
+                    "} Pop " + top.getClass().getName());
+        }
+
+    }
+
+
+    /**
+     * Clean up after parsing is complete.
+     */
+    @Override
+    public void finish() throws Exception {
+        // NO-OP
+    }
+
+
+    /**
+     * Render a printable version of this Rule.
+     */
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder("FactoryCreateRule[");
+        if (creationFactory != null) {
+            sb.append("creationFactory=");
+            sb.append(creationFactory);
+        }
+        sb.append("]");
+        return sb.toString();
+    }
+}