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java/org/apache/el/lang/VariableMapperFactory.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.el.lang;
+
+import javax.el.ValueExpression;
+import javax.el.VariableMapper;
+
+public class VariableMapperFactory extends VariableMapper {
+
+    private final VariableMapper target;
+    private VariableMapper momento;
+
+    public VariableMapperFactory(VariableMapper target) {
+        if (target == null) {
+            throw new NullPointerException("Target VariableMapper cannot be null");
+        }
+        this.target = target;
+    }
+
+    public VariableMapper create() {
+        return this.momento;
+    }
+
+    @Override
+    public ValueExpression resolveVariable(String variable) {
+        ValueExpression expr = this.target.resolveVariable(variable);
+        if (expr != null) {
+            if (this.momento == null) {
+                this.momento = new VariableMapperImpl();
+            }
+            this.momento.setVariable(variable, expr);
+        }
+        return expr;
+    }
+
+    @Override
+    public ValueExpression setVariable(String variable, ValueExpression expression) {
+        throw new UnsupportedOperationException("Cannot Set Variables on Factory");
+    }
+}