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java/javax/el/LambdaExpression.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 javax.el;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+public class LambdaExpression {
+
+    private final List<String> formalParameters;
+    private final ValueExpression expression;
+    private final Map<String,Object> nestedArguments = new HashMap<>();
+    private ELContext context = null;
+
+    public LambdaExpression(List<String> formalParameters,
+            ValueExpression expression) {
+        this.formalParameters = formalParameters;
+        this.expression = expression;
+
+    }
+
+    public void setELContext(ELContext context) {
+        this.context = context;
+    }
+
+    @SuppressWarnings("null") // args[i] can't be null due to earlier checks
+    public Object invoke(ELContext context, Object... args)
+            throws ELException {
+
+        Objects.requireNonNull(context);
+
+        int formalParamCount = 0;
+        if (formalParameters != null) {
+            formalParamCount = formalParameters.size();
+        }
+
+        int argCount = 0;
+        if (args != null) {
+            argCount = args.length;
+        }
+
+        if (formalParamCount > argCount) {
+            throw new ELException(Util.message(context,
+                    "lambdaExpression.tooFewArgs",
+                    Integer.valueOf(argCount),
+                    Integer.valueOf(formalParamCount)));
+        }
+
+        // Build the argument map
+        // Start with the arguments from any outer expressions so if there is
+        // any overlap the local arguments have priority
+        Map<String,Object> lambdaArguments = new HashMap<>();
+        lambdaArguments.putAll(nestedArguments);
+        for (int i = 0; i < formalParamCount; i++) {
+            lambdaArguments.put(formalParameters.get(i), args[i]);
+        }
+
+        context.enterLambdaScope(lambdaArguments);
+
+        try {
+            Object result = expression.getValue(context);
+            // Make arguments from this expression available to any nested
+            // expression
+            if (result instanceof LambdaExpression) {
+                ((LambdaExpression) result).nestedArguments.putAll(
+                        lambdaArguments);
+            }
+            return result;
+        } finally {
+            context.exitLambdaScope();
+        }
+    }
+
+    public java.lang.Object invoke(Object... args) {
+        return invoke (context, args);
+    }
+}