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java/org/apache/el/stream/Optional.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.stream;
+
+import javax.el.ELException;
+import javax.el.LambdaExpression;
+
+import org.apache.el.util.MessageFactory;
+
+public class Optional {
+
+    private final Object obj;
+
+    static final Optional EMPTY = new Optional(null);
+
+    Optional(Object obj) {
+        this.obj = obj;
+    }
+
+
+    public Object get() throws ELException {
+        if (obj == null) {
+            throw new ELException(MessageFactory.get("stream.optional.empty"));
+        } else {
+            return obj;
+        }
+    }
+
+
+    public void ifPresent(LambdaExpression le) {
+        if (obj != null) {
+            le.invoke(obj);
+        }
+    }
+
+
+    public Object orElse(Object other) {
+        if (obj == null) {
+            return other;
+        } else {
+            return obj;
+        }
+    }
+
+
+    public Object orElseGet(Object le) {
+        if (obj == null) {
+            // EL 3.0 specification says parameter is LambdaExpression but it
+            // may already have been evaluated. If that is the case, the
+            // original parameter will have been checked to ensure it was a
+            // LambdaExpression before it was evaluated.
+
+            if (le instanceof LambdaExpression) {
+                return ((LambdaExpression) le).invoke((Object[]) null);
+            } else {
+                return le;
+            }
+        } else {
+            return obj;
+        }
+    }
+}

java/org/apache/el/stream/StreamELResolverImpl.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.stream;
+
+import java.beans.FeatureDescriptor;
+import java.lang.reflect.Array;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+import javax.el.ELContext;
+import javax.el.ELResolver;
+
+public class StreamELResolverImpl extends ELResolver {
+
+    @Override
+    public Object getValue(ELContext context, Object base, Object property) {
+        return null;
+    }
+
+    @Override
+    public Class<?> getType(ELContext context, Object base, Object property) {
+        return null;
+    }
+
+    @Override
+    public void setValue(ELContext context, Object base, Object property,
+            Object value) {
+        // NO-OP
+    }
+
+    @Override
+    public boolean isReadOnly(ELContext context, Object base, Object property) {
+        return false;
+    }
+
+    @Override
+    public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context,
+            Object base) {
+        return null;
+    }
+
+    @Override
+    public Class<?> getCommonPropertyType(ELContext context, Object base) {
+        return null;
+    }
+
+    @Override
+    public Object invoke(ELContext context, Object base, Object method,
+            Class<?>[] paramTypes, Object[] params) {
+
+        if ("stream".equals(method) && params.length == 0) {
+            if (base.getClass().isArray()) {
+                context.setPropertyResolved(true);
+                return new Stream(new ArrayIterator(base));
+            } else if (base instanceof Collection) {
+                context.setPropertyResolved(true);
+                @SuppressWarnings("unchecked")
+                Collection<Object> collection = (Collection<Object>) base;
+                return new Stream(collection.iterator());
+            }
+        }
+
+        // Not for handling by this resolver
+        return null;
+    }
+
+
+    private static class ArrayIterator implements Iterator<Object> {
+
+        private final Object base;
+        private final int size;
+        private int index = 0;
+
+        public ArrayIterator(Object base) {
+            this.base = base;
+            size = Array.getLength(base);
+        }
+
+        @Override
+        public boolean hasNext() {
+            return size > index;
+        }
+
+        @Override
+        public Object next() {
+            try {
+                return Array.get(base, index++);
+            } catch (ArrayIndexOutOfBoundsException e) {
+                throw new NoSuchElementException();
+            }
+        }
+
+        @Override
+        public void remove() {
+            throw new UnsupportedOperationException();
+        }
+    }
+}