1/*
2 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25package com.sun.beans.decoder;
26
27import com.sun.beans.finder.ConstructorFinder;
28
29import java.lang.reflect.Array;
30import java.lang.reflect.Constructor;
31
32import java.util.ArrayList;
33import java.util.List;
34
35/**
36 * This class is intended to handle <new> element.
37 * It describes instantiation of the object.
38 * The {@code class} attribute denotes
39 * the name of the class to instantiate.
40 * The inner elements specifies the arguments of the constructor.
41 * For example:<pre>
42 * &lt;new class="java.lang.Long"&gt;
43 *     &lt;string&gt;10&lt;/string&gt;
44 * &lt;/new&gt;</pre>
45 * is equivalent to {@code Long.valueOf("10")} in Java code.
46 * <p>The following attributes are supported:
47 * <dl>
48 * <dt>class
49 * <dd>the type of object for instantiation
50 * <dt>id
51 * <dd>the identifier of the variable that is intended to store the result
52 * </dl>
53 *
54 * @since 1.7
55 *
56 * @author Sergey A. Malenkov
57 */
58class NewElementHandler extends ElementHandler {
59    private List<Object> arguments = new ArrayList<Object>();
60    private ValueObject value = ValueObjectImpl.VOID;
61
62    private Class<?> type;
63
64    /**
65     * Parses attributes of the element.
66     * The following attributes are supported:
67     * <dl>
68     * <dt>class
69     * <dd>the type of object for instantiation
70     * <dt>id
71     * <dd>the identifier of the variable that is intended to store the result
72     * </dl>
73     *
74     * @param name   the attribute name
75     * @param value  the attribute value
76     */
77    @Override
78    public void addAttribute(String name, String value) {
79        if (name.equals("class")) { // NON-NLS: the attribute name
80            this.type = getOwner().findClass(value);
81        } else {
82            super.addAttribute(name, value);
83        }
84    }
85
86    /**
87     * Adds the argument to the list of arguments
88     * that is used to calculate the value of this element.
89     *
90     * @param argument  the value of the element that contained in this one
91     */
92    @Override
93    protected final void addArgument(Object argument) {
94        if (this.arguments == null) {
95            throw new IllegalStateException("Could not add argument to evaluated element");
96        }
97        this.arguments.add(argument);
98    }
99
100    /**
101     * Returns the context of the method.
102     * The context of the static method is the class object.
103     * The context of the non-static method is the value of the parent element.
104     *
105     * @return the context of the method
106     */
107    @Override
108    protected final Object getContextBean() {
109        return (this.type != null)
110                ? this.type
111                : super.getContextBean();
112    }
113
114    /**
115     * Returns the value of this element.
116     *
117     * @return the value of this element
118     */
119    @Override
120    protected final ValueObject getValueObject() {
121        if (this.arguments != null) {
122            try {
123                this.value = getValueObject(this.type, this.arguments.toArray());
124            }
125            catch (Exception exception) {
126                getOwner().handleException(exception);
127            }
128            finally {
129                this.arguments = null;
130            }
131        }
132        return this.value;
133    }
134
135    /**
136     * Calculates the value of this element
137     * using the base class and the array of arguments.
138     * By default, it creates an instance of the base class.
139     * This method should be overridden in those handlers
140     * that extend behavior of this element.
141     *
142     * @param type  the base class
143     * @param args  the array of arguments
144     * @return the value of this element
145     * @throws Exception if calculation is failed
146     */
147    ValueObject getValueObject(Class<?> type, Object[] args) throws Exception {
148        if (type == null) {
149            throw new IllegalArgumentException("Class name is not set");
150        }
151        Class<?>[] types = getArgumentTypes(args);
152        Constructor<?> constructor = ConstructorFinder.findConstructor(type, types);
153        if (constructor.isVarArgs()) {
154            args = getArguments(args, constructor.getParameterTypes());
155        }
156        return ValueObjectImpl.create(constructor.newInstance(args));
157    }
158
159    /**
160     * Converts the array of arguments to the array of corresponding classes.
161     * If argument is {@code null} the class is {@code null} too.
162     *
163     * @param arguments  the array of arguments
164     * @return the array of corresponding classes
165     */
166    static Class<?>[] getArgumentTypes(Object[] arguments) {
167        Class<?>[] types = new Class<?>[arguments.length];
168        for (int i = 0; i < arguments.length; i++) {
169            if (arguments[i] != null) {
170                types[i] = arguments[i].getClass();
171            }
172        }
173        return types;
174    }
175
176    /**
177     * Resolves variable arguments.
178     *
179     * @param arguments  the array of arguments
180     * @param types      the array of parameter types
181     * @return the resolved array of arguments
182     */
183    static Object[] getArguments(Object[] arguments, Class<?>[] types) {
184        int index = types.length - 1;
185        if (types.length == arguments.length) {
186            Object argument = arguments[index];
187            if (argument == null) {
188                return arguments;
189            }
190            Class<?> type = types[index];
191            if (type.isAssignableFrom(argument.getClass())) {
192                return arguments;
193            }
194        }
195        int length = arguments.length - index;
196        Class<?> type = types[index].getComponentType();
197        Object array = Array.newInstance(type, length);
198        System.arraycopy(arguments, index, array, 0, length);
199
200        Object[] args = new Object[types.length];
201        System.arraycopy(arguments, 0, args, 0, index);
202        args[index] = array;
203        return args;
204    }
205}
206