001// Copyright 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.plastic;
016
017import java.lang.annotation.Annotation;
018import java.lang.reflect.Method;
019import java.util.List;
020import java.util.Set;
021
022/**
023 * The representation of a class while it is being instrumented and transformed. PlasticClass allows
024 * for an imperative style of development: the PlasticClass is provided to other objects; they can query it
025 * for relevant fields or methods, and invoke methods that modify the class in various ways. Ultimately, the
026 * end result is a {@link ClassInstantiator} used to create instances of the fully instrumented and transformed class.
027 * <p/>
028 * The terminology is that a class that is being transformed is "plastic", but the end result is a normal concrete class
029 * (albeit in a different class loader).
030 * <p/>
031 * Implements {@link AnnotationAccess} to provide access to annotations on the type itself.
032 * <p/>
033 * This class is expressly <em>not thread safe</em>; only a single thread should be responsible for operating on a
034 * PlasticClass.
035 * <p/>
036 * TODO: what about annotation inheritance?
037 */
038@SuppressWarnings("rawtypes")
039public interface PlasticClass extends AnnotationAccess
040{
041    /**
042     * Returns the fully qualified class name of the class being transformed.
043     */
044    String getClassName();
045
046    /**
047     * Matches all fields (claimed or not) that have the given annotation. Returns the fields in sorted order.
048     *
049     * @return Unmodifiable List of fields.
050     */
051    <T extends Annotation> List<PlasticField> getFieldsWithAnnotation(Class<T> annotationType);
052
053    /**
054     * Returns all non-introduced fields, in sorted order by name.
055     *
056     * @return Unmodifiable list of fields.
057     */
058    List<PlasticField> getAllFields();
059
060    /**
061     * Returns all unclaimed fields, in sorted order by name. This does not include introduced fields.
062     *
063     * @return Unmodifiable list of fields.
064     * @see PlasticField#claim(Object)
065     */
066    List<PlasticField> getUnclaimedFields();
067
068    /**
069     * Introduces a new private field into the class.
070     *
071     * @param typeName      the Java class name for the field, or (possibly) a primitive type name or an array
072     * @param suggestedName the suggested name for the field, which may be modified to ensure that the field name
073     *                      is unique
074     * @return PlasticField for the introduced field
075     */
076    PlasticField introduceField(String typeName, String suggestedName);
077
078    /**
079     * Convenience method that uses a Java class rather than a type name.
080     */
081    PlasticField introduceField(Class fieldType, String suggestedName);
082
083    /**
084     * Introduces a new private method into the class, ensuring that the method name is unique.
085     *
086     * @param typeName       return type of method
087     * @param suggestedName  suggested name for the method; the actual method name may be modified to ensure uniqueness
088     * @param argumentTypes  types of any arguments (may be null)
089     * @param exceptionTypes type of any checked exceptions (may be null)
090     * @return new method, with default implementation
091     */
092    PlasticMethod introducePrivateMethod(String typeName, String suggestedName, String[] argumentTypes,
093                                         String[] exceptionTypes);
094
095    /**
096     * Matches methods with the given annotation.
097     *
098     * @return Unmodifiable list of methods, in sorted order.
099     */
100    <T extends Annotation> List<PlasticMethod> getMethodsWithAnnotation(Class<T> annotationType);
101
102    /**
103     * Returns all methods of the class, in sorted order. This does not include static methods,
104     * or any {@linkplain #introduceMethod(MethodDescription) introduced methods}.
105     *
106     * @return Unmodifiable list of methods.
107     */
108    List<PlasticMethod> getMethods();
109
110    /**
111     * Returns an existing method declared in this class, or introduces a new method into this class.
112     * The method is created with default behavior. If the method overrides a non-private, non-abstract method
113     * implemented in a <em>transformed</em> super class, the the default behavior is to invoke that method and return
114     * its value. Otherwise, the default behavior is to ignore parameters and return 0, false, or null. Void methods
115     * will invoke the super-class implementation (if it exists) and return no value.
116     * <p/>
117     * It is allowed for the method description to indicate an abstract method; however the abstract flag will be
118     * removed, and a non-abstract method will be created.
119     *
120     * @param description describes the method name, visibility, return value, etc.
121     * @return a new (or previously created) PlasticMethod for the method
122     * @throws IllegalArgumentException if the method is abstract or static
123     */
124    PlasticMethod introduceMethod(MethodDescription description);
125
126    /**
127     * Returns an existing method declared in this class, or introduces a new method into this class.
128     * The method is created with default behavior.
129     * <p/>
130     * It is allowed for the method description to indicate an abstract method; however the abstract flag will be
131     * removed, and a non-abstract method will be created.
132     *
133     * @param description describes the method name, visibility, return value, etc.
134     * @param callback    used to create the implementation of the method
135     * @return a new (or previously created) PlasticMethod for the method
136     * @throws IllegalArgumentException if the method is abstract or static
137     */
138    PlasticMethod introduceMethod(MethodDescription description, InstructionBuilderCallback callback);
139
140    /**
141     * A convenience that creates a {@link MethodDescription} from the Method and introduces that. This is often
142     * invoked when walking the methods of an interface and introducing each of those methods.
143     * <p/>
144     * Introduced methods are always concrete, not abstract. The abstract flag on the method modifiers will always be
145     * stripped off, which is handy when {@linkplain #introduceInterface(Class) introducing methods from an interface}.
146     *
147     * @param method to introduce
148     * @return new (or previously created) PlasticMethod
149     */
150    PlasticMethod introduceMethod(Method method);
151
152    /**
153     * Introduces each method defined by the interface into the class. Determines which new methods must
154     * be introduced in order to ensure that all methods of the interface are implemented. The newly introduced methods,
155     * if any, are returned.
156     */
157    Set<PlasticMethod> introduceInterface(Class interfaceType);
158
159    /**
160     * Introduces the interface, and then invokes {@link PlasticMethod#delegateTo(PlasticField)} on each method
161     * defined by the interface.
162     *
163     * @param interfaceType defines the interface to proxy
164     * @param field         field containing an object to delegate to
165     * @return this plastic class, for further configuration
166     */
167    PlasticClass proxyInterface(Class interfaceType, PlasticField field);
168
169    /**
170     * Conditionally adds an implementation of <code>toString()</code> to the class, but only if it is not already
171     * present in the class, or in a (transformed) super-class.
172     *
173     * @param toStringValue the fixed value to be returned from invoking toString()
174     * @return this plastic class, for further configuration
175     */
176    PlasticClass addToString(String toStringValue);
177
178    /**
179     * Returns true if this class has an implementation of the indicated method, or a super-class provides
180     * a non-abstract implementation.
181     */
182    boolean isMethodImplemented(MethodDescription description);
183
184    /**
185     * Returns true if this class, or a super-class, implements the indicated interface.
186     *
187     * @param interfaceType
188     * @return true if the interface is implemented
189     */
190    boolean isInterfaceImplemented(Class interfaceType);
191
192    /**
193     * Returns the name of the super-class of the class being transformed.
194     */
195    String getSuperClassName();
196
197    /**
198     * Adds the callback for execution when an instance of the class is instantiated.
199     *
200     * @param callback to execute at instance construction time
201     */
202    PlasticClass onConstruct(ConstructorCallback callback);
203}