/*

 * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.lang.reflect;

import sun.reflect.FieldAccessor;

import sun.reflect.Reflection;

import sun.reflect.generics.repository.FieldRepository;

import sun.reflect.generics.factory.CoreReflectionFactory;

import sun.reflect.generics.factory.GenericsFactory;

import sun.reflect.generics.scope.ClassScope;

import java.lang.annotation.Annotation;

import java.util.Map;

import sun.reflect.annotation.AnnotationParser;

/**

 * A {@code Field} provides information about, and dynamic access to, a

 * single field of a class or an interface.  The reflected field may

 * be a class (static) field or an instance field.

 *

 * <p>A {@code Field} permits widening conversions to occur during a get or

 * set access operation, but throws an {@code IllegalArgumentException} if a

 * narrowing conversion would occur.

 *

 * @see Member

 * @see java.lang.Class

 * @see java.lang.Class#getFields()

 * @see java.lang.Class#getField(String)

 * @see java.lang.Class#getDeclaredFields()

 * @see java.lang.Class#getDeclaredField(String)

 *

 * @author Kenneth Russell

 * @author Nakul Saraiya

 */

public final

class Field extends AccessibleObject implements Member {

    private Class<?>            clazz;

    private int                 slot;

    // This is guaranteed to be interned by the VM in the 1.4

    // reflection implementation

    private String              name;

    private Class<?>            type;

    private int                 modifiers;

    // Generics and annotations support

    private transient String    signature;

    // generic info repository; lazily initialized

    private transient FieldRepository genericInfo;

    private byte[]              annotations;

    // Cached field accessor created without override

    private FieldAccessor fieldAccessor;

    // Cached field accessor created with override

    private FieldAccessor overrideFieldAccessor;

    // For sharing of FieldAccessors. This branching structure is

    // currently only two levels deep (i.e., one root Field and

    // potentially many Field objects pointing to it.)

    private Field               root;

    // Generics infrastructure

    private String getGenericSignature() {return signature;}

    // Accessor for factory

    private GenericsFactory getFactory() {

        Class<?> c = getDeclaringClass();

        // create scope and factory

        return CoreReflectionFactory.make(c, ClassScope.make(c));

    }

    // Accessor for generic info repository

    private FieldRepository getGenericInfo() {

        // lazily initialize repository if necessary

        if (genericInfo == null) {

            // create and cache generic info repository

            genericInfo = FieldRepository.make(getGenericSignature(),

                                               getFactory());

        }

        return genericInfo; //return cached repository

    }

    /**

     * Package-private constructor used by ReflectAccess to enable

     * instantiation of these objects in Java code from the java.lang

     * package via sun.reflect.LangReflectAccess.

     */

    Field(Class<?> declaringClass,

          String name,

          Class<?> type,

          int modifiers,

          int slot,

          String signature,

          byte[] annotations)

    {

        this.clazz = declaringClass;

        this.name = name;

        this.type = type;

        this.modifiers = modifiers;

        this.slot = slot;

        this.signature = signature;

        this.annotations = annotations;

    }

    /**

     * Package-private routine (exposed to java.lang.Class via

     * ReflectAccess) which returns a copy of this Field. The copy's

     * "root" field points to this Field.

     */

    Field copy() {

        // This routine enables sharing of FieldAccessor objects

        // among Field objects which refer to the same underlying

        // method in the VM. (All of this contortion is only necessary

        // because of the "accessibility" bit in AccessibleObject,

        // which implicitly requires that new java.lang.reflect

        // objects be fabricated for each reflective call on Class

        // objects.)

        Field res = new Field(clazz, name, type, modifiers, slot, signature, annotations);

        res.root = this;

        // Might as well eagerly propagate this if already present

        res.fieldAccessor = fieldAccessor;

        res.overrideFieldAccessor = overrideFieldAccessor;

        return res;

    }

    /**

     * Returns the {@code Class} object representing the class or interface

     * that declares the field represented by this {@code Field} object.

     */

    public Class<?> getDeclaringClass() {

        return clazz;

    }

    /**

     * Returns the name of the field represented by this {@code Field} object.

     */

    public String getName() {

        return name;

    }

    /**

     * Returns the Java language modifiers for the field represented

     * by this {@code Field} object, as an integer. The {@code Modifier} class should

     * be used to decode the modifiers.

     *

     * @see Modifier

     */

    public int getModifiers() {

        return modifiers;

    }

    /**

     * Returns {@code true} if this field represents an element of

     * an enumerated type; returns {@code false} otherwise.

     *

     * @return {@code true} if and only if this field represents an element of

     * an enumerated type.

     * @since 1.5

     */

    public boolean isEnumConstant() {

        return (getModifiers() & Modifier.ENUM) != 0;

    }

    /**

     * Returns {@code true} if this field is a synthetic

     * field; returns {@code false} otherwise.

     *

     * @return true if and only if this field is a synthetic

     * field as defined by the Java Language Specification.

     * @since 1.5

     */

    public boolean isSynthetic() {

        return Modifier.isSynthetic(getModifiers());

    }

    /**

     * Returns a {@code Class} object that identifies the

     * declared type for the field represented by this

     * {@code Field} object.

     *

     * @return a {@code Class} object identifying the declared

     * type of the field represented by this object

     */

    public Class<?> getType() {

        return type;

    }

    /**

     * Returns a {@code Type} object that represents the declared type for

     * the field represented by this {@code Field} object.

     *

     * <p>If the {@code Type} is a parameterized type, the

     * {@code Type} object returned must accurately reflect the

     * actual type parameters used in the source code.

     *

     * <p>If the type of the underlying field is a type variable or a

     * parameterized type, it is created. Otherwise, it is resolved.

     *

     * @return a {@code Type} object that represents the declared type for

     *     the field represented by this {@code Field} object

     * @throws GenericSignatureFormatError if the generic field

     *     signature does not conform to the format specified in

     *     <cite>The Java&trade; Virtual Machine Specification</cite>

     * @throws TypeNotPresentException if the generic type

     *     signature of the underlying field refers to a non-existent

     *     type declaration

     * @throws MalformedParameterizedTypeException if the generic

     *     signature of the underlying field refers to a parameterized type

     *     that cannot be instantiated for any reason

     * @since 1.5

     */

    public Type getGenericType() {

        if (getGenericSignature() != null)

            return getGenericInfo().getGenericType();

        else

            return getType();

    }

    /**

     * Compares this {@code Field} against the specified object.  Returns

     * true if the objects are the same.  Two {@code Field} objects are the same if

     * they were declared by the same class and have the same name

     * and type.

     */

    public boolean equals(Object obj) {

        if (obj != null && obj instanceof Field) {

            Field other = (Field)obj;

            return (getDeclaringClass() == other.getDeclaringClass())

                && (getName() == other.getName())

                && (getType() == other.getType());

        }

        return false;

    }

    /**

     * Returns a hashcode for this {@code Field}.  This is computed as the

     * exclusive-or of the hashcodes for the underlying field's

     * declaring class name and its name.

     */

    public int hashCode() {

        return getDeclaringClass().getName().hashCode() ^ getName().hashCode();

    }

    /**

     * Returns a string describing this {@code Field}.  The format is

     * the access modifiers for the field, if any, followed

     * by the field type, followed by a space, followed by

     * the fully-qualified name of the class declaring the field,

     * followed by a period, followed by the name of the field.

     * For example:

     * <pre>

     *    public static final int java.lang.Thread.MIN_PRIORITY

     *    private int java.io.FileDescriptor.fd

     * </pre>

     *

     * <p>The modifiers are placed in canonical order as specified by

     * "The Java Language Specification".  This is {@code public},

     * {@code protected} or {@code private} first, and then other

     * modifiers in the following order: {@code static}, {@code final},

     * {@code transient}, {@code volatile}.

     */

    public String toString() {

        int mod = getModifiers();

        return (((mod == 0) ? "" : (Modifier.toString(mod) + " "))

            + getTypeName(getType()) + " "

            + getTypeName(getDeclaringClass()) + "."

            + getName());

    }

    /**

     * Returns a string describing this {@code Field}, including

     * its generic type.  The format is the access modifiers for the

     * field, if any, followed by the generic field type, followed by

     * a space, followed by the fully-qualified name of the class

     * declaring the field, followed by a period, followed by the name

     * of the field.

     *

     * <p>The modifiers are placed in canonical order as specified by

     * "The Java Language Specification".  This is {@code public},

     * {@code protected} or {@code private} first, and then other

     * modifiers in the following order: {@code static}, {@code final},

     * {@code transient}, {@code volatile}.

     *

     * @return a string describing this {@code Field}, including

     * its generic type

     *

     * @since 1.5

     */

    public String toGenericString() {

        int mod = getModifiers();

        Type fieldType = getGenericType();

        return (((mod == 0) ? "" : (Modifier.toString(mod) + " "))

            +  ((fieldType instanceof Class) ?

                getTypeName((Class)fieldType): fieldType.toString())+ " "

            + getTypeName(getDeclaringClass()) + "."

            + getName());

    }

    /**

     * Returns the value of the field represented by this {@code Field}, on

     * the specified object. The value is automatically wrapped in an

     * object if it has a primitive type.

     *

     * <p>The underlying field's value is obtained as follows:

     *

     * <p>If the underlying field is a static field, the {@code obj} argument

     * is ignored; it may be null.

     *

     * <p>Otherwise, the underlying field is an instance field.  If the

     * specified {@code obj} argument is null, the method throws a

     * {@code NullPointerException}. If the specified object is not an

     * instance of the class or interface declaring the underlying

     * field, the method throws an {@code IllegalArgumentException}.

     *

     * <p>If this {@code Field} object is enforcing Java language access control, and

     * the underlying field is inaccessible, the method throws an

     * {@code IllegalAccessException}.

     * If the underlying field is static, the class that declared the

     * field is initialized if it has not already been initialized.

     *

     * <p>Otherwise, the value is retrieved from the underlying instance

     * or static field.  If the field has a primitive type, the value

     * is wrapped in an object before being returned, otherwise it is

     * returned as is.

     *

     * <p>If the field is hidden in the type of {@code obj},

     * the field's value is obtained according to the preceding rules.

     *

     * @param obj object from which the represented field's value is

     * to be extracted

     * @return the value of the represented field in object

     * {@code obj}; primitive values are wrapped in an appropriate

     * object before being returned

     *

     * @exception IllegalAccessException    if this {@code Field} object

     *              is enforcing Java language access control and the underlying

     *              field is inaccessible.

     * @exception IllegalArgumentException  if the specified object is not an

     *              instance of the class or interface declaring the underlying

     *              field (or a subclass or implementor thereof).

     * @exception NullPointerException      if the specified object is null

     *              and the field is an instance field.

     * @exception ExceptionInInitializerError if the initialization provoked

     *              by this method fails.

     */

    public Object get(Object obj)

        throws IllegalArgumentException, IllegalAccessException

    {

        return getFieldAccessor(obj).get(obj);

    }

    /**

     * Gets the value of a static or instance {@code boolean} field.

     *

     * @param obj the object to extract the {@code boolean} value

     * from

     * @return the value of the {@code boolean} field

     *

     * @exception IllegalAccessException    if this {@code Field} object

     *              is enforcing Java language access control and the underlying

     *              field is inaccessible.

     * @exception IllegalArgumentException  if the specified object is not

     *              an instance of the class or interface declaring the

     *              underlying field (or a subclass or implementor

     *              thereof), or if the field value cannot be

     *              converted to the type {@code boolean} by a

     *              widening conversion.

     * @exception NullPointerException      if the specified object is null

     *              and the field is an instance field.

     * @exception ExceptionInInitializerError if the initialization provoked

     *              by this method fails.

     * @see       Field#get

     */

    public boolean getBoolean(Object obj)

        throws IllegalArgumentException, IllegalAccessException

    {

        return getFieldAccessor(obj).getBoolean(obj);

    }

    /**

     * Gets the value of a static or instance {@code byte} field.

     *

     * @param obj the object to extract the {@code byte} value

     * from

     * @return the value of the {@code byte} field

     *

     * @exception IllegalAccessException    if this {@code Field} object

     *              is enforcing Java language access control and the underlying

     *              field is inaccessible.

     * @exception IllegalArgumentException  if the specified object is not

     *              an instance of the class or interface declaring the

     *              underlying field (or a subclass or implementor

     *              thereof), or if the field value cannot be

     *              converted to the type {@code byte} by a

     *              widening conversion.

     * @exception NullPointerException      if the specified object is null

     *              and the field is an instance field.

     * @exception ExceptionInInitializerError if the initialization provoked

     *              by this method fails.

     * @see       Field#get

     */

    public byte getByte(Object obj)

        throws IllegalArgumentException, IllegalAccessException

    {

        return getFieldAccessor(obj).getByte(obj);

    }

    /**

     * Gets the value of a static or instance field of type

     * {@code char} or of another primitive type convertible to

     * type {@code char} via a widening conversion.

     *

     * @param obj the object to extract the {@code char} value

     * from

     * @return the value of the field converted to type {@code char}

     *

     * @exception IllegalAccessException    if this {@code Field} object

     *              is enforcing Java language access control and the underlying

     *              field is inaccessible.

     * @exception IllegalArgumentException  if the specified object is not

     *              an instance of the class or interface declaring the

     *              underlying field (or a subclass or implementor

     *              thereof), or if the field value cannot be

     *              converted to the type {@code char} by a

     *              widening conversion.

     * @exception NullPointerException      if the specified object is null

     *              and the field is an instance field.

     * @exception ExceptionInInitializerError if the initialization provoked

     *              by this method fails.

     * @see Field#get

     */

    public char getChar(Object obj)

        throws IllegalArgumentException, IllegalAccessException

    {

        return getFieldAccessor(obj).getChar(obj);

    }

    /**

     * Gets the value of a static or instance field of type

     * {@code short} or of another primitive type convertible to

     * type {@code short} via a widening conversion.

     *

     * @param obj the object to extract the {@code short} value

     * from

     * @return the value of the field converted to type {@code short}

     *

     * @exception IllegalAccessException    if this {@code Field} object

     *              is enforcing Java language access control and the underlying

     *              field is inaccessible.

     * @exception IllegalArgumentException  if the specified object is not

     *              an instance of the class or interface declaring the

     *              underlying field (or a subclass or implementor

     *              thereof), or if the field value cannot be

     *              converted to the type {@code short} by a

     *              widening conversion.

     * @exception NullPointerException      if the specified object is null

     *              and the field is an instance field.

     * @exception ExceptionInInitializerError if the initialization provoked

     *              by this method fails.

     * @see       Field#get

     */

    public short getShort(Object obj)

        throws IllegalArgumentException, IllegalAccessException

    {

        return getFieldAccessor(obj).getShort(obj);

    }

    /**

     * Gets the value of a static or instance field of type

     * {@code int} or of another primitive type convertible to

     * type {@code int} via a widening conversion.

     *

     * @param obj the object to extract the {@code int} value

     * from

     * @return the value of the field converted to type {@code int}

     *

     * @exception IllegalAccessException    if this {@code Field} object

     *              is enforcing Java language access control and the underlying

     *              field is inaccessible.

     * @exception IllegalArgumentException  if the specified object is not

     *              an instance of the class or interface declaring the

     *              underlying field (or a subclass or implementor

     *              thereof), or if the field value cannot be

     *              converted to the type {@code int} by a

     *              widening conversion.

     * @exception NullPointerException      if the specified object is null

     *              and the field is an instance field.

     * @exception ExceptionInInitializerError if the initialization provoked

     *              by this method fails.

     * @see       Field#get

     */

    public int getInt(Object obj)

        throws IllegalArgumentException, IllegalAccessException

    {

        return getFieldAccessor(obj).getInt(obj);

    }

    /**

     * Gets the value of a static or instance field of type

     * {@code long} or of another primitive type convertible to

     * type {@code long} via a widening conversion.