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 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.lang.reflect;

import java.security.AccessController;
import sun.reflect.LangReflectAccess;
import sun.reflect.ReflectionFactory;

/**
 * <p> Modifier主要提供一系列的静态方法,用于判断基于int类型的修饰符参数的具体类型,
 * 这个修饰符参数来源于Class、Constructor、Method、Field、Parameter的getModifiers()方法
 * <p>
 * <p>
 * The Modifier class provides {@code static} methods and
 * constants to decode class and member access modifiers. The sets of
 * modifiers are represented as integers with distinct bit positions
 * representing different modifiers. The values for the constants
 * representing the modifiers are taken from the tables in sections 4.1, 4.4, 4.5, and 4.7 of
 * <cite>The Java&trade; Virtual Machine Specification</cite>.
 *
 * @see Class#getModifiers()
 * @see Member#getModifiers()
 *
 * @author Nakul Saraiya
 * @author Kenneth Russell
 */
@SuppressWarnings("ALL")
public class Modifier {

 /*
 * Bootstrapping protocol between java.lang and java.lang.reflect
 * packages
 */
 static {
 sun.reflect.ReflectionFactory factory =
 AccessController.doPrivileged(new ReflectionFactory.GetReflectionFactoryAction());
 factory.setLangReflectAccess(new java.lang.reflect.ReflectAccess());
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code public} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code public} modifier; {@code false} otherwise.
 */
 public static boolean isPublic(int mod) {
 return (mod & PUBLIC) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code private} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code private} modifier; {@code false} otherwise.
 */
 public static boolean isPrivate(int mod) {
 return (mod & PRIVATE) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code protected} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code protected} modifier; {@code false} otherwise.
 */
 public static boolean isProtected(int mod) {
 return (mod & PROTECTED) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code static} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code static} modifier; {@code false} otherwise.
 */
 public static boolean isStatic(int mod) {
 return (mod & STATIC) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code final} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code final} modifier; {@code false} otherwise.
 */
 public static boolean isFinal(int mod) {
 return (mod & FINAL) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code synchronized} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code synchronized} modifier; {@code false} otherwise.
 */
 // 是否是合成的
 public static boolean isSynchronized(int mod) {
 return (mod & SYNCHRONIZED) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code volatile} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code volatile} modifier; {@code false} otherwise.
 */
 public static boolean isVolatile(int mod) {
 return (mod & VOLATILE) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code transient} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code transient} modifier; {@code false} otherwise.
 */
 public static boolean isTransient(int mod) {
 return (mod & TRANSIENT) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code native} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code native} modifier; {@code false} otherwise.
 */
 public static boolean isNative(int mod) {
 return (mod & NATIVE) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code interface} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code interface} modifier; {@code false} otherwise.
 */
 public static boolean isInterface(int mod) {
 return (mod & INTERFACE) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code abstract} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code abstract} modifier; {@code false} otherwise.
 */
 public static boolean isAbstract(int mod) {
 return (mod & ABSTRACT) != 0;
 }

 /**
 * Return {@code true} if the integer argument includes the
 * {@code strictfp} modifier, {@code false} otherwise.
 *
 * @param mod a set of modifiers
 * @return {@code true} if {@code mod} includes the
 * {@code strictfp} modifier; {@code false} otherwise.
 */
 // 整数modifier参数是否包括strictfp修饰符
 // Java中的strictfp关键字可以用来确保浮点数运算在不同平台下的结果是一致的
 // strictfp关键字可以用在类、接口、方法、内部类和匿名内部类上。使用该关键字修饰的类或方法,
 // 其浮点数计算结果会按照IEEE 754规范进行舍入,从而确保了计算结果的一致性
 // TODO 可以了解以下strictfp关键字,无需过度了解
 public static boolean isStrict(int mod) {
 return (mod & STRICT) != 0;
 }

 /**
 * Return a string describing the access modifier flags in
 * the specified modifier. For example:
 * <blockquote><pre>
 * public final synchronized strictfp
 * </pre></blockquote>
 * The modifier names are returned in an order consistent with the
 * suggested modifier orderings given in sections 8.1.1, 8.3.1, 8.4.3, 8.8.3, and 9.1.1 of
 * <cite>The Java&trade; Language Specification</cite>.
 * The full modifier ordering used by this method is:
 * <blockquote> {@code
 * public protected private abstract static final transient
 * volatile synchronized native strictfp
 * interface } </blockquote>
 * The {@code interface} modifier discussed in this class is
 * not a true modifier in the Java language and it appears after
 * all other modifiers listed by this method. This method may
 * return a string of modifiers that are not valid modifiers of a
 * Java entity; in other words, no checking is done on the
 * possible validity of the combination of modifiers represented
 * by the input.
 *
 * Note that to perform such checking for a known kind of entity,
 * such as a constructor or method, first AND the argument of
 * {@code toString} with the appropriate mask from a method like
 * {@link #constructorModifiers} or {@link #methodModifiers}.
 *
 * @param mod a set of modifiers
 * @return a string representation of the set of modifiers
 * represented by {@code mod}
 */
 public static String toString(int mod) {
 StringBuilder sb = new StringBuilder();
 int len;

 if ((mod & PUBLIC) != 0) sb.append("public ");
 if ((mod & PROTECTED) != 0) sb.append("protected ");
 if ((mod & PRIVATE) != 0) sb.append("private ");

 /* Canonical order */
 if ((mod & ABSTRACT) != 0) sb.append("abstract ");
 if ((mod & STATIC) != 0) sb.append("static ");
 if ((mod & FINAL) != 0) sb.append("final ");
 if ((mod & TRANSIENT) != 0) sb.append("transient ");
 if ((mod & VOLATILE) != 0) sb.append("volatile ");
 if ((mod & SYNCHRONIZED) != 0) sb.append("synchronized ");
 if ((mod & NATIVE) != 0) sb.append("native ");
 if ((mod & STRICT) != 0) sb.append("strictfp ");
 if ((mod & INTERFACE) != 0) sb.append("interface ");

 if ((len = sb.length()) > 0) /* trim trailing space */
 return sb.toString().substring(0, len-1);
 return "";
 }

 /*
 * Access modifier flag constants from tables 4.1, 4.4, 4.5, and 4.7 of
 * <cite>The Java&trade; Virtual Machine Specification</cite>
 */

 /**
 * The {@code int} value representing the {@code public}
 * modifier.
 */
 public static final int PUBLIC = 0x00000001;

 /**
 * The {@code int} value representing the {@code private}
 * modifier.
 */
 public static final int PRIVATE = 0x00000002;

 /**
 * The {@code int} value representing the {@code protected}
 * modifier.
 */
 public static final int PROTECTED = 0x00000004;

 /**
 * The {@code int} value representing the {@code static}
 * modifier.
 */
 public static final int STATIC = 0x00000008;

 /**
 * The {@code int} value representing the {@code final}
 * modifier.
 */
 public static final int FINAL = 0x00000010;

 /**
 * The {@code int} value representing the {@code synchronized}
 * modifier.
 */
 public static final int SYNCHRONIZED = 0x00000020;

 /**
 * The {@code int} value representing the {@code volatile}
 * modifier.
 */
 public static final int VOLATILE = 0x00000040;

 /**
 * The {@code int} value representing the {@code transient}
 * modifier.
 */
 public static final int TRANSIENT = 0x00000080;

 /**
 * The {@code int} value representing the {@code native}
 * modifier.
 */
 public static final int NATIVE = 0x00000100;

 /**
 * The {@code int} value representing the {@code interface}
 * modifier.
 */
 public static final int INTERFACE = 0x00000200;

 /**
 * The {@code int} value representing the {@code abstract}
 * modifier.
 */
 public static final int ABSTRACT = 0x00000400;

 /**
 * The {@code int} value representing the {@code strictfp}
 * modifier.
 */
 public static final int STRICT = 0x00000800;

 // Bits not (yet) exposed in the public API either because they
 // have different meanings for fields and methods and there is no
 // way to distinguish between the two in this class, or because
 // they are not Java programming language keywords
 static final int BRIDGE = 0x00000040;
 static final int VARARGS = 0x00000080;
 static final int SYNTHETIC = 0x00001000;
 static final int ANNOTATION = 0x00002000;
 static final int ENUM = 0x00004000;
 static final int MANDATED = 0x00008000;
 static boolean isSynthetic(int mod) {
 return (mod & SYNTHETIC) != 0;
 }

 static boolean isMandated(int mod) {
 return (mod & MANDATED) != 0;
 }

 // Note on the FOO_MODIFIERS fields and fooModifiers() methods:
 // the sets of modifiers are not guaranteed to be constants
 // across time and Java SE releases. Therefore, it would not be
 // appropriate to expose an external interface to this information
 // that would allow the values to be treated as Java-level
 // constants since the values could be constant folded and updates
 // to the sets of modifiers missed. Thus, the fooModifiers()
 // methods return an unchanging values for a given release, but a
 // value that can potentially change over time.

 /**
 * The Java source modifiers that can be applied to a class.
 * @jls 8.1.1 Class Modifiers
 */
 private static final int CLASS_MODIFIERS =
 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL |
 Modifier.STRICT;

 /**
 * The Java source modifiers that can be applied to an interface.
 * @jls 9.1.1 Interface Modifiers
 */
 private static final int INTERFACE_MODIFIERS =
 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
 Modifier.ABSTRACT | Modifier.STATIC | Modifier.STRICT;


 /**
 * The Java source modifiers that can be applied to a constructor.
 * @jls 8.8.3 Constructor Modifiers
 */
 private static final int CONSTRUCTOR_MODIFIERS =
 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE;

 /**
 * The Java source modifiers that can be applied to a method.
 * @jls8.4.3 Method Modifiers
 */
 private static final int METHOD_MODIFIERS =
 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
 Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL |
 Modifier.SYNCHRONIZED | Modifier.NATIVE | Modifier.STRICT;

 /**
 * The Java source modifiers that can be applied to a field.
 * @jls 8.3.1 Field Modifiers
 */
 private static final int FIELD_MODIFIERS =
 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE |
 Modifier.STATIC | Modifier.FINAL | Modifier.TRANSIENT |
 Modifier.VOLATILE;

 /**
 * The Java source modifiers that can be applied to a method or constructor parameter.
 * @jls 8.4.1 Formal Parameters
 */
 private static final int PARAMETER_MODIFIERS =
 Modifier.FINAL;

 /**
 *
 */
 static final int ACCESS_MODIFIERS =
 Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE;

 /**
 * Return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a class.
 * @return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a class.
 *
 * @jls 8.1.1 Class Modifiers
 * @since 1.7
 */
 public static int classModifiers() {
 return CLASS_MODIFIERS;
 }

 /**
 * Return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to an interface.
 * @return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to an interface.
 *
 * @jls 9.1.1 Interface Modifiers
 * @since 1.7
 */
 public static int interfaceModifiers() {
 return INTERFACE_MODIFIERS;
 }

 /**
 * Return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a constructor.
 * @return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a constructor.
 *
 * @jls 8.8.3 Constructor Modifiers
 * @since 1.7
 */
 public static int constructorModifiers() {
 return CONSTRUCTOR_MODIFIERS;
 }

 /**
 * Return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a method.
 * @return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a method.
 *
 * @jls 8.4.3 Method Modifiers
 * @since 1.7
 */
 public static int methodModifiers() {
 return METHOD_MODIFIERS;
 }

 /**
 * Return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a field.
 * @return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a field.
 *
 * @jls 8.3.1 Field Modifiers
 * @since 1.7
 */
 public static int fieldModifiers() {
 return FIELD_MODIFIERS;
 }

 /**
 * Return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a parameter.
 * @return an {@code int} value OR-ing together the source language
 * modifiers that can be applied to a parameter.
 *
 * @jls 8.4.1 Formal Parameters
 * @since 1.8
 */
 public static int parameterModifiers() {
 return PARAMETER_MODIFIERS;
 }
}