type.java

asm的源码包 并且包含英文的文档

/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2005 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.objectweb.asm;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

/**
 * A Java type. This class can be used to make it easier to manipulate type and
 * method descriptors.
 * 
 * @author Eric Bruneton
 * @author Chris Nokleberg
 */
public class Type {

    /**
     * The sort of the <tt>void</tt> type. See {@link #getSort getSort}.
     */
    public final static int VOID = 0;

    /**
     * The sort of the <tt>boolean</tt> type. See {@link #getSort getSort}.
     */
    public final static int BOOLEAN = 1;

    /**
     * The sort of the <tt>char</tt> type. See {@link #getSort getSort}.
     */
    public final static int CHAR = 2;

    /**
     * The sort of the <tt>byte</tt> type. See {@link #getSort getSort}.
     */
    public final static int BYTE = 3;

    /**
     * The sort of the <tt>short</tt> type. See {@link #getSort getSort}.
     */
    public final static int SHORT = 4;

    /**
     * The sort of the <tt>int</tt> type. See {@link #getSort getSort}.
     */
    public final static int INT = 5;

    /**
     * The sort of the <tt>float</tt> type. See {@link #getSort getSort}.
     */
    public final static int FLOAT = 6;

    /**
     * The sort of the <tt>long</tt> type. See {@link #getSort getSort}.
     */
    public final static int LONG = 7;

    /**
     * The sort of the <tt>double</tt> type. See {@link #getSort getSort}.
     */
    public final static int DOUBLE = 8;

    /**
     * The sort of array reference types. See {@link #getSort getSort}.
     */
    public final static int ARRAY = 9;

    /**
     * The sort of object reference type. See {@link #getSort getSort}.
     */
    public final static int OBJECT = 10;

    /**
     * The <tt>void</tt> type.
     */
    public final static Type VOID_TYPE = new Type(VOID);

    /**
     * The <tt>boolean</tt> type.
     */
    public final static Type BOOLEAN_TYPE = new Type(BOOLEAN);

    /**
     * The <tt>char</tt> type.
     */
    public final static Type CHAR_TYPE = new Type(CHAR);

    /**
     * The <tt>byte</tt> type.
     */
    public final static Type BYTE_TYPE = new Type(BYTE);

    /**
     * The <tt>short</tt> type.
     */
    public final static Type SHORT_TYPE = new Type(SHORT);

    /**
     * The <tt>int</tt> type.
     */
    public final static Type INT_TYPE = new Type(INT);

    /**
     * The <tt>float</tt> type.
     */
    public final static Type FLOAT_TYPE = new Type(FLOAT);

    /**
     * The <tt>long</tt> type.
     */
    public final static Type LONG_TYPE = new Type(LONG);

    /**
     * The <tt>double</tt> type.
     */
    public final static Type DOUBLE_TYPE = new Type(DOUBLE);

    // ------------------------------------------------------------------------
    // Fields
    // ------------------------------------------------------------------------

    /**
     * The sort of this Java type.
     */
    private final int sort;

    /**
     * A buffer containing the descriptor of this Java type. This field is only
     * used for reference types.
     */
    private char[] buf;

    /**
     * The offset of the descriptor of this Java type in {@link #buf buf}. This
     * field is only used for reference types.
     */
    private int off;

    /**
     * The length of the descriptor of this Java type.
     */
    private int len;

    // ------------------------------------------------------------------------
    // Constructors
    // ------------------------------------------------------------------------

    /**
     * Constructs a primitive type.
     * 
     * @param sort the sort of the primitive type to be constructed.
     */
    private Type(final int sort) {
        this.sort = sort;
        this.len = 1;
    }

    /**
     * Constructs a reference type.
     * 
     * @param sort the sort of the reference type to be constructed.
     * @param buf a buffer containing the descriptor of the previous type.
     * @param off the offset of this descriptor in the previous buffer.
     * @param len the length of this descriptor.
     */
    private Type(final int sort, final char[] buf, final int off, final int len)
    {
        this.sort = sort;
        this.buf = buf;
        this.off = off;
        this.len = len;
    }

    /**
     * Returns the Java type corresponding to the given type descriptor.
     * 
     * @param typeDescriptor a type descriptor.
     * @return the Java type corresponding to the given type descriptor.
     */
    public static Type getType(final String typeDescriptor) {
        return getType(typeDescriptor.toCharArray(), 0);
    }

    /**
     * Returns the Java type corresponding to the given class.
     * 
     * @param c a class.
     * @return the Java type corresponding to the given class.
     */
    public static Type getType(final Class c) {
        if (c.isPrimitive()) {
            if (c == Integer.TYPE) {
                return INT_TYPE;
            } else if (c == Void.TYPE) {
                return VOID_TYPE;
            } else if (c == Boolean.TYPE) {
                return BOOLEAN_TYPE;
            } else if (c == Byte.TYPE) {
                return BYTE_TYPE;
            } else if (c == Character.TYPE) {
                return CHAR_TYPE;
            } else if (c == Short.TYPE) {
                return SHORT_TYPE;
            } else if (c == Double.TYPE) {
                return DOUBLE_TYPE;
            } else if (c == Float.TYPE) {
                return FLOAT_TYPE;
            } else /* if (c == Long.TYPE) */{
                return LONG_TYPE;
            }
        } else {
            return getType(getDescriptor(c));
        }
    }
    
    /**
     * Returns the {@link Type#OBJECT} type for the given internal class name.
     * This is a shortcut method for <code>Type.getType("L"+name+";")</code>.
     * <i>Note that opposed to {@link Type#getType(String)}, this method takes 
     * internal class names and not class descriptor.</i> 
     * 
     * @param name an internal class name.
     * @return the the {@link Type#OBJECT} type for the given class name.
     */
    public static Type getObjectType(String name) {
        int l = name.length();
        char[] buf = new char[l + 2];
        buf[0] = 'L';
        buf[l + 1] = ';';
        name.getChars(0, l, buf, 1);
        return new Type(OBJECT, buf, 0, l + 2);
    }

    /**
     * Returns the Java types corresponding to the argument types of the given
     * method descriptor.
     * 
     * @param methodDescriptor a method descriptor.
     * @return the Java types corresponding to the argument types of the given
     *         method descriptor.
     */
    public static Type[] getArgumentTypes(final String methodDescriptor) {
        char[] buf = methodDescriptor.toCharArray();
        int off = 1;
        int size = 0;
        while (true) {
            char car = buf[off++];
            if (car == ')') {
                break;
            } else if (car == 'L') {
                while (buf[off++] != ';') {
                }
                ++size;
            } else if (car != '[') {
                ++size;
            }
        }
        Type[] args = new Type[size];
        off = 1;
        size = 0;
        while (buf[off] != ')') {
            args[size] = getType(buf, off);
            off += args[size].len;
            size += 1;
        }
        return args;
    }

    /**
     * Returns the Java types corresponding to the argument types of the given
     * method.
     * 
     * @param method a method.
     * @return the Java types corresponding to the argument types of the given
     *         method.
     */
    public static Type[] getArgumentTypes(final Method method) {
        Class[] classes = method.getParameterTypes();
        Type[] types = new Type[classes.length];
        for (int i = classes.length - 1; i >= 0; --i) {
            types[i] = getType(classes[i]);
        }
        return types;
    }

    /**
     * Returns the Java type corresponding to the return type of the given
     * method descriptor.
     * 
     * @param methodDescriptor a method descriptor.
     * @return the Java type corresponding to the return type of the given
     *         method descriptor.
     */
    public static Type getReturnType(final String methodDescriptor) {
        char[] buf = methodDescriptor.toCharArray();
        return getType(buf, methodDescriptor.indexOf(')') + 1);
    }

    /**
     * Returns the Java type corresponding to the return type of the given
     * method.
     * 
     * @param method a method.
     * @return the Java type corresponding to the return type of the given
     *         method.
     */
    public static Type getReturnType(final Method method) {
        return getType(method.getReturnType());
    }

    /**
     * Returns the Java type corresponding to the given type descriptor.
     * 
     * @param buf a buffer containing a type descriptor.
     * @param off the offset of this descriptor in the previous buffer.
     * @return the Java type corresponding to the given type descriptor.
     */
    private static Type getType(final char[] buf, final int off) {
        int len;
        switch (buf[off]) {
            case 'V':
                return VOID_TYPE;
            case 'Z':
                return BOOLEAN_TYPE;
            case 'C':
                return CHAR_TYPE;
            case 'B':
                return BYTE_TYPE;
            case 'S':
                return SHORT_TYPE;
            case 'I':
                return INT_TYPE;
            case 'F':
                return FLOAT_TYPE;
            case 'J':
                return LONG_TYPE;
            case 'D':
                return DOUBLE_TYPE;
            case '[':
                len = 1;
                while (buf[off + len] == '[') {
                    ++len;
                }
                if (buf[off + len] == 'L') {
                    ++len;
                    while (buf[off + len] != ';') {
                        ++len;
                    }
                }
                return new Type(ARRAY, buf, off, len + 1);
                // case 'L':
            default:
                len = 1;
                while (buf[off + len] != ';') {
                    ++len;
                }
                return new Type(OBJECT, buf, off, len + 1);
        }
    }

    // ------------------------------------------------------------------------
    // Accessors
    // ------------------------------------------------------------------------

    /**
     * Returns the sort of this Java type.
     * 
     * @return {@link #VOID VOID}, {@link #BOOLEAN BOOLEAN},
     *         {@link #CHAR CHAR}, {@link #BYTE BYTE}, {@link #SHORT SHORT},
     *         {@link #INT INT}, {@link #FLOAT FLOAT}, {@link #LONG LONG},
     *         {@link #DOUBLE DOUBLE}, {@link #ARRAY ARRAY} or
     *         {@link #OBJECT OBJECT}.