classwriter.java

是一款用JAVA 编写的编译器 具有很强的编译功能

/*
 * Copyright 1999-2006 Sun Microsystems, Inc.  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.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.tools.javac.jvm;

import java.io.*;
import java.util.*;
import java.util.Set;
import java.util.HashSet;

import javax.tools.JavaFileManager;
import javax.tools.FileObject;
import javax.tools.JavaFileObject;

import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.code.Type.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.List;

import static com.sun.tools.javac.code.BoundKind.*;
import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.Kinds.*;
import static com.sun.tools.javac.code.TypeTags.*;
import static com.sun.tools.javac.jvm.UninitializedType.*;
import static javax.tools.StandardLocation.CLASS_OUTPUT;

/** This class provides operations to map an internal symbol table graph
 *  rooted in a ClassSymbol into a classfile.
 *
 *  <p><b>This is NOT part of any API supported by Sun Microsystems.  If
 *  you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
public class ClassWriter extends ClassFile {
    protected static final Context.Key<ClassWriter> classWriterKey =
        new Context.Key<ClassWriter>();

    private final Symtab syms;

    private final Options options;

    /** Switch: verbose output.
     */
    private boolean verbose;

    /** Switch: scrable private names.
     */
    private boolean scramble;

    /** Switch: scrable private names.
     */
    private boolean scrambleAll;

    /** Switch: retrofit mode.
     */
    private boolean retrofit;

    /** Switch: emit source file attribute.
     */
    private boolean emitSourceFile;

    /** Switch: generate CharacterRangeTable attribute.
     */
    private boolean genCrt;

    /** Switch: describe the generated stackmap
     */
    boolean debugstackmap;

    /**
     * Target class version.
     */
    private Target target;

    /**
     * Source language version.
     */
    private Source source;

    /** Type utilities. */
    private Types types;

    /** The initial sizes of the data and constant pool buffers.
     *  sizes are increased when buffers get full.
     */
    static final int DATA_BUF_SIZE = 0x0fff0;
    static final int POOL_BUF_SIZE = 0x1fff0;

    /** An output buffer for member info.
     */
    ByteBuffer databuf = new ByteBuffer(DATA_BUF_SIZE);

    /** An output buffer for the constant pool.
     */
    ByteBuffer poolbuf = new ByteBuffer(POOL_BUF_SIZE);

    /** An output buffer for type signatures.
     */
    ByteBuffer sigbuf = new ByteBuffer();

    /** The constant pool.
     */
    Pool pool;

    /** The inner classes to be written, as a set.
     */
    Set<ClassSymbol> innerClasses;

    /** The inner classes to be written, as a queue where
     *  enclosing classes come first.
     */
    ListBuffer<ClassSymbol> innerClassesQueue;

    /** The log to use for verbose output.
     */
    private final Log log;

    /** The name table. */
    private final Name.Table names;

    /** Access to files. */
    private final JavaFileManager fileManager;
    
    /** The tags and constants used in compressed stackmap. */
    static final int SAME_FRAME_SIZE = 64;
    static final int SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247;
    static final int SAME_FRAME_EXTENDED = 251;
    static final int FULL_FRAME = 255;
    static final int MAX_LOCAL_LENGTH_DIFF = 4;

    /** Get the ClassWriter instance for this context. */
    public static ClassWriter instance(Context context) {
        ClassWriter instance = context.get(classWriterKey);
        if (instance == null)
            instance = new ClassWriter(context);
        return instance;
    }

    /** Construct a class writer, given an options table.
     */
    private ClassWriter(Context context) {
        context.put(classWriterKey, this);

        log = Log.instance(context);
        names = Name.Table.instance(context);
        syms = Symtab.instance(context);
        options = Options.instance(context);
        target = Target.instance(context);
        source = Source.instance(context);
        types = Types.instance(context);
        fileManager = context.get(JavaFileManager.class);

        verbose        = options.get("-verbose")     != null;
        scramble       = options.get("-scramble")    != null;
        scrambleAll    = options.get("-scrambleAll") != null;
        retrofit       = options.get("-retrofit") != null;
        genCrt         = options.get("-Xjcov") != null;
        debugstackmap  = options.get("debugstackmap") != null;

        emitSourceFile = options.get("-g:")==null || options.get("-g:source")!=null;

        String dumpModFlags = options.get("dumpmodifiers");
        dumpClassModifiers =
            (dumpModFlags != null && dumpModFlags.indexOf('c') != -1);
        dumpFieldModifiers =
            (dumpModFlags != null && dumpModFlags.indexOf('f') != -1);
        dumpInnerClassModifiers =
            (dumpModFlags != null && dumpModFlags.indexOf('i') != -1);
        dumpMethodModifiers =
            (dumpModFlags != null && dumpModFlags.indexOf('m') != -1);
    }

/******************************************************************
 * Diagnostics: dump generated class names and modifiers
 ******************************************************************/

    /** Value of option 'dumpmodifiers' is a string
     *  indicating which modifiers should be dumped for debugging:
     *    'c' -- classes
     *    'f' -- fields
     *    'i' -- innerclass attributes
     *    'm' -- methods
     *  For example, to dump everything:
     *    javac -XDdumpmodifiers=cifm MyProg.java
     */
    private final boolean dumpClassModifiers; // -XDdumpmodifiers=c
    private final boolean dumpFieldModifiers; // -XDdumpmodifiers=f
    private final boolean dumpInnerClassModifiers; // -XDdumpmodifiers=i
    private final boolean dumpMethodModifiers; // -XDdumpmodifiers=m


    /** Return flags as a string, separated by " ".
     */
    public static String flagNames(long flags) {
        StringBuffer sbuf = new StringBuffer();
        int i = 0;
        long f = flags & StandardFlags;
        while (f != 0) {
            if ((f & 1) != 0) sbuf.append(" " + flagName[i]);
            f = f >> 1;
            i++;
        }
        return sbuf.toString();
    }
    //where
        private final static String[] flagName = {
            "PUBLIC", "PRIVATE", "PROTECTED", "STATIC", "FINAL",
            "SUPER", "VOLATILE", "TRANSIENT", "NATIVE", "INTERFACE",
            "ABSTRACT", "STRICTFP"};

/******************************************************************
 * Output routines
 ******************************************************************/

    /** Write a character into given byte buffer;
     *  byte buffer will not be grown.
     */
    void putChar(ByteBuffer buf, int op, int x) {
        buf.elems[op  ] = (byte)((x >>  8) & 0xFF);
        buf.elems[op+1] = (byte)((x      ) & 0xFF);
    }

    /** Write an integer into given byte buffer;
     *  byte buffer will not be grown.
     */
    void putInt(ByteBuffer buf, int adr, int x) {
        buf.elems[adr  ] = (byte)((x >> 24) & 0xFF);
        buf.elems[adr+1] = (byte)((x >> 16) & 0xFF);
        buf.elems[adr+2] = (byte)((x >>  8) & 0xFF);
        buf.elems[adr+3] = (byte)((x      ) & 0xFF);
    }

/******************************************************************
 * Signature Generation
 ******************************************************************/

    /** Assemble signature of given type in string buffer.
     */
    void assembleSig(Type type) {
        switch (type.tag) {
        case BYTE:
            sigbuf.appendByte('B');
            break;
        case SHORT:
            sigbuf.appendByte('S');
            break;
        case CHAR:
            sigbuf.appendByte('C');
            break;
        case INT:
            sigbuf.appendByte('I');
            break;
        case LONG:
            sigbuf.appendByte('J');
            break;
        case FLOAT:
            sigbuf.appendByte('F');
            break;
        case DOUBLE:
            sigbuf.appendByte('D');
            break;
        case BOOLEAN:
            sigbuf.appendByte('Z');
            break;
        case VOID:
            sigbuf.appendByte('V');
            break;
        case CLASS:
            sigbuf.appendByte('L');
            assembleClassSig(type);
            sigbuf.appendByte(';');
            break;
        case ARRAY:
            ArrayType at = (ArrayType)type;
            sigbuf.appendByte('[');
            assembleSig(at.elemtype);
            break;
        case METHOD:
            MethodType mt = (MethodType)type;
            sigbuf.appendByte('(');
            assembleSig(mt.argtypes);
            sigbuf.appendByte(')');
            assembleSig(mt.restype);
            if (hasTypeVar(mt.thrown)) {
                for (List<Type> l = mt.thrown; l.nonEmpty(); l = l.tail) {
                    sigbuf.appendByte('^');
                    assembleSig(l.head);
                }
            }
            break;
        case WILDCARD: {
            WildcardType ta = (WildcardType) type;
            switch (ta.kind) {
            case SUPER:
                sigbuf.appendByte('-');
                assembleSig(ta.type);
                break;
            case EXTENDS:
                sigbuf.appendByte('+');
                assembleSig(ta.type);
                break;
            case UNBOUND:
                sigbuf.appendByte('*');
                break;
            default:
                throw new AssertionError(ta.kind);
            }
            break;
        }
        case TYPEVAR:
            sigbuf.appendByte('T');
            sigbuf.appendName(type.tsym.name);
            sigbuf.appendByte(';');
            break;
        case FORALL:
            ForAll ft = (ForAll)type;
            assembleParamsSig(ft.tvars);
            assembleSig(ft.qtype);
            break;
        case UNINITIALIZED_THIS:
        case UNINITIALIZED_OBJECT:
            // we don't yet have a spec for uninitialized types in the
            // local variable table
            assembleSig(types.erasure(((UninitializedType)type).qtype));
            break;
        default:
            throw new AssertionError("typeSig " + type.tag);
        }
    }

    boolean hasTypeVar(List<Type> l) {
        while (l.nonEmpty()) {
            if (l.head.tag == TypeTags.TYPEVAR) return true;
            l = l.tail;
        }
        return false;
    }

    void assembleClassSig(Type type) {
        ClassType ct = (ClassType)type;
        ClassSymbol c = (ClassSymbol)ct.tsym;
        enterInner(c);
        Type outer = ct.getEnclosingType();
        if (outer.allparams().nonEmpty()) {
            boolean rawOuter =
                c.owner.kind == MTH || // either a local class
                c.name == names.empty; // or anonymous
            assembleClassSig(rawOuter
                             ? types.erasure(outer)
                             : outer);
            sigbuf.appendByte('.');
            assert c.flatname.startsWith(c.owner.enclClass().flatname);
            sigbuf.appendName(rawOuter
                              ? c.flatname.subName(c.owner.enclClass()
                                                   .flatname.len+1,
                                                   c.flatname.len)
                              : c.name);
        } else {
            sigbuf.appendBytes(externalize(c.flatname));
        }
        if (ct.getTypeArguments().nonEmpty()) {
            sigbuf.appendByte('<');
            assembleSig(ct.getTypeArguments());
            sigbuf.appendByte('>');
        }
    }


    void assembleSig(List<Type> types) {
        for (List<Type> ts = types; ts.nonEmpty(); ts = ts.tail)
            assembleSig(ts.head);
    }

    void assembleParamsSig(List<Type> typarams) {
        sigbuf.appendByte('<');
        for (List<Type> ts = typarams; ts.nonEmpty(); ts = ts.tail) {
            TypeVar tvar = (TypeVar)ts.head;
            sigbuf.appendName(tvar.tsym.name);
            List<Type> bounds = types.getBounds(tvar);
            if ((bounds.head.tsym.flags() & INTERFACE) != 0) {
                sigbuf.appendByte(':');
            }