membercodegen.java

Javassist是一个开源的分析、编辑和创建Java字节码的类库。是由东京技术学院的数学和计算机科学系的 Shigeru Chiba 所创建的。它已加入了开放源代码JBoss 应用服务器项目,通过使

/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999-2006 Shigeru Chiba. All Rights Reserved.
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 */

package javassist.compiler;

import javassist.*;
import javassist.bytecode.*;
import javassist.compiler.ast.*;

import java.util.ArrayList;

/* Code generator methods depending on javassist.* classes.
 */
public class MemberCodeGen extends CodeGen {
    protected MemberResolver resolver;
    protected CtClass   thisClass;
    protected MethodInfo thisMethod;

    protected boolean resultStatic;

    public MemberCodeGen(Bytecode b, CtClass cc, ClassPool cp) {
        super(b);
        resolver = new MemberResolver(cp);
        thisClass = cc;
        thisMethod = null;
    }

    /**
     * Records the currently compiled method.
     */
    public void setThisMethod(CtMethod m) {
        thisMethod = m.getMethodInfo2();
        if (typeChecker != null)
            typeChecker.setThisMethod(thisMethod);
    }

    public CtClass getThisClass() { return thisClass; }

    /**
     * Returns the JVM-internal representation of this class name.
     */
    protected String getThisName() {
        return MemberResolver.javaToJvmName(thisClass.getName());
    }

    /**
     * Returns the JVM-internal representation of this super class name.
     */
    protected String getSuperName() throws CompileError {
        return MemberResolver.javaToJvmName(
                        MemberResolver.getSuperclass(thisClass).getName());
    }

    protected void insertDefaultSuperCall() throws CompileError {
        bytecode.addAload(0);
        bytecode.addInvokespecial(MemberResolver.getSuperclass(thisClass),
                                  "<init>", "()V");
    }

    static class JsrHook extends ReturnHook {
        ArrayList jsrList;
        int var;

        JsrHook(CodeGen gen) {
            super(gen);
            jsrList = new ArrayList();
            var = gen.getMaxLocals();
            gen.incMaxLocals(1);
        }

        private void jsrJmp(Bytecode b) {
            b.addOpcode(JSR);
            jsrList.add(new Integer(b.currentPc()));
            b.addIndex(0);
        }

        protected void doit(Bytecode b, int opcode) {
            switch (opcode) {
            case Opcode.RETURN :
                jsrJmp(b);
                break;
            case ARETURN :
                b.addAstore(var);
                jsrJmp(b);
                b.addAload(var);
                break;
            case IRETURN :
                b.addIstore(var);
                jsrJmp(b);
                b.addIload(var);
                break;
            case LRETURN :
                b.addLstore(var);
                jsrJmp(b);
                b.addLload(var);
                break;
            case DRETURN :
                b.addDstore(var);
                jsrJmp(b);
                b.addDload(var);
                break;
            case FRETURN :
                b.addFstore(var);
                jsrJmp(b);
                b.addFload(var);
                break;
            default :
                throw new RuntimeException("fatal");
            }
        }
    }

    protected void atTryStmnt(Stmnt st) throws CompileError {
        Bytecode bc = bytecode;
        Stmnt body = (Stmnt)st.getLeft();
        if (body == null)
            return;

        ASTList catchList = (ASTList)st.getRight().getLeft();
        Stmnt finallyBlock = (Stmnt)st.getRight().getRight().getLeft();
        ArrayList gotoList = new ArrayList(); 

        JsrHook jsrHook = null;
        if (finallyBlock != null)
            jsrHook = new JsrHook(this);

        int start = bc.currentPc();
        body.accept(this);
        int end = bc.currentPc();
        if (start == end)
            throw new CompileError("empty try block");

        boolean tryNotReturn = !hasReturned;
        if (tryNotReturn) {
            bc.addOpcode(Opcode.GOTO);
            gotoList.add(new Integer(bc.currentPc()));
            bc.addIndex(0);   // correct later
        }

        int var = getMaxLocals();
        incMaxLocals(1);
        while (catchList != null) {
            // catch clause
            Pair p = (Pair)catchList.head();
            catchList = catchList.tail();
            Declarator decl = (Declarator)p.getLeft();
            Stmnt block = (Stmnt)p.getRight();

            decl.setLocalVar(var);

            CtClass type = resolver.lookupClassByJvmName(decl.getClassName());
            decl.setClassName(MemberResolver.javaToJvmName(type.getName()));
            bc.addExceptionHandler(start, end, bc.currentPc(), type);
            bc.growStack(1);
            bc.addAstore(var);
            hasReturned = false;
            if (block != null)
                block.accept(this);

            if (!hasReturned) {
                bc.addOpcode(Opcode.GOTO);
                gotoList.add(new Integer(bc.currentPc()));
                bc.addIndex(0);   // correct later
                tryNotReturn = true;
            }
        }

        int pcFinally = -1;
        if (finallyBlock != null) {
            jsrHook.remove(this);
            // catch (any) clause
            int pcAnyCatch = bc.currentPc();
            bc.addExceptionHandler(start, pcAnyCatch, pcAnyCatch, 0);
            bc.growStack(1);
            bc.addAstore(var);
            bc.addOpcode(JSR);
            int pcJsrIndex = bc.currentPc();
            bc.addIndex(0);       // correct later
            bc.addAload(var);
            bc.addOpcode(ATHROW);

            // finally clause
            pcFinally = bc.currentPc();
            bc.write16bit(pcJsrIndex, pcFinally - pcJsrIndex + 1);
            int retAddr = getMaxLocals();
            incMaxLocals(1);
            bc.growStack(1);    // return address
            bc.addAstore(retAddr);
            hasReturned = false;
            finallyBlock.accept(this);
            if (!hasReturned) {
                bc.addOpcode(RET);
                bc.add(retAddr);
            }
        }

        int pcEnd = bc.currentPc();
        patchGoto(gotoList, pcEnd);
        if (finallyBlock != null) {
            patchGoto(jsrHook.jsrList, pcFinally);
            if (tryNotReturn) {
                bc.addOpcode(JSR);
                bc.addIndex(pcFinally - pcEnd);
            }
        }

        hasReturned = !tryNotReturn;
    }

    public void atNewExpr(NewExpr expr) throws CompileError {
        if (expr.isArray())
            atNewArrayExpr(expr);
        else {
            CtClass clazz = resolver.lookupClassByName(expr.getClassName());
            String cname = clazz.getName();
            ASTList args = expr.getArguments();
            bytecode.addNew(cname);
            bytecode.addOpcode(DUP);

            atMethodCallCore(clazz, MethodInfo.nameInit, args,
                             false, true, -1, null);

            exprType = CLASS;
            arrayDim = 0;
            className = MemberResolver.javaToJvmName(cname);
        }
    }

    public void atNewArrayExpr(NewExpr expr) throws CompileError {
        int type = expr.getArrayType();
        ASTList size = expr.getArraySize();
        ASTList classname = expr.getClassName();
        ArrayInit init = expr.getInitializer();
        if (size.length() > 1) {
            if (init != null)
                throw new CompileError(
                        "sorry, multi-dimensional array initializer " +
                        "for new is not supported");

            atMultiNewArray(type, classname, size);
            return;
        }

        ASTree sizeExpr = size.head();
        atNewArrayExpr2(type, sizeExpr, Declarator.astToClassName(classname, '/'), init);
    }

    private void atNewArrayExpr2(int type, ASTree sizeExpr,
                        String jvmClassname, ArrayInit init) throws CompileError {
        if (init == null)
            if (sizeExpr == null)
                throw new CompileError("no array size");
            else
                sizeExpr.accept(this);
        else
            if (sizeExpr == null) {
                int s = init.length();
                bytecode.addIconst(s);
            }
            else
                throw new CompileError("unnecessary array size specified for new");

        String elementClass;
        if (type == CLASS) {
            elementClass = resolveClassName(jvmClassname);
            bytecode.addAnewarray(MemberResolver.jvmToJavaName(elementClass));
        }
        else {
            elementClass = null;
            int atype = 0;
            switch (type) {
            case BOOLEAN :
                atype = T_BOOLEAN;
                break;
            case CHAR :
                atype = T_CHAR;
                break;
            case FLOAT :
                atype = T_FLOAT;
                break;
            case DOUBLE :
                atype = T_DOUBLE;
                break;
            case BYTE :
                atype = T_BYTE;
                break;
            case SHORT :
                atype = T_SHORT;
                break;
            case INT :
                atype = T_INT;
                break;
            case LONG :
                atype = T_LONG;
                break;
            default :
                badNewExpr();
                break;
            }

            bytecode.addOpcode(NEWARRAY);
            bytecode.add(atype);
        }

        if (init != null) {
            int s = init.length();
            ASTList list = init;
            for (int i = 0; i < s; i++) {
                bytecode.addOpcode(DUP);
                bytecode.addIconst(i);
                list.head().accept(this);
                if (!isRefType(type))
                    atNumCastExpr(exprType, type);

                bytecode.addOpcode(getArrayWriteOp(type, 0));
                list = list.tail();
            }
        }

        exprType = type;
        arrayDim = 1;
        className = elementClass;
    }

    private static void badNewExpr() throws CompileError {
        throw new CompileError("bad new expression");
    }

    protected void atArrayVariableAssign(ArrayInit init, int varType,
                                         int varArray, String varClass) throws CompileError {
        atNewArrayExpr2(varType, null, varClass, init);
    }

    public void atArrayInit(ArrayInit init) throws CompileError {
        throw new CompileError("array initializer is not supported");
    }

    protected void atMultiNewArray(int type, ASTList classname, ASTList size)
        throws CompileError
    {
        int count, dim;
        dim = size.length();
        for (count = 0; size != null; size = size.tail()) {
            ASTree s = size.head();