typechecker.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.CtClass;
import javassist.CtField;
import javassist.ClassPool;
import javassist.Modifier;
import javassist.NotFoundException;
import javassist.compiler.ast.*;
import javassist.bytecode.*;

public class TypeChecker extends Visitor implements Opcode, TokenId {
    static final String javaLangObject = "java.lang.Object";
    static final String jvmJavaLangObject = "java/lang/Object";
    static final String jvmJavaLangString = "java/lang/String";
    static final String jvmJavaLangClass = "java/lang/Class";

    /* The following fields are used by atXXX() methods
     * for returning the type of the compiled expression.
     */
    protected int exprType;     // VOID, NULL, CLASS, BOOLEAN, INT, ...
    protected int arrayDim;
    protected String className; // JVM-internal representation

    protected MemberResolver resolver;
    protected CtClass   thisClass;
    protected MethodInfo thisMethod;

    public TypeChecker(CtClass cc, ClassPool cp) {
        resolver = new MemberResolver(cp);
        thisClass = cc;
        thisMethod = null;
    }

    /*
     * Converts an array of tuples of exprType, arrayDim, and className
     * into a String object.
     */
    protected static String argTypesToString(int[] types, int[] dims,
                                             String[] cnames) {
        StringBuffer sbuf = new StringBuffer();
        sbuf.append('(');
        int n = types.length;
        if (n > 0) {
            int i = 0;
            while (true) {
                typeToString(sbuf, types[i], dims[i], cnames[i]);
                if (++i < n)
                    sbuf.append(',');
                else
                    break;
            }
        }

        sbuf.append(')');
        return sbuf.toString();
    }

    /*
     * Converts a tuple of exprType, arrayDim, and className
     * into a String object.
     */
    protected static StringBuffer typeToString(StringBuffer sbuf,
                                        int type, int dim, String cname) {
        String s;
        if (type == CLASS)
            s = MemberResolver.jvmToJavaName(cname);
        else if (type == NULL)
            s = "Object";
        else
            try {
                s = MemberResolver.getTypeName(type);
            }
            catch (CompileError e) {
                s = "?";
            }

        sbuf.append(s);
        while (dim-- > 0)
            sbuf.append("[]");

        return sbuf;
    }

    /**
     * Records the currently compiled method.
     */
    public void setThisMethod(MethodInfo m) {
        thisMethod = m;
    }

    protected static void fatal() throws CompileError {
        throw new CompileError("fatal");
    }

    /**
     * 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());
    }

    /* Converts a class name into a JVM-internal representation.
     *
     * It may also expand a simple class name to java.lang.*.
     * For example, this converts Object into java/lang/Object.
     */
    protected String resolveClassName(ASTList name) throws CompileError {
        return resolver.resolveClassName(name);
    }

    /* Expands a simple class name to java.lang.*.
     * For example, this converts Object into java/lang/Object.
     */
    protected String resolveClassName(String jvmName) throws CompileError {
        return resolver.resolveJvmClassName(jvmName);
    }

    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();
            atMethodCallCore(clazz, MethodInfo.nameInit, args);
            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();
        ASTree init = expr.getInitializer();
        if (init != null)
            init.accept(this);

        if (size.length() > 1)
            atMultiNewArray(type, classname, size);
        else {
            ASTree sizeExpr = size.head();
            if (sizeExpr != null)
                sizeExpr.accept(this);

            exprType = type;
            arrayDim = 1;
            if (type == CLASS)
                className = resolveClassName(classname);
            else
                className = null;
        }
    }

    public void atArrayInit(ArrayInit init) throws CompileError {
        ASTList list = init;
        while (list != null) {
            ASTree h = list.head();
            list = list.tail();
            if (h != null)
                h.accept(this);
        }
    }

    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();
            if (s == null)
                break;          // int[][][] a = new int[3][4][];

            ++count;
            s.accept(this);
        }

        exprType = type;
        arrayDim = dim;
        if (type == CLASS)
            className = resolveClassName(classname);
        else
            className = null;
    }

    public void atAssignExpr(AssignExpr expr) throws CompileError {
        // =, %=, &=, *=, /=, +=, -=, ^=, |=, <<=, >>=, >>>=
        int op = expr.getOperator();
        ASTree left = expr.oprand1();
        ASTree right = expr.oprand2();
        if (left instanceof Variable)
            atVariableAssign(expr, op, (Variable)left,
                             ((Variable)left).getDeclarator(),
                             right);
        else {
            if (left instanceof Expr) {
                Expr e = (Expr)left;
                if (e.getOperator() == ARRAY) {
                    atArrayAssign(expr, op, (Expr)left, right);
                    return;
                }
            }

            atFieldAssign(expr, op, left, right);
        }
    }

    /* op is either =, %=, &=, *=, /=, +=, -=, ^=, |=, <<=, >>=, or >>>=.
     *
     * expr and var can be null.
     */
    private void atVariableAssign(Expr expr, int op, Variable var,
                                  Declarator d, ASTree right)
        throws CompileError
    {
        int varType = d.getType();
        int varArray = d.getArrayDim();
        String varClass = d.getClassName();

        if (op != '=')
            atVariable(var);

        right.accept(this);
        exprType = varType;
        arrayDim = varArray;
        className = varClass;
    }

    private void atArrayAssign(Expr expr, int op, Expr array,
                        ASTree right) throws CompileError
    {
        atArrayRead(array.oprand1(), array.oprand2());
        int aType = exprType;
        int aDim = arrayDim;
        String cname = className;
        right.accept(this);
        exprType = aType;
        arrayDim = aDim;
        className = cname;
    }

    protected void atFieldAssign(Expr expr, int op, ASTree left, ASTree right)
        throws CompileError
    {
        CtField f = fieldAccess(left);
        atFieldRead(f);
        int fType = exprType;
        int fDim = arrayDim;
        String cname = className;
        right.accept(this);
        exprType = fType;
        arrayDim = fDim;
        className = cname;
    }

    public void atCondExpr(CondExpr expr) throws CompileError {
        booleanExpr(expr.condExpr());
        expr.thenExpr().accept(this);
        int type1 = exprType;
        int dim1 = arrayDim;
        String cname1 = className;
        expr.elseExpr().accept(this);

        if (dim1 == 0 && dim1 == arrayDim)
            if (CodeGen.rightIsStrong(type1, exprType))
                expr.setThen(new CastExpr(exprType, 0, expr.thenExpr()));
            else if (CodeGen.rightIsStrong(exprType, type1)) {
                expr.setElse(new CastExpr(type1, 0, expr.elseExpr()));
                exprType = type1;
            }
    }

    /*
     * If atBinExpr() substitutes a new expression for the original
     * binary-operator expression, it changes the operator name to '+'
     * (if the original is not '+') and sets the new expression to the
     * left-hand-side expression and null to the right-hand-side expression. 
     */
    public void atBinExpr(BinExpr expr) throws CompileError {
        int token = expr.getOperator();
        int k = CodeGen.lookupBinOp(token);
        if (k >= 0) {
            /* arithmetic operators: +, -, *, /, %, |, ^, &, <<, >>, >>>
             */
            if (token == '+') {
                Expr e = atPlusExpr(expr);
                if (e != null) {
                    /* String concatenation has been translated into
                     * an expression using StringBuffer.
                     */
                    e = CallExpr.makeCall(Expr.make('.', e,
                                            new Member("toString")), null);
                    expr.setOprand1(e);
                    expr.setOprand2(null);    // <---- look at this!
                    className = jvmJavaLangString;
                }
            }
            else {
                ASTree left = expr.oprand1();
                ASTree right = expr.oprand2();
                left.accept(this);