classwriter.java

是一款用JAVA 编写的编译器 具有很强的编译功能

            case FLOAT:
                databuf.appendByte('F');
                break;
            case DOUBLE:
                databuf.appendByte('D');
                break;
            case BOOLEAN:
                databuf.appendByte('Z');
                break;
            case CLASS:
                assert value instanceof String;
                databuf.appendByte('s');
                value = names.fromString(value.toString()); // CONSTANT_Utf8
                break;
            default:
                throw new AssertionError(_value.type);
            }
            databuf.appendChar(pool.put(value));
        }
        public void visitEnum(Attribute.Enum e) {
            databuf.appendByte('e');
            databuf.appendChar(pool.put(typeSig(e.value.type)));
            databuf.appendChar(pool.put(e.value.name));
        }
        public void visitClass(Attribute.Class clazz) {
            databuf.appendByte('c');
            databuf.appendChar(pool.put(typeSig(clazz.type)));
        }
        public void visitCompound(Attribute.Compound compound) {
            databuf.appendByte('@');
            writeCompoundAttribute(compound);
        }
        public void visitError(Attribute.Error x) {
            throw new AssertionError(x);
        }
        public void visitArray(Attribute.Array array) {
            databuf.appendByte('[');
            databuf.appendChar(array.values.length);
            for (Attribute a : array.values) {
                a.accept(this);
            }
        }
    }
    AttributeWriter awriter = new AttributeWriter();

    /** Write a compound attribute excluding the '@' marker. */
    void writeCompoundAttribute(Attribute.Compound c) {
        databuf.appendChar(pool.put(typeSig(c.type)));
        databuf.appendChar(c.values.length());
        for (Pair<Symbol.MethodSymbol,Attribute> p : c.values) {
            databuf.appendChar(pool.put(p.fst.name));
            p.snd.accept(awriter);
        }
    }

/**********************************************************************
 * Writing Objects
 **********************************************************************/

    /** Enter an inner class into the `innerClasses' set/queue.
     */
    void enterInner(ClassSymbol c) {
        assert !c.type.isCompound();
        try {
            c.complete();
        } catch (CompletionFailure ex) {
            System.err.println("error: " + c + ": " + ex.getMessage());
            throw ex;
        }
        if (c.type.tag != CLASS) return; // arrays
        if (pool != null && // pool might be null if called from xClassName
            c.owner.kind != PCK &&
            (innerClasses == null || !innerClasses.contains(c))) {
//          log.errWriter.println("enter inner " + c);//DEBUG
            if (c.owner.kind == TYP) enterInner((ClassSymbol)c.owner);
            pool.put(c);
            pool.put(c.name);
            if (innerClasses == null) {
                innerClasses = new HashSet<ClassSymbol>();
                innerClassesQueue = new ListBuffer<ClassSymbol>();
                pool.put(names.InnerClasses);
            }
            innerClasses.add(c);
            innerClassesQueue.append(c);
        }
    }

    /** Write "inner classes" attribute.
     */
    void writeInnerClasses() {
        int alenIdx = writeAttr(names.InnerClasses);
        databuf.appendChar(innerClassesQueue.length());
        for (List<ClassSymbol> l = innerClassesQueue.toList();
             l.nonEmpty();
             l = l.tail) {
            ClassSymbol inner = l.head;
            char flags = (char) adjustFlags(inner.flags_field);            	    
	    if ((flags & INTERFACE) != 0) flags |= ABSTRACT; // Interfaces are always ABSTRACT
            if (inner.name.isEmpty()) flags &= ~FINAL; // Anonymous class: unset FINAL flag
            if (dumpInnerClassModifiers) {
                log.errWriter.println("INNERCLASS  " + inner.name);
                log.errWriter.println("---" + flagNames(flags));
            }
            databuf.appendChar(pool.get(inner));
            databuf.appendChar(
                inner.owner.kind == TYP ? pool.get(inner.owner) : 0);
            databuf.appendChar(
                inner.name.len != 0 ? pool.get(inner.name) : 0);
            databuf.appendChar(flags);
        }
        endAttr(alenIdx);
    }

    /** Write field symbol, entering all references into constant pool.
     */
    void writeField(VarSymbol v) {
        int flags = adjustFlags(v.flags());
        databuf.appendChar(flags);
        if (dumpFieldModifiers) {
            log.errWriter.println("FIELD  " + fieldName(v));
            log.errWriter.println("---" + flagNames(v.flags()));
        }
        databuf.appendChar(pool.put(fieldName(v)));
        databuf.appendChar(pool.put(typeSig(v.erasure(types))));
        int acountIdx = beginAttrs();
        int acount = 0;
        if (v.getConstValue() != null) {
            int alenIdx = writeAttr(names.ConstantValue);
            databuf.appendChar(pool.put(v.getConstValue()));
            endAttr(alenIdx);
            acount++;
        }
        acount += writeMemberAttrs(v);
        endAttrs(acountIdx, acount);
    }

    /** Write method symbol, entering all references into constant pool.
     */
    void writeMethod(MethodSymbol m) {
        int flags = adjustFlags(m.flags());
        databuf.appendChar(flags);
        if (dumpMethodModifiers) {
            log.errWriter.println("METHOD  " + fieldName(m));
            log.errWriter.println("---" + flagNames(m.flags()));
        }
        databuf.appendChar(pool.put(fieldName(m)));
        databuf.appendChar(pool.put(typeSig(m.externalType(types))));
        int acountIdx = beginAttrs();
        int acount = 0;
        if (m.code != null) {
            int alenIdx = writeAttr(names.Code);
            writeCode(m.code);
            m.code = null; // to conserve space
            endAttr(alenIdx);
            acount++;
        }
        List<Type> thrown = m.erasure(types).getThrownTypes();
        if (thrown.nonEmpty()) {
            int alenIdx = writeAttr(names.Exceptions);
            databuf.appendChar(thrown.length());
            for (List<Type> l = thrown; l.nonEmpty(); l = l.tail)
                databuf.appendChar(pool.put(l.head.tsym));
            endAttr(alenIdx);
            acount++;
        }
        if (m.defaultValue != null) {
            int alenIdx = writeAttr(names.AnnotationDefault);
            m.defaultValue.accept(awriter);
            endAttr(alenIdx);
            acount++;
        }
        acount += writeMemberAttrs(m);
        acount += writeParameterAttrs(m);
        endAttrs(acountIdx, acount);
    }

    /** Write code attribute of method.
     */
    void writeCode(Code code) {
        databuf.appendChar(code.max_stack);
        databuf.appendChar(code.max_locals);
        databuf.appendInt(code.cp);
        databuf.appendBytes(code.code, 0, code.cp);
        databuf.appendChar(code.catchInfo.length());
        for (List<char[]> l = code.catchInfo.toList();
             l.nonEmpty();
             l = l.tail) {
            for (int i = 0; i < l.head.length; i++)
                databuf.appendChar(l.head[i]);
        }
        int acountIdx = beginAttrs();
        int acount = 0;

        if (code.lineInfo.nonEmpty()) {
            int alenIdx = writeAttr(names.LineNumberTable);
            databuf.appendChar(code.lineInfo.length());
            for (List<char[]> l = code.lineInfo.reverse();
                 l.nonEmpty();
                 l = l.tail)
                for (int i = 0; i < l.head.length; i++)
                    databuf.appendChar(l.head[i]);
            endAttr(alenIdx);
            acount++;
        }

        if (genCrt && (code.crt != null)) {
            CRTable crt = code.crt;
            int alenIdx = writeAttr(names.CharacterRangeTable);
            int crtIdx = beginAttrs();
            int crtEntries = crt.writeCRT(databuf, code.lineMap, log);
            endAttrs(crtIdx, crtEntries);
            endAttr(alenIdx);
            acount++;
        }

        // counter for number of generic local variables
        int nGenericVars = 0;

        if (code.varBufferSize > 0) {
            int alenIdx = writeAttr(names.LocalVariableTable);
            databuf.appendChar(code.varBufferSize);

            for (int i=0; i<code.varBufferSize; i++) {
                Code.LocalVar var = code.varBuffer[i];

                // write variable info
                assert var.start_pc >= 0;
                assert var.start_pc <= code.cp;
                databuf.appendChar(var.start_pc);
                assert var.length >= 0;
                assert (var.start_pc + var.length) <= code.cp;
                databuf.appendChar(var.length);
                VarSymbol sym = var.sym;
                databuf.appendChar(pool.put(sym.name));
                Type vartype = sym.erasure(types);
                if (!types.isSameType(sym.type, vartype))
                    nGenericVars++;
                databuf.appendChar(pool.put(typeSig(vartype)));
                databuf.appendChar(var.reg);
            }
            endAttr(alenIdx);
            acount++;
        }

        if (nGenericVars > 0) {
            int alenIdx = writeAttr(names.LocalVariableTypeTable);
            databuf.appendChar(nGenericVars);
            int count = 0;

            for (int i=0; i<code.varBufferSize; i++) {
                Code.LocalVar var = code.varBuffer[i];
                VarSymbol sym = var.sym;
                if (types.isSameType(sym.type, sym.erasure(types)))
                    continue;
                count++;
                // write variable info
                databuf.appendChar(var.start_pc);
                databuf.appendChar(var.length);
                databuf.appendChar(pool.put(sym.name));
                databuf.appendChar(pool.put(typeSig(sym.type)));
                databuf.appendChar(var.reg);
            }
            assert count == nGenericVars;
            endAttr(alenIdx);
            acount++;
        }

        if (code.stackMapBufferSize > 0) {
            if (debugstackmap) System.out.println("Stack map for " + code.meth);
            int alenIdx = writeAttr(code.stackMap.getAttributeName(names));
            writeStackMap(code);
            endAttr(alenIdx);
            acount++;
        }
        endAttrs(acountIdx, acount);
    }

    void writeStackMap(Code code) {
        int nframes = code.stackMapBufferSize;
        if (debugstackmap) System.out.println(" nframes = " + nframes);
        databuf.appendChar(nframes);

        switch (code.stackMap) {
        case CLDC:
            for (int i=0; i<nframes; i++) {
                if (debugstackmap) System.out.print("  " + i + ":");
                Code.StackMapFrame frame = code.stackMapBuffer[i];

                // output PC
                if (debugstackmap) System.out.print(" pc=" + frame.pc);
                databuf.appendChar(frame.pc);

                // output locals
                int localCount = 0;
                for (int j=0; j<frame.locals.length;
                     j += (target.generateEmptyAfterBig() ? 1 : Code.width(frame.locals[j]))) {
                    localCount++;
                }
                if (debugstackmap) System.out.print(" nlocals=" +
                                                    localCount);
                databuf.appendChar(localCount);
                for (int j=0; j<frame.locals.length;
                     j += (target.generateEmptyAfterBig() ? 1 : Code.width(frame.locals[j]))) {
                    if (debugstackmap) System.out.print(" local[" + j + "]=");
                    writeStackMapType(frame.locals[j]);
                }

                // output stack
                int stackCount = 0;
                for (int j=0; j<frame.stack.length;
                     j += (target.generateEmptyAfterBig() ? 1 : Code.width(frame.stack[j]))) {
                    stackCount++;
                }
                if (debugstackmap) System.out.print(" nstack=" +
                                                    stackCount);
                databuf.appendChar(stackCount);
                for (int j=0; j<frame.stack.length;
                     j += (target.generateEmptyAfterBig() ? 1 : Code.width(frame.stack[j]))) {
                    if (debugstackmap) System.out.print(" stack[" + j + "]=");
                    writeStackMapType(frame.stack[j]);
                }
                if (debugstackmap) System.out.println();
            }
            break;
        case JSR202: {
            assert code.stackMapBuffer == null;
            for (int i=0; i<nframes; i++) {
                if (debugstackmap) System.out.print("  " + i + ":");
                StackMapTableFrame frame = code.stackMapTableBuffer[i];
                frame.write(this);
                if (debugstackmap) System.out.println();                
            }
            break;
        }
        default:
            throw new AssertionError("Unexpected stackmap format value");
        }
    }

        //where
        void writeStackMapType(Type t) {
            if (t == null) {
                if (debugstackmap) System.out.print("empty");
                databuf.appendByte(0);
            }
            else switch(t.tag) {
            case BYTE:
            case CHAR:
            case SHORT:
            case INT:
            case BOOLEAN:
                if (debugstackmap) System.out.print("int");
                databuf.appendByte(1);
                break;
            case FLOAT:
                if (debugstackmap) System.out.print("float");
                databuf.appendByte(2);
                break;
            case DOUBLE:
                if (debugstackmap) System.out.print("double");
                databuf.appendByte(3);
                break;
            case LONG:
                if (debugstackmap) System.out.print("long");
                databuf.appendByte(4);
                break;
            case BOT: // null
                if (debugstackmap) System.out.print("null");
                databuf.appendByte(5);
                break;
            case CLASS:
            case ARRAY:
                if (debugstackmap) System.out.print("object(" + t + ")");
                databuf.appendByte(7);
                databuf.appendChar(pool.put(t));
                break;
            case TYPEVAR:
                if (debugstackmap) System.out.print("object(" + types.erasure(t).tsym + ")");
                databuf.appendByte(7);
                databuf.appendChar(pool.put(types.erasure(t).tsym));
                break;
            case UNINITIALIZED_THIS:
                if (debugstackmap) System.out.print("uninit_this");
                databuf.appendByte(6);
                break;
            case UNINITIALIZED_OBJECT:
                { UninitializedType uninitType = (UninitializedType)t;
                databuf.appendByte(8);
                if (debugstackmap) System.out.print("uninit_object@" + uninitType.offset);
                databuf.appendChar(uninitType.offset);
                }
                break;
            default:
                throw new AssertionError();
            }
        }
    
    /** An entry in the JSR202 StackMapTable */
    abstract static class StackMapTableFrame {
        abstract int getFrameType();
        
        void write(ClassWriter writer) {
            int frameType = getFrameType();
            writer.databuf.appendByte(frameType);
            if (writer.debugstackmap) System.out.print(" frame_type=" + frameType);
        }