util/attrs/ASMStackMapTableAttribute.java

/**
 * 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.util.attrs;

import java.util.List;
import java.util.Map;

import org.objectweb.asm.Attribute;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.Label;
import org.objectweb.asm.attrs.StackMapTableAttribute;
import org.objectweb.asm.attrs.StackMapFrame;
import org.objectweb.asm.attrs.StackMapType;

/**
 * An {@link ASMifiable} {@link StackMapTableAttribute} sub class.
 *
 * @author Eugene Kuleshov
 */
public class ASMStackMapTableAttribute extends StackMapTableAttribute implements
        ASMifiable,
        Traceable
{
    /**
     * Length of the attribute used for comparison
     */
    private int len;

    public ASMStackMapTableAttribute() {
        super();
    }

    public ASMStackMapTableAttribute(List frames, int len) {
        super(frames);
        this.len = len;
    }

    protected Attribute read(
        ClassReader cr,
        int off,
        int len,
        char[] buf,
        int codeOff,
        Label[] labels)
    {
        StackMapTableAttribute attr = (StackMapTableAttribute) super.read(cr,
                off,
                len,
                buf,
                codeOff,
                labels);

        return new ASMStackMapTableAttribute(attr.getFrames(), len);
    }

    public void asmify(StringBuffer buf, String varName, Map labelNames) {
        List frames = getFrames();
        if (frames.size() == 0) {
            buf.append("List frames = Collections.EMPTY_LIST;\n");
        } else {
            buf.append("List frames = new ArrayList();\n");
            for (int i = 0; i < frames.size(); i++) {
                buf.append("{\n");
                StackMapFrame f = (StackMapFrame) frames.get(i);
                declareLabel(buf, labelNames, f.label);

                String frameVar = varName + "frame" + i;
                asmifyTypeInfo(buf, frameVar, labelNames, f.locals, "locals");
                asmifyTypeInfo(buf, frameVar, labelNames, f.stack, "stack");

                buf.append("StackMapFrame ")
                        .append(frameVar)
                        .append(" = new StackMapFrame(")
                        .append(labelNames.get(f.label))
                        .append(", locals, stack);\n");
                buf.append("frames.add(").append(frameVar).append(");\n");
                buf.append("}\n");
            }
        }
        buf.append("StackMapTableAttribute ").append(varName);
        buf.append(" = new StackMapTableAttribute(frames);\n");
    }

    void asmifyTypeInfo(
        StringBuffer buf,
        String varName,
        Map labelNames,
        List infos,
        String field)
    {
        if (infos.size() == 0) {
            buf.append("List ")
                    .append(field)
                    .append(" = Collections.EMPTY_LIST;\n");
        } else {
            buf.append("List ").append(field).append(" = new ArrayList();\n");
            buf.append("{\n");
            for (int i = 0; i < infos.size(); i++) {
                StackMapType typeInfo = (StackMapType) infos.get(i);
                String localName = varName + "Info" + i;
                int type = typeInfo.getType();
                buf.append("StackMapType ")
                        .append(localName)
                        .append(" = StackMapType.getTypeInfo( StackMapType.ITEM_")
                        .append(StackMapType.ITEM_NAMES[type])
                        .append(");\n");

                switch (type) {
                    case StackMapType.ITEM_Object: //
                        buf.append(localName)
                                .append(".setObject(\"")
                                .append(typeInfo.getObject())
                                .append("\");\n");
                        break;

                    case StackMapType.ITEM_Uninitialized: //
                        declareLabel(buf, labelNames, typeInfo.getLabel());
                        buf.append(localName)
                                .append(".setLabel(")
                                .append(labelNames.get(typeInfo.getLabel()))
                                .append(");\n");
                        break;
                }
                buf.append(field)
                        .append(".add(")
                        .append(localName)
                        .append(");\n");
            }
            buf.append("}\n");
        }
    }

    static void declareLabel(StringBuffer buf, Map labelNames, Label l) {
        String name = (String) labelNames.get(l);
        if (name == null) {
            name = "l" + labelNames.size();
            labelNames.put(l, name);
            buf.append("Label ").append(name).append(" = new Label();\n");
        }
    }

    public void trace(StringBuffer buf, Map labelNames) {
        List frames = getFrames();
        buf.append("[\n");
        for (int i = 0; i < frames.size(); i++) {
            StackMapFrame f = (StackMapFrame) frames.get(i);

            buf.append("    Frame:");
            appendLabel(buf, labelNames, f.label);

            buf.append(" locals[");
            traceTypeInfo(buf, labelNames, f.locals);
            buf.append("]");
            buf.append(" stack[");
            traceTypeInfo(buf, labelNames, f.stack);
            buf.append("]\n");
        }
        buf.append("  ] length:").append(len).append("\n");
    }

    private void traceTypeInfo(StringBuffer buf, Map labelNames, List infos) {
        String sep = "";
        for (int i = 0; i < infos.size(); i++) {
            StackMapType t = (StackMapType) infos.get(i);

            buf.append(sep).append(StackMapType.ITEM_NAMES[t.getType()]);
            sep = ", ";
            if (t.getType() == StackMapType.ITEM_Object) {
                buf.append(":").append(t.getObject());
            }
            if (t.getType() == StackMapType.ITEM_Uninitialized) {
                buf.append(":");
                appendLabel(buf, labelNames, t.getLabel());
            }
        }
    }

    protected void appendLabel(StringBuffer buf, Map labelNames, Label l) {
        String name = (String) labelNames.get(l);
        if (name == null) {
            name = "L" + labelNames.size();
            labelNames.put(l, name);
        }
        buf.append(name);
    }

}