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Java example source code file (JSJavaFrame.java)

This example Java source code file (JSJavaFrame.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

field_bci, field_line_number, field_locals, field_method, field_this_object, field_thread, field_undefined, integer, localvariabletableelement, map, object, objectheap, oophandle, string, util

The JSJavaFrame.java Java example source code

/*
 * Copyright (c) 2004, 2012, Oracle and/or its affiliates. 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.
 *
 * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

package sun.jvm.hotspot.utilities.soql;

import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.runtime.*;

public class JSJavaFrame extends DefaultScriptObject {
    private static final int FIELD_METHOD      = 0;
    private static final int FIELD_BCI         = 1;
    private static final int FIELD_LINE_NUMBER = 2;
    private static final int FIELD_LOCALS      = 3;
    private static final int FIELD_THIS_OBJECT = 4;
    private static final int FIELD_THREAD      = 5;
    private static final int FIELD_UNDEFINED   = -1;

    public JSJavaFrame(JavaVFrame jvf, JSJavaFactory fac) {
        this.jvf = jvf;
        this.factory = fac;
    }

    public Object get(String name) {
        int fieldID = getFieldID(name);
        switch (fieldID) {
        case FIELD_METHOD:
            return getMethod();
        case FIELD_BCI:
            return new Integer(getBCI());
        case FIELD_LINE_NUMBER:
            return new Integer(getLineNumber());
        case FIELD_LOCALS:
            return getLocals();
        case FIELD_THIS_OBJECT:
            return getThisObject();
        case FIELD_THREAD:
            return getThread();
        case FIELD_UNDEFINED:
        default:
            return super.get(name);
        }
    }

    public Object[] getIds() {
       Object[] fieldNames = fields.keySet().toArray();
       Object[] superFields = super.getIds();
       Object[] res = new Object[fieldNames.length + superFields.length];
       System.arraycopy(fieldNames, 0, res, 0, fieldNames.length);
       System.arraycopy(superFields, 0, res, fieldNames.length, superFields.length);
       return res;
   }

    public boolean has(String name) {
        if (getFieldID(name) != FIELD_UNDEFINED) {
            return true;
        } else {
            return super.has(name);
        }
    }

    public void put(String name, Object value) {
        if (getFieldID(name) == FIELD_UNDEFINED) {
            super.put(name, value);
        }
    }

    public String toString() {
        StringBuffer buf = new StringBuffer();
        buf.append("Frame (method=");
        buf.append(jvf.getMethod().externalNameAndSignature());
        buf.append(", bci=");
        buf.append(getBCI());
        buf.append(", line=");
        buf.append(getLineNumber());
        buf.append(')');
        return buf.toString();
    }

    //-- Internals only below this point
    private static Map fields = new HashMap();
    private static void addField(String name, int fieldId) {
        fields.put(name, new Integer(fieldId));
    }

    private static int getFieldID(String name) {
        Integer res = (Integer) fields.get(name);
        return (res != null)? res.intValue() : FIELD_UNDEFINED;
    }

    static {
        addField("method", FIELD_METHOD);
        addField("bci", FIELD_BCI);
        addField("line", FIELD_LINE_NUMBER);
        addField("locals", FIELD_LOCALS);
        addField("thisObject", FIELD_THIS_OBJECT);
        addField("thread", FIELD_THREAD);
    }

    private JSJavaMethod getMethod() {
        return factory.newJSJavaMethod(jvf.getMethod());
    }

    private int getBCI() {
        return jvf.getBCI();
    }

    private int getLineNumber() {
        int bci = jvf.getBCI();
        if (bci == -1) {
            return 0;
        } else {
            int lineNum = jvf.getMethod().getLineNumberFromBCI(bci);
            return (lineNum <= 0)? 0 : lineNum;
        }
    }

    private synchronized JSMap getLocals() {
        if (localsCache == null) {
            Map map = new HashMap();
            localsCache = factory.newJSMap(map);
            StackValueCollection values = jvf.getLocals();
            Method method = jvf.getMethod();
            if (method.isNative() || ! method.hasLocalVariableTable() ||
                values == null) {
                return localsCache;
            }

            LocalVariableTableElement[] localVars = method.getLocalVariableTable();
            int bci = getBCI();
            List visibleVars = new ArrayList(0);
            for (int i = 0; i < localVars.length; i++) {
                LocalVariableTableElement cur = localVars[i];
                int startBCI = cur.getStartBCI();
                if (startBCI <= bci && bci < startBCI + cur.getLength()) {
                    visibleVars.add(cur);
                }
            }

            OopHandle handle = null;
            ObjectHeap heap = VM.getVM().getObjectHeap();
            for (Iterator varItr = visibleVars.iterator(); varItr.hasNext();) {
                LocalVariableTableElement cur = (LocalVariableTableElement) varItr.next();
                String name =  method.getConstants().getSymbolAt(cur.getNameCPIndex()).asString();
                int slot = cur.getSlot();

                String signature = method.getConstants().getSymbolAt(cur.getDescriptorCPIndex()).asString();
                BasicType variableType = BasicType.charToBasicType(signature.charAt(0));
                Object value = null;
                if (variableType == BasicType.T_BOOLEAN) {
                    value = Boolean.valueOf(values.booleanAt(slot));
                } else if (variableType == BasicType.T_CHAR) {
                    value = new Character(values.charAt(slot));
                } else if (variableType == BasicType.T_FLOAT) {
                    value = new Float(values.floatAt(slot));
                } else if (variableType == BasicType.T_DOUBLE) {
                    value = new Double(values.doubleAt(slot));
                } else if (variableType == BasicType.T_BYTE) {
                    value = new Byte(values.byteAt(slot));
                } else if (variableType == BasicType.T_SHORT) {
                    value = new Short(values.shortAt(slot));
                } else if (variableType == BasicType.T_INT) {
                    value = new Integer(values.intAt(slot));
                } else if (variableType == BasicType.T_LONG) {
                    value = new Long(values.longAt(slot));
                } else if (variableType == BasicType.T_OBJECT ||
                       variableType == BasicType.T_ARRAY) {
                    handle = values.oopHandleAt(slot);
                    value = factory.newJSJavaObject(heap.newOop(handle));
                } else {
                    // ignore
                }
                map.put(name, value);
            }
        }
        return localsCache;
    }

    private JSJavaObject getThisObject() {
        Method method = jvf.getMethod();
        if (method.isStatic()) {
            return null;
        }
        StackValueCollection values = jvf.getLocals();
        if (values != null) {
            // 'this' at index 0.
            OopHandle handle = values.oopHandleAt(0);
            ObjectHeap heap = VM.getVM().getObjectHeap();
            return factory.newJSJavaObject(heap.newOop(handle));
        } else {
            // can't get locals, return null.
            return null;
        }
    }

    private JSJavaThread getThread() {
        return factory.newJSJavaThread(jvf.getThread());
    }

    private final JavaVFrame jvf;
    private final JSJavaFactory factory;
    private JSMap localsCache;
}

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