common/src/main/java/flex/messaging/util/ObjectTrace.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package flex.messaging.util;

import flex.messaging.log.Log;

/**
 * Simple utility to trace an Object graph out to a StringBuffer.
 * <p>
 * Note that new lines are NOT added after the individual values
 * in complex type properties.
 */
public class ObjectTrace {


    /* This boolean is used for suppressing debug output for selected properties.
     * The logger will check this before printing a property.
     */
    public boolean nextElementExclude;

    public ObjectTrace() {
        buffer = new StringBuffer(4096);
    }

    public ObjectTrace(int bufferSize) {
        buffer = new StringBuffer(bufferSize);
    }

    public String toString() {
        return buffer.toString();
    }

    public void write(Object o) {
        if (m_nested <= 0)
            buffer.append(indentString());

        buffer.append(String.valueOf(o));
    }

    public void writeNull() {
        if (m_nested <= 0)
            buffer.append(indentString());

        buffer.append("null");
    }

    public void writeRef(int ref) {
        if (m_nested <= 0)
            buffer.append(indentString());

        buffer.append("(Ref #").append(ref).append(")");
    }

    public void writeString(String s) {
        if (m_nested <= 0)
            buffer.append(indentString());

        buffer.append("\"").append(s).append("\"");
    }

    public void startArray(String header) {
        if (header != null && header.length() > 0) {
            if (m_nested <= 0)
                buffer.append(indentString());

            buffer.append(header).append(newLine);
        }

        m_indent++;
        m_nested++;
    }

    public void arrayElement(int index) {
        buffer.append(indentString()).append("[").append(index).append("] = ");
    }

    public void endArray() {
        m_indent--;
        m_nested--;
    }

    public void startObject(String header) {
        if (header != null && header.length() > 0) {
            if (m_nested <= 0)
                buffer.append(indentString());

            buffer.append(header).append(newLine);
        }

        m_indent++;
        m_nested++;
    }

    public void namedElement(String name) {
        if (Log.isExcludedProperty(name)) {
            nextElementExclude = true;
        }

        buffer.append(indentString()).append(name).append(" = ");
    }

    public void endObject() {
        m_indent--;
        m_nested--;
    }

    public void newLine() {
        boolean alreadyPadded = false;
        int length = buffer.length();

        if (length > 3) {
            String tail = buffer.substring(length - 3, length - 1); //Get last two chars in buffer
            alreadyPadded = tail.equals(newLine);
        }

        if (!alreadyPadded)
            buffer.append(newLine);
    }

    /**
     * Uses the static member, m_indent to create a string of spaces of
     * the appropriate indentation.
     *
     * @return the ident string.
     */
    protected String indentString() {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < m_indent; ++i) {
            sb.append("  ");
        }
        return sb.toString();
    }

    protected StringBuffer buffer;
    protected int m_indent;
    protected int m_nested;
    public static String newLine = StringUtils.NEWLINE;
}