ForwardingLayout.cs :  » Logging-Tools » log4net » SampleLayoutsApp » Layout » C# / CSharp Open Source

#region Copyright & License
//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed 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.
//
#endregion

using System;
using System.IO;
using log4net.Layout;
using log4net.Core;
using log4net.Util;

namespace SampleLayoutsApp.Layout{
  /// <summary>
  /// The ForwardingLayout forwards to a nested <see cref="ILayout"/>
  /// </summary>
  /// <remarks>
  /// The ForwardingLayout base class is used by layouts that want
  /// to decorate other <see cref="ILayout"/> objects.
  /// </remarks>
  public abstract class ForwardingLayout : ILayout, IOptionHandler
  {
    private ILayout m_nestedLayout;

    protected ForwardingLayout()
    {
    }

    public ILayout Layout
    {
      get { return m_nestedLayout; }
      set { m_nestedLayout = value; }
    }

    #region Implementation of IOptionHandler

    /// <summary>
    /// Activate component options
    /// </summary>
    /// <remarks>
    /// <para>
    /// This is part of the <see cref="IOptionHandler"/> delayed object
    /// activation scheme. The <see cref="ActivateOptions"/> method must 
    /// be called on this object after the configuration properties have
    /// been set. Until <see cref="ActivateOptions"/> is called this
    /// object is in an undefined state and must not be used. 
    /// </para>
    /// <para>
    /// If any of the configuration properties are modified then 
    /// <see cref="ActivateOptions"/> must be called again.
    /// </para>
    /// <para>
    /// This method must be implemented by the subclass.
    /// </para>
    /// </remarks>
    public virtual void ActivateOptions()
    {
      IOptionHandler optionHandler = m_nestedLayout as IOptionHandler;
      if (optionHandler != null)
      {
        optionHandler.ActivateOptions();
      }
    }

    #endregion

    #region Implementation of ILayout

    /// <summary>
    /// Implement this method to create your own layout format.
    /// </summary>
    /// <param name="writer">The TextWriter to write the formatted event to</param>
    /// <param name="loggingEvent">The event to format</param>
    /// <remarks>
    /// <para>
    /// This method is called by an appender to format
    /// the <paramref name="loggingEvent"/> as text.
    /// </para>
    /// </remarks>
    virtual public void Format(TextWriter writer, LoggingEvent loggingEvent)
    {
      if (m_nestedLayout != null)
      {
        m_nestedLayout.Format(writer, loggingEvent);
      }
    }

    /// <summary>
    /// The content type output by this layout. 
    /// </summary>
    /// <value>The content type is <c>"text/plain"</c></value>
    /// <remarks>
    /// <para>
    /// The content type output by this layout.
    /// </para>
    /// <para>
    /// This base class uses the value <c>"text/plain"</c>.
    /// To change this value a subclass must override this
    /// property.
    /// </para>
    /// </remarks>
    virtual public string ContentType
    {
      get 
      {
        if (m_nestedLayout != null)
        {
          return m_nestedLayout.ContentType;
        }
        return "text/plain"; 
      }
    }

    /// <summary>
    /// The header for the layout format.
    /// </summary>
    /// <value>the layout header</value>
    /// <remarks>
    /// <para>
    /// The Header text will be appended before any logging events
    /// are formatted and appended.
    /// </para>
    /// </remarks>
    virtual public string Header
    {
      get 
      { 
        if (m_nestedLayout != null)
        {
          return m_nestedLayout.Header;
        }
        return null;
      }
    }

    /// <summary>
    /// The footer for the layout format.
    /// </summary>
    /// <value>the layout footer</value>
    /// <remarks>
    /// <para>
    /// The Footer text will be appended after all the logging events
    /// have been formatted and appended.
    /// </para>
    /// </remarks>
    virtual public string Footer
    {
      get 
      { 
        if (m_nestedLayout != null)
        {
          return m_nestedLayout.Footer;
        }
        return null;
      }
    }

    /// <summary>
    /// Flag indicating if this layout handles exceptions
    /// </summary>
    /// <value><c>false</c> if this layout handles exceptions</value>
    /// <remarks>
    /// <para>
    /// If this layout handles the exception object contained within
    /// <see cref="LoggingEvent"/>, then the layout should return
    /// <c>false</c>. Otherwise, if the layout ignores the exception
    /// object, then the layout should return <c>true</c>.
    /// </para>
    /// <para>
    /// Set this value to override a this default setting. The default
    /// value is <c>true</c>, this layout does not handle the exception.
    /// </para>
    /// </remarks>
    virtual public bool IgnoresException 
    { 
      get 
      { 
        if (m_nestedLayout != null)
        {
          return m_nestedLayout.IgnoresException;
        }
        return true;
      }
    }

    #endregion
  }
}