optionconverter.cs

精通SQL Server2005项目开发

#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.Collections;
using System.Globalization;
using System.Reflection;
using System.Text;

using log4net.Core;
using log4net.Util.TypeConverters;

namespace log4net.Util
{
	/// <summary>
	/// A convenience class to convert property values to specific types.
	/// </summary>
	/// <remarks>
	/// <para>
	/// Utility functions for converting types and parsing values.
	/// </para>
	/// </remarks>
	/// <author>Nicko Cadell</author>
	/// <author>Gert Driesen</author>
	public sealed class OptionConverter
	{
		#region Private Instance Constructors

		/// <summary>
		/// Initializes a new instance of the <see cref="OptionConverter" /> class. 
		/// </summary>
		/// <remarks>
		/// <para>
		/// Uses a private access modifier to prevent instantiation of this class.
		/// </para>
		/// </remarks>
		private OptionConverter()
		{
		}

		#endregion Private Instance Constructors

		#region Public Static Methods

//		/// <summary>
//		/// Concatenates two string arrays.
//		/// </summary>
//		/// <param name="l">Left array.</param>
//		/// <param name="r">Right array.</param>
//		/// <returns>Array containing both left and right arrays.</returns>
//		public static string[] ConcatenateArrays(string[] l, string[] r) 
//		{
//			return (string[])ConcatenateArrays(l, r);
//		}

//		/// <summary>
//		/// Concatenates two arrays.
//		/// </summary>
//		/// <param name="l">Left array</param>
//		/// <param name="r">Right array</param>
//		/// <returns>Array containing both left and right arrays.</returns>
//		public static Array ConcatenateArrays(Array l, Array r) 
//		{
//			if (l == null)
//			{
//				throw new ArgumentNullException("l");
//			}
//			if (r == null)
//			{
//				throw new ArgumentNullException("r");
//			}
//
//			int len = l.Length + r.Length;
//			Array a = Array.CreateInstance(l.GetType(), len);
//
//			Array.Copy(l, 0, a, 0, l.Length);
//			Array.Copy(r, 0, a, l.Length, r.Length);
//
//			return a;
//		}
  
//		/// <summary>
//		/// Converts string escape characters back to their correct values.
//		/// </summary>
//		/// <param name="s">String to convert.</param>
//		/// <returns>Converted result.</returns>
//		public static string ConvertSpecialChars(string s) 
//		{
//			if (s == null)
//			{
//				throw new ArgumentNullException("s");
//			}
//			char c;
//			int len = s.Length;
//			StringBuilder buf = new StringBuilder(len);
//	
//			int i = 0;
//			while(i < len) 
//			{
//				c = s[i++];
//				if (c == '\\') 
//				{
//					c =  s[i++];
//					if (c == 'n')	  c = '\n';
//					else if (c == 'r') c = '\r';
//					else if (c == 't') c = '\t';
//					else if (c == 'f') c = '\f';
//					else if (c == '\b') c = '\b';					
//					else if (c == '\"') c = '\"';				
//					else if (c == '\'') c = '\'';			
//					else if (c == '\\') c = '\\';			
//				}
//				buf.Append(c);	  
//			}
//			return buf.ToString();
//		}

		/// <summary>
		/// Converts a string to a <see cref="bool" /> value.
		/// </summary>
		/// <param name="argValue">String to convert.</param>
		/// <param name="defaultValue">The default value.</param>
		/// <returns>The <see cref="bool" /> value of <paramref name="argValue" />.</returns>
		/// <remarks>
		/// <para>
		/// If <paramref name="argValue"/> is "true", then <c>true</c> is returned. 
		/// If <paramref name="argValue"/> is "false", then <c>false</c> is returned. 
		/// Otherwise, <paramref name="defaultValue"/> is returned.
		/// </para>
		/// </remarks>
		public static bool ToBoolean(string argValue, bool defaultValue) 
		{
			if (argValue != null && argValue.Length > 0)
			{
				try
				{
					return bool.Parse(argValue);
				}
				catch(Exception e)
				{
					LogLog.Error("OptionConverter: [" + argValue + "] is not in proper bool form.", e);
				}
			}
			return defaultValue;
		}

//		/// <summary>
//		/// Converts a string to an integer.
//		/// </summary>
//		/// <param name="argValue">String to convert.</param>
//		/// <param name="defaultValue">The default value.</param>
//		/// <returns>The <see cref="int" /> value of <paramref name="argValue" />.</returns>
//		/// <remarks>
//		/// <para>
//		/// <paramref name="defaultValue"/> is returned when <paramref name="argValue"/>
//		/// cannot be converted to a <see cref="int" /> value.
//		/// </para>
//		/// </remarks>
//		public static int ToInt(string argValue, int defaultValue) 
//		{
//			if (argValue != null) 
//			{
//				string s = argValue.Trim();
//				try 
//				{
//					return int.Parse(s, NumberFormatInfo.InvariantInfo);
//				}
//				catch (Exception e) 
//				{
//					LogLog.Error("OptionConverter: [" + s + "] is not in proper int form.", e);
//				}
//			}
//			return defaultValue;
//		}

		/// <summary>
		/// Parses a file size into a number.
		/// </summary>
		/// <param name="argValue">String to parse.</param>
		/// <param name="defaultValue">The default value.</param>
		/// <returns>The <see cref="long" /> value of <paramref name="argValue" />.</returns>
		/// <remarks>
		/// <para>
		/// Parses a file size of the form: number[KB|MB|GB] into a
		/// long value. It is scaled with the appropriate multiplier.
		/// </para>
		/// <para>
		/// <paramref name="defaultValue"/> is returned when <paramref name="argValue"/>
		/// cannot be converted to a <see cref="long" /> value.
		/// </para>
		/// </remarks>
		public static long ToFileSize(string argValue, long defaultValue) 
		{
			if (argValue == null)
			{
				return defaultValue;
			}
	
			string s = argValue.Trim().ToUpper(CultureInfo.InvariantCulture);
			long multiplier = 1;
			int index;
	
			if ((index = s.IndexOf("KB")) != -1) 
			{	  
				multiplier = 1024;
				s = s.Substring(0, index);
			}
			else if ((index = s.IndexOf("MB")) != -1) 
			{
				multiplier = 1024 * 1024;
				s = s.Substring(0, index);
			}
			else if ((index = s.IndexOf("GB")) != -1) 
			{
				multiplier = 1024 * 1024 * 1024;
				s = s.Substring(0, index);
			}	
			if (s != null) 
			{
				// Try again to remove whitespace between the number and the size specifier
				s = s.Trim();
				
				long longVal;
				if (SystemInfo.TryParse(s, out longVal))
				{
					return longVal * multiplier;
				}
				else
				{
					LogLog.Error("OptionConverter: ["+ s +"] is not in the correct file size syntax.");
				}
			}
			return defaultValue;
		}

		/// <summary>
		/// Converts a string to an object.
		/// </summary>
		/// <param name="target">The target type to convert to.</param>
		/// <param name="txt">The string to convert to an object.</param>
		/// <returns>
		/// The object converted from a string or <c>null</c> when the 
		/// conversion failed.
		/// </returns>
		/// <remarks>
		/// <para>
		/// Converts a string to an object. Uses the converter registry to try
		/// to convert the string value into the specified target type.
		/// </para>
		/// </remarks>
		public static object ConvertStringTo(Type target, string txt)
		{
			if (target == null)
			{
				throw new ArgumentNullException("target");
			}

			// If we want a string we already have the correct type
			if (typeof(string) == target || typeof(object) == target)
			{
				return txt;
			}

			// First lets try to find a type converter
			IConvertFrom typeConverter = ConverterRegistry.GetConvertFrom(target);
			if (typeConverter != null && typeConverter.CanConvertFrom(typeof(string)))
			{
				// Found appropriate converter
				return typeConverter.ConvertFrom(txt);
			}
			else
			{
				if (target.IsEnum)
				{
					// Target type is an enum.

					// Use the Enum.Parse(EnumType, string) method to get the enum value
					return ParseEnum(target, txt, true);
				}
				else
				{
					// We essentially make a guess that to convert from a string
					// to an arbitrary type T there will be a static method defined on type T called Parse
					// that will take an argument of type string. i.e. T.Parse(string)->T we call this
					// method to convert the string to the type required by the property.
					System.Reflection.MethodInfo meth = target.GetMethod("Parse", new Type[] {typeof(string)});
					if (meth != null)
					{
						// Call the Parse method
						return meth.Invoke(null, BindingFlags.InvokeMethod, null, new object[] {txt}, CultureInfo.InvariantCulture);
					}
					else
					{
						// No Parse() method found.
					}
				}
			}
			return null;
		}

//		/// <summary>
//		/// Looks up the <see cref="IConvertFrom"/> for the target type.
//		/// </summary>
//		/// <param name="target">The type to lookup the converter for.</param>
//		/// <returns>The converter for the specified type.</returns>
//		public static IConvertFrom GetTypeConverter(Type target)
//		{
//			IConvertFrom converter = ConverterRegistry.GetConverter(target);
//			if (converter == null)
//			{