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Demonstrating Custom Attributes: Build An Assembly Searching Tool.

, 25 Dec 2005 CPOL
Build an assembly searching system via custom attributes and reflection.
keywordattributesystem_src.zip
DirectoryLister
KeywordAttribute
Clients
Implementations
Interfaces
KeywordAttributeAssemblyLister
KeywordAttributedAssemblies
App.ico
KeywordAttributeAssemblyLister.csproj.user
KAAssembly01
KAClass01
KADelegate01
KAParameters01
KAProperty01
App.ico
KAAssembly01.csproj.user
keyfile.snk
KAClass01.csproj.user
keyfile.snk
KADelegate01.csproj.user
keyfile.snk
App.ico
KAParameters01.csproj.user
keyfile.snk
KAProperty01.csproj.user
keyfile.snk
AssemblyFilesLister
DirectoryListerBase
AssemblyFilesLister.csproj.user
DirectoryListerBase.csproj.user
DirectoryListerInterface
DirectoryListerInterface.csproj.user
keyfile.snk
KeywordAttribute.csproj.user
using System;
using AssemblyFilesListerNamespace;
using DirectoryListerInterfaceNamespace;
using KeywordAttributeNamespace;
using System.Reflection;
using System.Collections;

namespace KeywordAttributeAssemblyLister
{
	// Structure that holds information about a 
	// type that is keyword attributed.
	public struct KeywordAttributedType
	{
		public string	m_TypeName;
		public int		m_iRelevance;
	}

	// Structure that holds information about an
	// assembly that is keyword attributed.
	public struct KeywordAttributedAssembly
	{
		public string		m_strAssemblyFullPath;
		public string		m_strKeyword;
		public ArrayList	m_KeywordAttributedTypesArray;
	}

	/// <summary>
	/// Summary description for ClassMain.
	/// </summary>
	class ClassMain
	{
		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main(string[] args)
		{
			// We make use of the services of an IDirectoryLister interface implemented 
			// by the AssemblyFilesLister class.
			IDirectoryLister	dl = new AssemblyFilesLister();
			// The "dl" DirectoryLister object will return to us a DirectoryEntry object
			// filled with sub-directories and files contained inside a target directory.
			DirectoryEntry		de;
			// KeywordAttributedAssembliesArray is an ArrayList object which holds
			// an array of KeywordAttributedAssembly entries. Each entry represents
			// an assembly that uses the specified Keyword Attribute.
			ArrayList			KeywordAttributedAssembliesArray = new ArrayList();
			int					i = 0;

			// Indicate to the IDirectoryLister object which directory to scan.
			// In our case, this will be the directory supplied by the user in 
			// the first argument to this program.
			dl.DirectoryToList = args[0];
			// Indicate that we want the directory scanning to be recursive.
			dl.Recursive = true;
			// Tell the IDirectoryLister object to begin scanning.
			dl.BeginListing();

			// At this point, directory scanning is done and we obtain the main directory entry object.
			de = dl.DirectoryEntry;

			Console.WriteLine("Searching [{0}] for Assemblies Attributed with Keyword \"{1}\" and Minimum Relevance {2}.", args[0], args[1], args[2]);
			Console.WriteLine();

			// Search through the main directory and all its subdirectories and scan for 
			// Keyword Attributed Assemblies.
			SearchAndCollectKeywordAttributesAssemblies(de, args[1], Convert.ToInt32(args[2]), ref KeywordAttributedAssembliesArray);

			// Once done, KeywordAttributedAssembliesArray will contain KeywordAttributedAssembly objects
			// each of which contains information on one assembly that uses the specified Keyword Attribute.
			for (i = 0; i < KeywordAttributedAssembliesArray.Count; i++)
			{
				KeywordAttributedAssembly keyword_attributed_assembly = (KeywordAttributedAssembly)(KeywordAttributedAssembliesArray[i]);

				Console.WriteLine("Listing Types in Assembly : [{0}]", keyword_attributed_assembly.m_strAssemblyFullPath);

				// Each keyword_attributed_assembly contains an internal array of KeywordAttributedType
				// objects. Each object contains information on a type that uses the specified Keyword Attribute.
				// The relevance level is also included.
				int j = 0;
				for (j = 0; j < keyword_attributed_assembly.m_KeywordAttributedTypesArray.Count; j++)
				{
					KeywordAttributedType keyword_attributed_type = (KeywordAttributedType)(keyword_attributed_assembly.m_KeywordAttributedTypesArray[j]);

					Console.WriteLine("Type Name : {0}. Relevance : {1}.", keyword_attributed_type.m_TypeName, keyword_attributed_type.m_iRelevance);
				}

				Console.WriteLine();
			}
		}

		// This function searches through the files contained in the m_feArray of an input
		// DirectoryEntry struct searching for types which are KeywordAttributed by a 
		// specific keyword string and are above a minimum relevance value.
		// 
		// This function also recursively calls itself on all the directories contained
		// inside the m_deArray array of the input DirectoryEntry struct.
		static void SearchAndCollectKeywordAttributesAssemblies(DirectoryEntry de, string strKeyword, int iMinRelevance, ref ArrayList KeywordAttributedAssembliesArray)
		{
			if (de.m_feArray != null)
			{
				foreach(FileEntry fe in de.m_feArray)
				{
					CollectKeywordAttributedTypes(fe.m_strName, strKeyword, iMinRelevance, ref KeywordAttributedAssembliesArray);
				}
			}

			if (de.m_deArray != null)
			{
				foreach(DirectoryEntry _de in de.m_deArray)
				{
					SearchAndCollectKeywordAttributesAssemblies(_de, strKeyword, iMinRelevance, ref KeywordAttributedAssembliesArray);
				}
			}
		}

		static void CollectKeywordAttributedTypes(string strAssembly, string strKeyword, int iMinRelevance, ref ArrayList KeywordAttributedAssembliesArray)
		{
			Assembly assembly;

			try
			{
				// Load the assembly from a filename
				assembly = Assembly.LoadFrom(strAssembly);
			}
			catch (Exception)
			{
				// Could not load the assembly.
				return;
			}

			try
			{
				KeywordAttributedAssembly	current_keyword_attributed_assembly = new KeywordAttributedAssembly();
				bool						bAddToKeywordAttributedAssembliesArray = false;

				// Prepare a new AssemblyWithKeyword object in case we are indeed 
				// currently working with an Assembly that uses the Keyword attribute.
				current_keyword_attributed_assembly.m_strAssemblyFullPath = strAssembly;
				current_keyword_attributed_assembly.m_strKeyword = strKeyword;
				current_keyword_attributed_assembly.m_KeywordAttributedTypesArray = new ArrayList();

				// Collect all the Keyword Attrbutes from the Assembly itself.
				// Check for the KeywordAttribute on the Assembly itself.
				KeywordAttribute[] keyword_attributes_in_assembly = (KeywordAttribute[])(assembly.GetCustomAttributes(typeof(KeywordAttribute), true));
				// The collection is non-zero in size.
				if (keyword_attributes_in_assembly.Length > 0)
				{
					// We enumerate through the Keyword Attributes in the assembly.
					foreach (KeywordAttribute a in keyword_attributes_in_assembly)
					{
						// We filter through the keyword attributes and select
						// only those whose keywords match the search keyword (strKeyword)
						// and whose relevance is at least equal to the required 
						// relevance (i.e. iMinRelevance).
						if ((a.Keyword == strKeyword) && (a.Relevance >= iMinRelevance))
						{
							KeywordAttributedType keyword_attributed_type = new KeywordAttributedType();

							keyword_attributed_type.m_TypeName = "assembly";
							keyword_attributed_type.m_iRelevance = a.Relevance;

							// Add the current TypeWithKeyword object to the ArrayList
							// of TypeWithKeyword objects in the Current AssemblyWithKeyword 
							// object (current_assembly_with_keyword).
							current_keyword_attributed_assembly.m_KeywordAttributedTypesArray.Add((object)keyword_attributed_type);

							// Indicate that the Current AssemblyWithKeyword object (current_assembly_with_keyword)
							// is to be added to the input reference ArrayList AssemblyWithKeywordArray later on.
							bAddToKeywordAttributedAssembliesArray = true;
						}
					}
				}

				// Enumerate over the types in the current assembly and search for the 
				// occurrence of the usage of the Keyword Attribute.
				foreach (Type t in assembly.GetTypes())
				{
					// Check for the KeywordAttribute on the type
					KeywordAttribute[] keyword_attributes_in_types = (KeywordAttribute[])(t.GetCustomAttributes(typeof(KeywordAttribute), true));

					if (keyword_attributes_in_types.Length > 0)
					{
						foreach (KeywordAttribute a in keyword_attributes_in_types)
						{
							if ((a.Keyword == strKeyword) && (a.Relevance >= iMinRelevance))
							{
								KeywordAttributedType keyword_attributed_type = new KeywordAttributedType();

								keyword_attributed_type.m_TypeName = t.ToString();
								keyword_attributed_type.m_iRelevance = a.Relevance;

								current_keyword_attributed_assembly.m_KeywordAttributedTypesArray.Add((object)keyword_attributed_type);

								bAddToKeywordAttributedAssembliesArray = true;
							}
						}
					}

					// Enumerate over the members of the current type
					foreach (MemberInfo member in t.GetMembers())
					{
						// Check for the KeywordAttribute on the member
						KeywordAttribute[] keyword_attributes_in_type_members = (KeywordAttribute [])(member.GetCustomAttributes(typeof(KeywordAttribute), true));

						if (keyword_attributes_in_type_members.Length > 0)
						{
							foreach (KeywordAttribute a in keyword_attributes_in_type_members)
							{
								if ((a.Keyword == strKeyword) && (a.Relevance >= iMinRelevance))
								{
									KeywordAttributedType keyword_attributed_type = new KeywordAttributedType();

									keyword_attributed_type.m_TypeName = t.ToString() + "." + member.Name;
									keyword_attributed_type.m_iRelevance = a.Relevance;

									current_keyword_attributed_assembly.m_KeywordAttributedTypesArray.Add((object)keyword_attributed_type);

									bAddToKeywordAttributedAssembliesArray = true;
								}
							}
						}

						// If the current member is a method, we determine if any of the
						// method's parameters is also Keyword Attributed.
						if (member.MemberType == MemberTypes.Method)
						{
							MethodInfo mi = (MethodInfo)member;

							foreach(ParameterInfo p in mi.GetParameters())
							{
								KeywordAttribute[] keyword_attributes_in_method_parameters = (KeywordAttribute [])(p.GetCustomAttributes(typeof(KeywordAttribute), true));

								if (keyword_attributes_in_method_parameters.Length > 0)
								{
									foreach (KeywordAttribute a in keyword_attributes_in_method_parameters)
									{
										if ((a.Keyword == strKeyword) && (a.Relevance >= iMinRelevance))
										{
											KeywordAttributedType keyword_attributed_type = new KeywordAttributedType();

											keyword_attributed_type.m_TypeName = "Parameter to Method " + member.Name + "() : " + p.Name;
											keyword_attributed_type.m_iRelevance = a.Relevance;

											current_keyword_attributed_assembly.m_KeywordAttributedTypesArray.Add((object)keyword_attributed_type);

											bAddToKeywordAttributedAssembliesArray = true;
										}
									}
								}
							}
						}
					}
				}

				if (bAddToKeywordAttributedAssembliesArray)
				{
					KeywordAttributedAssembliesArray.Add((object)current_keyword_attributed_assembly);
				}
			}
			catch (Exception)
			{
			}
		}
	}
}

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About the Author

Lim Bio Liong
Web Developer
Singapore Singapore
Lim Bio Liong is a Specialist at a leading Software House in Singapore.
 
Bio has been in software development for over 10 years. He specialises in C/C++ programming and Windows software development.
 
Bio has also done device-driver development and enjoys low-level programming. Bio has recently picked up C# programming and has been researching in this area.

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