Demonstrating Custom Attributes: Build An Assembly Searching Tool.

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)
			{
			}
		}
	}
}