2002-09-20 Miguel de Icaza <miguel@ximian.com>

[mono.git] / mcs / mcs / decl.cs

//
// decl.cs: Declaration base class for structs, classes, enums and interfaces.
//
// Author: Miguel de Icaza (miguel@gnu.org)
//
// Licensed under the terms of the GNU GPL
//
// (C) 2001 Ximian, Inc (http://www.ximian.com)
//
// TODO: Move the method verification stuff from the class.cs and interface.cs here
//

using System;
using System.Collections;
using System.Reflection.Emit;
using System.Reflection;

namespace Mono.CSharp {

        /// <summary>
        ///   Base representation for members.  This is only used to keep track
        ///   of Name, Location and Modifier flags.
        /// </summary>
        public abstract class MemberCore {
                /// <summary>
                ///   Public name
                /// </summary>
                public string Name;

                /// <summary>
                ///   Modifier flags that the user specified in the source code
                /// </summary>
                public int ModFlags;

                /// <summary>
                ///   Location where this declaration happens
                /// </summary>
                public readonly Location Location;

                public MemberCore (string name, Location loc)
                {
                        Name = name;
                        Location = loc;
                }

                protected void WarningNotHiding (TypeContainer parent)
                {
                        Report.Warning (
                                109, Location,
                                "The member " + parent.MakeName (Name) + " does not hide an " +
                                "inherited member.  The keyword new is not required");
                                                           
                }

                void Error_CannotChangeAccessModifiers (TypeContainer parent, MethodInfo parent_method,
                                                        string name)
                {
                        //
                        // FIXME: report the old/new permissions?
                        //
                        Report.Error (
                                507, Location, parent.MakeName (Name) +
                                ": can't change the access modifiers when overriding inherited " +
                                "member `" + name + "'");
                }
                
                //
                // Performs various checks on the MethodInfo `mb' regarding the modifier flags
                // that have been defined.
                //
                // `name' is the user visible name for reporting errors (this is used to
                // provide the right name regarding method names and properties)
                //
                protected bool CheckMethodAgainstBase (TypeContainer parent, MethodAttributes my_attrs,
                                                       MethodInfo mb, string name)
                {
                        bool ok = true;
                        
                        if ((ModFlags & Modifiers.OVERRIDE) != 0){
                                if (!(mb.IsAbstract || mb.IsVirtual)){
                                        Report.Error (
                                                506, Location, parent.MakeName (Name) +
                                                ": cannot override inherited member `" +
                                                name + "' because it is not " +
                                                "virtual, abstract or override");
                                        ok = false;
                                }
                                
                                // Now we check that the overriden method is not final
                                
                                if (mb.IsFinal) {
                                        Report.Error (239, Location, parent.MakeName (Name) + " : cannot " +
                                                      "override inherited member `" + name +
                                                      "' because it is sealed.");
                                        ok = false;
                                }

                                //
                                // Check that the permissions are not being changed
                                //
                                MethodAttributes thisp = my_attrs & MethodAttributes.MemberAccessMask;
                                MethodAttributes parentp = mb.Attributes & MethodAttributes.MemberAccessMask;

                                if (thisp != parentp){
                                        Error_CannotChangeAccessModifiers (parent, mb, name);
                                        ok = false;
                                }
                        }

                        if (mb.IsVirtual || mb.IsAbstract){
                                if ((ModFlags & (Modifiers.NEW | Modifiers.OVERRIDE)) == 0){
                                        if (Name != "Finalize"){
                                                Report.Warning (
                                                        114, 2, Location, parent.MakeName (Name) + 
                                                        " hides inherited member `" + name +
                                                        "'.  To make the current member override that " +
                                                        "implementation, add the override keyword, " +
                                                        "otherwise use the new keyword");
                                                ModFlags |= Modifiers.NEW;
                                        }
                                }
                        } else {
                                if ((ModFlags & (Modifiers.NEW | Modifiers.OVERRIDE)) == 0){
                                        if (Name != "Finalize"){
                                                Report.Warning (
                                                        108, 1, Location, "The keyword new is required on " +
                                                        parent.MakeName (Name) + " because it hides " +
                                                        "inherited member `" + name + "'");
                                                ModFlags |= Modifiers.NEW;
                                        }
                                }
                        }

                        return ok;
                }

                public abstract bool Define (TypeContainer parent);

                // 
                // Whehter is it ok to use an unsafe pointer in this type container
                //
                public bool UnsafeOK (DeclSpace parent)
                {
                        //
                        // First check if this MemberCore modifier flags has unsafe set
                        //
                        if ((ModFlags & Modifiers.UNSAFE) != 0)
                                return true;

                        if (parent.UnsafeContext)
                                return true;

                        Expression.UnsafeError (Location);
                        return false;
                }
        }

        //
        // FIXME: This is temporary outside DeclSpace, because I have to fix a bug
        // in MCS that makes it fail the lookup for the enum
        //

                /// <summary>
                ///   The result value from adding an declaration into
                ///   a struct or a class
                /// </summary>
                public enum AdditionResult {
                        /// <summary>
                        /// The declaration has been successfully
                        /// added to the declation space.
                        /// </summary>
                        Success,

                        /// <summary>
                        ///   The symbol has already been defined.
                        /// </summary>
                        NameExists,

                        /// <summary>
                        ///   Returned if the declation being added to the
                        ///   name space clashes with its container name.
                        ///
                        ///   The only exceptions for this are constructors
                        ///   and static constructors
                        /// </summary>
                        EnclosingClash,

                        /// <summary>
                        ///   Returned if a constructor was created (because syntactically
                        ///   it looked like a constructor) but was not (because the name
                        ///   of the method is not the same as the container class
                        /// </summary>
                        NotAConstructor,

                        /// <summary>
                        ///   This is only used by static constructors to emit the
                        ///   error 111, but this error for other things really
                        ///   happens at another level for other functions.
                        /// </summary>
                        MethodExists
                }

        /// <summary>
        ///   Base class for structs, classes, enumerations and interfaces.  
        /// </summary>
        /// <remarks>
        ///   They all create new declaration spaces.  This
        ///   provides the common foundation for managing those name
        ///   spaces.
        /// </remarks>
        public abstract class DeclSpace : MemberCore {
                /// <summary>
                ///   this points to the actual definition that is being
                ///   created with System.Reflection.Emit
                /// </summary>
                public TypeBuilder TypeBuilder;

                /// <summary>
                ///   This variable tracks whether we have Closed the type
                /// </summary>
                public bool Created = false;
                
                //
                // This is the namespace in which this typecontainer
                // was declared.  We use this to resolve names.
                //
                public Namespace Namespace;

                public Hashtable Cache = new Hashtable ();
                
                public string Basename;
                
                /// <summary>
                ///   defined_names is used for toplevel objects
                /// </summary>
                protected Hashtable defined_names;

                TypeContainer parent;           

                public DeclSpace (TypeContainer parent, string name, Location l)
                        : base (name, l)
                {
                        Basename = name.Substring (1 + name.LastIndexOf ('.'));
                        defined_names = new Hashtable ();
                        this.parent = parent;
                }

                /// <summary>
                ///   Returns a status code based purely on the name
                ///   of the member being added
                /// </summary>
                protected AdditionResult IsValid (string name)
                {
                        if (name == Basename)
                                return AdditionResult.EnclosingClash;

                        if (defined_names.Contains (name))
                                return AdditionResult.NameExists;

                        return AdditionResult.Success;
                }

                /// <summary>
                ///   Introduce @name into this declaration space and
                ///   associates it with the object @o.  Note that for
                ///   methods this will just point to the first method. o
                /// </summary>
                protected void DefineName (string name, object o)
                {
                        defined_names.Add (name, o);
                }

                /// <summary>
                ///   Returns the object associated with a given name in the declaration
                ///   space.  This is the inverse operation of `DefineName'
                /// </summary>
                public object GetDefinition (string name)
                {
                        return defined_names [name];
                }
                
                bool in_transit = false;
                
                /// <summary>
                ///   This function is used to catch recursive definitions
                ///   in declarations.
                /// </summary>
                public bool InTransit {
                        get {
                                return in_transit;
                        }

                        set {
                                in_transit = value;
                        }
                }

                public TypeContainer Parent {
                        get {
                                return parent;
                        }
                }

                /// <summary>
                ///   Looks up the alias for the name
                /// </summary>
                public string LookupAlias (string name)
                {
                        if (Namespace != null)
                                return Namespace.LookupAlias (name);
                        else
                                return null;
                }
                
                // 
                // root_types contains all the types.  All TopLevel types
                // hence have a parent that points to `root_types', that is
                // why there is a non-obvious test down here.
                //
                public bool IsTopLevel {
                        get {
                                if (parent != null){
                                        if (parent.parent == null)
                                                return true;
                                }
                                return false;
                        }
                }

                public virtual void CloseType ()
                {
                        if (!Created){
                                try {
                                        TypeBuilder.CreateType ();
                                } catch {
                                        //
                                        // The try/catch is needed because
                                        // nested enumerations fail to load when they
                                        // are defined.
                                        //
                                        // Even if this is the right order (enumerations
                                        // declared after types).
                                        //
                                        // Note that this still creates the type and
                                        // it is possible to save it
                                }
                                Created = true;
                        }
                }

                /// <remarks>
                ///  Should be overriten by the appropriate declaration space
                /// <remarks>
                public abstract TypeBuilder DefineType ();
                
                /// <summary>
                ///   Define all members, but don't apply any attributes or do anything which may
                ///   access not-yet-defined classes.  This method also creates the MemberCache.
                /// </summary>
                public abstract bool DefineMembers (TypeContainer parent);

                //
                // Whether this is an `unsafe context'
                //
                public bool UnsafeContext {
                        get {
                                if ((ModFlags & Modifiers.UNSAFE) != 0)
                                        return true;
                                if (parent != null)
                                        return parent.UnsafeContext;
                                return false;
                        }
                }

                public static string MakeFQN (string nsn, string name)
                {
                        string prefix = (nsn == "" ? "" : nsn + ".");

                        return prefix + name;
                }

                EmitContext type_resolve_ec;
                EmitContext GetTypeResolveEmitContext (TypeContainer parent, Location loc)
                {
                        type_resolve_ec = new EmitContext (parent, this, loc, null, null, ModFlags, false);
                        type_resolve_ec.ResolvingTypeTree = true;

                        return type_resolve_ec;
                }

                // <summary>
                //    Looks up the type, as parsed into the expression `e' 
                // </summary>
                public Type ResolveType (Expression e, bool silent, Location loc)
                {
                        if (type_resolve_ec == null)
                                type_resolve_ec = GetTypeResolveEmitContext (parent, loc);
                        type_resolve_ec.loc = loc;

                        int errors = Report.Errors;
                        Expression d = e.Resolve (type_resolve_ec, ResolveFlags.Type);
                        if (d == null || d.eclass != ExprClass.Type){
                                if (!silent && errors == Report.Errors){
                                        Report.Error (246, loc, "Cannot find type `"+ e.ToString () +"'");
                                }
                                return null;
                        }

                        return d.Type;
                }

                // <summary>
                //    Resolves the expression `e' for a type, and will recursively define
                //    types. 
                // </summary>
                public Expression ResolveTypeExpr (Expression e, bool silent, Location loc)
                {
                        if (type_resolve_ec == null)
                                type_resolve_ec = GetTypeResolveEmitContext (parent, loc);

                        Expression d = e.Resolve (type_resolve_ec, ResolveFlags.Type);
                        if (d == null || d.eclass != ExprClass.Type){
                                if (!silent){
                                        Report.Error (246, loc, "Cannot find type `"+ e +"'");
                                }
                                return null;
                        }

                        return d;
                }
                
                Type LookupInterfaceOrClass (string ns, string name, out bool error)
                {
                        DeclSpace parent;
                        Type t;

                        error = false;
                        name = MakeFQN (ns, name);
                        
                        t  = TypeManager.LookupType (name);
                        if (t != null)
                                return t;

                        parent = (DeclSpace) RootContext.Tree.Decls [name];
                        if (parent == null)
                                return null;
                        
                        t = parent.DefineType ();
                        if (t == null){
                                Report.Error (146, "Class definition is circular: `"+name+"'");
                                error = true;
                                return null;
                        }
                        return t;
                }
                
                /// <summary>
                ///   GetType is used to resolve type names at the DeclSpace level.
                ///   Use this to lookup class/struct bases, interface bases or 
                ///   delegate type references
                /// </summary>
                ///
                /// <remarks>
                ///   Contrast this to LookupType which is used inside method bodies to 
                ///   lookup types that have already been defined.  GetType is used
                ///   during the tree resolution process and potentially define
                ///   recursively the type
                /// </remarks>
                public Type FindType (string name)
                {
                        Type t;
                        bool error;

                        //
                        // For the case the type we are looking for is nested within this one
                        // or is in any base class
                        //
                        DeclSpace containing_ds = this;

                        while (containing_ds != null){
                                Type current_type = containing_ds.TypeBuilder;

                                while (current_type != null) {
                                        string pre = current_type.FullName;
                                        
                                        t = LookupInterfaceOrClass (pre, name, out error);
                                        if (error)
                                                return null;
                                
                                        if (t != null) 
                                                return t;

                                        current_type = current_type.BaseType;
                                }
                                containing_ds = containing_ds.Parent;
                        }
                        
                        //
                        // Attempt to lookup the class on our namespace and all it's implicit parents
                        //
                        for (string ns = Namespace.Name; ns != null; ns = RootContext.ImplicitParent (ns)) {

                                t = LookupInterfaceOrClass (ns, name, out error);
                                if (error)
                                        return null;
                                
                                if (t != null) 
                                        return t;
                        }
                        
                        //
                        // Attempt to do a direct unqualified lookup
                        //
                        t = LookupInterfaceOrClass ("", name, out error);
                        if (error)
                                return null;
                        
                        if (t != null)
                                return t;
                        
                        //
                        // Attempt to lookup the class on any of the `using'
                        // namespaces
                        //

                        for (Namespace ns = Namespace; ns != null; ns = ns.Parent){

                                t = LookupInterfaceOrClass (ns.Name, name, out error);
                                if (error)
                                        return null;

                                if (t != null)
                                        return t;

                                //
                                // Now check the using clause list
                                //
                                ArrayList using_list = ns.UsingTable;
                                
                                if (using_list == null)
                                        continue;

                                Type match = null;
                                foreach (Namespace.UsingEntry ue in using_list){
                                        match = LookupInterfaceOrClass (ue.Name, name, out error);
                                        if (error)
                                                return null;

                                        if (match != null){
                                                if (t != null){
                                                        Report.Error (104, "`" + name + "' is an ambiguous reference");
                                                        return null;
                                                }
                                                
                                                t = match;
                                                ue.Used = true;
                                        }
                                }
                                if (t != null)
                                        return t;
                        }

                        //Report.Error (246, Location, "Can not find type `"+name+"'");
                        return null;
                }

                /// <remarks>
                ///   This function is broken and not what you're looking for.  It should only
                ///   be used while the type is still being created since it doesn't use the cache
                ///   and relies on the filter doing the member name check.
                /// </remarks>
                public abstract MemberList FindMembers (MemberTypes mt, BindingFlags bf,
                                                        MemberFilter filter, object criteria);

                /// <remarks>
                ///   If we have a MemberCache, return it.  This property may return null if the
                ///   class doesn't have a member cache or while it's still being created.
                /// </remarks>
                public abstract MemberCache MemberCache {
                        get;
                }
        }

        /// <summary>
        ///   This is a readonly list of MemberInfo's.      
        /// </summary>
        public class MemberList : IList {
                public readonly IList List;
                int count;

                /// <summary>
                ///   Create a new MemberList from the given IList.
                /// </summary>
                public MemberList (IList list)
                {
                        if (list != null)
                                this.List = list;
                        else
                                this.List = new ArrayList ();
                        count = List.Count;
                }

                /// <summary>
                ///   Concatenate the ILists `first' and `second' to a new MemberList.
                /// </summary>
                public MemberList (IList first, IList second)
                {
                        ArrayList list = new ArrayList ();
                        list.AddRange (first);
                        list.AddRange (second);
                        count = list.Count;
                        List = list;
                }

                public static readonly MemberList Empty = new MemberList (new ArrayList ());

                /// <summary>
                ///   Cast the MemberList into a MemberInfo[] array.
                /// </summary>
                /// <remarks>
                ///   This is an expensive operation, only use it if it's really necessary.
                /// </remarks>
                public static explicit operator MemberInfo [] (MemberList list)
                {
                        Timer.StartTimer (TimerType.MiscTimer);
                        MemberInfo [] result = new MemberInfo [list.Count];
                        list.CopyTo (result, 0);
                        Timer.StopTimer (TimerType.MiscTimer);
                        return result;
                }

                // ICollection

                public int Count {
                        get {
                                return count;
                        }
                }

                public bool IsSynchronized {
                        get {
                                return List.IsSynchronized;
                        }
                }

                public object SyncRoot {
                        get {
                                return List.SyncRoot;
                        }
                }

                public void CopyTo (Array array, int index)
                {
                        List.CopyTo (array, index);
                }

                // IEnumerable

                public IEnumerator GetEnumerator ()
                {
                        return List.GetEnumerator ();
                }

                // IList

                public bool IsFixedSize {
                        get {
                                return true;
                        }
                }

                public bool IsReadOnly {
                        get {
                                return true;
                        }
                }

                object IList.this [int index] {
                        get {
                                return List [index];
                        }

                        set {
                                throw new NotSupportedException ();
                        }
                }

                // FIXME: try to find out whether we can avoid the cast in this indexer.
                public MemberInfo this [int index] {
                        get {
                                return (MemberInfo) List [index];
                        }
                }

                public int Add (object value)
                {
                        throw new NotSupportedException ();
                }

                public void Clear ()
                {
                        throw new NotSupportedException ();
                }

                public bool Contains (object value)
                {
                        return List.Contains (value);
                }

                public int IndexOf (object value)
                {
                        return List.IndexOf (value);
                }

                public void Insert (int index, object value)
                {
                        throw new NotSupportedException ();
                }

                public void Remove (object value)
                {
                        throw new NotSupportedException ();
                }

                public void RemoveAt (int index)
                {
                        throw new NotSupportedException ();
                }
        }

        /// <summary>
        ///   This interface is used to get all members of a class when creating the
        ///   member cache.  It must be implemented by all DeclSpace derivatives which
        ///   want to support the member cache and by TypeHandle to get caching of
        ///   non-dynamic types.
        /// </summary>
        public interface IMemberContainer {
                /// <summary>
                ///   The name of the IMemberContainer.  This is only used for
                ///   debugging purposes.
                /// </summary>
                string Name {
                        get;
                }

                /// <summary>
                ///   The type of this IMemberContainer.
                /// </summary>
                Type Type {
                        get;
                }

                /// <summary>
                ///   Returns the IMemberContainer of the parent class or null if this
                ///   is an interface or TypeManger.object_type.
                ///   This is used when creating the member cache for a class to get all
                ///   members from the parent class.
                /// </summary>
                IMemberContainer Parent {
                        get;
                }

                /// <summary>
                ///   Whether this is an interface.
                /// </summary>
                bool IsInterface {
                        get;
                }

                /// <summary>
                ///   Returns all members of this class with the corresponding MemberTypes
                ///   and BindingFlags.
                /// </summary>
                /// <remarks>
                ///   When implementing this method, make sure not to return any inherited
                ///   members and check the MemberTypes and BindingFlags properly.
                ///   Unfortunately, System.Reflection is lame and doesn't provide a way to
                ///   get the BindingFlags (static/non-static,public/non-public) in the
                ///   MemberInfo class, but the cache needs this information.  That's why
                ///   this method is called multiple times with different BindingFlags.
                /// </remarks>
                MemberList GetMembers (MemberTypes mt, BindingFlags bf);

                /// <summary>
                ///   Return the container's member cache.
                /// </summary>
                MemberCache MemberCache {
                        get;
                }
        }

        /// <summary>
        ///   The MemberCache is used by dynamic and non-dynamic types to speed up
        ///   member lookups.  It has a member name based hash table; it maps each member
        ///   name to a list of CacheEntry objects.  Each CacheEntry contains a MemberInfo
        ///   and the BindingFlags that were initially used to get it.  The cache contains
        ///   all members of the current class and all inherited members.  If this cache is
        ///   for an interface types, it also contains all inherited members.
        ///
        ///   There are two ways to get a MemberCache:
        ///   * if this is a dynamic type, lookup the corresponding DeclSpace and then
        ///     use the DeclSpace.MemberCache property.
        ///   * if this not a dynamic type, call TypeHandle.GetTypeHandle() to get a
        ///     TypeHandle instance for the type and then use TypeHandle.MemberCache.
        /// </summary>
        public class MemberCache {
                public readonly IMemberContainer Container;
                protected Hashtable member_hash;
                protected Hashtable method_hash;
                protected Hashtable interface_hash;

                /// <summary>
                ///   Create a new MemberCache for the given IMemberContainer `container'.
                /// </summary>
                public MemberCache (IMemberContainer container)
                {
                        this.Container = container;

                        Timer.IncrementCounter (CounterType.MemberCache);
                        Timer.StartTimer (TimerType.CacheInit);

                        interface_hash = new Hashtable ();

                        // If we have a parent class (we have a parent class unless we're
                        // TypeManager.object_type), we deep-copy its MemberCache here.
                        if (Container.Parent != null)
                                member_hash = SetupCache (Container.Parent.MemberCache);
                        else if (Container.IsInterface)
                                member_hash = SetupCacheForInterface ();
                        else
                                member_hash = new Hashtable ();

                        // If this is neither a dynamic type nor an interface, create a special
                        // method cache with all declared and inherited methods.
                        Type type = container.Type;
                        if (!(type is TypeBuilder) && !type.IsInterface) {
                                method_hash = new Hashtable ();
                                AddMethods (type);
                        }

                        // Add all members from the current class.
                        AddMembers (Container);

                        Timer.StopTimer (TimerType.CacheInit);
                }

                /// <summary>
                ///   Bootstrap this member cache by doing a deep-copy of our parent.
                /// </summary>
                Hashtable SetupCache (MemberCache parent)
                {
                        Hashtable hash = new Hashtable ();

                        IDictionaryEnumerator it = parent.member_hash.GetEnumerator ();
                        while (it.MoveNext ()) {
                                hash [it.Key] = ((ArrayList) it.Value).Clone ();
                        }

                        return hash;
                }

                void AddInterfaces (MemberCache parent)
                {
                        foreach (Type iface in parent.interface_hash.Keys) {
                                if (!interface_hash.Contains (iface))
                                        interface_hash.Add (iface, true);
                        }
                }

                /// <summary>
                ///   Add the contents of `new_hash' to `hash'.
                /// </summary>
                void AddHashtable (Hashtable hash, Hashtable new_hash)
                {
                        IDictionaryEnumerator it = new_hash.GetEnumerator ();
                        while (it.MoveNext ()) {
                                ArrayList list = (ArrayList) hash [it.Key];
                                if (list != null)
                                        list.AddRange ((ArrayList) it.Value);
                                else
                                        hash [it.Key] = ((ArrayList) it.Value).Clone ();
                        }
                }

                /// <summary>
                ///   Bootstrap the member cache for an interface type.
                ///   Type.GetMembers() won't return any inherited members for interface types,
                ///   so we need to do this manually.  Interfaces also inherit from System.Object.
                /// </summary>
                Hashtable SetupCacheForInterface ()
                {
                        Hashtable hash = SetupCache (TypeHandle.ObjectType.MemberCache);
                        Type [] ifaces = TypeManager.GetInterfaces (Container.Type);

                        foreach (Type iface in ifaces) {
                                if (interface_hash.Contains (iface))
                                        continue;
                                interface_hash.Add (iface, true);

                                IMemberContainer iface_container =
                                        TypeManager.LookupMemberContainer (iface);

                                MemberCache iface_cache = iface_container.MemberCache;
                                AddHashtable (hash, iface_cache.member_hash);
                                AddInterfaces (iface_cache);
                        }

                        return hash;
                }

                /// <summary>
                ///   Add all members from class `container' to the cache.
                /// </summary>
                void AddMembers (IMemberContainer container)
                {
                        // We need to call AddMembers() with a single member type at a time
                        // to get the member type part of CacheEntry.EntryType right.
                        AddMembers (MemberTypes.Constructor, container);
                        AddMembers (MemberTypes.Field, container);
                        AddMembers (MemberTypes.Method, container);
                        AddMembers (MemberTypes.Property, container);
                        AddMembers (MemberTypes.Event, container);
                        // Nested types are returned by both Static and Instance searches.
                        AddMembers (MemberTypes.NestedType,
                                    BindingFlags.Static | BindingFlags.Public, container);
                        AddMembers (MemberTypes.NestedType,
                                    BindingFlags.Static | BindingFlags.NonPublic, container);
                }

                void AddMembers (MemberTypes mt, IMemberContainer container)
                {
                        AddMembers (mt, BindingFlags.Static | BindingFlags.Public, container);
                        AddMembers (mt, BindingFlags.Static | BindingFlags.NonPublic, container);
                        AddMembers (mt, BindingFlags.Instance | BindingFlags.Public, container);
                        AddMembers (mt, BindingFlags.Instance | BindingFlags.NonPublic, container);
                }

                /// <summary>
                ///   Add all members from class `container' with the requested MemberTypes and
                ///   BindingFlags to the cache.  This method is called multiple times with different
                ///   MemberTypes and BindingFlags.
                /// </summary>
                void AddMembers (MemberTypes mt, BindingFlags bf, IMemberContainer container)
                {
                        MemberList members = container.GetMembers (mt, bf);
                        BindingFlags new_bf = (container == Container) ?
                                bf | BindingFlags.DeclaredOnly : bf;

                        foreach (MemberInfo member in members) {
                                string name = member.Name;

                                // We use a name-based hash table of ArrayList's.
                                ArrayList list = (ArrayList) member_hash [name];
                                if (list == null) {
                                        list = new ArrayList ();
                                        member_hash.Add (name, list);
                                }

                                // When this method is called for the current class, the list will
                                // already contain all inherited members from our parent classes.
                                // We cannot add new members in front of the list since this'd be an
                                // expensive operation, that's why the list is sorted in reverse order
                                // (ie. members from the current class are coming last).
                                list.Add (new CacheEntry (container, member, mt, bf));
                        }
                }

                /// <summary>
                ///   Add all declared and inherited methods from class `type' to the method cache.
                /// </summary>
                void AddMethods (Type type)
                {
                        AddMethods (BindingFlags.Static | BindingFlags.Public, type);
                        AddMethods (BindingFlags.Static | BindingFlags.NonPublic, type);
                        AddMethods (BindingFlags.Instance | BindingFlags.Public, type);
                        AddMethods (BindingFlags.Instance | BindingFlags.NonPublic, type);
                }

                void AddMethods (BindingFlags bf, Type type)
                {
                        MemberInfo [] members = type.GetMethods (bf);

                        foreach (MethodBase member in members) {
                                string name = member.Name;

                                // Varargs methods aren't allowed in C# code.
                                if ((member.CallingConvention & CallingConventions.VarArgs) != 0)
                                        continue;

                                // We use a name-based hash table of ArrayList's.
                                ArrayList list = (ArrayList) method_hash [name];
                                if (list == null) {
                                        list = new ArrayList ();
                                        method_hash.Add (name, list);
                                }

                                // Unfortunately, the elements returned by Type.GetMethods() aren't
                                // sorted so we need to do this check for every member.
                                BindingFlags new_bf = bf;
                                if (member.DeclaringType == type)
                                        new_bf |= BindingFlags.DeclaredOnly;

                                list.Add (new CacheEntry (Container, member, MemberTypes.Method, new_bf));
                        }
                }

                /// <summary>
                ///   Compute and return a appropriate `EntryType' magic number for the given
                ///   MemberTypes and BindingFlags.
                /// </summary>
                protected static EntryType GetEntryType (MemberTypes mt, BindingFlags bf)
                {
                        EntryType type = EntryType.None;

                        if ((mt & MemberTypes.Constructor) != 0)
                                type |= EntryType.Constructor;
                        if ((mt & MemberTypes.Event) != 0)
                                type |= EntryType.Event;
                        if ((mt & MemberTypes.Field) != 0)
                                type |= EntryType.Field;
                        if ((mt & MemberTypes.Method) != 0)
                                type |= EntryType.Method;
                        if ((mt & MemberTypes.Property) != 0)
                                type |= EntryType.Property;
                        // Nested types are returned by static and instance searches.
                        if ((mt & MemberTypes.NestedType) != 0)
                                type |= EntryType.NestedType | EntryType.Static | EntryType.Instance;

                        if ((bf & BindingFlags.Instance) != 0)
                                type |= EntryType.Instance;
                        if ((bf & BindingFlags.Static) != 0)
                                type |= EntryType.Static;
                        if ((bf & BindingFlags.Public) != 0)
                                type |= EntryType.Public;
                        if ((bf & BindingFlags.NonPublic) != 0)
                                type |= EntryType.NonPublic;
                        if ((bf & BindingFlags.DeclaredOnly) != 0)
                                type |= EntryType.Declared;

                        return type;
                }

                /// <summary>
                ///   The `MemberTypes' enumeration type is a [Flags] type which means that it may
                ///   denote multiple member types.  Returns true if the given flags value denotes a
                ///   single member types.
                /// </summary>
                public static bool IsSingleMemberType (MemberTypes mt)
                {
                        switch (mt) {
                        case MemberTypes.Constructor:
                        case MemberTypes.Event:
                        case MemberTypes.Field:
                        case MemberTypes.Method:
                        case MemberTypes.Property:
                        case MemberTypes.NestedType:
                                return true;

                        default:
                                return false;
                        }
                }

                /// <summary>
                ///   We encode the MemberTypes and BindingFlags of each members in a "magic"
                ///   number to speed up the searching process.
                /// </summary>
                [Flags]
                protected enum EntryType {
                        None            = 0x000,

                        Instance        = 0x001,
                        Static          = 0x002,
                        MaskStatic      = Instance|Static,

                        Public          = 0x004,
                        NonPublic       = 0x008,
                        MaskProtection  = Public|NonPublic,

                        Declared        = 0x010,

                        Constructor     = 0x020,
                        Event           = 0x040,
                        Field           = 0x080,
                        Method          = 0x100,
                        Property        = 0x200,
                        NestedType      = 0x400,

                        MaskType        = Constructor|Event|Field|Method|Property|NestedType
                }

                protected struct CacheEntry {
                        public readonly IMemberContainer Container;
                        public readonly EntryType EntryType;
                        public readonly MemberInfo Member;

                        public CacheEntry (IMemberContainer container, MemberInfo member,
                                           MemberTypes mt, BindingFlags bf)
                        {
                                this.Container = container;
                                this.Member = member;
                                this.EntryType = GetEntryType (mt, bf);
                        }
                }

                /// <summary>
                ///   This is called each time we're walking up one level in the class hierarchy
                ///   and checks whether we can abort the search since we've already found what
                ///   we were looking for.
                /// </summary>
                protected bool DoneSearching (ArrayList list)
                {
                        //
                        // We've found exactly one member in the current class and it's not
                        // a method or constructor.
                        //
                        if (list.Count == 1 && !(list [0] is MethodBase))
                                return true;

                        //
                        // Multiple properties: we query those just to find out the indexer
                        // name
                        //
                        if ((list.Count > 0) && (list [0] is PropertyInfo))
                                return true;

                        return false;
                }

                /// <summary>
                ///   Looks up members with name `name'.  If you provide an optional
                ///   filter function, it'll only be called with members matching the
                ///   requested member name.
                ///
                ///   This method will try to use the cache to do the lookup if possible.
                ///
                ///   Unlike other FindMembers implementations, this method will always
                ///   check all inherited members - even when called on an interface type.
                ///
                ///   If you know that you're only looking for methods, you should use
                ///   MemberTypes.Method alone since this speeds up the lookup a bit.
                ///   When doing a method-only search, it'll try to use a special method
                ///   cache (unless it's a dynamic type or an interface) and the returned
                ///   MemberInfo's will have the correct ReflectedType for inherited methods.
                ///   The lookup process will automatically restart itself in method-only
                ///   search mode if it discovers that it's about to return methods.
                /// </summary>
                public MemberList FindMembers (MemberTypes mt, BindingFlags bf, string name,
                                               MemberFilter filter, object criteria)
                {
                        bool declared_only = (bf & BindingFlags.DeclaredOnly) != 0;
                        bool method_search = mt == MemberTypes.Method;
                        // If we have a method cache and we aren't already doing a method-only search,
                        // then we restart a method search if the first match is a method.
                        bool do_method_search = !method_search && (method_hash != null);

                        ArrayList applicable;

                        // If this is a method-only search, we try to use the method cache if
                        // possible; a lookup in the method cache will return a MemberInfo with
                        // the correct ReflectedType for inherited methods.
                        if (method_search && (method_hash != null))
                                applicable = (ArrayList) method_hash [name];
                        else
                                applicable = (ArrayList) member_hash [name];

                        if (applicable == null)
                                return MemberList.Empty;

                        ArrayList list = new ArrayList ();

                        Timer.StartTimer (TimerType.CachedLookup);

                        EntryType type = GetEntryType (mt, bf);

                        IMemberContainer current = Container;

                        // `applicable' is a list of all members with the given member name `name'
                        // in the current class and all its parent classes.  The list is sorted in
                        // reverse order due to the way how the cache is initialy created (to speed
                        // things up, we're doing a deep-copy of our parent).

                        for (int i = applicable.Count-1; i >= 0; i--) {
                                CacheEntry entry = (CacheEntry) applicable [i];

                                // This happens each time we're walking one level up in the class
                                // hierarchy.  If we're doing a DeclaredOnly search, we must abort
                                // the first time this happens (this may already happen in the first
                                // iteration of this loop if there are no members with the name we're
                                // looking for in the current class).
                                if (entry.Container != current) {
                                        if (declared_only || DoneSearching (list))
                                                break;

                                        current = entry.Container;
                                }

                                // Is the member of the correct type ?
                                if ((entry.EntryType & type & EntryType.MaskType) == 0)
                                        continue;

                                // Is the member static/non-static ?
                                if ((entry.EntryType & type & EntryType.MaskStatic) == 0)
                                        continue;

                                // Apply the filter to it.
                                if (filter (entry.Member, criteria)) {
                                        if ((entry.EntryType & EntryType.MaskType) != EntryType.Method)
                                                do_method_search = false;
                                        list.Add (entry.Member);
                                }
                        }

                        Timer.StopTimer (TimerType.CachedLookup);

                        // If we have a method cache and we aren't already doing a method-only
                        // search, we restart in method-only search mode if the first match is
                        // a method.  This ensures that we return a MemberInfo with the correct
                        // ReflectedType for inherited methods.
                        if (do_method_search && (list.Count > 0))
                                return FindMembers (MemberTypes.Method, bf, name, filter, criteria);

                        return new MemberList (list);
                }
        }
}