2002-08-16 Martin Baulig <martin@gnome.org>

[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" && (RootContext.WarningLevel >= 2)){
                                                Report.Warning (
                                                        114, 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");
                                        }
                                }
                        } else {
                                if ((ModFlags & (Modifiers.NEW | Modifiers.OVERRIDE)) == 0){
                                        if (Name != "Finalize" && (RootContext.WarningLevel >= 1)){
                                                Report.Warning (
                                                        108, Location, "The keyword new is required on " +
                                                        parent.MakeName (Name) + " because it hides " +
                                                        "inherited member `" + name + "'");
                                        }
                                }
                        }

                        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;
                        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.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;

                                foreach (string n in using_list){
                                        t = LookupInterfaceOrClass (n, name, out error);
                                        if (error)
                                                return null;

                                        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>
                internal 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;
                }
        }
}