source: trunk/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Parser/mcs/pending.cs @ 15888

//
// pending.cs: Pending method implementation
//
// Authors:
//   Miguel de Icaza (miguel@gnu.org)
//   Marek Safar (marek.safar@gmail.com)
//
// Dual licensed under the terms of the MIT X11 or GNU GPL
//
// Copyright 2001, 2002 Ximian, Inc (http://www.ximian.com)
// Copyright 2003-2008 Novell, Inc.
// Copyright 2011 Xamarin Inc
//

using System;
using System.Collections.Generic;
using System.Linq;

#if STATIC
using IKVM.Reflection;
using IKVM.Reflection.Emit;
#else
using System.Reflection;
using System.Reflection.Emit;
#endif

namespace Mono.CSharp {

  struct TypeAndMethods {
    public TypeSpec          type;
    public IList<MethodSpec> methods;

    // 
    // Whether it is optional, this is used to allow the explicit/implicit
    // implementation when a base class already implements an interface. 
    //
    // For example:
    //
    // class X : IA { }  class Y : X, IA { IA.Explicit (); }
    //
    public bool          optional;
        
    //
    // This flag on the method says `We found a match, but
    // because it was private, we could not use the match
    //
    public MethodData [] found;

    // If a method is defined here, then we always need to
    // create a proxy for it.  This is used when implementing
    // an interface's indexer with a different IndexerName.
    public MethodSpec [] need_proxy;
  }

  struct ProxyMethodContext : IMemberContext
  {
    readonly TypeContainer container;

    public ProxyMethodContext (TypeContainer container)
    {
      this.container = container;
    }

    public TypeSpec CurrentType {
      get {
        throw new NotImplementedException ();
      }
    }

    public TypeParameters CurrentTypeParameters {
      get {
        throw new NotImplementedException ();
      }
    }

    public MemberCore CurrentMemberDefinition {
      get {
        throw new NotImplementedException ();
      }
    }

    public bool IsObsolete {
      get {
        return false;
      }
    }

    public bool IsUnsafe {
      get {
        throw new NotImplementedException ();
      }
    }

    public bool IsStatic {
      get {
        return false;
      }
    }

    public ModuleContainer Module {
      get {
        return container.Module;
      }
    }

    public string GetSignatureForError ()
    {
      throw new NotImplementedException ();
    }

    public ExtensionMethodCandidates LookupExtensionMethod (TypeSpec extensionType, string name, int arity)
    {
      throw new NotImplementedException ();
    }

    public FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc)
    {
      throw new NotImplementedException ();
    }

    public FullNamedExpression LookupNamespaceAlias (string name)
    {
      throw new NotImplementedException ();
    }
  }

  public class PendingImplementation
  {
    /// <summary>
    ///   The container for this PendingImplementation
    /// </summary>
    readonly TypeDefinition container;
    
    /// <summary>
    ///   This is the array of TypeAndMethods that describes the pending implementations
    ///   (both interfaces and abstract methods in base class)
    /// </summary>
    TypeAndMethods [] pending_implementations;

    PendingImplementation (TypeDefinition container, MissingInterfacesInfo[] missing_ifaces, MethodSpec[] abstract_methods, int total)
    {
      var type_builder = container.Definition;
      
      this.container = container;
      pending_implementations = new TypeAndMethods [total];

      int i = 0;
      if (abstract_methods != null) {
        int count = abstract_methods.Length;
        pending_implementations [i].methods = new MethodSpec [count];
        pending_implementations [i].need_proxy = new MethodSpec [count];

        pending_implementations [i].methods = abstract_methods;
        pending_implementations [i].found = new MethodData [count];
        pending_implementations [i].type = type_builder;
        ++i;
      }

      foreach (MissingInterfacesInfo missing in missing_ifaces) {
        var iface = missing.Type;
        var mi = MemberCache.GetInterfaceMethods (iface);

        int count = mi.Count;
        pending_implementations [i].type = iface;
        pending_implementations [i].optional = missing.Optional;
        pending_implementations [i].methods = mi;
        pending_implementations [i].found = new MethodData [count];
        pending_implementations [i].need_proxy = new MethodSpec [count];
        i++;
      }
    }

    Report Report {
      get {
        return container.Module.Compiler.Report;
      }
    }

    struct MissingInterfacesInfo {
      public TypeSpec Type;
      public bool Optional;

      public MissingInterfacesInfo (TypeSpec t)
      {
        Type = t;
        Optional = false;
      }
    }

    static readonly MissingInterfacesInfo [] EmptyMissingInterfacesInfo = new MissingInterfacesInfo [0];
    
    static MissingInterfacesInfo [] GetMissingInterfaces (TypeDefinition container)
    {
      //
      // Interfaces will return all interfaces that the container
      // implements including any inherited interfaces
      //
      var impl = container.Definition.Interfaces;

      if (impl == null || impl.Count == 0)
        return EmptyMissingInterfacesInfo;

      var ret = new MissingInterfacesInfo[impl.Count];

      for (int i = 0; i < ret.Length; i++)
        ret [i] = new MissingInterfacesInfo (impl [i]);

      // we really should not get here because Object doesnt implement any
      // interfaces. But it could implement something internal, so we have
      // to handle that case.
      if (container.BaseType == null)
        return ret;
      
      var base_impls = container.BaseType.Interfaces;
      if (base_impls != null) {
        foreach (TypeSpec t in base_impls) {
          for (int i = 0; i < ret.Length; i++) {
            if (t == ret[i].Type) {
              ret[i].Optional = true;
              break;
            }
          }
        }
      }

      return ret;
    }
    
    //
    // Factory method: if there are pending implementation methods, we return a PendingImplementation
    // object, otherwise we return null.
    //
    // Register method implementations are either abstract methods
    // flagged as such on the base class or interface methods
    //
    static public PendingImplementation GetPendingImplementations (TypeDefinition container)
    {
      TypeSpec b = container.BaseType;

      var missing_interfaces = GetMissingInterfaces (container);

      //
      // If we are implementing an abstract class, and we are not
      // ourselves abstract, and there are abstract methods (C# allows
      // abstract classes that have no abstract methods), then allocate
      // one slot.
      //
      // We also pre-compute the methods.
      //
      bool implementing_abstract = ((b != null) && b.IsAbstract && (container.ModFlags & Modifiers.ABSTRACT) == 0);
      MethodSpec[] abstract_methods = null;

      if (implementing_abstract){
        var am = MemberCache.GetNotImplementedAbstractMethods (b);

        if (am == null) {
          implementing_abstract = false;
        } else {
          abstract_methods = new MethodSpec[am.Count];
          am.CopyTo (abstract_methods, 0);
        }
      }
      
      int total = missing_interfaces.Length +  (implementing_abstract ? 1 : 0);
      if (total == 0)
        return null;

      var pending = new PendingImplementation (container, missing_interfaces, abstract_methods, total);

      //
      // check for inherited conflicting methods
      //
      foreach (var p in pending.pending_implementations) {
        //
        // It can happen for generic interfaces only
        //
        if (!p.type.IsGeneric)
          continue;

        //
        // CLR does not distinguishes between ref and out
        //
        for (int i = 0; i < p.methods.Count; ++i) {
          MethodSpec compared_method = p.methods[i];
          if (compared_method.Parameters.IsEmpty)
            continue;

          for (int ii = i + 1; ii < p.methods.Count; ++ii) {
            MethodSpec tested_method = p.methods[ii];
            if (compared_method.Name != tested_method.Name)
              continue;

            if (p.type != tested_method.DeclaringType)
              continue;

            if (!TypeSpecComparer.Override.IsSame (compared_method.Parameters.Types, tested_method.Parameters.Types))
              continue;

            bool exact_match = true;
            bool ref_only_difference = false;
            var cp = compared_method.Parameters.FixedParameters;
            var tp = tested_method.Parameters.FixedParameters;

            for (int pi = 0; pi < cp.Length; ++pi) {
              //
              // First check exact modifiers match
              //
              if ((cp[pi].ModFlags & Parameter.Modifier.RefOutMask) == (tp[pi].ModFlags & Parameter.Modifier.RefOutMask))
                continue;

              if (((cp[pi].ModFlags | tp[pi].ModFlags) & Parameter.Modifier.RefOutMask) == Parameter.Modifier.RefOutMask) {
                ref_only_difference = true;
                continue;
              }

              exact_match = false;
              break;
            }

            if (!exact_match || !ref_only_difference)
              continue;

            pending.Report.SymbolRelatedToPreviousError (compared_method);
            pending.Report.SymbolRelatedToPreviousError (tested_method);
            pending.Report.Error (767, container.Location,
              "Cannot implement interface `{0}' with the specified type parameters because it causes method `{1}' to differ on parameter modifiers only",
              p.type.GetDefinition().GetSignatureForError (), compared_method.GetSignatureForError ());

            break;
          }
        }
      }

      return pending;
    }

    public enum Operation {
      //
      // If you change this, review the whole InterfaceMethod routine as there
      // are a couple of assumptions on these three states
      //
      Lookup, ClearOne, ClearAll
    }

    /// <summary>
    ///   Whether the specified method is an interface method implementation
    /// </summary>
    public MethodSpec IsInterfaceMethod (MemberName name, TypeSpec ifaceType, MethodData method, out MethodSpec ambiguousCandidate, ref bool optional)
    {
      return InterfaceMethod (name, ifaceType, method, Operation.Lookup, out ambiguousCandidate, ref optional);
    }

    public void ImplementMethod (MemberName name, TypeSpec ifaceType, MethodData method, bool clear_one, out MethodSpec ambiguousCandidate, ref bool optional)
    {
      InterfaceMethod (name, ifaceType, method, clear_one ? Operation.ClearOne : Operation.ClearAll, out ambiguousCandidate, ref optional);
    }

    /// <remarks>
    ///   If a method in Type `t' (or null to look in all interfaces
    ///   and the base abstract class) with name `Name', return type `ret_type' and
    ///   arguments `args' implements an interface, this method will
    ///   return the MethodInfo that this method implements.
    ///
    ///   If `name' is null, we operate solely on the method's signature.  This is for
    ///   instance used when implementing indexers.
    ///
    ///   The `Operation op' controls whether to lookup, clear the pending bit, or clear
    ///   all the methods with the given signature.
    ///
    ///   The `MethodInfo need_proxy' is used when we're implementing an interface's
    ///   indexer in a class.  If the new indexer's IndexerName does not match the one
    ///   that was used in the interface, then we always need to create a proxy for it.
    ///
    /// </remarks>
    public MethodSpec InterfaceMethod (MemberName name, TypeSpec iType, MethodData method, Operation op, out MethodSpec ambiguousCandidate, ref bool optional)
    {
      ambiguousCandidate = null;

      if (pending_implementations == null)
        return null;

      TypeSpec ret_type = method.method.ReturnType;
      ParametersCompiled args = method.method.ParameterInfo;
      bool is_indexer = method.method is Indexer.SetIndexerMethod || method.method is Indexer.GetIndexerMethod;
      MethodSpec m;

      foreach (TypeAndMethods tm in pending_implementations){
        if (!(iType == null || tm.type == iType))
          continue;

        int method_count = tm.methods.Count;
        for (int i = 0; i < method_count; i++){
          m = tm.methods [i];

          if (m == null)
            continue;

          if (is_indexer) {
            if (!m.IsAccessor || m.Parameters.IsEmpty)
              continue;
          } else {
            if (name.Name != m.Name)
              continue;

            if (m.Arity != name.Arity)
              continue;
          }

          if (!TypeSpecComparer.Override.IsEqual (m.Parameters, args))
            continue;

          if (!TypeSpecComparer.Override.IsEqual (m.ReturnType, ret_type)) {
            tm.found[i] = method;
            continue;
          }

          //
          // `need_proxy' is not null when we're implementing an
          // interface indexer and this is Clear(One/All) operation.
          //
          // If `name' is null, then we do a match solely based on the
          // signature and not on the name (this is done in the Lookup
          // for an interface indexer).
          //
          if (op != Operation.Lookup) {
            if (m.IsAccessor != method.method.IsAccessor)
              continue;

            // If `t != null', then this is an explicitly interface
            // implementation and we can always clear the method.
            // `need_proxy' is not null if we're implementing an
            // interface indexer.  In this case, we need to create
            // a proxy if the implementation's IndexerName doesn't
            // match the IndexerName in the interface.
            if (m.DeclaringType.IsInterface && iType == null && name.Name != m.Name) {  // TODO: This is very expensive comparison
              tm.need_proxy[i] = method.method.Spec;
            } else {
              tm.methods[i] = null;
            }
          } else {
            tm.found [i] = method;
            optional = tm.optional;
          }

          if (op == Operation.Lookup && name.ExplicitInterface != null && ambiguousCandidate == null) {
            ambiguousCandidate = m;
            continue;
          }

          //
          // Lookups and ClearOne return
          //
          if (op != Operation.ClearAll)
            return m;
        }

        // If a specific type was requested, we can stop now.
        if (tm.type == iType)
          break;
      }

      m = ambiguousCandidate;
      ambiguousCandidate = null;
      return m;
    }

    /// <summary>
    ///   C# allows this kind of scenarios:
    ///   interface I { void M (); }
    ///   class X { public void M (); }
    ///   class Y : X, I { }
    ///
    ///   For that case, we create an explicit implementation function
    ///   I.M in Y.
    /// </summary>
    void DefineProxy (TypeSpec iface, MethodSpec base_method, MethodSpec iface_method)
    {
      // TODO: Handle nested iface names
      string proxy_name;
      var ns = iface.MemberDefinition.Namespace;
      if (string.IsNullOrEmpty (ns))
        proxy_name = iface.MemberDefinition.Name + "." + iface_method.Name;
      else
        proxy_name = ns + "." + iface.MemberDefinition.Name + "." + iface_method.Name;

      var param = iface_method.Parameters;

      MethodBuilder proxy = container.TypeBuilder.DefineMethod (
        proxy_name,
        MethodAttributes.Private |
        MethodAttributes.HideBySig |
        MethodAttributes.NewSlot |
        MethodAttributes.CheckAccessOnOverride |
        MethodAttributes.Virtual | MethodAttributes.Final,
        CallingConventions.Standard | CallingConventions.HasThis,
        base_method.ReturnType.GetMetaInfo (), param.GetMetaInfo ());

      if (iface_method.IsGeneric) {
        var gnames = iface_method.GenericDefinition.TypeParameters.Select (l => l.Name).ToArray ();
        proxy.DefineGenericParameters (gnames);
      }

      for (int i = 0; i < param.Count; i++) {
        string name = param.FixedParameters [i].Name;
        ParameterAttributes attr = ParametersCompiled.GetParameterAttribute (param.FixedParameters [i].ModFlags);
        proxy.DefineParameter (i + 1, attr, name);
      }

      int top = param.Count;
      var ec = new EmitContext (new ProxyMethodContext (container), proxy.GetILGenerator (), null, null);
      ec.EmitThis ();
      // TODO: GetAllParametersArguments
      for (int i = 0; i < top; i++)
        ec.EmitArgumentLoad (i);

      ec.Emit (OpCodes.Call, base_method);
      ec.Emit (OpCodes.Ret);

      container.TypeBuilder.DefineMethodOverride (proxy, (MethodInfo) iface_method.GetMetaInfo ());
    }
    
    /// <summary>
    ///   This function tells whether one of our base classes implements
    ///   the given method (which turns out, it is valid to have an interface
    ///   implementation in a base
    /// </summary>
    bool BaseImplements (TypeSpec iface_type, MethodSpec mi, out MethodSpec base_method)
    {
      base_method = null;
      var base_type = container.BaseType;

      //
      // Setup filter with no return type to give better error message
      // about mismatch at return type when the check bellow rejects them
      //
      var parameters = mi.Parameters;
      MethodSpec close_match = null;

      while (true) {
        var candidates = MemberCache.FindMembers (base_type, mi.Name, false);
        if (candidates == null) {
          base_method = close_match;
          return false;
        }

        MethodSpec similar_candidate = null;
        foreach (var candidate in candidates) {
          if (candidate.Kind != MemberKind.Method)
            continue;

          if (candidate.Arity != mi.Arity)
            continue;

          var candidate_param = ((MethodSpec) candidate).Parameters;
          if (!TypeSpecComparer.Override.IsEqual (parameters.Types, candidate_param.Types))
            continue;

          bool modifiers_match = true;
          for (int i = 0; i < parameters.Count; ++i) {
            //
            // First check exact ref/out match
            //
            if ((parameters.FixedParameters[i].ModFlags & Parameter.Modifier.RefOutMask) == (candidate_param.FixedParameters[i].ModFlags & Parameter.Modifier.RefOutMask))
              continue;

            modifiers_match = false;

            //
            // Different in ref/out only
            //
            if ((parameters.FixedParameters[i].ModFlags & Parameter.Modifier.RefOutMask) != (candidate_param.FixedParameters[i].ModFlags & Parameter.Modifier.RefOutMask)) {
              if (similar_candidate == null) {
                if (!candidate.IsPublic)
                  break;

                if (!TypeSpecComparer.Override.IsEqual (mi.ReturnType, ((MethodSpec) candidate).ReturnType))
                  break;

                // It's used for ref/out ambiguity overload check
                similar_candidate = (MethodSpec) candidate;
              }

              continue;
            }

            similar_candidate = null;
            break;
          }

          if (!modifiers_match)
            continue;

          //
          // From this point the candidate is used for detailed error reporting
          // because it's very close match to what we are looking for
          //
          var m = (MethodSpec) candidate;

          if (!m.IsPublic) {
            if (close_match == null)
              close_match = m;

            continue;
          }

          if (!TypeSpecComparer.Override.IsEqual (mi.ReturnType, m.ReturnType)) {
            if (close_match == null)
              close_match = m;

            continue;
          }
            
          base_method = m;

          if (mi.IsGeneric && !Method.CheckImplementingMethodConstraints (container, m, mi)) {
            return true;
          }
        }
        
        if (base_method != null) {
          if (similar_candidate != null) {
            Report.SymbolRelatedToPreviousError (similar_candidate);
            Report.SymbolRelatedToPreviousError (mi);
            Report.SymbolRelatedToPreviousError (container);
            Report.Warning (1956, 1, ((MemberCore) base_method.MemberDefinition).Location,
              "The interface method `{0}' implementation is ambiguous between following methods: `{1}' and `{2}' in type `{3}'",
              mi.GetSignatureForError (), base_method.GetSignatureForError (), similar_candidate.GetSignatureForError (), container.GetSignatureForError ());
          }

          break;
        }

        base_type = candidates[0].DeclaringType.BaseType;
        if (base_type == null) {
          base_method = close_match;
          return false;
        }
      }

      if (!base_method.IsVirtual) {
#if STATIC
        var base_builder = base_method.GetMetaInfo () as MethodBuilder;
        if (base_builder != null) {
          //
          // We can avoid creating a proxy if base_method can be marked 'final virtual'. This can
          // be done for all methods from compiled assembly
          //
          base_builder.__SetAttributes (base_builder.Attributes | MethodAttributes.Virtual | MethodAttributes.Final | MethodAttributes.NewSlot);
          return true;
        }
#endif
        DefineProxy (iface_type, base_method, mi);
      }

      return true;
    }

    /// <summary>
    ///   Verifies that any pending abstract methods or interface methods
    ///   were implemented.
    /// </summary>
    public bool VerifyPendingMethods ()
    {
      int top = pending_implementations.Length;
      bool errors = false;
      int i;
      
      for (i = 0; i < top; i++){
        TypeSpec type = pending_implementations [i].type;

        bool base_implements_type = type.IsInterface &&
          container.BaseType != null &&
          container.BaseType.ImplementsInterface (type, false);

        for (int j = 0; j < pending_implementations [i].methods.Count; ++j) {
          var mi = pending_implementations[i].methods[j];
          if (mi == null)
            continue;

          if (type.IsInterface){
            var need_proxy =
              pending_implementations [i].need_proxy [j];

            if (need_proxy != null) {
              DefineProxy (type, need_proxy, mi);
              continue;
            }

            if (pending_implementations [i].optional)
              continue;

            MethodSpec candidate;
            if (base_implements_type || BaseImplements (type, mi, out candidate))
              continue;

            if (candidate == null) {
              MethodData md = pending_implementations [i].found [j];
              if (md != null)
                candidate = md.method.Spec;
            }

            Report.SymbolRelatedToPreviousError (mi);
            if (candidate != null) {
              Report.SymbolRelatedToPreviousError (candidate);
              if (candidate.IsStatic) {
                Report.Error (736, container.Location,
                  "`{0}' does not implement interface member `{1}' and the best implementing candidate `{2}' is static",
                  container.GetSignatureForError (), mi.GetSignatureForError (), candidate.GetSignatureForError ());
              } else if ((candidate.Modifiers & Modifiers.PUBLIC) == 0) {
                Report.Error (737, container.Location,
                  "`{0}' does not implement interface member `{1}' and the best implementing candidate `{2}' is not public",
                  container.GetSignatureForError (), mi.GetSignatureForError (), candidate.GetSignatureForError ());
              } else {
                Report.Error (738, container.Location,
                  "`{0}' does not implement interface member `{1}' and the best implementing candidate `{2}' return type `{3}' does not match interface member return type `{4}'",
                  container.GetSignatureForError (), mi.GetSignatureForError (), candidate.GetSignatureForError (),
                  candidate.ReturnType.GetSignatureForError (), mi.ReturnType.GetSignatureForError ());
              }
            } else {
              Report.Error (535, container.Location, "`{0}' does not implement interface member `{1}'",
                container.GetSignatureForError (), mi.GetSignatureForError ());
            }
          } else {
            Report.SymbolRelatedToPreviousError (mi);
            Report.Error (534, container.Location, "`{0}' does not implement inherited abstract member `{1}'",
              container.GetSignatureForError (), mi.GetSignatureForError ());
          }
          errors = true;
        }
      }
      return errors;
    }
  }
}