' Licensed to the .NET Foundation under one or more agreements.
' The .NET Foundation licenses this file to you under the MIT license.
' See the LICENSE file in the project root for more information.

Imports System.Collections.Immutable
Imports Microsoft.CodeAnalysis.VisualBasic.Symbols

Namespace Microsoft.CodeAnalysis.VisualBasic

    Partial Friend Class DataFlowPass

        ''' <summary> 
        ''' AmbiguousLocalsPseudoSymbol is a pseudo-symbol used in flow analysis representing 
        ''' a symbol of the implicit receiver in case Dim statement defines more than one variable,
        ''' but uses the same object initializer for all of them, like: 
        '''     Dim a,b As New C() With { .X = .Y } 
        ''' </summary>
        Protected NotInheritable Class AmbiguousLocalsPseudoSymbol
            Inherits LocalSymbol

            Public ReadOnly Locals As ImmutableArray(Of LocalSymbol)

            Private Sub New(container As Symbol, type As TypeSymbol, locals As ImmutableArray(Of LocalSymbol))
                MyBase.New(container, type)

                Debug.Assert(type IsNot Nothing)
                Me.Locals = locals
            End Sub

            Friend Overrides ReadOnly Property DeclarationKind As LocalDeclarationKind
                Get
                    Return LocalDeclarationKind.AmbiguousLocals
                End Get
            End Property

            Friend Overrides ReadOnly Property SynthesizedKind As SynthesizedLocalKind
                Get
                    Return SynthesizedLocalKind.UserDefined
                End Get
            End Property

            Public Overrides ReadOnly Property IsFunctionValue As Boolean
                Get
                    Return False
                End Get
            End Property

            Friend Shared Shadows Function Create(locals As ImmutableArray(Of LocalSymbol)) As LocalSymbol
                Debug.Assert(Not locals.IsDefault AndAlso locals.Length > 1)
                Dim firstLocal As LocalSymbol = locals(0)
                Return New AmbiguousLocalsPseudoSymbol(firstLocal.ContainingSymbol, firstLocal.Type, locals)
            End Function

            Public Overrides ReadOnly Property Locations As ImmutableArray(Of Location)
                Get
                    Return ImmutableArray(Of Location).Empty
                End Get
            End Property

            Public Overrides ReadOnly Property DeclaringSyntaxReferences As ImmutableArray(Of SyntaxReference)
                Get
                    Return ImmutableArray(Of SyntaxReference).Empty
                End Get
            End Property

            Friend Overrides Function GetDeclaratorSyntax() As SyntaxNode
                Throw ExceptionUtilities.Unreachable
            End Function

            Friend Overrides ReadOnly Property IdentifierToken As SyntaxToken
                Get
                    Return Nothing
                End Get
            End Property

            Friend Overrides ReadOnly Property IdentifierLocation As Location
                Get
                    Return NoLocation.Singleton
                End Get
            End Property

            Public Overrides ReadOnly Property Name As String
                Get
                    Return Nothing
                End Get
            End Property

            Friend Overrides ReadOnly Property IsByRef As Boolean
                Get
                    Return False
                End Get
            End Property
        End Class
    End Class
End Namespace