' 
' Visual Basic.Net Compiler
' Copyright (C) 2004 - 2010 Rolf Bjarne Kvinge, RKvinge@novell.com
' 
' This library is free software; you can redistribute it and/or
' modify it under the terms of the GNU Lesser General Public
' License as published by the Free Software Foundation; either
' version 2.1 of the License, or (at your option) any later version.
' 
' This library is distributed in the hope that it will be useful,
' but WITHOUT ANY WARRANTY; without even the implied warranty of
' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
' Lesser General Public License for more details.
' 
' You should have received a copy of the GNU Lesser General Public
' License along with this library; if not, write to the Free Software
' Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
' 

Public Class RShiftExpression
    Inherits BinaryExpression

    Protected Overrides Function GenerateCodeInternal(ByVal Info As EmitInfo) As Boolean
        Dim result As Boolean = True

        ValidateBeforeGenerateCode(Info)

        Dim expInfo As EmitInfo = Info.Clone(Me, True, False, OperandType)

        result = m_LeftExpression.GenerateCode(expInfo) AndAlso result
        result = m_RightExpression.GenerateCode(expInfo.Clone(Me, Compiler.TypeCache.System_Int32)) AndAlso result


        Select Case OperandTypeCode
            Case TypeCode.Int16, TypeCode.Int32, TypeCode.Int64, TypeCode.UInt16, TypeCode.UInt32, TypeCode.UInt64, TypeCode.Byte, TypeCode.SByte
                Dim shift As Integer
                Select Case OperandTypeCode
                    Case TypeCode.Byte, TypeCode.SByte
                        shift = 7
                    Case TypeCode.Int16, TypeCode.UInt16
                        shift = 15
                    Case TypeCode.Int32, TypeCode.UInt32
                        shift = 31
                    Case TypeCode.Int64, TypeCode.UInt64
                        shift = 63
                End Select
                Emitter.EmitLoadI4Value(Info, shift)
                Emitter.EmitAnd(Info, Info.Compiler.TypeCache.System_Int32)
                Emitter.EmitRShift(Info, OperandType)
            Case TypeCode.Object
                Helper.Assert(Helper.CompareType(OperandType, Compiler.TypeCache.System_Object))
                Emitter.EmitCall(Info, Compiler.TypeCache.MS_VB_CS_Operators__RightShiftObject_Object_Object)
            Case Else
                Throw New InternalException(Me)
        End Select

        Return result
    End Function

    Public Overrides ReadOnly Property RightOperandTypeCode() As System.TypeCode
        Get
            If MyBase.OperandTypeCode = TypeCode.Object Then
                Return TypeCode.Object
            Else
                Return TypeCode.Int32
            End If
        End Get
    End Property

    Sub New(ByVal Parent As ParsedObject, ByVal LExp As Expression, ByVal RExp As Expression)
        MyBase.New(Parent, LExp, RExp)
    End Sub

    Public Overrides ReadOnly Property Keyword() As KS
        Get
            Return KS.ShiftRight
        End Get
    End Property

    Public Overrides Function GetConstant(ByRef m_ConstantValue As Object, ByVal lvalue As Object, ByVal rvalue As Object) As Boolean
        Dim shifts As Integer 'This needs to be an integer.
        Dim tmpShifts As Object = Nothing

        If Compiler.TypeResolution.CheckNumericRange(rvalue, tmpShifts, Compiler.TypeCache.System_Int32) = False Then
            Return Helper.AddError(Me, "Invalid numeric range")
        Else
            shifts = CInt(tmpShifts)
        End If

        Dim tlvalue As Mono.Cecil.TypeReference
        Dim clvalue As TypeCode
        tlvalue = CecilHelper.GetType(Compiler, lvalue)
        clvalue = Helper.GetTypeCode(Compiler, tlvalue)

        Select Case clvalue
            Case TypeCode.Byte
                m_ConstantValue = CByte(lvalue) >> shifts
            Case TypeCode.SByte
                m_ConstantValue = CSByte(lvalue) >> shifts
            Case TypeCode.Int16
                m_ConstantValue = CShort(lvalue) >> shifts
            Case TypeCode.UInt16
                m_ConstantValue = CUShort(lvalue) >> shifts
            Case TypeCode.Int32
                m_ConstantValue = CInt(lvalue) >> shifts
            Case TypeCode.UInt32
                m_ConstantValue = CUInt(lvalue) >> shifts
            Case TypeCode.Int64
                m_ConstantValue = CLng(lvalue) >> shifts
            Case TypeCode.UInt64
                m_ConstantValue = CULng(lvalue) >> shifts
            Case Else
                Return False
        End Select

        Return True
    End Function
End Class
