operators.vb

大名鼎鼎的mono是.NET平台的跨平台（支持linux

'
' Operators.vb
'
' Author:
'   Mizrahi Rafael ([e-mail])
'   Rolf Bjarne Kvinge ([e-mail])

'
' Copyright (C) 2002-2006 Mainsoft Corporation.
' Copyright (C) 2004-2006 Novell, Inc (http://www.novell.com)
'
' Permission is hereby granted, free of charge, to any person obtaining
' a copy of this software and associated documentation files (the
' "Software"), to deal in the Software without restriction, including
' without limitation the rights to use, copy, modify, merge, publish,
' distribute, sublicense, and/or sell copies of the Software, and to
' permit persons to whom the Software is furnished to do so, subject to
' the following conditions:
' 
' The above copyright notice and this permission notice shall be
' included in all copies or substantial portions of the Software.
' 
' THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
' EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
' MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
' NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
' LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
' OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
' WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#If NET_2_0 Then
Imports System
Imports System.Reflection
Namespace Microsoft.VisualBasic.CompilerServices
    <System.ComponentModel.EditorBrowsable(ComponentModel.EditorBrowsableState.Never)> _
    Public NotInheritable Class Operators

        Enum CompareResult
            Less
            Equal
            Greater
            NotResolved
        End Enum

        Private Shared Function CompareBoolean(ByVal Left As Boolean, ByVal Right As Boolean) As CompareResult
            If Left = Right Then Return CompareResult.Equal
            If Left > Right Then
                Return CompareResult.Greater
            Else
                Return CompareResult.Less
            End If
        End Function

        Private Shared Function CompareByte(ByVal Left As Byte, ByVal Right As Byte) As CompareResult
            If Left = Right Then
                Return CompareResult.Equal
            ElseIf Left > Right Then
                Return CompareResult.Greater
            Else
                Return CompareResult.Less
            End If
        End Function

        Private Shared Function CompareChar(ByVal Left As Char, ByVal Right As Char) As CompareResult
            If Left = Right Then Return CompareResult.Equal
            If Left > Right Then
                Return CompareResult.Greater
            Else
                Return CompareResult.Less
            End If
        End Function

        Private Shared Function CompareDate(ByVal Left As Date, ByVal Right As Date) As CompareResult
            Return IntToCompareResult(DateTime.Compare(Left, Right))
        End Function

        Private Shared Function IntToCompareResult(ByVal val As Integer) As CompareResult
            If (val = 0) Then
                Return CompareResult.Equal
            ElseIf (val > 0) Then
                Return CompareResult.Greater
            Else
                Return CompareResult.Less
            End If
        End Function

        Private Shared Function CompareDecimal(ByVal Left As Decimal, ByVal Right As Decimal) As CompareResult
            Return IntToCompareResult(Decimal.Compare(Left, Right))
        End Function

        Private Shared Function CompareDouble(ByVal Left As Double, ByVal Right As Double) As CompareResult
            If Left = Right Then
                Return CompareResult.Equal
            ElseIf Left > Right Then
                Return CompareResult.Greater
            Else
                Return CompareResult.Less
            End If
        End Function

        Private Shared Function CompareInt16(ByVal Left As Int16, ByVal Right As Int16) As CompareResult
            If Left = Right Then
                Return CompareResult.Equal
            ElseIf Left > Right Then
                Return CompareResult.Greater
            Else
                Return CompareResult.Less
            End If
        End Function

        Private Shared Function CompareInt32(ByVal Left As Int32, ByVal Right As Int32) As CompareResult
            If Left = Right Then
                Return CompareResult.Equal
            ElseIf Left > Right Then
                Return CompareResult.Greater
            Else
                Return CompareResult.Less