latebinder.vb

大名鼎鼎的mono是.NET平台的跨平台（支持linux

                If args.Length > parameters.Length Then
                    Return Nothing 'there are more arguments than parameters
                End If

                ReDim preparedArguments(parameters.Length - 1)
                For i As Integer = 0 To parameters.Length - 1
                    Dim mappedArgument As Integer = Array.IndexOf(mapping, i)
                    If mappedArgument = -1 Or mappedArgument > args.Length - 1 Then
                        If parameters(i).IsOptional Then
                            preparedArguments(i) = parameters(i).DefaultValue 'initialize optional parameter
                        Else
                            Return Nothing 'not-optional parameter missing
                        End If
                    Else
                        preparedArguments(i) = args(mappedArgument) 'initialize parameter from argument
                    End If
                Next
                Return preparedArguments
            End If

            ' param array case
            If IsParamArray(parameters, parameters.Length - 1) Then
                If args.Length > 0 Then
                    If Not names Is Nothing Then ' for simplicity, care about named prameters case separately
                        For i As Integer = 0 To args.Length - 1
                            Dim mappedArgument As Integer = Array.IndexOf(mapping, i)
                            If mappedArgument = -1 Then
                                If i = args.Length - 1 Then ' i.e. there is no mapping for param array
                                    Exit For ' its ok, just finish preparing arguments
                                End If
                            Else
                                If i = parameters.Length - 1 Then
                                    Return Nothing ' param array can not be mapped by name
                                End If
                                preparedArguments(i) = args(mappedArgument) 'initialize parameter from argument
                            End If
                        Next
                    Else
                        If args(args.Length - 1).GetType().IsArray Then
                            If args.Length > parameters.Length Then  'last arg matches param array, but there are too much args
                                Return Nothing
                            End If
                            ' param array passed as array argument
                            Dim index As Integer = args.Length - 1
                            Dim pcount As Integer = CType(args(args.Length - 1), Array).Length
                            Dim arr As Object = args(index)
                            ReDim Preserve preparedArguments(index + pcount - 1)
                            For i As Integer = 0 To pcount - 1
                                preparedArguments(index + i) = CType(arr, Array).GetValue(i)
                            Next
                        End If
                    End If
                End If
                Return preparedArguments
            End If

            For i As Integer = 0 To args.Length - 1
                Dim mappedArgument As Integer = Array.IndexOf(mapping, i)
                If mappedArgument = -1 Or mappedArgument > args.Length - 1 Then
                    Return Nothing 'not-optional parameter missing
                Else
                    preparedArguments(i) = args(mappedArgument) 'initialize parameter from argument
                End If
            Next

            Return preparedArguments
        End Function

        Private Function GetArgumentsMapping(ByVal parameters() As ParameterInfo, ByVal names() As String, ByVal args() As Object) As Integer()
            Dim mapping(parameters.Length - 1) As Integer
            For i As Integer = 0 To mapping.Length - 1
                mapping(i) = i
            Next

            If names Is Nothing Then
                Return mapping
            End If

            Dim parameterNames(parameters.Length - 1) As String
            For i As Integer = 0 To parameters.Length - 1
                parameterNames(i) = parameters(i).Name
            Next

            Dim namedArgumentsStart As Integer = args.Length - names.Length

            For i As Integer = 0 To mapping.Length - 1
                If i < names.Length Then
                    Dim m As Integer = Array.IndexOf(parameterNames, names(i))
                    If m = -1 Then
                        Return Nothing ' mapping failed
                    End If
                    mapping(i + namedArgumentsStart) = m
                End If
            Next

            Return mapping
        End Function

        Private Sub PrepareParameters(ByRef args() As Object, ByVal f As MethodBase, ByVal names() As String, ByVal bstate As BState)

            Dim parameters() As ParameterInfo = f.GetParameters()

            Dim vals() As Object
            Dim i As Integer

            If parameters.Length = 0 Then
                Return
            End If

            vals = PrepareArguments(args, parameters, names, bstate)

            If parameters.Length <> args.Length Then
                ReDim args(parameters.Length - 1) ' args must be the same size as parameters
            End If

            Dim hasParamArray As Boolean = False
            For i = 0 To args.Length - 1 ' fit args to parameters until param array
                If IsParamArray(parameters, i) Then
                    hasParamArray = True
                    Exit For
                End If
                args(i) = ConvertValue(vals(i), GetParameterType(parameters, i))
            Next

            If hasParamArray Then
                ' special case when param array args are passed as one argument that is actually an array
                If (vals.Length - i) = 1 Then
                    If vals(i).GetType().IsArray Then
                        args(i) = vals(i)
                        Return
                    End If
                    ' if the last value remained is not array, put it in args array as usual
                End If

                ' store rest of args (if any) in param array
                ' if args count is the same as params count excluding param array
                ' we pass empty param array
                Dim arrType As Type = GetParameterType(parameters, i)
                Dim pcount As Integer = vals.Length - i
                Dim parr As Array = Array.CreateInstance(arrType, pcount)

                For j As Integer = 0 To pcount - 1
                    parr.SetValue(ConvertValue(vals(i + j), arrType), j)
                Next

                args(parameters.Length - 1) = parr
            End If
        End Sub

        Private Function ConvertValue(ByVal value As Object, ByVal type2 As Type) As Object

            If value Is Nothing Then
                Return Nothing
            End If

            Dim type1 As Type = value.GetType()

            If type1 Is type2 Then
                Return value
            End If

            If type1.IsByRef Then
                type1 = type1.GetElementType()
            End If

            If type1.IsPrimitive And type2.IsPrimitive Then
                Select Case Type.GetTypeCode(type2)
                    Case TypeCode.Boolean
                        Return CBool(value)
                    Case TypeCode.Byte
                        Return CByte(value)
#If NET_VER >= 2.0 Then
                    Case TypeCode.SByte
                        Return CSByte(value)
#End If
                    Case TypeCode.Char
                        Return CChar(value)
                    Case TypeCode.DateTime
                        Return CDate(value)
                    Case TypeCode.Double
                        Return CDbl(value)
                    Case TypeCode.Decimal
                        Return (CDec(value))
                    Case TypeCode.Int32
                        Return CInt(value)
                    Case TypeCode.Int16
                        Return CShort(value)
                    Case TypeCode.Int64
                        Return CLng(value)
#If NET_VER >= 2.0 Then
                    Case TypeCode.UInt32
                        Return CUInt(value)
                    Case TypeCode.UInt16
                        Return CUShort(value)
                    Case TypeCode.UInt64
                        Return CULng(value)
#End If
                    Case TypeCode.Single
                        Return CSng(value)
                End Select
                Return Convert.ChangeType(value, type2)
            Else
                If type2 Is GetType(String) Then
                    Return CStr(value)
                End If

                If type1 Is GetType(String) And type2.IsPrimitive Then
                    Select Case Type.GetTypeCode(type2)
                        Case TypeCode.Boolean
                            Return CBool(value)
                        Case TypeCode.Byte
                            Return CByte(value)
#If NET_VER >= 2.0 Then
                        Case TypeCode.SByte
                            Return CSByte(value)
#End If
                        Case TypeCode.Char
                            Return CChar(value)
                        Case TypeCode.DateTime
                            Return CDate(value)
                        Case TypeCode.Double
                            Return CDbl(value)
                        Case TypeCode.Decimal
                            Return (CDec(value))
                        Case TypeCode.Int32
                            Return CInt(value)
                        Case TypeCode.Int16
                            Return CShort(value)
                        Case TypeCode.Int64
                            Return CLng(value)
#If NET_VER >= 2.0 Then
                        Case TypeCode.UInt32
                            Return CUInt(value)
                        Case TypeCode.UInt16
                            Return CUShort(value)
                        Case TypeCode.UInt64
                            Return CULng(value)
#End If
                        Case TypeCode.Single
                            Return CSng(value)
                    End Select
                End If
            End If

            Return value
        End Function

        Private Function CompareMethods(ByVal f1 As MethodBase, ByVal f2 As MethodBase, ByVal args() As Object) As SignatureCompare
            Dim params1() As ParameterInfo = f1.GetParameters()
            Dim params2() As ParameterInfo = f2.GetParameters()
            Dim previous As SignatureCompare = SignatureCompare.Equal
            Dim current As SignatureCompare
            Dim paramArrayDecision As Boolean = False

            For i As Integer = 0 To Math.Max(args.Length, Math.Min(params1.Length, params2.Length)) - 1 'args.Length - 1
                Dim f1iType As Type = GetParameterType(params1, i)
                Dim f2iType As Type = GetParameterType(params2, i)
                Dim ptype As Type = GetArgumentType(args, i)

                Dim f1i As TypeConversion = CompareTypes(ptype, f1iType)
                Dim f2i As TypeConversion = CompareTypes(ptype, f2iType)

                If f1i = TypeConversion.Widening And f2i = TypeConversion.Widening Then
                    'current = CompareWideningTypes(f1iType, f2iType, IsParamArray(params1, i), IsParamArray(params2, i))
                    If Not ptype Is Nothing Then
                        current = CompareWideningTypes(f1iType, f2iType)
                    Else
                        current = CompareWideningTypesWithNothing(f1iType, f2iType) ' for explicit null arguments
                    End If

                    If current = SignatureCompare.Equal Then
                        Dim type1isParamArray As Boolean = IsParamArray(params1, i)
                        Dim type2isParamArray As Boolean = IsParamArray(params2, i)

                        'If paramArrayDecision Then
                        If previous = SignatureCompare.Equal Or paramArrayDecision Then
                            If type1isParamArray And type2isParamArray Then
                                'if occurs, it will be always the case until we reach the args end
                                If paramArrayDecision Then
                                    current = SignatureCompare.Ambiguity