Darwinism/Google.Protobuf/Reflection/ReflectionUtil.vb

#Region "Microsoft.VisualBasic::93f3651bb031be5bfb8de94934f48e9d, Google.Protobuf\Reflection\ReflectionUtil.vb"

    ' Author:
    ' 
    '       asuka (amethyst.asuka@gcmodeller.org)
    '       xie (genetics@smrucc.org)
    '       xieguigang (xie.guigang@live.com)
    ' 
    ' Copyright (c) 2018 GPL3 Licensed
    ' 
    ' 
    ' GNU GENERAL PUBLIC LICENSE (GPL3)
    ' 
    ' 
    ' This program is free software: you can redistribute it and/or modify
    ' it under the terms of the GNU General Public License as published by
    ' the Free Software Foundation, either version 3 of the License, or
    ' (at your option) any later version.
    ' 
    ' This program 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 General Public License for more details.
    ' 
    ' You should have received a copy of the GNU General Public License
    ' along with this program. If not, see <http://www.gnu.org/licenses/>.



    ' /********************************************************************************/

    ' Summaries:

    '     Module ReflectionUtil
    ' 
    '         Function: CreateActionIMessage, CreateActionIMessageObject, CreateFuncIMessageObject, CreateFuncIMessageT
    ' 
    ' 
    ' /********************************************************************************/

#End Region

#Region "Copyright notice and license"
' Protocol Buffers - Google's data interchange format
' Copyright 2008 Google Inc.  All rights reserved.
' https://developers.google.com/protocol-buffers/
'
' Redistribution and use in source and binary forms, with or without
' modification, are permitted provided that the following conditions are
' met:
'
'     * Redistributions of source code must retain the above copyright
' notice, this list of conditions and the following disclaimer.
'     * Redistributions in binary form must reproduce the above
' copyright notice, this list of conditions and the following disclaimer
' in the documentation and/or other materials provided with the
' distribution.
'     * Neither the name of Google Inc. nor the names of its
' contributors may be used to endorse or promote products derived from
' this software without specific prior written permission.
'
' THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
' "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
' LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
' A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
' OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
' SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
' LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
' DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
' THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
' (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
' OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#End Region

Imports System
Imports System.Reflection

Namespace Google.Protobuf.Reflection
    ''' <summary>
    ''' In order to run on iOS (no JIT) we had to use Invoke which results in a bit
    ''' of a performance cost. The original description is as follows:
    ''' The methods in this class are somewhat evil, and should not be tampered with lightly.
    ''' Basically they allow the creation of relatively weakly typed delegates from MethodInfos
    ''' which are more strongly typed. They do this by creating an appropriate strongly typed
    ''' delegate from the MethodInfo, and then calling that within an anonymous method.
    ''' Mind-bending stuff (at least to your humble narrator) but the resulting delegates are
    ''' very fast compared with calling Invoke later on.
    ''' </summary>
    Friend Module ReflectionUtil
        ''' <summary>
        ''' Empty Type[] used when calling GetProperty to force property instead of indexer fetching.
        ''' </summary>
        Friend ReadOnly EmptyTypes As Type() = New Type(-1) {}

        ''' <summary>
        ''' Creates a delegate which will cast the argument to the appropriate method target type,
        ''' call the method on it, then convert the result to object.
        ''' </summary>
        Friend Function CreateFuncIMessageObject(method As MethodInfo) As Func(Of IMessage, Object)
            Return Function(message)
                       Dim returnValue = TryCast(method.Invoke(message, Nothing), Object)
                       Return returnValue
                   End Function
        End Function

        ''' <summary>
        ''' Creates a delegate which will cast the argument to the appropriate method target type,
        ''' call the method on it, then convert the result to the specified type.
        ''' </summary>
        Friend Function CreateFuncIMessageT(Of T)(method As MethodInfo) As Func(Of IMessage, T)
            Return Function(message)
                       Dim returnValue = CType(method.Invoke(message, Nothing), T)
                       Return returnValue
                   End Function
        End Function

        ''' <summary>
        ''' Creates a delegate which will execute the given method after casting the first argument to
        ''' the target type of the method, and the second argument to the first parameter type of the method.
        ''' </summary>
        Friend Function CreateActionIMessageObject(method As MethodInfo) As Action(Of IMessage, Object)
            Return Sub(arg1, arg2) method.Invoke(arg1, New Object() {arg2})
        End Function

        ''' <summary>
        ''' Creates a delegate which will execute the given method after casting the first argument to
        ''' the target type of the method.
        ''' </summary>
        Friend Function CreateActionIMessage(method As MethodInfo) As Action(Of IMessage)
            Return Sub(obj) method.Invoke(obj, Nothing)
        End Function
    End Module
End Namespace