1 | #Region "Microsoft.VisualBasic::6b42e92667b5a2a717e45d70ec84fc63, Microsoft.VisualBasic.Core\Scripting\Runtime\CType\Narrowing.vb" |
2 | |
3 | ' Author: |
4 | ' |
5 | ' asuka (amethyst.asuka@gcmodeller.org) |
6 | ' xie (genetics@smrucc.org) |
7 | ' xieguigang (xie.guigang@live.com) |
8 | ' |
9 | ' Copyright (c) 2018 GPL3 Licensed |
10 | ' |
11 | ' |
12 | ' GNU GENERAL PUBLIC LICENSE (GPL3) |
13 | ' |
14 | ' |
15 | ' This program is free software: you can redistribute it and/or modify |
16 | ' it under the terms of the GNU General Public License as published by |
17 | ' the Free Software Foundation, either version 3 of the License, or |
18 | ' (at your option) any later version. |
19 | ' |
20 | ' This program is distributed in the hope that it will be useful, |
21 | ' but WITHOUT ANY WARRANTY; without even the implied warranty of |
22 | ' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
23 | ' GNU General Public License for more details. |
24 | ' |
25 | ' You should have received a copy of the GNU General Public License |
26 | ' along with this program. If not, see <http://www.gnu.org/licenses/>. |
27 | |
28 | |
29 | |
30 | ' /********************************************************************************/ |
31 | |
32 | ' Summaries: |
33 | |
34 | ' Module NarrowingReflection |
35 | ' |
36 | ' |
37 | ' Delegate Function |
38 | ' |
39 | ' Function: (+2 Overloads) GetNarrowingOperator, GetOperatorMethod |
40 | ' |
41 | ' |
42 | ' |
43 | ' /********************************************************************************/ |
44 | |
45 | #End Region |
46 | |
47 | Imports System.Reflection |
48 | Imports System.Runtime.CompilerServices |
49 | |
50 | Namespace Scripting.Runtime |
51 | |
52 | Public Module NarrowingReflection |
53 | |
54 | ''' <summary> |
55 | ''' 2070 = SpecialName |
56 | ''' </summary> |
57 | Const NarrowingOperator As BindingFlags = BindingFlags.Public Or BindingFlags.Static Or 2070 |
58 | Const op_Explicit$ = NameOf(op_Explicit) |
59 | |
60 | Public Delegate Function INarrowingOperator(Of TIn, TOut)(obj As TIn) As TOut |
61 | |
62 | Public Function GetNarrowingOperator(Of TIn, TOut)() As INarrowingOperator(Of TIn, TOut) |
63 | Dim op As MethodInfo = CType(GetType(TIn), TypeInfo).GetOperatorMethod(Of TOut) |
64 | |
65 | If op Is Nothing Then |
66 | Return Nothing |
67 | Else |
68 | Dim op_Explicit As INarrowingOperator(Of TIn, TOut) = op.CreateDelegate(GetType(INarrowingOperator(Of TIn, TOut))) |
69 | Return op_Explicit |
70 | End If |
71 | End Function |
72 | |
73 | ''' <summary> |
74 | ''' 直接使用GetMethod方法仍然会出错??如果目标类型是继承类型,基类型也有一个收缩的操作符的话,会爆出目标不明确的错误 |
75 | ''' |
76 | ''' ```vbnet |
77 | ''' type.GetMethod(op_Explicit, NarrowingOperator) |
78 | ''' ``` |
79 | ''' </summary> |
80 | ''' <typeparam name="T"></typeparam> |
81 | ''' <param name="type"></param> |
82 | ''' <returns>函数找不到会返回Nothing</returns> |
83 | <MethodImpl(MethodImplOptions.AggressiveInlining)> |
84 | <Extension> |
85 | Private Function GetOperatorMethod(Of T)(type As TypeInfo) As MethodInfo |
86 | Return type.DeclaredMethods _ |
87 | .Where(Function(m) m.Name = op_Explicit AndAlso m.ReturnType Is GetType(T)) _ |
88 | .FirstOrDefault |
89 | End Function |
90 | |
91 | <Extension> |
92 | Public Function GetNarrowingOperator(Of T)(type As Type) As INarrowingOperator(Of Object, T) |
93 | ' 函数找不到会返回Nothing |
94 | Dim op As MethodInfo = CType(type, TypeInfo).GetOperatorMethod(Of T) |
95 | |
96 | If op Is Nothing Then |
97 | Return Nothing |
98 | Else |
99 | Dim op_Explicit As INarrowingOperator(Of Object, T) = Function(obj) DirectCast(op.Invoke(Nothing, {obj}), T) |
100 | Return op_Explicit |
101 | End If |
102 | End Function |
103 | End Module |
104 | End Namespace |