microsoft-visualbasic-runtime/ComponentModel/DataSource/SchemaMaps/BindProperty.vb

#Region "Microsoft.VisualBasic::846e9343a1f39e358aabc37998874578, Microsoft.VisualBasic.Core\ComponentModel\DataSource\SchemaMaps\BindProperty.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:

    '     Structure BindProperty
    ' 
    '         Properties: Identity, IsNull, IsPrimitive, Type
    ' 
    '         Constructor: (+6 Overloads) Sub New
    ' 
    '         Function: FromSchemaTable, GetValue, ToString
    ' 
    '         Sub: SetValue
    ' 
    ' 
    ' /********************************************************************************/

#End Region

Imports System.Reflection
Imports System.Runtime.CompilerServices
Imports Microsoft.VisualBasic.ComponentModel.Collection.Generic
Imports Microsoft.VisualBasic.Emit.Delegates
Imports Microsoft.VisualBasic.Serialization

Namespace ComponentModel.DataSourceModel.SchemaMaps

    ''' <summary>
    ''' Schema for <see cref="Attribute"/> and its bind <see cref="PropertyInfo"/>/<see cref="FieldInfo"/> object target.
    ''' (使用这个对象将公共的域或者属性的读写统一起来)
    ''' </summary>
    ''' <typeparam name="T"></typeparam>
    Public Structure BindProperty(Of T As Attribute)
        Implements IReadOnlyId
        Implements INamedValue
        Implements IProperty

        ''' <summary>
        ''' The property/field object that bind with its custom attribute <see cref="field"/> of type <typeparamref name="T"/>
        ''' </summary>
        Dim member As MemberInfo
        ''' <summary>
        ''' The flag for this field binding.
        ''' </summary>
        Dim field As T
        Dim name As String

        Friend ReadOnly handleSetValue As Action(Of Object, Object)
        Friend ReadOnly handleGetValue As Func(Of Object, Object)

#Region "Property List"

        ''' <summary>
        ''' Gets the type of this <see cref="member"/>.
        ''' </summary>
        ''' <returns></returns>
        Public ReadOnly Property Type As Type

        ''' <summary>
        ''' The map name or the <see cref="PropertyInfo.Name"/>.
        ''' (这个属性会首先查找标记的自定义属性的名称结果，如果不存在才会使用属性或者字段的反射成员名称)
        ''' </summary>
        ''' <returns></returns>
        Public Property Identity As String Implements IReadOnlyId.Identity, INamedValue.Key
            <MethodImpl(MethodImplOptions.AggressiveInlining)>
            Get
                If name.StringEmpty Then
                    name = member.Name
                End If

                Return name
            End Get
            Friend Set(value As String)
                name = value
            End Set
        End Property

        ''' <summary>
        ''' Is this map data is null on its attribute or property data?
        ''' </summary>
        ''' <returns></returns>
        Public ReadOnly Property IsNull As Boolean
            <MethodImpl(MethodImplOptions.AggressiveInlining)>
            Get
                Return member Is Nothing OrElse field Is Nothing
            End Get
        End Property

        ''' <summary>
        ''' Gets a value indicating whether the <see cref="System.Type"/> is one of the primitive types.
        ''' </summary>
        ''' <returns>
        ''' true if the <see cref="System.Type"/> is one of the primitive types; otherwise, false.
        ''' </returns>
        Public ReadOnly Property IsPrimitive As Boolean
            <MethodImpl(MethodImplOptions.AggressiveInlining)>
            Get
                Return Scripting.IsPrimitive(Type)
            End Get
        End Property
#End Region

        Sub New(attr As T, prop As PropertyInfo, Optional getName As IToString(Of T) = Nothing)
            field = attr
            member = prop
            Type = prop.PropertyType

            If Not getName Is Nothing Then
                name = getName(attr)
            End If

            ' Compile the property get/set as the delegate
            With prop
                handleSetValue = AddressOf prop.SetValue  ' .DeclaringType.PropertySet(.Name)
                handleGetValue = AddressOf prop.GetValue  ' .DeclaringType.PropertyGet(.Name)
            End With
        End Sub

        <MethodImpl(MethodImplOptions.AggressiveInlining)>
        Sub New([property] As PropertyInfo)
            Call Me.New(Nothing, [property])
        End Sub

        <MethodImpl(MethodImplOptions.AggressiveInlining)>
        Sub New(field As FieldInfo)
            Call Me.New(Nothing, field)
        End Sub

        <MethodImpl(MethodImplOptions.AggressiveInlining)>
        Sub New(method As MethodInfo)
            Call Me.New(Nothing, method)
        End Sub

        Sub New(attr As T, field As FieldInfo, Optional getName As IToString(Of T) = Nothing)
            Me.field = attr
            Me.member = field
            Type = field.FieldType

            If Not getName Is Nothing Then
                name = getName(attr)
            End If

            With field
                handleSetValue = AddressOf field.SetValue  ' .DeclaringType.FieldSet(.Name)
                handleGetValue = AddressOf field.GetValue  ' .DeclaringType.FieldGet(.Name)
            End With
        End Sub

        Sub New(attr As T, method As MethodInfo, Optional getName As IToString(Of T) = Nothing)
            Me.field = attr
            Me.member = method

            Type = method.ReturnType

            If Not getName Is Nothing Then
                name = getName(attr)
            End If

            If method.IsNonParametric(optionalAsNone:=True) Then
                Throw New InvalidConstraintException("Only allows parameterless method or all of the parameter should be optional!")
            End If

            With field
                handleSetValue = Sub(a, b)
                                     Throw New ReadOnlyException
                                 End Sub
                handleGetValue = Function(obj) method.Invoke(obj, {})
            End With
        End Sub

        ' Exceptions:
        '   T:System.ArgumentException:
        '     The index array does not contain the type of arguments needed.-or- The property's
        '     set accessor is not found. -or-value cannot be converted to the type of System.Reflection.PropertyInfo.PropertyType.
        '
        '   T:System.Reflection.TargetException:
        '     In the .NET for Windows Store apps or the Portable Class Library, catch System.Exception
        '     instead.The object does not match the target type, or a property is an instance
        '     property but obj is null.
        '
        '   T:System.Reflection.TargetParameterCountException:
        '     The number of parameters in index does not match the number of parameters the
        '     indexed property takes.
        '
        '   T:System.MethodAccessException:
        '     In the .NET for Windows Store apps or the Portable Class Library, catch the base
        '     class exception, System.MemberAccessException, instead.There was an illegal attempt
        '     to access a private or protected method inside a class.
        '
        '   T:System.Reflection.TargetInvocationException:
        '     An error occurred while setting the property value. For example, an index value
        '     specified for an indexed property is out of range. The System.Exception.InnerException
        '     property indicates the reason for the error.

        ''' <summary>
        ''' Sets the property value of a specified object with optional index values for
        ''' index properties.
        ''' (这个设置值的函数只适用于``Class``类型，对于``Structure``类型而言，则无法正常的工作)
        ''' </summary>
        ''' <param name="obj">The object whose property value will be set.</param>
        ''' <param name="value">The new property value.</param>
        ''' 
        <MethodImpl(MethodImplOptions.AggressiveInlining)>
        Public Sub SetValue(obj As Object, value As Object) Implements IProperty.SetValue
            ' 2017-6-26 目前value参数为空值的话，会报错，故而在这里添加了一个If分支判断
            If value IsNot Nothing Then
                Call handleSetValue(obj, value)
            End If
        End Sub

        ' Exceptions:
        '   T:System.ArgumentException:
        '     The index array does not contain the type of arguments needed.-or- The property's
        '     get accessor is not found.
        '
        '   T:System.Reflection.TargetException:
        '     In the .NET for Windows Store apps or the Portable Class Library, catch System.Exception
        '     instead.The object does not match the target type, or a property is an instance
        '     property but obj is null.
        '
        '   T:System.Reflection.TargetParameterCountException:
        '     The number of parameters in index does not match the number of parameters the
        '     indexed property takes.
        '
        '   T:System.MethodAccessException:
        '     In the .NET for Windows Store apps or the Portable Class Library, catch the base
        '     class exception, System.MemberAccessException, instead.There was an illegal attempt
        '     to access a private or protected method inside a class.
        '
        '   T:System.Reflection.TargetInvocationException:
        '     An error occurred while retrieving the property value. For example, an index
        '     value specified for an indexed property is out of range. The System.Exception.InnerException
        '     property indicates the reason for the error.

        ''' <summary>
        ''' Returns the property value of a specified object with optional index values for
        ''' indexed properties.
        ''' </summary>
        ''' <param name="x">The object whose property value will be returned.</param>
        ''' <returns>The property value of the specified object.</returns>
        ''' 
        <MethodImpl(MethodImplOptions.AggressiveInlining)>
        Public Function GetValue(x As Object) As Object Implements IProperty.GetValue
            Return handleGetValue(x)
        End Function

        ''' <summary>
        ''' Display this schema maps in Visualbasic style.
        ''' </summary>
        ''' <returns></returns>
        Public Overrides Function ToString() As String
            Return $"Dim {member.Name} As {Type.FullName}"
        End Function

        <MethodImpl(MethodImplOptions.AggressiveInlining)>
        Public Shared Function FromSchemaTable(x As KeyValuePair(Of T, PropertyInfo)) As BindProperty(Of T)
            Return New BindProperty(Of T) With {
                .field = x.Key,
                .member = x.Value
            }
        End Function
    End Structure
End Namespace