Add VB impl.

src/Compilers/VisualBasic/Portable/Compilation/VisualBasicCompilation.vb

@@ -2724,7 +2724,19 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 Throw New ArgumentException(VBResources.NoNoneSearchCriteria, NameOf(filter))
             End If
 
-            Return New SymbolSearcher(Me).GetSymbolsWithName(predicate, filter, cancellationToken)
+            Return New PredicateSymbolSearcher(Me, filter, predicate, cancellationToken).GetSymbolsWithName()
+        End Function
+
+        Friend Overrides Function GetSymbolsWithName(name As String, Optional filter As SymbolFilter = SymbolFilter.TypeAndMember, Optional cancellationToken As CancellationToken = Nothing) As IEnumerable(Of ISymbol)
+            If name Is Nothing Then
+                Throw New ArgumentNullException(NameOf(name))
+            End If
+
+            If filter = SymbolFilter.None Then
+                Throw New ArgumentException(VBResources.NoNoneSearchCriteria, NameOf(filter))
+            End If
+
+            Return New NameSymbolSearcher(Me, filter, name, cancellationToken).GetSymbolsWithName()
         End Function
 
         Friend Overrides Function IsUnreferencedAssemblyIdentityDiagnosticCode(code As Integer) As Boolean
@@ -2740,34 +2752,50 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
 #End Region
 
-        Private Class SymbolSearcher
+        Private MustInherit Class AbstractSymbolSearcher
+            Private Shared ReadOnly s_cachePool As New ObjectPool(Of Dictionary(Of Declaration, NamespaceOrTypeSymbol))(
+                Function() New Dictionary(Of Declaration, NamespaceOrTypeSymbol)())
 
             Private ReadOnly _cache As Dictionary(Of Declaration, NamespaceOrTypeSymbol)
             Private ReadOnly _compilation As VisualBasicCompilation
+            Private ReadOnly _includeNamespace As Boolean
+            Private ReadOnly _includeType As Boolean
+            Private ReadOnly _includeMember As Boolean
+            Private ReadOnly _cancellationToken As CancellationToken
+
+            Public Sub New(compilation As VisualBasicCompilation, filter As SymbolFilter, cancellationToken As CancellationToken)
+                _cache = s_cachePool.Allocate()
+                _compilation = compilation
 
-            Public Sub New(compilation As VisualBasicCompilation)
-                Me._cache = New Dictionary(Of Declaration, NamespaceOrTypeSymbol)()
-                Me._compilation = compilation
+                _includeNamespace = (filter And SymbolFilter.Namespace) = SymbolFilter.Namespace
+                _includeType = (filter And SymbolFilter.Type) = SymbolFilter.Type
+                _includeMember = (filter And SymbolFilter.Member) = SymbolFilter.Member
+
+                _cancellationToken = cancellationToken
             End Sub
 
-            Public Function GetSymbolsWithName(predicate As Func(Of String, Boolean), filter As SymbolFilter, cancellationToken As CancellationToken) As IEnumerable(Of ISymbol)
+            Protected MustOverride Function Matches(name As String) As Boolean
+            Protected MustOverride Function ShouldCheckTypeForMembers(typeDeclaration As MergedTypeDeclaration) As Boolean
+
+            Public Function GetSymbolsWithName() As IEnumerable(Of ISymbol)
                 Dim result = New HashSet(Of ISymbol)()
-                Dim spine = New List(Of MergedNamespaceOrTypeDeclaration)()
+                Dim spine = ArrayBuilder(Of MergedNamespaceOrTypeDeclaration).GetInstance()
 
-                AppendSymbolsWithName(spine, _compilation.MergedRootDeclaration, predicate, filter, result, cancellationToken)
+                AppendSymbolsWithName(spine, _compilation.MergedRootDeclaration, result)
+
+                spine.Clear()
+
+                _cache.Clear()
+                s_cachePool.Free(_cache)
 
                 Return result
             End Function
 
             Private Sub AppendSymbolsWithName(
-                spine As List(Of MergedNamespaceOrTypeDeclaration), current As MergedNamespaceOrTypeDeclaration, predicate As Func(Of String, Boolean), filter As SymbolFilter, [set] As HashSet(Of ISymbol), cancellationToken As CancellationToken)
-
-                Dim includeNamespace = (filter And SymbolFilter.Namespace) = SymbolFilter.Namespace
-                Dim includeType = (filter And SymbolFilter.Type) = SymbolFilter.Type
-                Dim includeMember = (filter And SymbolFilter.Member) = SymbolFilter.Member
+                spine As ArrayBuilder(Of MergedNamespaceOrTypeDeclaration), current As MergedNamespaceOrTypeDeclaration, [set] As HashSet(Of ISymbol))
 
                 If current.Kind = DeclarationKind.Namespace Then
-                    If includeNamespace AndAlso predicate(current.Name) Then
+                    If _includeNamespace AndAlso Matches(current.Name) Then
                         Dim container = GetSpineSymbol(spine)
                         Dim symbol = GetSymbol(container, current)
                         If symbol IsNot Nothing Then
@@ -2775,7 +2803,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                         End If
                     End If
                 Else
-                    If includeType AndAlso predicate(current.Name) Then
+                    If _includeType AndAlso Matches(current.Name) Then
                         Dim container = GetSpineSymbol(spine)
                         Dim symbol = GetSymbol(container, current)
                         If symbol IsNot Nothing Then
@@ -2783,20 +2811,21 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                         End If
                     End If
 
-                    If includeMember Then
-                        AppendMemberSymbolsWithName(spine, current, predicate, [set], cancellationToken)
+                    If _includeMember Then
+                        Dim typeDeclaration = DirectCast(current, MergedTypeDeclaration)
+                        If ShouldCheckTypeForMembers(typeDeclaration) Then
+                            AppendMemberSymbolsWithName(spine, typeDeclaration, [set])
+                        End If
                     End If
                 End If
 
                 spine.Add(current)
-                For Each child In current.Children.OfType(Of MergedNamespaceOrTypeDeclaration)()
-                    If includeMember OrElse includeType Then
-                        AppendSymbolsWithName(spine, child, predicate, filter, [set], cancellationToken)
-                        Continue For
-                    End If
-
-                    If child.Kind = DeclarationKind.Namespace Then
-                        AppendSymbolsWithName(spine, child, predicate, filter, [set], cancellationToken)
+                For Each child In current.Children
+                    Dim mergedNamespaceOrType = TryCast(child, MergedNamespaceOrTypeDeclaration)
+                    If mergedNamespaceOrType IsNot Nothing Then
+                        If _includeMember OrElse _includeType OrElse child.Kind = DeclarationKind.Namespace Then
+                            AppendSymbolsWithName(spine, mergedNamespaceOrType, [set])
+                        End If
                     End If
                 Next
 
@@ -2804,14 +2833,14 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             End Sub
 
             Private Sub AppendMemberSymbolsWithName(
-                spine As List(Of MergedNamespaceOrTypeDeclaration), current As MergedNamespaceOrTypeDeclaration, predicate As Func(Of String, Boolean), [set] As HashSet(Of ISymbol), cancellationToken As CancellationToken)
+                spine As ArrayBuilder(Of MergedNamespaceOrTypeDeclaration), current As MergedNamespaceOrTypeDeclaration, [set] As HashSet(Of ISymbol))
 
                 spine.Add(current)
 
                 Dim container As NamespaceOrTypeSymbol = Nothing
                 Dim mergedType = DirectCast(current, MergedTypeDeclaration)
                 For Each name In mergedType.MemberNames
-                    If predicate(name) Then
+                    If Matches(name) Then
                         container = If(container, GetSpineSymbol(spine))
                         If container IsNot Nothing Then
                             [set].UnionWith(container.GetMembers(name))
@@ -2822,7 +2851,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 spine.RemoveAt(spine.Count - 1)
             End Sub
 
-            Private Function GetSpineSymbol(spine As List(Of MergedNamespaceOrTypeDeclaration)) As NamespaceOrTypeSymbol
+            Private Function GetSpineSymbol(spine As ArrayBuilder(Of MergedNamespaceOrTypeDeclaration)) As NamespaceOrTypeSymbol
                 If spine.Count = 0 Then
                     Return Nothing
                 End If
@@ -2889,5 +2918,53 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 Next
             End Sub
         End Class
+
+        Private Class PredicateSymbolSearcher
+            Inherits AbstractSymbolSearcher
+
+            Private ReadOnly _predicate As Func(Of String, Boolean)
+
+            Public Sub New(
+                compilation As VisualBasicCompilation, filter As SymbolFilter, predicate As Func(Of String, Boolean), cancellationToken As CancellationToken)
+                MyBase.New(compilation, filter, cancellationToken)
+
+                _predicate = predicate
+            End Sub
+
+            Protected Overrides Function ShouldCheckTypeForMembers(current As MergedTypeDeclaration) As Boolean
+                Return True
+            End Function
+
+            Protected Overrides Function Matches(name As String) As Boolean
+                Return _predicate(name)
+            End Function
+        End Class
+
+        Private Class NameSymbolSearcher
+            Inherits AbstractSymbolSearcher
+
+            Private ReadOnly _name As String
+
+            Public Sub New(
+                compilation As VisualBasicCompilation, filter As SymbolFilter, name As String, cancellationToken As CancellationToken)
+                MyBase.New(compilation, filter, cancellationToken)
+
+                _name = name
+            End Sub
+
+            Protected Overrides Function ShouldCheckTypeForMembers(current As MergedTypeDeclaration) As Boolean
+                For Each typeDecl In current.Declarations
+                    If typeDecl.MemberNames.Contains(_name) Then
+                        Return True
+                    End If
+                Next
+
+                Return False
+            End Function
+
+            Protected Overrides Function Matches(name As String) As Boolean
+                Return IdentifierComparison.Equals(_name, name)
+            End Function
+        End Class
     End Class
 End Namespace