' Licensed to the .NET Foundation under one or more agreements.
' The .NET Foundation licenses this file to you under the MIT license.
' See the LICENSE file in the project root for more information.
 
Imports System.Collections.Generic
Imports System.Collections.Immutable
Imports System.Diagnostics
Imports System.Linq
Imports System.Threading
Imports Microsoft.CodeAnalysis.Collections
Imports Microsoft.CodeAnalysis.PooledObjects
Imports Microsoft.CodeAnalysis.Text
Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
Namespace Microsoft.CodeAnalysis.VisualBasic
 
    Friend NotInheritable Class StatementListBinder
        Inherits BlockBaseBinder
 
        Private ReadOnly _statementList As SyntaxList(Of StatementSyntax)
        Private _locals As ImmutableArray(Of LocalSymbol) = Nothing
 
        Public Sub New(containing As Binder,
                       statementList As SyntaxList(Of StatementSyntax))
            MyBase.New(containing)
            _statementList = statementList
        End Sub
 
        Friend Overrides ReadOnly Property Locals As ImmutableArray(Of LocalSymbol)
            Get
                If _locals.IsDefault Then
                    ImmutableInterlocked.InterlockedCompareExchange(_locals, BuildLocals(), Nothing)
                End If
 
                Return _locals
            End Get
        End Property
 
        ' Build a read only array of all the local variables declared in this statement list.
        Private Function BuildLocals() As ImmutableArray(Of LocalSymbol)
            Dim locals As ArrayBuilder(Of LocalSymbol) = Nothing
 
            For Each statement In _statementList
                If statement.Kind = SyntaxKind.LocalDeclarationStatement Then
                    If locals Is Nothing Then
                        locals = ArrayBuilder(Of LocalSymbol).GetInstance()
                    End If
 
                    Dim localDeclSyntax = DirectCast(statement, LocalDeclarationStatementSyntax)
 
                    Dim declarationKind As LocalDeclarationKind = LocalDeclarationKind.Variable
 
                    For Each modifier In localDeclSyntax.Modifiers
                        Select Case modifier.Kind
                            Case SyntaxKind.ConstKeyword
                                declarationKind = LocalDeclarationKind.Constant
                                Exit For
 
                            Case SyntaxKind.StaticKeyword
                                declarationKind = LocalDeclarationKind.Static
                        End Select
                    Next
 
                    For Each declarator As VariableDeclaratorSyntax In localDeclSyntax.Declarators
                        Dim asClauseOptSyntax = declarator.AsClause
                        Dim isNotAsNewAndHasInitializer = declarator.Initializer IsNot Nothing AndAlso
                                                      (declarator.AsClause Is Nothing OrElse declarator.AsClause.Kind <> SyntaxKind.AsNewClause)
 
                        Dim names = declarator.Names
                        For i = 0 To names.Count - 1
                            Dim modifiedIdentifier = names(i)
 
                            ' if this is not an AsNew declaration with multiple names and an initializer (error case), then only use
                            ' the initializer for the last variable.
                            Dim localVar = LocalSymbol.Create(Me.ContainingMember, Me,
                                                             modifiedIdentifier.Identifier, modifiedIdentifier, asClauseOptSyntax,
                                                             If(isNotAsNewAndHasInitializer AndAlso i = names.Count - 1,
                                                                declarator.Initializer,
                                                                Nothing),
                                                             declarationKind)
                            locals.Add(localVar)
                        Next
                    Next
                End If
            Next
 
            If locals IsNot Nothing Then
                Return locals.ToImmutableAndFree()
            Else
                Return ImmutableArray(Of LocalSymbol).Empty
            End If
        End Function
    End Class
End Namespace