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// 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.
using System.Threading;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Shared.Extensions;
namespace Microsoft.CodeAnalysis.CSharp.Completion.KeywordRecommenders;
internal class NamespaceKeywordRecommender : AbstractSyntacticSingleKeywordRecommender
{
public NamespaceKeywordRecommender()
: base(SyntaxKind.NamespaceKeyword)
{
}
protected override bool IsValidContext(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
{
var syntaxTree = context.SyntaxTree;
// namespaces are illegal in interactive code:
if (syntaxTree.IsScript())
{
return false;
}
// cases:
// root: |
// root: n|
// extern alias a;
// |
// extern alias a;
// n|
// using Goo;
// |
// using Goo;
// n|
// using Goo = Bar;
// |
// using Goo = Bar;
// n|
// namespace N {}
// |
// namespace N {}
// n|
// class C {}
// |
// class C {}
// n|
var leftToken = context.LeftToken;
var token = context.TargetToken;
// root: n|
// ns Goo { n|
// extern alias a;
// n|
// using Goo;
// n|
// using Goo = Bar;
// n|
// a namespace can't come before usings/externs
// a child namespace can't come before usings/externs
var nextToken = leftToken.GetNextToken(includeSkipped: true);
if (nextToken.IsUsingOrExternKeyword() ||
(nextToken.Kind() == SyntaxKind.GlobalKeyword && nextToken.GetAncestor<UsingDirectiveSyntax>()?.GlobalKeyword == nextToken))
{
return false;
}
// root: |
if (token.Kind() == SyntaxKind.None)
{
// root namespace
var root = (CompilationUnitSyntax)syntaxTree.GetRoot(cancellationToken);
if (root.Externs.Count > 0 ||
root.Usings.Count > 0)
{
return false;
}
return true;
}
if (token.Kind() == SyntaxKind.OpenBraceToken &&
token.Parent.IsKind(SyntaxKind.NamespaceDeclaration))
{
return true;
}
// extern alias a;
// |
// using Goo;
// |
if (token.Kind() == SyntaxKind.SemicolonToken)
{
if (token.Parent is (kind: SyntaxKind.ExternAliasDirective or SyntaxKind.UsingDirective) &&
!token.Parent.Parent.IsKind(SyntaxKind.FileScopedNamespaceDeclaration))
{
return true;
}
}
// class C {}
// |
if (token.Kind() == SyntaxKind.CloseBraceToken)
{
if (token.Parent is TypeDeclarationSyntax &&
token.Parent.Parent is not TypeDeclarationSyntax)
{
return true;
}
else if (token.Parent.IsKind(SyntaxKind.NamespaceDeclaration))
{
return true;
}
}
// delegate void D();
// |
if (token.Kind() == SyntaxKind.SemicolonToken)
{
if (token.Parent.IsKind(SyntaxKind.DelegateDeclaration) &&
token.Parent.Parent is not TypeDeclarationSyntax)
{
return true;
}
}
// [assembly: goo]
// |
if (token.Kind() == SyntaxKind.CloseBracketToken &&
token.Parent.IsKind(SyntaxKind.AttributeList) &&
token.Parent.IsParentKind(SyntaxKind.CompilationUnit))
{
return true;
}
return false;
}
}
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