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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.Collections.Generic;
using System.Threading;
using Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery;
using Microsoft.CodeAnalysis.CSharp.Utilities;
using Microsoft.CodeAnalysis.Shared.Extensions;
namespace Microsoft.CodeAnalysis.CSharp.Completion.KeywordRecommenders;
internal class ExternKeywordRecommender : AbstractSyntacticSingleKeywordRecommender
{
private static readonly ISet<SyntaxKind> s_validModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
{
SyntaxKind.InternalKeyword,
SyntaxKind.NewKeyword,
SyntaxKind.OverrideKeyword,
SyntaxKind.PublicKeyword,
SyntaxKind.PrivateKeyword,
SyntaxKind.ProtectedKeyword,
SyntaxKind.SealedKeyword,
SyntaxKind.StaticKeyword,
SyntaxKind.UnsafeKeyword,
SyntaxKind.VirtualKeyword,
};
private static readonly ISet<SyntaxKind> s_validGlobalModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
{
SyntaxKind.InternalKeyword,
SyntaxKind.NewKeyword,
SyntaxKind.PublicKeyword,
SyntaxKind.PrivateKeyword,
SyntaxKind.StaticKeyword,
SyntaxKind.UnsafeKeyword,
};
private static readonly ISet<SyntaxKind> s_validLocalFunctionModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
{
SyntaxKind.StaticKeyword,
SyntaxKind.UnsafeKeyword
};
public ExternKeywordRecommender()
: base(SyntaxKind.ExternKeyword)
{
}
protected override bool IsValidContext(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
{
var syntaxTree = context.SyntaxTree;
return
IsExternAliasContext(context) ||
(context.IsGlobalStatementContext && syntaxTree.IsScript()) ||
syntaxTree.IsGlobalMemberDeclarationContext(position, s_validGlobalModifiers, cancellationToken) ||
context.IsMemberDeclarationContext(
validModifiers: s_validModifiers,
validTypeDeclarations: SyntaxKindSet.ClassInterfaceStructRecordTypeDeclarations,
canBePartial: false,
cancellationToken: cancellationToken) ||
context.SyntaxTree.IsLocalFunctionDeclarationContext(position, s_validLocalFunctionModifiers, cancellationToken);
}
private static bool IsExternAliasContext(CSharpSyntaxContext context)
{
// cases:
// root: |
// root: e|
// extern alias a;
// |
// extern alias a;
// e|
// all the above, but inside a namespace.
// usings and other constructs *cannot* precede.
var token = context.TargetToken;
// root: |
if (token.Kind() == SyntaxKind.None)
{
// root namespace
return true;
}
if (token.Kind() == SyntaxKind.OpenBraceToken &&
token.Parent.IsKind(SyntaxKind.NamespaceDeclaration))
{
return true;
}
// namespace N;
// |
if (token.Kind() == SyntaxKind.SemicolonToken &&
token.Parent.IsKind(SyntaxKind.FileScopedNamespaceDeclaration))
{
return true;
}
// extern alias a;
// |
if (token.Kind() == SyntaxKind.SemicolonToken &&
token.Parent.IsKind(SyntaxKind.ExternAliasDirective))
{
return true;
}
return false;
}
}
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