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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;
using System.Composition;
using System.Threading;
using Microsoft.CodeAnalysis.BraceCompletion;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
namespace Microsoft.CodeAnalysis.CSharp.BraceCompletion;
/// <summary>
/// Brace completion service used for completing curly braces inside interpolated strings.
/// In other curly brace completion scenarios the <see cref="CurlyBraceCompletionService"/> should be used.
/// </summary>
[ExportBraceCompletionService(LanguageNames.CSharp), Shared]
[method: ImportingConstructor]
[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
internal sealed class InterpolationBraceCompletionService() : AbstractCSharpBraceCompletionService
{
protected override char OpeningBrace => CurlyBrace.OpenCharacter;
protected override char ClosingBrace => CurlyBrace.CloseCharacter;
public override bool AllowOverType(BraceCompletionContext context, CancellationToken cancellationToken)
=> AllowOverTypeWithValidClosingToken(context);
/// <summary>
/// Only return this service as valid when we're typing curly braces inside an interpolated string.
/// Otherwise curly braces should be completed using the <see cref="CurlyBraceCompletionService"/>
/// </summary>
public override bool CanProvideBraceCompletion(char brace, int openingPosition, ParsedDocument document, CancellationToken cancellationToken)
=> OpeningBrace == brace && IsPositionInInterpolationContext(document, openingPosition);
protected override bool IsValidOpenBraceTokenAtPosition(SourceText text, SyntaxToken token, int position)
=> IsValidOpeningBraceToken(token) && token.SpanStart == position;
protected override bool IsValidOpeningBraceToken(SyntaxToken token)
=> token.IsKind(SyntaxKind.OpenBraceToken) && token.Parent.IsKind(SyntaxKind.Interpolation);
protected override bool IsValidClosingBraceToken(SyntaxToken token)
=> token.IsKind(SyntaxKind.CloseBraceToken);
/// <summary>
/// Returns true when the input position could be starting an interpolation expression if a curly brace was typed.
/// </summary>
public static bool IsPositionInInterpolationContext(ParsedDocument document, int position)
{
// First, check to see if the character to the left of the position is an open curly.
// If it is, we shouldn't complete because the user may be trying to escape a curly.
// E.g. they are trying to type $"{{"
if (CouldEscapePreviousOpenBrace('{', position, document.Text))
{
return false;
}
var token = document.Root.FindTokenOnLeftOfPosition(position);
if (!token.Span.IntersectsWith(position))
{
return false;
}
// We can be starting an interpolation expression if we're inside an interpolated string.
return token.Parent.IsKind(SyntaxKind.InterpolatedStringExpression) || token.Parent.IsParentKind(SyntaxKind.InterpolatedStringExpression);
}
}
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