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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.
#nullable disable
using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Debugging;
using Microsoft.CodeAnalysis.ErrorReporting;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
namespace Microsoft.CodeAnalysis.CSharp.Debugging;
internal static class DataTipInfoGetter
{
internal static async Task<DebugDataTipInfo> GetInfoAsync(Document document, int position, CancellationToken cancellationToken)
{
try
{
var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
if (root == null)
{
return default;
}
var token = root.FindToken(position);
if (token.Parent is not ExpressionSyntax expression)
{
return token.IsKind(SyntaxKind.IdentifierToken)
? new DebugDataTipInfo(token.Span, text: null)
: default;
}
if (expression is LiteralExpressionSyntax)
{
// If the user hovers over a literal, give them a DataTip for the type of the
// literal they're hovering over.
// Partial semantics should always be sufficient because the (unconverted) type
// of a literal can always easily be determined.
var (_, semanticModel) = await document.GetFullOrPartialSemanticModelAsync(cancellationToken).ConfigureAwait(false);
var type = semanticModel.GetTypeInfo(expression, cancellationToken).Type;
return type == null
? default
: new DebugDataTipInfo(expression.Span, type.ToNameDisplayString());
}
if (expression.IsRightSideOfDotOrArrow())
{
var curr = expression.GetRootConditionalAccessExpression() ?? expression;
if (curr == expression)
{
// NB: Parent.Span, not Span as below.
return new DebugDataTipInfo(expression.Parent.Span, text: null);
}
// NOTE: There may not be an ExpressionSyntax corresponding to the range we want.
// For example, for input a?.$$B?.C, we want span [|a?.B|]?.C.
return new DebugDataTipInfo(TextSpan.FromBounds(curr.SpanStart, expression.Span.End), text: null);
}
// NOTE(cyrusn): This behavior is to mimic what we did in Dev10, I'm not sure if it's
// necessary or not.
if (expression is InvocationExpressionSyntax invocation)
{
expression = invocation.Expression;
}
string textOpt = null;
if (expression is TypeSyntax typeSyntax && typeSyntax.IsVar)
{
// If the user is hovering over 'var', then pass back the full type name that 'var'
// binds to.
var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
var type = semanticModel.GetTypeInfo(typeSyntax, cancellationToken).Type;
if (type != null)
{
textOpt = type.ToNameDisplayString();
}
}
return new DebugDataTipInfo(expression.Span, textOpt);
}
catch (Exception e) when (FatalError.ReportAndCatchUnlessCanceled(e, cancellationToken))
{
return default;
}
}
}
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