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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.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis.CodeGeneration;
internal abstract partial class AbstractCodeGenerationService<TCodeGenerationContextInfo>
{
protected abstract IList<bool>? GetAvailableInsertionIndices(SyntaxNode destination, CancellationToken cancellationToken);
private IList<bool>? GetAvailableInsertionIndices<TDeclarationNode>(TDeclarationNode destination, CancellationToken cancellationToken) where TDeclarationNode : SyntaxNode
=> GetAvailableInsertionIndices((SyntaxNode)destination, cancellationToken);
public bool CanAddTo(ISymbol destination, Solution solution, CancellationToken cancellationToken)
{
var declarations = _symbolDeclarationService.GetDeclarations(destination);
return declarations.Any(static (r, arg) => arg.self.CanAddTo(r.GetSyntax(arg.cancellationToken), arg.solution, arg.cancellationToken), (self: this, solution, cancellationToken));
}
protected static SyntaxToken GetEndToken(SyntaxNode node)
{
var lastToken = node.GetLastToken(includeZeroWidth: true, includeSkipped: true);
if (lastToken.IsMissing)
{
var nextToken = lastToken.GetNextToken(includeZeroWidth: true, includeSkipped: true);
if (nextToken.RawKind != 0)
{
return nextToken;
}
}
return lastToken;
}
protected static TextSpan GetSpan(SyntaxNode node)
{
var start = node.GetFirstToken();
var end = GetEndToken(node);
return TextSpan.FromBounds(start.SpanStart, end.Span.End);
}
public bool CanAddTo(SyntaxNode destination, Solution solution, CancellationToken cancellationToken)
=> CanAddTo(destination, solution, cancellationToken, out _);
private bool CanAddTo(SyntaxNode? destination, Solution solution, CancellationToken cancellationToken,
out IList<bool>? availableIndices, bool checkGeneratedCode = false)
{
availableIndices = null;
if (destination == null)
{
return false;
}
var syntaxTree = destination.SyntaxTree;
var document = solution.GetDocument(syntaxTree);
if (document == null)
{
return false;
}
// We can never generate into a document from a source generator, because those are immutable
if (document is SourceGeneratedDocument)
{
return false;
}
#if !CODE_STYLE
// If we are avoiding generating into files marked as generated (but are still regular files)
// then check accordingly. This is distinct from the prior check in that we as a fallback
// will generate into these files is we have no alternative.
if (checkGeneratedCode && document.IsGeneratedCode(cancellationToken))
{
return false;
}
#endif
// Anything completely hidden is something you can't add to. Anything completely visible
// is something you can add to. Anything that is partially hidden will have to defer to
// the underlying language to make a determination.
var span = GetSpan(destination);
if (syntaxTree.IsEntirelyHidden(span, cancellationToken))
{
// It's entirely hidden, there's no place to generate inside of this.
return false;
}
var overlapsHiddenRegion = syntaxTree.OverlapsHiddenPosition(span, cancellationToken);
if (cancellationToken.IsCancellationRequested)
{
return false;
}
if (!overlapsHiddenRegion)
{
// Totally safe to add to this node.
return true;
}
// Part of this node overlaps a hidden region. We have to defer to the specific language
// to see if there's anywhere we can generate into here.
availableIndices = GetAvailableInsertionIndices(destination, cancellationToken);
return availableIndices != null && availableIndices.Any(b => b);
}
/// <summary>
/// Return the most relevant declaration to namespaceOrType,
/// it will first search the context node contained within,
/// then the declaration in the same file, then non auto-generated file,
/// then all the potential location. Return null if no declaration.
/// </summary>
public async Task<SyntaxNode?> FindMostRelevantNameSpaceOrTypeDeclarationAsync(
Solution solution,
INamespaceOrTypeSymbol namespaceOrType,
Location? location,
CancellationToken cancellationToken)
{
var (declaration, _) = await FindMostRelevantDeclarationAsync(solution, namespaceOrType, location, cancellationToken).ConfigureAwait(false);
return declaration;
}
private async Task<(SyntaxNode? declaration, IList<bool>? availableIndices)> FindMostRelevantDeclarationAsync(
Solution solution,
INamespaceOrTypeSymbol namespaceOrType,
Location? location,
CancellationToken cancellationToken)
{
var declaration = (SyntaxNode?)null;
IList<bool>? availableIndices = null;
var symbol = namespaceOrType;
var declarations = _symbolDeclarationService.GetDeclarations(symbol);
var fallbackDeclaration = (SyntaxNode?)null;
if (location != null && location.IsInSource)
{
var token = location.FindToken(cancellationToken);
// Prefer a declaration that the context node is contained within.
//
// Note: This behavior is slightly suboptimal in some cases. For example, when the
// user has the pattern:
//
// C.cs
//
// partial class C
// {
// // Stuff.
// }
//
// C.NestedType.cs
//
// partial class C
// {
// class NestedType
// {
// // Context location.
// }
// }
//
// If we're at the specified context location, but we're trying to find the most
// relevant part for C, then we want to pick the part in C.cs not the one in
// C.NestedType.cs that contains the context location. This is because this
// container isn't really used by the user to place code, but is instead just
// used to separate out the nested type. It would be nice to detect this and do the
// right thing.
declaration = await SelectFirstOrDefaultAsync(declarations, token.GetRequiredParent().AncestorsAndSelf().Contains, cancellationToken).ConfigureAwait(false);
fallbackDeclaration = declaration;
if (CanAddTo(declaration, solution, cancellationToken, out availableIndices))
{
return (declaration, availableIndices);
}
// Then, prefer a declaration from the same file.
declaration = await SelectFirstOrDefaultAsync(declarations.Where(r => r.SyntaxTree == location.SourceTree), node => true, cancellationToken).ConfigureAwait(false);
fallbackDeclaration ??= declaration;
if (CanAddTo(declaration, solution, cancellationToken, out availableIndices))
{
return (declaration, availableIndices);
}
}
// If there is a declaration in a non auto-generated file, prefer it.
foreach (var decl in declarations)
{
declaration = await decl.GetSyntaxAsync(cancellationToken).ConfigureAwait(false);
if (CanAddTo(declaration, solution, cancellationToken, out availableIndices, checkGeneratedCode: true))
{
return (declaration, availableIndices);
}
}
// Generate into any declaration we can find.
availableIndices = null;
declaration = fallbackDeclaration ?? await SelectFirstOrDefaultAsync(declarations, node => true, cancellationToken).ConfigureAwait(false);
return (declaration, availableIndices);
}
private static async Task<SyntaxNode?> SelectFirstOrDefaultAsync(IEnumerable<SyntaxReference> references, Func<SyntaxNode, bool> predicate, CancellationToken cancellationToken)
{
foreach (var r in references)
{
var node = await r.GetSyntaxAsync(cancellationToken).ConfigureAwait(false);
if (predicate(node))
{
return node;
}
}
return null;
}
}
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