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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.Immutable;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis;
using DocumentAndHashBuilder = ArrayBuilder<(Document newDocument, ImmutableArray<byte> newContentHash)>;
internal sealed class LinkedFileDiffMergingSession(Solution oldSolution, Solution newSolution, SolutionChanges solutionChanges)
{
internal async Task<LinkedFileMergeSessionResult> MergeDiffsAsync(IMergeConflictHandler? mergeConflictHandler, CancellationToken cancellationToken)
{
using var _1 = PooledDictionary<string, DocumentAndHashBuilder>.GetInstance(out var filePathToNewDocumentsAndHashes);
try
{
foreach (var documentId in solutionChanges.GetProjectChanges().SelectMany(p => p.GetChangedDocuments()))
{
// Don't need to do any merging whatsoever for documents that are not linked files.
var newDocument = newSolution.GetRequiredDocument(documentId);
var relatedDocumentIds = newSolution.GetRelatedDocumentIds(newDocument.Id);
if (relatedDocumentIds.Length == 1)
continue;
var filePath = newDocument.FilePath;
Contract.ThrowIfNull(filePath);
var newDocumentsAndHashes = filePathToNewDocumentsAndHashes.GetOrAdd(filePath, static (_, capacity) => DocumentAndHashBuilder.GetInstance(capacity), relatedDocumentIds.Length);
var newText = await newDocument.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
var newContentHash = newText.GetContentHash();
// Ignore any linked documents that we have the same contents as.
if (newDocumentsAndHashes.Any(t => t.newContentHash.SequenceEqual(newContentHash)))
continue;
newDocumentsAndHashes.Add((newDocument, newContentHash));
}
var updatedSolution = newSolution;
using var _ = ArrayBuilder<LinkedFileMergeResult>.GetInstance(
filePathToNewDocumentsAndHashes.Count(static kvp => kvp.Value.Count > 1),
out var linkedFileMergeResults);
foreach (var (filePath, newDocumentsAndHashes) in filePathToNewDocumentsAndHashes)
{
Contract.ThrowIfTrue(newDocumentsAndHashes.Count == 0);
// Don't need to do anything if this document has no linked siblings.
var firstNewDocument = newDocumentsAndHashes[0].newDocument;
var relatedDocuments = newSolution.GetRelatedDocumentIds(firstNewDocument.Id);
Contract.ThrowIfTrue(relatedDocuments.Length == 1, "We should have skipped non-linked files in the prior loop.");
if (newDocumentsAndHashes.Count == 1)
{
// The file has linked siblings, but we collapsed down to only one actual document change. Ensure that
// any linked files have that same content as well.
var firstSourceText = await firstNewDocument.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
updatedSolution = updatedSolution.WithDocumentTexts(
relatedDocuments.SelectAsArray(d => (d, firstSourceText)));
}
else
{
// Otherwise, merge the changes and set all the linked files to that merged content.
var mergeGroupResult = await MergeLinkedDocumentGroupAsync(newDocumentsAndHashes, mergeConflictHandler, cancellationToken).ConfigureAwait(false);
linkedFileMergeResults.Add(mergeGroupResult);
updatedSolution = updatedSolution.WithDocumentTexts(
relatedDocuments.SelectAsArray(d => (d, mergeGroupResult.MergedSourceText)));
}
}
return new LinkedFileMergeSessionResult(updatedSolution, linkedFileMergeResults);
}
finally
{
foreach (var (_, newDocumentsAndHashes) in filePathToNewDocumentsAndHashes)
newDocumentsAndHashes.Free();
}
}
private async Task<LinkedFileMergeResult> MergeLinkedDocumentGroupAsync(
DocumentAndHashBuilder newDocumentsAndHashes,
IMergeConflictHandler? mergeConflictHandler,
CancellationToken cancellationToken)
{
Contract.ThrowIfTrue(newDocumentsAndHashes.Count < 2);
// Automatically merge non-conflicting diffs while collecting the conflicting diffs
var textDifferencingService = oldSolution.Services.GetRequiredService<IDocumentTextDifferencingService>();
var firstNewDocument = newDocumentsAndHashes[0].newDocument;
var firstOldDocument = oldSolution.GetRequiredDocument(firstNewDocument.Id);
var firstOldSourceText = await firstOldDocument.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
var allTextChangesAcrossLinkedFiles = await textDifferencingService.GetTextChangesAsync(
firstOldDocument, firstNewDocument, TextDifferenceTypes.Line, cancellationToken).ConfigureAwait(false);
using var _ = ArrayBuilder<UnmergedDocumentChanges>.GetInstance(out var unmergedChanges);
for (int i = 1, n = newDocumentsAndHashes.Count; i < n; i++)
{
var siblingNewDocument = newDocumentsAndHashes[i].newDocument;
var siblingOldDocument = oldSolution.GetRequiredDocument(siblingNewDocument.Id);
allTextChangesAcrossLinkedFiles = await AddDocumentMergeChangesAsync(
siblingOldDocument,
siblingNewDocument,
allTextChangesAcrossLinkedFiles,
unmergedChanges,
textDifferencingService,
cancellationToken).ConfigureAwait(false);
}
var linkedDocuments = oldSolution.GetRelatedDocumentIds(firstOldDocument.Id);
if (unmergedChanges.Count == 0)
return new LinkedFileMergeResult(linkedDocuments, firstOldSourceText.WithChanges(allTextChangesAcrossLinkedFiles), []);
mergeConflictHandler ??= firstOldDocument.GetRequiredLanguageService<ILinkedFileMergeConflictCommentAdditionService>();
var mergeConflictTextEdits = mergeConflictHandler.CreateEdits(firstOldSourceText, unmergedChanges);
// Add comments in source explaining diffs that could not be merged
var (allChanges, mergeConflictResolutionSpans) = MergeChangesWithMergeFailComments(allTextChangesAcrossLinkedFiles, mergeConflictTextEdits);
return new LinkedFileMergeResult(linkedDocuments, firstOldSourceText.WithChanges(allChanges), mergeConflictResolutionSpans);
}
private static async Task<ImmutableArray<TextChange>> AddDocumentMergeChangesAsync(
Document oldDocument,
Document newDocument,
ImmutableArray<TextChange> cumulativeChanges,
ArrayBuilder<UnmergedDocumentChanges> unmergedChanges,
IDocumentTextDifferencingService textDiffService,
CancellationToken cancellationToken)
{
using var _1 = ArrayBuilder<TextChange>.GetInstance(out var unmergedDocumentChanges);
using var _2 = ArrayBuilder<TextChange>.GetInstance(out var successfullyMergedChanges);
var cumulativeChangeIndex = 0;
var textChanges = await textDiffService.GetTextChangesAsync(
oldDocument, newDocument, TextDifferenceTypes.Line, cancellationToken).ConfigureAwait(false);
foreach (var change in textChanges)
{
while (cumulativeChangeIndex < cumulativeChanges.Length && cumulativeChanges[cumulativeChangeIndex].Span.End < change.Span.Start)
{
// Existing change that does not overlap with the current change in consideration
successfullyMergedChanges.Add(cumulativeChanges[cumulativeChangeIndex]);
cumulativeChangeIndex++;
}
if (cumulativeChangeIndex < cumulativeChanges.Length)
{
var cumulativeChange = cumulativeChanges[cumulativeChangeIndex];
if (!cumulativeChange.Span.IntersectsWith(change.Span))
{
// The current change in consideration does not intersect with any existing change
successfullyMergedChanges.Add(change);
}
else
{
if (change.Span != cumulativeChange.Span || change.NewText != cumulativeChange.NewText)
{
// The current change in consideration overlaps an existing change but
// the changes are not identical.
unmergedDocumentChanges.Add(change);
}
else
{
// The current change in consideration is identical to an existing change
successfullyMergedChanges.Add(change);
cumulativeChangeIndex++;
}
}
}
else
{
// The current change in consideration does not intersect with any existing change
successfullyMergedChanges.Add(change);
}
}
while (cumulativeChangeIndex < cumulativeChanges.Length)
{
// Existing change that does not overlap with the current change in consideration
successfullyMergedChanges.Add(cumulativeChanges[cumulativeChangeIndex]);
cumulativeChangeIndex++;
}
if (unmergedDocumentChanges.Count != 0)
{
unmergedChanges.Add(new UnmergedDocumentChanges(
unmergedDocumentChanges.ToImmutableAndClear(),
oldDocument.Project.Name,
oldDocument.Id));
}
return successfullyMergedChanges.ToImmutableAndClear();
}
private static (ImmutableArray<TextChange> mergeChanges, ImmutableArray<TextSpan> mergeConflictResolutionSpans) MergeChangesWithMergeFailComments(
ImmutableArray<TextChange> mergedChanges,
ImmutableArray<TextChange> commentChanges)
{
var mergedChangesList = NormalizeChanges(mergedChanges);
var commentChangesList = NormalizeChanges(commentChanges);
using var _1 = ArrayBuilder<TextChange>.GetInstance(out var combinedChanges);
using var _2 = ArrayBuilder<TextSpan>.GetInstance(out var mergeConflictResolutionSpans);
var insertedMergeConflictCommentsAtAdjustedLocation = 0;
var commentChangeIndex = 0;
var currentPositionDelta = 0;
foreach (var mergedChange in mergedChangesList)
{
while (commentChangeIndex < commentChangesList.Length && commentChangesList[commentChangeIndex].Span.End <= mergedChange.Span.Start)
{
// Add a comment change that does not conflict with any merge change
combinedChanges.Add(commentChangesList[commentChangeIndex]);
mergeConflictResolutionSpans.Add(new TextSpan(commentChangesList[commentChangeIndex].Span.Start + currentPositionDelta, commentChangesList[commentChangeIndex].NewText!.Length));
currentPositionDelta += commentChangesList[commentChangeIndex].NewText!.Length - commentChangesList[commentChangeIndex].Span.Length;
commentChangeIndex++;
}
if (commentChangeIndex >= commentChangesList.Length || mergedChange.Span.End <= commentChangesList[commentChangeIndex].Span.Start)
{
// Add a merge change that does not conflict with any comment change
combinedChanges.Add(mergedChange);
currentPositionDelta += mergedChange.NewText!.Length - mergedChange.Span.Length;
continue;
}
// The current comment insertion location conflicts with a merge diff location. Add the comment before the diff.
var conflictingCommentInsertionLocation = new TextSpan(mergedChange.Span.Start, 0);
while (commentChangeIndex < commentChangesList.Length && commentChangesList[commentChangeIndex].Span.Start < mergedChange.Span.End)
{
combinedChanges.Add(new TextChange(conflictingCommentInsertionLocation, commentChangesList[commentChangeIndex].NewText!));
mergeConflictResolutionSpans.Add(new TextSpan(commentChangesList[commentChangeIndex].Span.Start + currentPositionDelta, commentChangesList[commentChangeIndex].NewText!.Length));
currentPositionDelta += commentChangesList[commentChangeIndex].NewText!.Length;
commentChangeIndex++;
insertedMergeConflictCommentsAtAdjustedLocation++;
}
combinedChanges.Add(mergedChange);
currentPositionDelta += mergedChange.NewText!.Length - mergedChange.Span.Length;
}
while (commentChangeIndex < commentChangesList.Length)
{
// Add a comment change that does not conflict with any merge change
combinedChanges.Add(commentChangesList[commentChangeIndex]);
mergeConflictResolutionSpans.Add(new TextSpan(commentChangesList[commentChangeIndex].Span.Start + currentPositionDelta, commentChangesList[commentChangeIndex].NewText!.Length));
currentPositionDelta += commentChangesList[commentChangeIndex].NewText!.Length - commentChangesList[commentChangeIndex].Span.Length;
commentChangeIndex++;
}
return (NormalizeChanges(combinedChanges.ToImmutableAndClear()), mergeConflictResolutionSpans.ToImmutableAndClear());
}
private static ImmutableArray<TextChange> NormalizeChanges(ImmutableArray<TextChange> changes)
{
if (changes.Length <= 1)
return changes;
var orderedChanges = changes.Sort(static (c1, c2) => c1.Span.Start - c2.Span.Start);
using var _ = ArrayBuilder<TextChange>.GetInstance(changes.Length, out var normalizedChanges);
var currentChange = changes[0];
foreach (var nextChange in changes.AsSpan()[1..])
{
if (nextChange.Span.Start == currentChange.Span.End)
{
currentChange = new TextChange(TextSpan.FromBounds(currentChange.Span.Start, nextChange.Span.End), currentChange.NewText + nextChange.NewText);
}
else
{
normalizedChanges.Add(currentChange);
currentChange = nextChange;
}
}
normalizedChanges.Add(currentChange);
// If we didn't merge anything, can just return the original ordered changes.
if (normalizedChanges.Count == orderedChanges.Length)
return orderedChanges;
return normalizedChanges.ToImmutableAndClear();
}
}
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