Fix TargetPlatformPresentationReconciler: stop scanning past damage end#2284
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vogella wants to merge 2 commits intoeclipse-pde:masterfrom
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Fix TargetPlatformPresentationReconciler: stop scanning past damage end#2284vogella wants to merge 2 commits intoeclipse-pde:masterfrom
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The reconciler always scanned the full document (offset 0 to document.getLength()) on every keystroke to ensure multi-line XML comment rules are honoured. While scanning from offset 0 is required for correctness, scanning *past* the damage end is wasted work because the returned TextPresentation is bounded by the damage region and silently discards any style ranges beyond it. Change the upper bound of TextUtilities.computePartitioning() from document.getLength() to damage.getOffset() + damage.getLength(). This avoids scanning content whose results would be thrown away, while preserving the full-context scan from offset 0 that multi-line rules require. Add TargetPlatformPresentationReconcilerTest to verify correctness for the common cases: simple documents, partial damage regions, multi-line comments before the damage, and damage inside a multi-line comment. Fixes: eclipse-pde#2283 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
Fixes #2283 (also related to eclipse-platform/eclipse.platform.ui#2276).
TargetPlatformPresentationReconciler.createPresentation()overrides the defaultPresentationReconcilerbehaviour to always scan from offset 0. This isnecessary to correctly handle multi-line XML comment rules (
<!-- ... -->):without the full context from the start of the document, a comment that opened
before the damaged region would not be recognised.
However, the scan was running all the way to
document.getLength()even thoughthe
TextPresentationreturned is constructed with the damage region as itsextent — meaning any style ranges added for content after the damage end are
silently discarded. This results in O(document length) work on the UI thread
for every keystroke, causing noticeable freezes in large
.targetfiles.Changes
TargetPlatformPresentationReconciler— change the upper bound ofTextUtilities.computePartitioning()fromdocument.getLength()todamage.getOffset() + damage.getLength(). Scanning still starts at offset 0(multi-line rule correctness is preserved); it just stops where it would have
discarded results anyway.
MANIFEST.MF(genericeditor.extension) — declareorg.eclipse.pde.genericeditor.extension.testsas a friend of thereconciler.presentationpackage so the new tests can subclass the reconciler.TargetPlatformPresentationReconcilerTest— new test class covering:Known limitation
For edits very close to the end of a large file the gain is small (the damage
end ≈ the document end). A more thorough fix — e.g. caching scanner state
between edits, using a real
IDocumentPartitionerfor comments, or movingreconciliation off the UI thread — is left for a follow-up.
Test plan
mvn clean compileon the two affected bundles)TargetPlatformPresentationReconcilerTestpasses in a running Eclipse test environmentAllTargetEditorTestscontinue to pass🤖 Generated with Claude Code