[vcs changes formatting] merge changed text ranges, in order to boost performance [IDEA-173139]

platform/core-api/src/com/intellij/psi/codeStyle/ChangedRangesInfo.java

@@ -15,7 +15,9 @@
  */
 package com.intellij.psi.codeStyle;
 
+import com.intellij.openapi.util.Segment;
 import com.intellij.openapi.util.TextRange;
+import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -23,12 +25,38 @@ import java.util.List;
 
 public class ChangedRangesInfo {
 
-  public final List<TextRange> insertedRanges;
-  public final List<TextRange> allChangedRanges;
+  private final List<TextRange> insertedRanges;
+  private final List<TextRange> allChangedRanges;
 
   public ChangedRangesInfo(@NotNull List<TextRange> allChangedRanges, @Nullable List<TextRange> insertedRanges) {
     this.insertedRanges = insertedRanges;
     this.allChangedRanges = allChangedRanges;
   }
+
+  public List<TextRange> insertedRanges() {
+    return insertedRanges;
+  }
+
+  public List<TextRange> optimizedChangedRanges() {
+    if (allChangedRanges.isEmpty()) return allChangedRanges;
+    allChangedRanges.sort(Segment.BY_START_OFFSET_THEN_END_OFFSET);
+
+    List<TextRange> result = ContainerUtil.newSmartList();
+
+    TextRange prev = allChangedRanges.get(0);
+    for (TextRange next : allChangedRanges) {
+      if (next.getStartOffset() <= prev.getEndOffset() + 5) {
+        int newEndOffset = Math.max(prev.getEndOffset(), next.getEndOffset());
+        prev = new TextRange(prev.getStartOffset(), newEndOffset);
+      }
+      else {
+        result.add(prev);
+        prev = next;
+      }
+    }
+    result.add(prev);
+
+    return result;
+  }
   
 }

platform/lang-impl/src/com/intellij/formatting/FormatTextRanges.java

@@ -39,8 +39,8 @@ public class FormatTextRanges implements FormattingRangesInfo {
   }
   
   public FormatTextRanges(@NotNull ChangedRangesInfo changedRangesInfo) {
-    changedRangesInfo.allChangedRanges.forEach((range) -> add(range, true));
-    myInsertedRanges = changedRangesInfo.insertedRanges;
+    changedRangesInfo.optimizedChangedRanges().forEach((range) -> add(range, true));
+    myInsertedRanges = changedRangesInfo.insertedRanges();
   }
 
   public void add(TextRange range, boolean processHeadingWhitespace) {

platform/platform-tests/testSrc/com/intellij/codeInsight/actions/MockCodeStyleManager.java

@@ -75,7 +75,7 @@ public class MockCodeStyleManager extends CodeStyleManager {
   @Override
   public void reformatTextWithContext(@NotNull PsiFile file, 
                                       @NotNull ChangedRangesInfo ranges) throws IncorrectOperationException {
-    reformatText(file, ranges.allChangedRanges);
+    reformatText(file, ranges.optimizedChangedRanges());
   }
 
   @NotNull

platform/vcs-impl/src/com/intellij/codeInsight/actions/VcsAwareFormatChangedTextUtil.java

@@ -48,7 +48,7 @@ class VcsAwareFormatChangedTextUtil extends FormatChangedTextUtil {
   @NotNull
   public List<TextRange> getChangedTextRanges(@NotNull Project project, @NotNull PsiFile file) throws FilesTooBigForDiffException {
     ChangedRangesInfo helper = getChangedRangesInfo(file);
-    return helper != null ? helper.allChangedRanges : ContainerUtil.newArrayList();
+    return helper != null ? helper.optimizedChangedRanges() : ContainerUtil.newArrayList();
   }
 
   @Override