IDEA-58070 Soft wrap: Improve soft wraps performance

1. Enforcing soft wraps cache population with entry for lines that contain tabulation symbol;
2. Corrected incremental soft wraps update on fold region collapsing/expanding;

platform/platform-impl/src/com/intellij/openapi/editor/impl/softwrap/mapping/CachingSoftWrapDataMapper.java

@@ -285,7 +285,7 @@ public class CachingSoftWrapDataMapper implements SoftWrapDataMapper, SoftWrapAw
 
   @Override
   public void onTabulation(@NotNull EditorPosition position, int widthInColumns) {
-    CacheEntry cacheEntry = getCacheEntryForVisualLine(position.visualLine, true);
+    CacheEntry cacheEntry = getCacheEntryForVisualLine(position.visualLine, false);
     if (cacheEntry == null) {
       return;
     }
@@ -600,6 +600,7 @@ public class CachingSoftWrapDataMapper implements SoftWrapDataMapper, SoftWrapAw
         CacheEntry cacheEntry = myCache.get(i);
         foldedLines += cacheEntry.endFoldedLines - cacheEntry.startFoldedLines;
       }
+      visualLines -= foldedLines;
 
       if (DEBUG_SOFT_WRAP_PROCESSING) {
         log(String.format("CachingSoftWrapDataMapper$CacheState.updateByDocumentOffsets(). Collected %d fold lines for cache entry indices "

platform/platform-impl/src/com/intellij/openapi/editor/impl/softwrap/mapping/SoftWrapApplianceManager.java

@@ -1004,6 +1004,7 @@ public class SoftWrapApplianceManager implements FoldingListener, DocumentListen
       }
       int widthInColumns = calculateWidthInColumns(c, widthInPixels, myContext.spaceWidth);
       if (c == '\t') {
+        notifyListenersOnVisualLineStart(myContext.lineStartPosition);
         notifyListenersOnTabulation(widthInColumns);
       }
       

platform/platform-impl/testSrc/com/intellij/openapi/editor/impl/softwrap/mapping/SoftWrapApplianceOnDocumentModificationTest.java

@@ -178,7 +178,7 @@ public class SoftWrapApplianceOnDocumentModificationTest extends LightPlatformCo
     // The main idea is to type on a logical line before soft wrap in order to ensure that its offset is correctly shifted back.
     String text = 
       "line1<caret>\n" +
-      "second line that is rather long to be soft wrapped";
+      "second line that is long enough to be soft wrapped";
     init(100, text);
 
     TIntHashSet offsetsBefore = collectSoftWrapStartOffsets(1);
@@ -196,6 +196,30 @@ public class SoftWrapApplianceOnDocumentModificationTest extends LightPlatformCo
     });
   }
   
+  public void testSoftWrapAwareMappingAfterLeadingFoldRegionCollapsing() throws IOException {
+    String text =
+      "line to fold 1\n" +
+      "line to fold 2\n" +
+      "line to fold 3\n" +
+      "ordinary line 1\n" +
+      "ordinary line 2\n" +
+      "ordinary line 3\n" +
+      "ordinary line 4\n" +
+      "line that is long enough to be soft wrapped\n" +
+      "ordinary line 5\n" +
+      "ordinary line 6\n" +
+      "ordinary line 7\n" +
+      "ordinary line 8\n";
+    
+    init(200, text);
+    LogicalPosition position = myEditor.visualToLogicalPosition(new VisualPosition(8, 0));
+    assertSame(7, position.line); // Position from soft-wrapped part of the line
+    
+    addFoldRegion(0, text.indexOf("ordinary line 1") - 1, "...");
+    toggleFoldRegionState(myEditor.getFoldingModel().getAllFoldRegions()[0], false);
+    assertSame(7, myEditor.visualToLogicalPosition(new VisualPosition(6, 0)).line); // Check that soft wraps cache is correctly updated
+  }
+  
   //private void init(final int visibleWidth) throws Exception {
   //  configureByFile(PATH + getFileName());
   //  initCommon(visibleWidth);