Fix FoldableBlock.joinIntersecting(), fix newline handling after a se…

…rvice comment, export TextEditingValue.typed, add TextEditingValue.select (#136)

lib/src/code/code.dart

@@ -246,13 +246,19 @@ class Code {
     }
     final lastLine = section.lastLine;
     if (lastLine != null && lastLine < lines.lines.length - 1) {
-      result['ending'] = HiddenRange(
-        lines.lines[lastLine].textRange.end,
-        lines.lines.last.textRange.end,
-        firstLine: lastLine,
-        lastLine: lines.lines.length - 1,
-        wholeFirstLine: false,
-      );
+      final start = lines.lines[lastLine].textRange.end;
+      final end = lines.lines.last.textRange.end;
+
+      // Can be equal if the last line has no \n.
+      if (end > start) {
+        result['ending'] = HiddenRange(
+          start,
+          end,
+          firstLine: lastLine,
+          lastLine: lines.lines.length - 1,
+          wholeFirstLine: false,
+        );
+      }
     }
     return result;
   }

lib/src/code_field/text_editing_value.dart

@@ -152,4 +152,39 @@ extension TextEditingValueExtension on TextEditingValue {
     }
     return text.substring(selection.end);
   }
+
+  TextEditingValue typed(String text) {
+    final lengthDiff = text.length - selected.length;
+
+    return replaced(selection, text).copyWith(
+      selection: TextSelection.collapsed(offset: selection.end + lengthDiff),
+    );
+  }
+
+  TextEditingValue? select(Pattern pattern, [int start = 0]) {
+    if (pattern == '') {
+      throw AssertionError('Cannot search for an empty pattern');
+    }
+
+    final position = text.indexOf(pattern, start);
+
+    if (position == -1) {
+      return null;
+    }
+
+    final match = pattern.matchAsPrefix(text, position);
+
+    if (match == null) {
+      throw AssertionError('');
+    }
+
+    return TextEditingValue(
+      composing: composing,
+      selection: TextSelection(
+        baseOffset: position,
+        extentOffset: match.end,
+      ),
+      text: text,
+    );
+  }
 }

lib/src/folding/foldable_block.dart

@@ -55,38 +55,102 @@ class FoldableBlock extends InclusiveRange with EquatableMixin {
 
     return false;
   }
+
+  bool isSameLines(FoldableBlock other) {
+    return firstLine == other.firstLine && lastLine == other.lastLine;
+  }
+
+  FoldableBlock join(FoldableBlock other) {
+    return FoldableBlock(
+      firstLine: min(firstLine, other.firstLine),
+      lastLine: max(lastLine, other.lastLine),
+      type: _getJoinType(this, other),
+    );
+  }
+
+  static FoldableBlockType _getJoinType(FoldableBlock a, FoldableBlock b) {
+    if (a.type == FoldableBlockType.imports) {
+      return FoldableBlockType.imports;
+    }
+
+    if (b.type == FoldableBlockType.imports) {
+      return FoldableBlockType.imports;
+    }
+
+    return FoldableBlockType.union;
+  }
 }
 
 extension FoldableBlockList on List<FoldableBlock> {
   void sortByStartLine() {
     sort((a, b) => a.firstLine - b.firstLine);
   }
 
-  /// Joins intersecting blocks in list.
-  /// Expected that list is sorted by start line.
+  /// Joins intersecting blocks.
+  ///
+  /// This list must be sorted by firstLine.
   void joinIntersecting() {
     if (length < 2) {
       return;
     }
 
-    for (int i = 1; i < length; i++) {
-      final currentBlock = this[i];
-      final previousBlock = this[i - 1];
-
-      final areIntersected = previousBlock.lastLine >= currentBlock.firstLine &&
-          previousBlock.lastLine < currentBlock.lastLine;
-
-      final isDuplicate = previousBlock.firstLine == currentBlock.firstLine &&
-          previousBlock.lastLine == currentBlock.lastLine;
-
-      if (areIntersected || isDuplicate) {
-        this[i - 1] = FoldableBlock(
-          firstLine: previousBlock.firstLine,
-          lastLine: currentBlock.lastLine,
-          type: FoldableBlockType.union,
-        );
-        removeAt(i);
-        i = max(i - 2, 0);
+    // A working list to lay down blocks to compare.
+    // As we iterate blocks, it will contain the current nesting hierarchy.
+    final ancestors = <FoldableBlock>[];
+    final ancestorIndexToOverallIndex = <int>[];
+
+    for (int overallIndex = 0; overallIndex < length; overallIndex++) {
+      FoldableBlock bubble = this[overallIndex];
+
+      // Throw the block into the current nesting hierarchy...
+      ancestors.add(bubble);
+      ancestorIndexToOverallIndex.add(overallIndex);
+
+      int bubbleIndexInAncestors = ancestors.length - 1;
+      int bubbleOverallIndex = overallIndex;
+
+      // And fix every violation of the hierarchy by bubbling the block up,
+      // removing non-ancestors from the working list, and joining when needed.
+      for (int ancestorIndex = ancestors.length - 1; --ancestorIndex >= 0;) {
+        final ancestor = ancestors[ancestorIndex];
+
+        if (ancestor.lastLine < bubble.firstLine) {
+          // `bubble` is not nested in `ancestor`.
+          // Remove `ancestor` from the working list and try the upper one.
+          ancestors.removeAt(ancestorIndex);
+          ancestorIndexToOverallIndex.removeAt(ancestorIndex);
+          bubbleIndexInAncestors--;
+          continue;
+        }
+
+        final isDuplicate = bubble.isSameLines(ancestor);
+
+        final areIntersecting = ancestor.lastLine >= bubble.firstLine &&
+            ancestor.lastLine < bubble.lastLine;
+
+        if (isDuplicate || areIntersecting) {
+          final joined = ancestor.join(bubble);
+
+          this[ancestorIndexToOverallIndex[ancestorIndex]] = joined;
+          ancestors[ancestorIndex] = joined;
+
+          removeAt(bubbleOverallIndex);
+          ancestors.removeAt(bubbleIndexInAncestors);
+          ancestorIndexToOverallIndex.removeAt(bubbleIndexInAncestors);
+          overallIndex--;
+
+          if (!areIntersecting) {
+            // `bubble` was a duplicate lines-wise.
+            // Do not go up the hierarchy because it is laid down alright there.
+            break; // to the top level, try the next block.
+          }
+
+          // Continue bubbling up the new joined block
+          // because it may still violate the hierarchy above.
+          bubbleIndexInAncestors = ancestorIndex;
+          bubbleOverallIndex = ancestorIndexToOverallIndex[ancestorIndex];
+          bubble = ancestors[bubbleIndexInAncestors];
+        }
       }
     }
   }

test/src/code_field/code_controller_visible_sections_test.dart

@@ -7,13 +7,17 @@ import 'package:highlight/languages/dart.dart';
 
 import '../common/create_app.dart';
 
+//                                    separate      separate      separate      trailing      trailing      trailing      no          no
+//                                    start         start         start         start         start         start         start       start
+//                                    no            separate      trailing      no            separate      trailing      trailing    separate
+//                                    end           end           end           end           end           end           end         end
 const _fullText = '''
-class MyClass {//    0 [START whole]
-  //                 1 [START separate_start_no_end][START separate_start_separate_end][START separate_start_trailing_end]
-  void method() {//  2 [START trailing_start_no_end][START trailing_start_separate_end][START trailing_start_trailing_end]
-  }//                3 [END separate_start_trailing_end][END trailing_start_trailing_end][END no_start_trailing_end]
-  //                 4 [END separate_start_separate_end][END trailing_start_separate_end][END no_start_separate_end]
-}//                  5 [END whole]''';
+class MyClass {//    0 [START whole]                                                                                      |           |
+  //                 1 |              [START ss_ne] [START ss_se] [START ss_te]                                           |           |
+  void method() {//  2 |              |             |             |             [START ts_ne] [START ts_se] [START ts_te] |           |
+  }//                3 |              |             |             [END ss_te]   |             |             [END ts_te]   [END ns_te] |
+  //                 4 |              |             [END ss_se]                 |             [END ts_se]                             [END ns_se]
+}//                  5 [END whole]    |                                         |''';
 
 const _fullVisibleText = '''
 class MyClass {
@@ -53,7 +57,7 @@ void main() {
     });
 
     test('Separate start no end', () {
-      final controller = createTestController({'separate_start_no_end'});
+      final controller = createTestController({'ss_ne'});
 
       expect(controller.value.text, '''
   
@@ -67,7 +71,7 @@ $_method
     });
 
     test('Separate start separate end', () {
-      final controller = createTestController({'separate_start_separate_end'});
+      final controller = createTestController({'ss_se'});
 
       expect(controller.value.text, '''
   
@@ -81,7 +85,7 @@ $_method
     });
 
     test('Separate start trailing end', () {
-      final controller = createTestController({'separate_start_trailing_end'});
+      final controller = createTestController({'ss_te'});
 
       expect(controller.value.text, '''
   
@@ -94,7 +98,7 @@ $_method
     });
 
     test('Trailing start no end', () {
-      final controller = createTestController({'trailing_start_no_end'});
+      final controller = createTestController({'ts_ne'});
 
       expect(controller.value.text, '''
 $_method
@@ -107,7 +111,7 @@ $_method
     });
 
     test('Trailing start separate end', () {
-      final controller = createTestController({'trailing_start_separate_end'});
+      final controller = createTestController({'ts_se'});
 
       expect(controller.value.text, '''
 $_method
@@ -120,7 +124,7 @@ $_method
     });
 
     test('Trailing start trailing end', () {
-      final controller = createTestController({'trailing_start_trailing_end'});
+      final controller = createTestController({'ts_te'});
 
       expect(controller.value.text, '''
 $_method
@@ -132,7 +136,7 @@ $_method
     });
 
     test('No start separate end', () {
-      final controller = createTestController({'no_start_separate_end'});
+      final controller = createTestController({'ns_se'});
 
       expect(controller.value.text, '''
 class MyClass {
@@ -147,7 +151,7 @@ $_method
     });
 
     test('No start trailing end', () {
-      final controller = createTestController({'no_start_trailing_end'});
+      final controller = createTestController({'ns_te'});
 
       expect(controller.value.text, '''
 class MyClass {
@@ -224,5 +228,18 @@ void method1() {
 
 void method2() {''');
     });
+
+    test('Newline after closing comment on the last line', () {
+      final controller = createController(
+        '''
+//[START show]
+//[END show]
+''',
+        language: dart,
+        visibleSectionNames: {'show'},
+      );
+
+      expect(controller.value.text, '\n\n');
+    });
   });
 }