Fix HiddenLineRanges.cutLineIndexIfVisible (#112)

lib/src/code_field/code_controller.dart

@@ -505,8 +505,6 @@ class CodeController extends TextEditingController {
     super.value = _getValueWithCode(_code);
   }
 
-
-
   /// The value with [newCode] preserving the current selection.
   TextEditingValue _getValueWithCode(Code newCode) {
     return TextEditingValue(

lib/src/hidden_ranges/hidden_line_ranges.dart

@@ -5,18 +5,15 @@ import 'line_numbering_breakpoint.dart';
 class HiddenLineRanges with EquatableMixin {
   final List<LineNumberingBreakpoint> breakpoints;
   final int fullLineCount;
-  final int visibleLineCount;
 
   const HiddenLineRanges({
     required this.breakpoints,
     required this.fullLineCount,
-    required this.visibleLineCount,
   });
 
   static const empty = HiddenLineRanges(
     breakpoints: [],
     fullLineCount: 1,
-    visibleLineCount: 1,
   );
 
   /// Returns the visible line index to which the full [lineIndex] maps
@@ -34,6 +31,14 @@ class HiddenLineRanges with EquatableMixin {
     if (breakpoints.isEmpty) {
       return lineIndex;
     }
+    if (lineIndex <= breakpoints.first.full) {
+      return breakpoints.first.cutLineIndexIfVisible(lineIndex);
+    }
+    if (lineIndex >= breakpoints.last.full) {
+      return breakpoints.last.cutLineIndexIfVisible(lineIndex);
+    }
+
+    // At this point, we always have a breakpoint before and after.
 
     int lower = 0;
     int upper = breakpoints.length - 1;
@@ -49,30 +54,32 @@ class HiddenLineRanges with EquatableMixin {
                   (upper - lower))
           .floor();
 
-      if (index < lower) {
-        return breakpoints[lower].cutLineIndexIfVisible(lineIndex);
-      }
-      if (index > upper) {
-        return breakpoints[upper].cutLineIndexIfVisible(lineIndex);
-      }
-
       final breakpoint = breakpoints[index];
 
       switch ((breakpoint.full - lineIndex).sign) {
-        case -1:
+        case -1: // We are after this breakpoint.
+          final nextBreakpoint = breakpoints[index + 1];
+          if (nextBreakpoint.full > lineIndex) {
+            // ... and before the next one.
+            return nextBreakpoint.cutLineIndexIfVisible(lineIndex);
+          }
           lower = index + 1;
           continue;
-        case 1:
+
+        case 1: // We are before this breakpoint.
+          final previousBreakpoint = breakpoints[index - 1];
+          if (previousBreakpoint.full < lineIndex) {
+            // ... and after the previous one.
+            return breakpoint.cutLineIndexIfVisible(lineIndex);
+          }
           upper = index - 1;
           continue;
       }
 
       return breakpoint.visible;
     }
 
-    // upper == lower
-    final breakpoint = breakpoints[upper];
-    return breakpoint.cutLineIndexIfVisible(lineIndex);
+    throw Exception('Never get here');
   }
 
   Iterable<int> get visibleLineNumbers sync* {

lib/src/hidden_ranges/hidden_line_ranges_builder.dart

@@ -60,7 +60,6 @@ class HiddenLineRangesBuilder {
       hiddenLineRanges: HiddenLineRanges(
         breakpoints: breakpoints,
         fullLineCount: codeLines.lines.length,
-        visibleLineCount: codeLines.lines.length - spread,
       ),
     );
   }

lib/src/hidden_ranges/hidden_ranges.dart

@@ -307,7 +307,7 @@ class HiddenRanges {
     }
   }
 
-  /// Translates the [selection] of the full text 
+  /// Translates the [selection] of the full text
   /// to selection of the visible text.
   TextSelection cutSelection(TextSelection selection) {
     if (selection.isCollapsed) {

test/src/hidden_ranges/hidden_line_ranges_builder_test.dart

@@ -29,7 +29,6 @@ void main() {
         const HiddenLineRanges(
           breakpoints: [],
           fullLineCount: 1,
-          visibleLineCount: 1,
         ),
       );
     });
@@ -45,7 +44,6 @@ void main() {
         const HiddenLineRanges(
           breakpoints: [],
           fullLineCount: 15,
-          visibleLineCount: 15,
         ),
       );
     });
@@ -86,7 +84,6 @@ void main() {
         const HiddenLineRanges(
           breakpoints: [],
           fullLineCount: 15,
-          visibleLineCount: 15,
         ),
       );
     });
@@ -130,7 +127,6 @@ void main() {
             LineNumberingBreakpoint(full: 14, visible: 10, spreadBefore: 2),
           ],
           fullLineCount: 15,
-          visibleLineCount: 11,
         ),
       );
     });
@@ -174,7 +170,6 @@ void main() {
             LineNumberingBreakpoint(full: 15, visible: 10, spreadBefore: 2),
           ],
           fullLineCount: 15,
-          visibleLineCount: 9,
         ),
       );
     });

test/src/hidden_ranges/hidden_line_ranges_test.dart

@@ -6,17 +6,18 @@ void main() {
   const noBreakpointsRanges = HiddenLineRanges(
     breakpoints: [],
     fullLineCount: 10,
-    visibleLineCount: 10,
   );
 
   const midBreakpointsRanges = HiddenLineRanges(
     breakpoints: [
       LineNumberingBreakpoint(full: 4, visible: 2, spreadBefore: 0),
       LineNumberingBreakpoint(full: 9, visible: 5, spreadBefore: 2),
       LineNumberingBreakpoint(full: 100, visible: 12, spreadBefore: 4),
+      LineNumberingBreakpoint(full: 210, visible: 113, spreadBefore: 88),
+      LineNumberingBreakpoint(full: 220, visible: 115, spreadBefore: 97),
+      LineNumberingBreakpoint(full: 230, visible: 118, spreadBefore: 105),
     ],
-    fullLineCount: 110,
-    visibleLineCount: 22,
+    fullLineCount: 231,
   );
 
   const startEndHiddenRanges = HiddenLineRanges(
@@ -25,7 +26,6 @@ void main() {
       LineNumberingBreakpoint(full: 10, visible: 5, spreadBefore: 3),
     ],
     fullLineCount: 10,
-    visibleLineCount: 5,
   );
 
   group('HiddenLineRanges.', () {
@@ -56,6 +56,9 @@ void main() {
         expect(midBreakpointsRanges.cutLineIndexIfVisible(100), 12);
         expect(midBreakpointsRanges.cutLineIndexIfVisible(101), 13);
         expect(midBreakpointsRanges.cutLineIndexIfVisible(200), 112);
+        expect(midBreakpointsRanges.cutLineIndexIfVisible(209), null);
+        expect(midBreakpointsRanges.cutLineIndexIfVisible(219), null);
+        expect(midBreakpointsRanges.cutLineIndexIfVisible(229), null);
       });
     });
 
@@ -75,7 +78,10 @@ void main() {
             0, 1,
             4, 5, 6,
             9, 10, 11, 12, 13, 14, 15,
-            100, 101, 102, 103, 104, 105, 106, 107, 108, 109,
+            ...List<int>.generate(200 - 100 + 1, (i) => i + 100), // 100-200
+            210, 211,
+            220, 221, 222,
+            230,
           ],
         );
       });