Created CodeEditor widget

example/lib/ide/editor/editor.dart

@@ -215,7 +215,7 @@ class _IdeEditorState extends State<IdeEditor> {
 
     final globalOffset = (context.findRenderObject() as RenderBox).localToGlobal(event.localPosition);
     final codeLines = _linesKey.asCodeLines;
-    final hoverPosition = codeLines.findCodePositionNearestGlobalOffset(globalOffset);
+    final hoverPosition = codeLines.findCodePositionNearestGlobalOffset(globalOffset).$1;
 
     final hoverWordRange = codeLines.findWordBoundaryAtGlobalOffset(globalOffset);
     if (hoverWordRange == null) {
@@ -285,7 +285,7 @@ class _IdeEditorState extends State<IdeEditor> {
     }
 
     final codeLines = _linesKey.asCodeLines;
-    final codePosition = codeLines.findCodePositionNearestGlobalOffset(details.globalPosition);
+    final codePosition = codeLines.findCodePositionNearestGlobalOffset(details.globalPosition).$1;
 
     _currentSelectedPosition = Position(
       line: codePosition.line,

lib/inception.dart

@@ -12,10 +12,7 @@ export 'src/editor/code_editor.dart';
 export 'src/editor/code_layout.dart';
 export 'src/editor/theme.dart';
 
-export 'src/languages/dart/dart_contextualizer.dart';
-export 'src/languages/dart/dart_lexer.dart';
-export 'src/languages/dart/dart_syntax_highlighter.dart';
-export 'src/languages/dart/dart_theme.dart';
+export 'src/infrastructure/text/code_comment_selection_rules.dart';
 
 export 'src/lsp/lsp_client.dart';
 export 'src/lsp/messages/initialize.dart';
@@ -29,6 +26,8 @@ export 'src/lsp/messages/rename_files_params.dart';
 export 'src/lsp/messages/type_hierarchy.dart';
 export 'src/lsp/messages/did_open_text_document.dart';
 
+export 'src/test/code_editor/code_editor_presenters_for_tests.dart';
+export 'src/test/code_editor/code_editor_test_inspector.dart';
 export 'src/test/code_layout/code_layout_finders.dart';
 export 'src/test/code_layout/code_layout_test_inspector.dart';
 export 'src/test/code_layout/code_layout_test_interactor.dart';

lib/language_dart.dart

@@ -0,0 +1,6 @@
+export 'src/languages/dart/dart_code_editor_presenter.dart';
+export 'src/languages/dart/dart_contextualizer.dart';
+export 'src/languages/dart/dart_lexer.dart';
+export 'src/languages/dart/dart_syntax_highlighter.dart';
+export 'src/languages/dart/dart_theme.dart';
+export 'src/languages/dart/dart_theme_pineapple.dart';

lib/src/document/code_document.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
+import 'package:inception/inception.dart';
 import 'package:inception/src/document/lexing.dart';
 import 'package:inception/src/document/piece_table.dart';
 
@@ -22,6 +23,15 @@ class CodeDocument {
   String get text => _pieceTable.getText();
   int get length => _pieceTable.length;
 
+  /// Extracts and returns a list of substrings for every line in the document.
+  List<String> computeLines() {
+    final lines = <String>[];
+    for (int i = 0; i < lineCount; i += 1) {
+      lines.add(getLine(i)!);
+    }
+    return lines;
+  }
+
   String? getLine(int lineIndex) {
     if (lineIndex < 0 || lineIndex >= lineCount) {
       return null;
@@ -30,6 +40,21 @@ class CodeDocument {
     return text.substring(getLineStart(lineIndex), getLineEnd(lineIndex));
   }
 
+  /// Returns `true` if the given [position] points to a location in this document
+  /// that exists, or `false` otherwise.
+  ///
+  /// A [position] can be invalid in one of four ways:
+  ///  1. Points to a negative line index.
+  ///  2. Points to a line beyond the end of this document.
+  ///  3. Points to a negative character offset.
+  ///  4. Points to a character offset beyond the end of the line.
+  bool containsPosition(CodePosition position) {
+    return position.line >= 0 &&
+        position.line < lineCount &&
+        position.characterOffset >= 0 &&
+        position.characterOffset <= getLine(position.line)!.length;
+  }
+
   // ----- START TOKENS --------
   Lexer lexer;
   List<LexerToken> _tokens = const [];
@@ -57,6 +82,80 @@ class CodeDocument {
     }
   }
 
+  LexerToken? findTokenAt(CodePosition position) {
+    final textOffset = lineColumnToOffset(position.line, position.characterOffset);
+    final tokens = _tokens.where((t) => textOffset == t.start || (t.start < textOffset && textOffset < t.end));
+
+    if (tokens.length > 1) {
+      throw Exception(
+        "Something went wrong when finding the token at $position - we expect to find either 0 or 1, but we found ${tokens.length}",
+      );
+    }
+    if (tokens.isEmpty) {
+      return null;
+    }
+
+    return tokens.first;
+  }
+
+  LexerToken? findTokenToTheLeftOnSameLine(
+    CodePosition from, {
+    TokenFilter? filter,
+  }) {
+    if (!containsPosition(from)) {
+      return null;
+    }
+
+    // FIXME: This logic probably needs to use a character iterator, rather than
+    // an index integer. Look into it and make the switch if necessary.
+    var tokenAtStartingPoint = findTokenAt(from);
+    var textIndex = lineColumnToOffset(from.line, from.characterOffset) - 1;
+    while (textIndex >= 0 && offsetToCodePosition(textIndex).line == from.line) {
+      final nextPosition = offsetToCodePosition(textIndex);
+      final nextToken = findTokenAt(nextPosition);
+      if (nextToken != tokenAtStartingPoint &&
+          nextToken != null &&
+          (filter == null || filter(nextToken, nextPosition))) {
+        // This is the nearest token to the left, that we're looking for.
+        return nextToken;
+      }
+
+      // Move one character to the left.
+      textIndex -= 1;
+    }
+
+    return null;
+  }
+
+  LexerToken? findTokenToTheRightOnSameLine(
+    CodePosition from, {
+    TokenFilter? filter,
+  }) {
+    if (!containsPosition(from)) {
+      return null;
+    }
+
+    // FIXME: This logic probably needs to use a character iterator, rather than
+    // an index integer. Look into it and make the switch if necessary.
+    var tokenAtStartingPoint = findTokenAt(from);
+    var textIndex = lineColumnToOffset(from.line, from.characterOffset) + 1;
+    while (textIndex < length && offsetToCodePosition(textIndex).line == from.line) {
+      final nextPosition = offsetToCodePosition(textIndex);
+      final nextToken = findTokenAt(nextPosition);
+      if (nextToken != tokenAtStartingPoint &&
+          nextToken != null &&
+          (filter == null || filter(nextToken, nextPosition))) {
+        // This is the nearest token to the left, that we're looking for.
+        return nextToken;
+      }
+
+      // Move one character to the right.
+      textIndex += 1;
+    }
+
+    return null;
+  }
+
   /// Returns all tokens that overlap the current selection or cursor position.
   /// If there is no selection, this returns an empty list.
   List<LexerToken> tokensInSelection() {
@@ -368,16 +467,16 @@ class CodeDocument {
       return null;
     }
 
-    final startLine = offsetToLineColumn(selectionStart).$1;
+    final startLine = offsetToCodePosition(selectionStart).line;
     final startOffset = getLineStart(startLine);
     final endOffset = startLine + 1 < lineCount ? getLineStart(startLine + 1) : length;
 
     return (start: startOffset, end: endOffset);
   }
 
-  (int line, int column) offsetToLineColumn(int offset) {
+  CodePosition offsetToCodePosition(int offset) {
     final lineIndex = _findLineIndex(offset);
-    return (lineIndex, offset - _lineStarts[lineIndex]);
+    return CodePosition(lineIndex, offset - _lineStarts[lineIndex]);
   }
 
   int lineColumnToOffset(int line, int column) => _lineStarts[line] + column;
@@ -668,6 +767,8 @@ class CodeDocument {
   }
 }
 
+typedef TokenFilter = bool Function(LexerToken token, CodePosition position);
+
 class _InsertAction implements _EditAction {
   _InsertAction(this.offset, this.text);
 

lib/src/document/selection.dart

@@ -13,10 +13,26 @@ class CodeSelection {
   final CodePosition base;
   final CodePosition extent;
 
+  /// Returns the [CodePosition] at the most upstream point in the selection, which might be the
+  /// [base] or the [extent], depending on the direction of the selection.
+  CodePosition get start => base <= extent ? base : extent;
+
+  /// Returns the [CodePosition] at the most downstream point in the selection, which might be the
+  /// [base] or the [extent], depending on the direction of the selection.
+  CodePosition get end => base <= extent ? extent : base;
+
   bool get isCollapsed => base == extent;
 
   bool get isExpanded => base != extent;
 
+  /// Returns `true` if the selection points from upstream to downstream, e.g., the
+  /// base of the selection comes before the extent.
+  bool get isDownstream => extent >= base;
+
+  /// Returns `true` if the selection points from downstream to upstream, e.g., the
+  /// extent of the selection comes before the base.
+  bool get isUpstream => base > extent;
+
   CodeRange toRange() {
     final affinity = extent.line > base.line || extent.characterOffset >= base.characterOffset
         ? TextAffinity.downstream
@@ -27,6 +43,18 @@ class CodeSelection {
       affinity == TextAffinity.downstream ? extent : base,
     );
   }
+
+  @override
+  String toString() =>
+      "[CodeRange]: L${base.line}:C${base.characterOffset} -> L${extent.line}:C${extent.characterOffset}";
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is CodeSelection && runtimeType == other.runtimeType && base == other.base && extent == other.extent;
+
+  @override
+  int get hashCode => base.hashCode ^ extent.hashCode;
 }
 
 /// A range of code, from a starting line and offset, to an ending line and offset.