[linter] Issue 295. Skip comment tokens with GitHub code blocks (in ```).

[email protected], [email protected]
BUG= https://github.com/dart-lang/linter/issues/295

Review URL: https://codereview.chromium.org/2302003003 .

Author: scheglov

pkg/analyzer/lib/src/generated/parser.dart

@@ -5178,9 +5178,22 @@ class Parser {
   List<CommentReference> _parseCommentReferences(
       List<DocumentationCommentToken> tokens) {
     List<CommentReference> references = <CommentReference>[];
+    bool isInGitHubCodeBlock = false;
     for (DocumentationCommentToken token in tokens) {
       String comment = token.lexeme;
-      comment = _removeCodeBlocksGitHub(comment);
+      // Skip GitHub code blocks.
+      // https://help.github.com/articles/creating-and-highlighting-code-blocks/
+      if (tokens.length != 1) {
+        if (comment.indexOf('```') != -1) {
+          isInGitHubCodeBlock = !isInGitHubCodeBlock;
+        }
+        if (isInGitHubCodeBlock) {
+          continue;
+        }
+      }
+      // Remove GitHub include code.
+      comment = _removeGitHubInlineCode(comment);
+      // Find references.
       int length = comment.length;
       List<List<int>> codeBlockRanges = _getCodeBlockRanges(comment);
       int leftIndex = comment.indexOf('[');
@@ -8883,7 +8896,7 @@ class Parser {
     return token;
   }
 
-  String _removeCodeBlocksGitHub(String comment) {
+  String _removeGitHubInlineCode(String comment) {
     int index = 0;
     while (true) {
       int beginIndex = comment.indexOf('`', index);

pkg/analyzer/test/generated/parser_test.dart

@@ -6534,6 +6534,46 @@ void''');
     expect(reference.offset, 16);
   }
 
+  void test_parseCommentReferences_skipCodeBlock_gitHub_multiLine() {
+    List<DocumentationCommentToken> tokens = <DocumentationCommentToken>[
+      new DocumentationCommentToken(
+          TokenType.MULTI_LINE_COMMENT,
+          r'''
+/**
+ * First.
+ * ```dart
+ * Some [int] reference.
+ * ```
+ * Last.
+ */
+''',
+          3)
+    ];
+    List<CommentReference> references =
+        parse("parseCommentReferences", <Object>[tokens], "")
+        as List<CommentReference>;
+    expect(references, isEmpty);
+  }
+
+  void test_parseCommentReferences_skipCodeBlock_gitHub_multiLine_lines() {
+    String commentText = r'''
+/// First.
+/// ```dart
+/// Some [int] reference.
+/// ```
+/// Last.
+''';
+    List<DocumentationCommentToken> tokens = commentText
+        .split('\n')
+        .map((line) => new DocumentationCommentToken(
+            TokenType.SINGLE_LINE_COMMENT, line, 0))
+        .toList();
+    List<CommentReference> references =
+        parse("parseCommentReferences", <Object>[tokens], "")
+        as List<CommentReference>;
+    expect(references, isEmpty);
+  }
+
   void test_parseCommentReferences_skipCodeBlock_gitHub_notTerminated() {
     List<DocumentationCommentToken> tokens = <DocumentationCommentToken>[
       new DocumentationCommentToken(