fix: node positional information for files with single-quotes in comments (#164)

* Add test to reproduce error

* Enhance test

* Drop .only

* Work on post-processing tree

* Enhance code + tests

* Add additional test assertions

* Fix computation of end offset of comment

* Add istanbul ignore comment

Author: nwalters512

lib/index.js

@@ -12,6 +12,53 @@ module.exports = {
 
     parser.parse();
 
+    // To handle double-slash comments (`//`) we end up creating a new tokenizer
+    // in certain cases (see `lib/nodes/inline-comment.js`). However, this means
+    // that any following node in the AST will have incorrect start/end positions
+    // on the `source` property. To fix that, we'll walk the AST and compute
+    // updated positions for all nodes.
+    parser.root.walk((node) => {
+      const offset = input.css.lastIndexOf(node.source.input.css);
+
+      if (offset === 0) {
+        // Short circuit - this node was processed with the original tokenizer
+        // and should therefore have correct position information.
+        return;
+      }
+
+      // This ensures that the chunk of source we're processing corresponds
+      // strictly to a terminal substring of the input CSS. This should always
+      // be the case, but if it ever isn't, we prefer to fail instead of
+      // producing potentially invalid output.
+      // istanbul ignore next
+      if (offset + node.source.input.css.length !== input.css.length) {
+        throw new Error('Invalid state detected in postcss-less');
+      }
+
+      const newStartOffset = offset + node.source.start.offset;
+      const newStartPosition = input.fromOffset(offset + node.source.start.offset);
+
+      // eslint-disable-next-line no-param-reassign
+      node.source.start = {
+        offset: newStartOffset,
+        line: newStartPosition.line,
+        column: newStartPosition.col
+      };
+
+      // Not all nodes have an `end` property.
+      if (node.source.end) {
+        const newEndOffset = offset + node.source.end.offset;
+        const newEndPosition = input.fromOffset(offset + node.source.end.offset);
+
+        // eslint-disable-next-line no-param-reassign
+        node.source.end = {
+          offset: newEndOffset,
+          line: newEndPosition.line,
+          column: newEndPosition.col
+        };
+      }
+    });
+
     return parser.root;
   },
 

lib/nodes/inline-comment.js

@@ -8,7 +8,7 @@ module.exports = {
     if (token[0] === 'word' && token[1].slice(0, 2) === '//') {
       const first = token;
       const bits = [];
-      let last;
+      let endOffset;
       let remainingInput;
 
       while (token) {
@@ -20,7 +20,12 @@ module.exports = {
 
             // Get remaining input and retokenize
             remainingInput = token[1].substring(token[1].indexOf('\n'));
-            remainingInput += this.input.css.valueOf().substring(this.tokenizer.position());
+            const untokenizedRemainingInput = this.input.css
+              .valueOf()
+              .substring(this.tokenizer.position());
+            remainingInput += untokenizedRemainingInput;
+
+            endOffset = token[3] + untokenizedRemainingInput.length - remainingInput.length;
           } else {
             // If the tokenizer went to the next line go back
             this.tokenizer.back(token);
@@ -29,11 +34,12 @@ module.exports = {
         }
 
         bits.push(token[1]);
-        last = token;
+        // eslint-disable-next-line prefer-destructuring
+        endOffset = token[2];
         token = this.tokenizer.nextToken({ ignoreUnclosed: true });
       }
 
-      const newToken = ['comment', bits.join(''), first[2], last[2]];
+      const newToken = ['comment', bits.join(''), first[2], endOffset];
       this.inlineComment(newToken);
 
       // Replace tokenizer to retokenize the rest of the string

test/parser/comments.test.js

@@ -179,3 +179,36 @@ test('inline comments with asterisk are persisted (#135)', (t) => {
   t.is(first.text, '*batman');
   t.is(nodeToString(root), less);
 });
+
+test('handles single quotes in comments (#163)', (t) => {
+  const less = `a {\n  // '\n  color: pink;\n}\n\n/** ' */`;
+
+  const root = parse(less);
+
+  const [ruleNode, commentNode] = root.nodes;
+
+  t.is(ruleNode.type, 'rule');
+  t.is(commentNode.type, 'comment');
+
+  t.is(commentNode.source.start.line, 6);
+  t.is(commentNode.source.start.column, 1);
+  t.is(commentNode.source.end.line, 6);
+  t.is(commentNode.source.end.column, 8);
+
+  const [innerCommentNode, declarationNode] = ruleNode.nodes;
+
+  t.is(innerCommentNode.type, 'comment');
+  t.is(declarationNode.type, 'decl');
+
+  t.is(innerCommentNode.source.start.line, 2);
+  t.is(innerCommentNode.source.start.column, 3);
+  t.is(innerCommentNode.source.end.line, 2);
+  t.is(innerCommentNode.source.end.column, 6);
+
+  t.is(declarationNode.source.start.line, 3);
+  t.is(declarationNode.source.start.column, 3);
+  t.is(declarationNode.source.end.line, 3);
+  t.is(declarationNode.source.end.column, 14);
+
+  t.is(nodeToString(root), less);
+});