1 files changed, 57 insertions, 0 deletions
diff --git a/tools/eslint/lib/token-store/forward-token-comment-cursor.js b/tools/eslint/lib/token-store/forward-token-comment-cursor.js
new file mode 100644
index 0000000000..be08552970
--- /dev/null
+++ b/tools/eslint/lib/token-store/forward-token-comment-cursor.js
@@ -0,0 +1,57 @@
+/**
+ * @fileoverview Define the cursor which iterates tokens and comments.
+ * @author Toru Nagashima
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const Cursor = require("./cursor");
+const utils = require("./utils");
+
+//------------------------------------------------------------------------------
+// Exports
+//------------------------------------------------------------------------------
+
+/**
+ * The cursor which iterates tokens and comments.
+ */
+module.exports = class ForwardTokenCommentCursor extends Cursor {
+
+    /**
+     * Initializes this cursor.
+     * @param {Token[]} tokens - The array of tokens.
+     * @param {Comment[]} comments - The array of comments.
+     * @param {Object} indexMap - The map from locations to indices in `tokens`.
+     * @param {number} startLoc - The start location of the iteration range.
+     * @param {number} endLoc - The end location of the iteration range.
+     */
+    constructor(tokens, comments, indexMap, startLoc, endLoc) {
+        super();
+        this.tokens = tokens;
+        this.comments = comments;
+        this.tokenIndex = utils.getFirstIndex(tokens, indexMap, startLoc);
+        this.commentIndex = utils.search(comments, startLoc);
+        this.border = endLoc;
+    }
+
+    /** @inheritdoc */
+    moveNext() {
+        const token = (this.tokenIndex < this.tokens.length) ? this.tokens[this.tokenIndex] : null;
+        const comment = (this.commentIndex < this.comments.length) ? this.comments[this.commentIndex] : null;
+
+        if (token && (!comment || token.range[0] < comment.range[0])) {
+            this.current = token;
+            this.tokenIndex += 1;
+        } else if (comment) {
+            this.current = comment;
+            this.commentIndex += 1;
+        } else {
+            this.current = null;
+        }
+
+        return Boolean(this.current) && (this.border === -1 || this.current.range[1] <= this.border);
+    }
+};