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diff --git a/tools/node_modules/eslint/lib/token-store/cursor.js b/tools/node_modules/eslint/lib/token-store/cursor.js
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+/**
+ * @fileoverview Define the abstract class about cursors which iterate tokens.
+ * @author Toru Nagashima
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Exports
+//------------------------------------------------------------------------------
+
+/**
+ * The abstract class about cursors which iterate tokens.
+ *
+ * This class has 2 abstract methods.
+ *
+ * - `current: Token | Comment | null` ... The current token.
+ * - `moveNext(): boolean` ... Moves this cursor to the next token. If the next token didn't exist, it returns `false`.
+ *
+ * This is similar to ES2015 Iterators.
+ * However, Iterators were slow (at 2017-01), so I created this class as similar to C# IEnumerable.
+ *
+ * There are the following known sub classes.
+ *
+ * - ForwardTokenCursor .......... The cursor which iterates tokens only.
+ * - BackwardTokenCursor ......... The cursor which iterates tokens only in reverse.
+ * - ForwardTokenCommentCursor ... The cursor which iterates tokens and comments.
+ * - BackwardTokenCommentCursor .. The cursor which iterates tokens and comments in reverse.
+ * - DecorativeCursor
+ *     - FilterCursor ............ The cursor which ignores the specified tokens.
+ *     - SkipCursor .............. The cursor which ignores the first few tokens.
+ *     - LimitCursor ............. The cursor which limits the count of tokens.
+ *
+ */
+module.exports = class Cursor {
+
+    /**
+     * Initializes this cursor.
+     */
+    constructor() {
+        this.current = null;
+    }
+
+    /**
+     * Gets the first token.
+     * This consumes this cursor.
+     * @returns {Token|Comment} The first token or null.
+     */
+    getOneToken() {
+        return this.moveNext() ? this.current : null;
+    }
+
+    /**
+     * Gets the first tokens.
+     * This consumes this cursor.
+     * @returns {(Token|Comment)[]} All tokens.
+     */
+    getAllTokens() {
+        const tokens = [];
+
+        while (this.moveNext()) {
+            tokens.push(this.current);
+        }
+
+        return tokens;
+    }
+
+    /**
+     * Moves this cursor to the next token.
+     * @returns {boolean} `true` if the next token exists.
+     * @abstract
+     */
+    /* istanbul ignore next */
+    moveNext() { // eslint-disable-line class-methods-use-this
+        throw new Error("Not implemented.");
+    }
+};