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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."); | |
| } | |
| }; |