77 lines
2.3 KiB
Plaintext
77 lines
2.3 KiB
Plaintext
/**
|
|
* @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
|
|
*/
|
|
/* c8 ignore next */
|
|
moveNext() { // eslint-disable-line class-methods-use-this -- Unused
|
|
throw new Error("Not implemented.");
|
|
}
|
|
};
|