58 lines
1.7 KiB
JavaScript
58 lines
1.7 KiB
JavaScript
/**
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* @fileoverview Define the cursor which iterates tokens only in reverse.
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* @author Toru Nagashima
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const Cursor = require("./cursor");
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const utils = require("./utils");
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//------------------------------------------------------------------------------
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// Exports
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//------------------------------------------------------------------------------
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/**
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* The cursor which iterates tokens only in reverse.
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*/
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module.exports = class BackwardTokenCursor extends Cursor {
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/**
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* Initializes this cursor.
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* @param {Token[]} tokens The array of tokens.
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* @param {Comment[]} comments The array of comments.
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* @param {Object} indexMap The map from locations to indices in `tokens`.
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* @param {number} startLoc The start location of the iteration range.
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* @param {number} endLoc The end location of the iteration range.
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*/
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constructor(tokens, comments, indexMap, startLoc, endLoc) {
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super();
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this.tokens = tokens;
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this.index = utils.getLastIndex(tokens, indexMap, endLoc);
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this.indexEnd = utils.getFirstIndex(tokens, indexMap, startLoc);
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}
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/** @inheritdoc */
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moveNext() {
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if (this.index >= this.indexEnd) {
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this.current = this.tokens[this.index];
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this.index -= 1;
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return true;
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}
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return false;
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}
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/*
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*
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* Shorthand for performance.
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*
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*/
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/** @inheritdoc */
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getOneToken() {
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return (this.index >= this.indexEnd) ? this.tokens[this.index] : null;
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}
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};
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