eslint/lib/source-code/token-store/utils.js

   1 /**
   2  * @fileoverview Define utility functions for token store.
   3  * @author Toru Nagashima
   4  */
   5 "use strict";
   6
   7 //------------------------------------------------------------------------------
   8 // Helpers
   9 //------------------------------------------------------------------------------
  10
  11 /**
  12  * Gets `token.range[0]` from the given token.
  13  * @param {Node|Token|Comment} token The token to get.
  14  * @returns {number} The start location.
  15  * @private
  16  */
  17 function getStartLocation(token) {
  18     return token.range[0];
  19 }
  20
  21 //------------------------------------------------------------------------------
  22 // Exports
  23 //------------------------------------------------------------------------------
  24
  25 /**
  26  * Finds the index of the first token which is after the given location.
  27  * If it was not found, this returns `tokens.length`.
  28  * @param {(Token|Comment)[]} tokens It searches the token in this list.
  29  * @param {number} location The location to search.
  30  * @returns {number} The found index or `tokens.length`.
  31  */
  32 exports.search = function search(tokens, location) {
  33     const index = tokens.findIndex(el => location <= getStartLocation(el));
  34
  35     return index === -1 ? tokens.length : index;
  36 };
  37
  38 /**
  39  * Gets the index of the `startLoc` in `tokens`.
  40  * `startLoc` can be the value of `node.range[1]`, so this checks about `startLoc - 1` as well.
  41  * @param {(Token|Comment)[]} tokens The tokens to find an index.
  42  * @param {Object} indexMap The map from locations to indices.
  43  * @param {number} startLoc The location to get an index.
  44  * @returns {number} The index.
  45  */
  46 exports.getFirstIndex = function getFirstIndex(tokens, indexMap, startLoc) {
  47     if (startLoc in indexMap) {
  48         return indexMap[startLoc];
  49     }
  50     if ((startLoc - 1) in indexMap) {
  51         const index = indexMap[startLoc - 1];
  52         const token = (index >= 0 && index < tokens.length) ? tokens[index] : null;
  53
  54         /*
  55          * For the map of "comment's location -> token's index", it points the next token of a comment.
  56          * In that case, +1 is unnecessary.
  57          */
  58         if (token && token.range[0] >= startLoc) {
  59             return index;
  60         }
  61         return index + 1;
  62     }
  63     return 0;
  64 };
  65
  66 /**
  67  * Gets the index of the `endLoc` in `tokens`.
  68  * The information of end locations are recorded at `endLoc - 1` in `indexMap`, so this checks about `endLoc - 1` as well.
  69  * @param {(Token|Comment)[]} tokens The tokens to find an index.
  70  * @param {Object} indexMap The map from locations to indices.
  71  * @param {number} endLoc The location to get an index.
  72  * @returns {number} The index.
  73  */
  74 exports.getLastIndex = function getLastIndex(tokens, indexMap, endLoc) {
  75     if (endLoc in indexMap) {
  76         return indexMap[endLoc] - 1;
  77     }
  78     if ((endLoc - 1) in indexMap) {
  79         const index = indexMap[endLoc - 1];
  80         const token = (index >= 0 && index < tokens.length) ? tokens[index] : null;
  81
  82         /*
  83          * For the map of "comment's location -> token's index", it points the next token of a comment.
  84          * In that case, -1 is necessary.
  85          */
  86         if (token && token.range[1] > endLoc) {
  87             return index - 1;
  88         }
  89         return index;
  90     }
  91     return tokens.length - 1;
  92 };