Skip to content
Permalink
9bfb9ba527
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Go to file
 
 
Cannot retrieve contributors at this time
107 lines (97 sloc) 3.66 KB
/**
* @fileoverview Define utility functions for token store.
* @author Toru Nagashima
*/
"use strict";
//------------------------------------------------------------------------------
// Exports
//------------------------------------------------------------------------------
/**
* Finds the index of the first token which is after the given location.
* If it was not found, this returns `tokens.length`.
* @param {(Token|Comment)[]} tokens It searches the token in this list.
* @param {number} location The location to search.
* @returns {number} The found index or `tokens.length`.
*/
exports.search = function search(tokens, location) {
for (let minIndex = 0, maxIndex = tokens.length - 1; minIndex <= maxIndex;) {
/*
* Calculate the index in the middle between minIndex and maxIndex.
* `| 0` is used to round a fractional value down to the nearest integer: this is similar to
* using `Math.trunc()` or `Math.floor()`, but performance tests have shown this method to
* be faster.
*/
const index = (minIndex + maxIndex) / 2 | 0;
const token = tokens[index];
const tokenStartLocation = token.range[0];
if (location <= tokenStartLocation) {
if (index === minIndex) {
return index;
}
maxIndex = index;
} else {
minIndex = index + 1;
}
}
return tokens.length;
};
/**
* Gets the index of the `startLoc` in `tokens`.
* `startLoc` can be the value of `node.range[1]`, so this checks about `startLoc - 1` as well.
* @param {(Token|Comment)[]} tokens The tokens to find an index.
* @param {Object} indexMap The map from locations to indices.
* @param {number} startLoc The location to get an index.
* @returns {number} The index.
*/
exports.getFirstIndex = function getFirstIndex(tokens, indexMap, startLoc) {
if (startLoc in indexMap) {
return indexMap[startLoc];
}
if ((startLoc - 1) in indexMap) {
const index = indexMap[startLoc - 1];
const token = tokens[index];
// If the mapped index is out of bounds, the returned cursor index will point after the end of the tokens array.
if (!token) {
return tokens.length;
}
/*
* For the map of "comment's location -> token's index", it points the next token of a comment.
* In that case, +1 is unnecessary.
*/
if (token.range[0] >= startLoc) {
return index;
}
return index + 1;
}
return 0;
};
/**
* Gets the index of the `endLoc` in `tokens`.
* The information of end locations are recorded at `endLoc - 1` in `indexMap`, so this checks about `endLoc - 1` as well.
* @param {(Token|Comment)[]} tokens The tokens to find an index.
* @param {Object} indexMap The map from locations to indices.
* @param {number} endLoc The location to get an index.
* @returns {number} The index.
*/
exports.getLastIndex = function getLastIndex(tokens, indexMap, endLoc) {
if (endLoc in indexMap) {
return indexMap[endLoc] - 1;
}
if ((endLoc - 1) in indexMap) {
const index = indexMap[endLoc - 1];
const token = tokens[index];
// If the mapped index is out of bounds, the returned cursor index will point before the end of the tokens array.
if (!token) {
return tokens.length - 1;
}
/*
* For the map of "comment's location -> token's index", it points the next token of a comment.
* In that case, -1 is necessary.
*/
if (token.range[1] > endLoc) {
return index - 1;
}
return index;
}
return tokens.length - 1;
};