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/**
* @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;
};
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