challenge-algorithms-v2.0-D.../node_modules/istanbul-lib-source-maps/lib/get-mapping.js

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2022-10-27 19:56:30 +00:00
/*
Copyright 2015, Yahoo Inc.
Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
*/
'use strict';
const pathutils = require('./pathutils');
const {
GREATEST_LOWER_BOUND,
LEAST_UPPER_BOUND
} = require('source-map').SourceMapConsumer;
/**
* AST ranges are inclusive for start positions and exclusive for end positions.
* Source maps are also logically ranges over text, though interacting with
* them is generally achieved by working with explicit positions.
*
* When finding the _end_ location of an AST item, the range behavior is
* important because what we're asking for is the _end_ of whatever range
* corresponds to the end location we seek.
*
* This boils down to the following steps, conceptually, though the source-map
* library doesn't expose primitives to do this nicely:
*
* 1. Find the range on the generated file that ends at, or exclusively
* contains the end position of the AST node.
* 2. Find the range on the original file that corresponds to
* that generated range.
* 3. Find the _end_ location of that original range.
*/
function originalEndPositionFor(sourceMap, generatedEnd) {
// Given the generated location, find the original location of the mapping
// that corresponds to a range on the generated file that overlaps the
// generated file end location. Note however that this position on its
// own is not useful because it is the position of the _start_ of the range
// on the original file, and we want the _end_ of the range.
const beforeEndMapping = originalPositionTryBoth(
sourceMap,
generatedEnd.line,
generatedEnd.column - 1
);
if (beforeEndMapping.source === null) {
return null;
}
// Convert that original position back to a generated one, with a bump
// to the right, and a rightward bias. Since 'generatedPositionFor' searches
// for mappings in the original-order sorted list, this will find the
// mapping that corresponds to the one immediately after the
// beforeEndMapping mapping.
const afterEndMapping = sourceMap.generatedPositionFor({
source: beforeEndMapping.source,
line: beforeEndMapping.line,
column: beforeEndMapping.column + 1,
bias: LEAST_UPPER_BOUND
});
if (
// If this is null, it means that we've hit the end of the file,
// so we can use Infinity as the end column.
afterEndMapping.line === null ||
// If these don't match, it means that the call to
// 'generatedPositionFor' didn't find any other original mappings on
// the line we gave, so consider the binding to extend to infinity.
sourceMap.originalPositionFor(afterEndMapping).line !==
beforeEndMapping.line
) {
return {
source: beforeEndMapping.source,
line: beforeEndMapping.line,
column: Infinity
};
}
// Convert the end mapping into the real original position.
return sourceMap.originalPositionFor(afterEndMapping);
}
/**
* Attempts to determine the original source position, first
* returning the closest element to the left (GREATEST_LOWER_BOUND),
* and next returning the closest element to the right (LEAST_UPPER_BOUND).
*/
function originalPositionTryBoth(sourceMap, line, column) {
const mapping = sourceMap.originalPositionFor({
line,
column,
bias: GREATEST_LOWER_BOUND
});
if (mapping.source === null) {
return sourceMap.originalPositionFor({
line,
column,
bias: LEAST_UPPER_BOUND
});
} else {
return mapping;
}
}
function isInvalidPosition(pos) {
return (
!pos ||
typeof pos.line !== 'number' ||
typeof pos.column !== 'number' ||
pos.line < 0 ||
pos.column < 0
);
}
/**
* determines the original position for a given location
* @param {SourceMapConsumer} sourceMap the source map
* @param {Object} generatedLocation the original location Object
* @returns {Object} the remapped location Object
*/
function getMapping(sourceMap, generatedLocation, origFile) {
if (!generatedLocation) {
return null;
}
if (
isInvalidPosition(generatedLocation.start) ||
isInvalidPosition(generatedLocation.end)
) {
return null;
}
const start = originalPositionTryBoth(
sourceMap,
generatedLocation.start.line,
generatedLocation.start.column
);
let end = originalEndPositionFor(sourceMap, generatedLocation.end);
/* istanbul ignore if: edge case too hard to test for */
if (!(start && end)) {
return null;
}
if (!(start.source && end.source)) {
return null;
}
if (start.source !== end.source) {
return null;
}
/* istanbul ignore if: edge case too hard to test for */
if (start.line === null || start.column === null) {
return null;
}
/* istanbul ignore if: edge case too hard to test for */
if (end.line === null || end.column === null) {
return null;
}
if (start.line === end.line && start.column === end.column) {
end = sourceMap.originalPositionFor({
line: generatedLocation.end.line,
column: generatedLocation.end.column,
bias: LEAST_UPPER_BOUND
});
end.column -= 1;
}
return {
source: pathutils.relativeTo(start.source, origFile),
loc: {
start: {
line: start.line,
column: start.column
},
end: {
line: end.line,
column: end.column
}
}
};
}
module.exports = getMapping;