devsite/node_modules/sucrase/dist/esm/computeSourceMap.js
2024-07-07 18:49:38 -07:00

90 lines
2.4 KiB
JavaScript

import {GenMapping, maybeAddSegment, toEncodedMap} from "@jridgewell/gen-mapping";
import {charCodes} from "./parser/util/charcodes";
/**
* Generate a source map indicating that each line maps directly to the original line,
* with the tokens in their new positions.
*/
export default function computeSourceMap(
{code: generatedCode, mappings: rawMappings},
filePath,
options,
source,
tokens,
) {
const sourceColumns = computeSourceColumns(source, tokens);
const map = new GenMapping({file: options.compiledFilename});
let tokenIndex = 0;
// currentMapping is the output source index for the current input token being
// considered.
let currentMapping = rawMappings[0];
while (currentMapping === undefined && tokenIndex < rawMappings.length - 1) {
tokenIndex++;
currentMapping = rawMappings[tokenIndex];
}
let line = 0;
let lineStart = 0;
if (currentMapping !== lineStart) {
maybeAddSegment(map, line, 0, filePath, line, 0);
}
for (let i = 0; i < generatedCode.length; i++) {
if (i === currentMapping) {
const genColumn = currentMapping - lineStart;
const sourceColumn = sourceColumns[tokenIndex];
maybeAddSegment(map, line, genColumn, filePath, line, sourceColumn);
while (
(currentMapping === i || currentMapping === undefined) &&
tokenIndex < rawMappings.length - 1
) {
tokenIndex++;
currentMapping = rawMappings[tokenIndex];
}
}
if (generatedCode.charCodeAt(i) === charCodes.lineFeed) {
line++;
lineStart = i + 1;
if (currentMapping !== lineStart) {
maybeAddSegment(map, line, 0, filePath, line, 0);
}
}
}
const {sourceRoot, sourcesContent, ...sourceMap} = toEncodedMap(map);
return sourceMap ;
}
/**
* Create an array mapping each token index to the 0-based column of the start
* position of the token.
*/
function computeSourceColumns(code, tokens) {
const sourceColumns = new Array(tokens.length);
let tokenIndex = 0;
let currentMapping = tokens[tokenIndex].start;
let lineStart = 0;
for (let i = 0; i < code.length; i++) {
if (i === currentMapping) {
sourceColumns[tokenIndex] = currentMapping - lineStart;
tokenIndex++;
currentMapping = tokens[tokenIndex].start;
}
if (code.charCodeAt(i) === charCodes.lineFeed) {
lineStart = i + 1;
}
}
return sourceColumns;
}