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prepend.js
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64 lines (62 loc) · 2.67 KB
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// @ts-check
const stream = require("stream");
const Vinyl = require("vinyl");
const ts = require("../../lib/typescript");
const fs = require("fs");
const { base64VLQFormatEncode } = require("./sourcemaps");
/**
* @param {string | ((file: import("vinyl")) => string)} data
*/
function prepend(data) {
return new stream.Transform({
objectMode: true,
/**
* @param {string | Buffer | import("vinyl")} input
* @param {(error: Error, data?: any) => void} cb
*/
transform(input, _, cb) {
if (typeof input === "string" || Buffer.isBuffer(input)) return cb(new Error("Only Vinyl files are supported."));
if (!input.isBuffer()) return cb(new Error("Streams not supported."));
try {
const output = input.clone();
const prependContent = typeof data === "function" ? data(input) : data;
output.contents = Buffer.concat([Buffer.from(prependContent, "utf8"), input.contents]);
if (input.sourceMap) {
if (typeof input.sourceMap === "string") input.sourceMap = /**@type {import("./sourcemaps").RawSourceMap}*/(JSON.parse(input.sourceMap));
const lineStarts = /**@type {*}*/(ts).computeLineStarts(prependContent);
let prependMappings = "";
for (let i = 1; i < lineStarts.length; i++) {
prependMappings += ";";
}
const offset = prependContent.length - lineStarts[lineStarts.length - 1];
if (offset > 0) {
prependMappings += base64VLQFormatEncode(offset) + ",";
}
output.sourceMap = {
version: input.sourceMap.version,
file: input.sourceMap.file,
sources: input.sourceMap.sources,
sourceRoot: input.sourceMap.sourceRoot,
mappings: prependMappings + input.sourceMap.mappings,
names: input.names,
sourcesContent: input.sourcesContent
};
}
return cb(null, output);
}
catch (e) {
return cb(e);
}
}
})
}
exports.prepend = prepend;
/**
* @param {string | ((file: import("vinyl")) => string)} file
*/
function prependFile(file) {
const data = typeof file === "string" ? fs.readFileSync(file, "utf8") :
vinyl => fs.readFileSync(file(vinyl), "utf8");
return prepend(data)
}
exports.prependFile = prependFile;