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massive speedup in sourcemaps.ts

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velzie 2024-09-02 14:20:45 -04:00
parent 7fa94bd9d3
commit 5d71685997
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4 changed files with 78 additions and 36 deletions
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62
src/client/shared/sourcemaps.ts
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@ -1,17 +1,17 @@
import { ScramjetClient } from "../client";
const sourcemaps: {
source: string;
map: [string, number, number][];
}[] = [];
type Mapping = [string, number, number];
const sourcemaps: Record<string, Mapping[]> = {};
export const enabled = () => self.$scramjet.config.flags.sourcemaps;
let t = 0;
export default function (client: ScramjetClient, self: Self) {
// every script will push a sourcemap
Object.defineProperty(self, "$scramjet$pushsourcemap", {
value: (map, source) => {
sourcemaps.push({ map, source });
value: (maps: Mapping[], tag: string) => {
sourcemaps[tag] = maps;
},
enumerable: false,
writable: false,
@ -22,44 +22,52 @@ export default function (client: ScramjetClient, self: Self) {
// this can lead to double rewrites which is bad
client.Proxy("Function.prototype.toString", {
apply(ctx) {
const stringified = ctx.fn.call(ctx.this);
let stringified: string = ctx.fn.call(ctx.this);
let newString = "";
// find the sourcemap, brute force, just check every file until the body of the function shows up
// it doesnt matter if there's multiple with the same content because it will be the same function
const sourcemap = sourcemaps.find(({ source }) =>
source.includes(stringified)
// every function rewritten will have a scramtag comment
// it will look like this:
// function name() /*scramtag [index] [tag] */ { ... }
const scramtag_ident = "/*scramtag ";
const scramtagstart = stringified.indexOf(scramtag_ident);
if (scramtagstart === -1) return ctx.return(stringified); // it's either a native function or something stolen from scramjet itself
// [index] holds the index of the first character in the scramtag (/)
const abstagindex = parseInt(
stringified
.substring(scramtagstart + scramtag_ident.length)
.split(" ")[0]
);
// i don't know what cases this would happen under, but it does
if (!sourcemap) return ctx.return(stringified);
const { source, map } = sourcemap;
// subtracting that from the index of the scramtag gives us the starting index of the function relative to the entire file
let absindex = abstagindex - scramtagstart;
// first we need to find the character # where the function starts relative to the *transformed* source
let starting = source.indexOf(stringified);
const scramtagend = stringified.indexOf("*/", scramtagstart);
const tag = stringified
.substring(scramtagstart + scramtag_ident.length, scramtagend)
.split(" ")[1];
const beforeFunctionRewrites = map.filter(
([str, start, end]) => start < starting
);
// delete the scramtag now that we're done with it
stringified =
stringified.slice(0, scramtagstart) +
stringified.slice(scramtagend + 2);
// map the offsets of the original source to the transformed source
for (const [str, start, end] of beforeFunctionRewrites) {
starting -= end - start - str.length;
}
const maps = sourcemaps[tag];
const relevantRewrites = map.filter(
const relevantRewrites = maps.filter(
([str, start, end]) =>
start >= starting && end <= starting + stringified.length
start >= absindex && end <= absindex + stringified.length
);
let i = 0;
let offset = 0;
for (const [str, start, end] of relevantRewrites) {
// ooh i should really document this before i forget how it works
newString += stringified.slice(i, start - starting + offset);
newString += stringified.slice(i, start - absindex + offset);
newString += str;
offset += end - start - str.length;
i = start - starting + offset + str.length;
i = start - absindex + offset + str.length;
}
return ctx.return(newString + stringified.slice(i));