Initial work of ESM transformation

font-src/gen/caching/index.mjs

@@ -0,0 +1,98 @@
+import fs from "fs";
+import zlib from "zlib";
+import { encode, decode } from "@msgpack/msgpack";
+
+const Edition = 20;
+const MAX_AGE = 16;
+class GfEntry {
+	constructor(age, value) {
+		this.age = age;
+		this.value = value;
+	}
+}
+class Cache {
+	constructor(freshAgeKey) {
+		this.freshAgeKey = freshAgeKey;
+		this.historyAgeKeys = [];
+		this.gf = new Map();
+		this.diff = new Set();
+	}
+	loadRep(version, rep) {
+		if (!rep || rep.version !== version + "@" + Edition) return;
+		this.historyAgeKeys = rep.ageKeys.slice(0, MAX_AGE);
+		const ageKeySet = new Set(this.historyAgeKeys);
+		for (const [k, e] of Object.entries(rep.gf)) {
+			if (ageKeySet.has(e.age)) this.gf.set(k, new GfEntry(e.age, e.value));
+		}
+	}
+	toRep(version, diffOnly) {
+		let gfRep = {};
+		for (const [k, e] of this.gf) {
+			if (!diffOnly || this.diff.has(k)) {
+				gfRep[k] = { age: e.age, value: e.value };
+			}
+		}
+		const mergedAgeKeys =
+			this.historyAgeKeys[0] === this.freshAgeKey
+				? this.historyAgeKeys
+				: [this.freshAgeKey, ...this.historyAgeKeys];
+		return {
+			version: version + "@" + Edition,
+			ageKeys: mergedAgeKeys,
+			gf: gfRep
+		};
+	}
+	isEmpty() {
+		return this.gf.size == 0;
+	}
+	isUpdated() {
+		return this.diff.size != 0;
+	}
+	// Geometry flattening conversion cache
+	getGF(k) {
+		const entry = this.gf.get(k);
+		if (!entry) return undefined;
+		else return entry.value;
+	}
+	refreshGF(k) {
+		const entry = this.gf.get(k);
+		if (!entry) return;
+		if (entry.age != this.freshAgeKey) {
+			this.diff.add(k);
+			entry.age = this.freshAgeKey;
+		}
+	}
+	saveGF(k, v) {
+		this.gf.set(k, new GfEntry(this.freshAgeKey, v));
+		this.diff.add(k);
+	}
+	merge(other) {
+		for (const [k, e] of other.gf) {
+			this.gf.set(k, e);
+		}
+	}
+}
+export const load = async function (path, version, freshAgeKey) {
+	let cache = new Cache(freshAgeKey);
+	if (path && fs.existsSync(path)) {
+		const buf = zlib.gunzipSync(await fs.promises.readFile(path));
+		cache.loadRep(version, decode(buf));
+	}
+	return cache;
+};
+export const save = async function savePTCache(path, version, cache, diffOnly) {
+	if (path) {
+		const buf = encode(cache.toRep(version, diffOnly));
+		const bufZip = zlib.gzipSync(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength));
+		await fs.promises.writeFile(path, bufZip);
+	}
+};
+export const merge = async function (base, diff, version, freshAgeKey) {
+	const cacheDiff = await load(diff, version, freshAgeKey);
+	if (!cacheDiff.isEmpty()) {
+		const cacheBase = await load(base, version, freshAgeKey);
+		cacheBase.merge(cacheDiff);
+		await save(base, version, cacheBase, false);
+	}
+	if (fs.existsSync(diff)) await fs.promises.rm(diff);
+};