53 lines
2.6 KiB
TypeScript
53 lines
2.6 KiB
TypeScript
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import { execFile as callback } from "node:child_process";
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import { promisify } from "node:util";
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const execFile = promisify(callback);
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export const nixLiteral = (value: string): string => JSON.stringify(value).replace(/\$\{/g, "\\${");
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/** Recognize the deliberately small scaffold edit surface, never evaluate Nix.
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* Authors may replace it with arbitrary Nix; then scaffolding declines the edit. */
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export async function componentEntries(source: string): Promise<Record<string, { entry: string; export: string }>> {
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const { stdout } = await execFile("nix-instantiate", ["--parse", "--expr", source], { maxBuffer: 1024 * 1024 });
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const tokens = stdout.match(/"(?:\\.|[^"\\])*"|[A-Za-z_][A-Za-z0-9_-]*|[{}=;]/g) ?? [];
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if (stdout.replace(/"(?:\\.|[^"\\])*"|[A-Za-z_][A-Za-z0-9_-]*|[{}=;]|\s+/g, ""))
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throw Error("components.nix is outside the supported literal-entry shape");
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let cursor = 0;
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const expect = (token: string) => {
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if (tokens[cursor++] !== token) throw Error("components.nix is outside the supported literal-entry shape");
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};
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const string = () => {
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const token = tokens[cursor++];
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if (!token?.startsWith('"')) throw Error("Component entries must use literal strings");
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const json = token.replace(/(\\*)\$\{/g, (_match, escapes: string) => {
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if (escapes.length % 2 === 0) throw Error("Component entries must use literal strings");
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return escapes.slice(1) + "${";
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});
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return JSON.parse(json) as string;
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};
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const entries: Record<string, { entry: string; export: string }> = Object.create(null);
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expect("{");
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while (tokens[cursor] !== "}") {
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const id = tokens[cursor]?.startsWith('"') ? string() : tokens[cursor++];
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if (!id) throw Error("Missing component identity");
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if (Object.hasOwn(entries, id)) throw Error("Duplicate component entry");
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expect("=");
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expect("{");
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const properties: Record<string, string> = Object.create(null);
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while (tokens[cursor] !== "}") {
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const key = tokens[cursor]?.startsWith('"') ? string() : tokens[cursor++];
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if (!key || !["entry", "export"].includes(key) || Object.hasOwn(properties, key))
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throw Error("Unsupported component entry property");
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expect("=");
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properties[key] = string();
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expect(";");
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}
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expect("}");
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expect(";");
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if (!properties.entry || !properties.export) throw Error("Component entry needs entry and export");
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entries[id] = { entry: properties.entry, export: properties.export };
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}
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expect("}");
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if (cursor !== tokens.length || !/\n}\s*$/.test(source))
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throw Error("components.nix is outside the supported scaffold shape");
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return entries;
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}
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