Function buildImportGraph

src/context/import-graph.ts:157–192

(
  root: string,
  files: Array<{ rel: string; content?: string }>,
  read?: (rel: string) => Promise<string | null>,
)

/** Build the import graph for a set of files. `read` lets callers inject cached content. */
export async function buildImportGraph(
  root: string,
  files: Array<{ rel: string; content?: string }>,
  read?: (rel: string) => Promise<string | null>,
): Promise<ImportGraph> {
  const fileSet = new Set(files.map(f => f.rel));
  const basenameIndex = new Map<string, string[]>();
  for (const f of fileSet) {
    const base = path.basename(f).replace(path.extname(f), '');
    const arr = basenameIndex.get(base) ?? [];
    arr.push(f);
    basenameIndex.set(base, arr);
  }

  const out = new Map<string, Set<string>>();
  const inMap = new Map<string, Set<string>>();
  for (const f of fileSet) { out.set(f, new Set()); inMap.set(f, new Set()); }

  for (const f of files) {
    let content = f.content;
    if (content == null) {
      content = read ? await read(f.rel) ?? undefined : await fs.readFile(path.join(root, f.rel), 'utf-8').catch(() => undefined);
    }
    if (!content) continue;
    const specs = extractImportSpecifiers(content, detectLang(f.rel));
    for (const spec of specs) {
      const target = resolveSpecifier(spec, f.rel, fileSet, basenameIndex);
      if (target && target !== f.rel) {
        out.get(f.rel)!.add(target);
        inMap.get(target)!.add(f.rel);
      }
    }
  }

  return { out, in: inMap, files: fileSet };
}

/**
 * Expand a seed set of files by following import edges up to `hops` hops in BOTH