Directory Search Library

Problem Description

Implement a small in-memory directory search API.

You are given a directory tree where each node has:

• name: str
• is_file: bool
• size: int (bytes, only meaningful for files)
• children: List[node] (only for directories)

Write:

findMatchingPaths(root, min_size, extension) -> List[str]

Requirements:

• Return file paths that match all provided filters.
• If min_size is None, ignore size filter.
• If extension is None, ignore extension filter.
• Use composition-style matcher logic, not hardcoded nested conditions.
• Output should be sorted lexicographically for deterministic results.

Example

min_size = 5_000_000
extension = "xml"
=> return all .xml files >= 5MB

Follow-up

• Add or/not matchers.
• Add cycle protection if symbolic links are introduced.