Persisted List

History

Date	Comment
2025-06-13	New elements come first
	Copied from: explain_java.py

from typing import List
from pathlib import Path

class PersistedList:
    """
    A tiny helper that remembers a list of strings on disk.
    """

    def __init__(self, filename: str) -> None:
        self.filename = Path(filename)
        self.names: List[str] = self._read_from_file()

    # ──────────────────────────────────────────────────────────────
    # Private helpers
    # ──────────────────────────────────────────────────────────────

    def _read_from_file(self) -> List[str]:
        """
        Return the list stored on disk (empty if the file is missing).
        """
        if self.filename.exists():
            with self.filename.open("r", encoding="utf-8") as fh:
                return [line.strip() for line in fh if line.strip()]
        return []

    def _write_to_file(self) -> None:
        """
        Persist the current list to disk (one item per line).
        """
        self.filename.parent.mkdir(parents=True, exist_ok=True)
        with self.filename.open("w", encoding="utf-8") as fh:
            fh.write("\n".join(self.names))

    @staticmethod
    def _remove_strings(source: List[str], to_remove: List[str]) -> List[str]:
        """
        Return a copy of *source* without any element that occurs in *to_remove*.
        """
        removal_set = set(to_remove)
        return [s for s in source if s not in removal_set]

    # ──────────────────────────────────────────────────────────────
    # Public API
    # ──────────────────────────────────────────────────────────────

    def sort_by_pattern(self, all_names: List[str]) -> List[str]:
        """
        Sort *all_names* so that previously‑stored names keep their old
        ordering, and every new name is appended alphabetically.
        The internal list is updated and re‑written to disk.
        """
        priority = {name: idx for idx, name in enumerate(self.names)}

        sorted_names = sorted(
            all_names,
            key=lambda n: (1, priority[n]) if n in priority else (0, n)
        )

        self.names = sorted_names
        self._write_to_file()
        return sorted_names

    def select(self, selected_name: str) -> None:
        """
        Move *selected_name* to the top of the list (inserting it if it
        wasn’t present) and persist the change.
        """
        self.names = self._remove_strings(self.names, [selected_name])
        self.names.insert(0, selected_name)
        self._write_to_file()

    # ──────────────────────────────────────────────────────────────
    # Convenience
    # ──────────────────────────────────────────────────────────────

    def __iter__(self):
        return iter(self.names)

    def __repr__(self) -> str:
        return f"{self.__class__.__name__}({self.filename!s}, {self.names})"