Text variants generation

variant-tree.py

"""
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or
distribute this software, either in source code form or as a compiled
binary, for any purpose, commercial or non-commercial, and by any
means.
In jurisdictions that recognize copyright laws, the author or authors
of this software dedicate any and all copyright interest in the
software to the public domain. We make this dedication for the benefit
of the public at large and to the detriment of our heirs and
successors. We intend this dedication to be an overt act of
relinquishment in perpetuity of all present and future rights to this
software under copyright law.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
For more information, please refer to <http://unlicense.org/>
"""
from __future__ import annotations
import json
from typing import Callable, Dict, List, Union


def identity(string: str) -> str:
    return string


class VariantTree:
    def __init__(
        self,
        original: str,
        transformer: Callable[[str], str] = identity,
        width: int = 3,
        depth: int = 3,
    ) -> None:
        """A class to perform variant generation.

        Use the .fit() method to actually perform variant generation.
        """
        self.width = width
        self.depth = depth
        self.original = original
        self.transformer = transformer
        self._levels: List[Dict[str, List[str]]] = []

    def dict(self) -> Dict[str, Union[List[str], Dict[str, List[str]]]]:
        """Return a dict representation of the tree.

        Dict is empty until tree is fitted (fitting can be done using .fit() method)
        """
        # Create dicts from bottom to top
        _tree: Dict[str, Union[List[str], Dict[str, List[str]]]] = dict()
        # Iterate from bottom to top
        for level in reversed(self._levels):
            # Create tree using bottom values
            if not _tree:
                _tree.update(level)
            else:
                # Create new tree
                _tree = {
                    key: {subkey: _tree[subkey] for subkey in values}  # type: ignore[misc]
                    for key, values in level.items()
                }
        return _tree

    def __repr__(self) -> str:
        """String representation of the tree"""
        return "Tree(" + json.dumps(self.dict(), indent=2) + ")"

    def _apply_once(self, value: str) -> List[str]:
        """Apply transformation on a single value"""
        return [self.transformer(value) for _ in range(self.width)]

    def fit(self) -> VariantTree:
        """Fit the tree, I.E, generate variants"""
        # Empty levels
        self._levels = []
        # Get first variants
        first_variants = self._apply_once(self.original)
        # Append first level
        self._levels.append({self.original: first_variants})
        # Keep track of remaining depth
        remaining_depth = self.depth - 1
        # Loop while there is reamining depth
        while remaining_depth >= 0:
            # Initialize new level
            new_level: Dict[str, List[str]] = {}
            # Gather values from last levels
            for values in self._levels[-1].values():
                for value in values:
                    new_variants = self._apply_once(value)
                    # FIXME: There might be a conflict here !!
                    # Because all keys are at the same level regardless of parent,
                    # if two ancestor lead to same text, the "oldest" will be forgotten
                    # Even indexing using tuple(ancestor, new_value) will not work
                    # We need an index
                    new_level[value] = new_variants
            # Append new level
            self._levels.append(new_level)
            # Decrease remaining depth
            remaining_depth -= 1
        # Return self
        return self


if __name__ == "__main__":
    import random

    def transform(value: str) -> str:
        value_list = list(value)
        random.shuffle(value_list)
        return "".join(value_list)

    tree = VariantTree("Hello world!", transformer=transform, width=2, depth=2)