81 lines
2.7 KiB
Python
81 lines
2.7 KiB
Python
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"""Methods for traversing trees of otData-driven OpenType tables."""
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from collections import deque
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from typing import Callable, Deque, Iterable, List, Optional, Tuple
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from .otBase import BaseTable
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__all__ = [
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"bfs_base_table",
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"dfs_base_table",
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]
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SubTablePath = Tuple[BaseTable.SubTableEntry, ...]
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# Given f(current frontier, new entries) add new entries to frontier
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AddToFrontierFn = Callable[[Deque[SubTablePath], List[SubTablePath]], None]
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def dfs_base_table(
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root: BaseTable, root_accessor: Optional[str] = None
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) -> Iterable[SubTablePath]:
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"""Depth-first search tree of BaseTables.
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Args:
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root (BaseTable): the root of the tree.
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root_accessor (Optional[str]): attribute name for the root table, if any (mostly
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useful for debugging).
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Yields:
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SubTablePath: tuples of BaseTable.SubTableEntry(name, table, index) namedtuples
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for each of the nodes in the tree. The last entry in a path is the current
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subtable, whereas preceding ones refer to its parent tables all the way up to
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the root.
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"""
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yield from _traverse_ot_data(
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root, root_accessor, lambda frontier, new: frontier.extendleft(reversed(new))
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)
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def bfs_base_table(
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root: BaseTable, root_accessor: Optional[str] = None
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) -> Iterable[SubTablePath]:
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"""Breadth-first search tree of BaseTables.
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Args:
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root (BaseTable): the root of the tree.
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root_accessor (Optional[str]): attribute name for the root table, if any (mostly
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useful for debugging).
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Yields:
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SubTablePath: tuples of BaseTable.SubTableEntry(name, table, index) namedtuples
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for each of the nodes in the tree. The last entry in a path is the current
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subtable, whereas preceding ones refer to its parent tables all the way up to
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the root.
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"""
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yield from _traverse_ot_data(
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root, root_accessor, lambda frontier, new: frontier.extend(new)
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)
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def _traverse_ot_data(
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root: BaseTable, root_accessor: Optional[str], add_to_frontier_fn: AddToFrontierFn
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) -> Iterable[SubTablePath]:
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# no visited because general otData cannot cycle (forward-offset only)
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if root_accessor is None:
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root_accessor = type(root).__name__
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frontier: Deque[SubTablePath] = deque()
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frontier.append((BaseTable.SubTableEntry(root_accessor, root),))
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while frontier:
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# path is (value, attr_name) tuples. attr_name is attr of parent to get value
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path = frontier.popleft()
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current = path[-1].value
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yield path
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new_entries = []
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for subtable_entry in current.iterSubTables():
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new_entries.append(path + (subtable_entry,))
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add_to_frontier_fn(frontier, new_entries)
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