103 lines
3.2 KiB
Python
103 lines
3.2 KiB
Python
from .element import Id, RenderedElement
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__all__ = ["TreeList"]
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class TreeList:
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def __init__(self,
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tree: List[RenderedElement],
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anchor_id: Id,
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) -> None:
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self._deque = collections.deque()
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self._anchor_id = anchor_id
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# The offsets can be thought of as the index of a line relative to the
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# anchor's first line.
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#
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# The upper offset is the index of the uppermost message's first line.
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# upper_offset <= 0.
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#
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# The lower offset is the index of the lowermost message's LAST line.
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# lower_offset >= 0.
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self._upper_offset: Int
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self._lower_offset: Int
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# The upper and lower tree ids are the ids of the uppermost or
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# lowermost tree added to the TreeList. They can be used to request the
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# previous or next tree from an ElementSupply.
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self._upper_tree_id: Id
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self._lower_tree_id: Id
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self._add_first_tree(tree)
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@property
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def upper_offset(self) -> Int:
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return self._upper_offset
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@property
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def lower_offset(self) -> Int:
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return self._lower_offset
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@property
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def upper_tree_id(self) -> Id:
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return self._upper_tree_id
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@property
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def lower_tree_id(self) -> Id:
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return self._lower_tree_id
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def _add_first_tree(self, tree: List[RenderedElement]) -> None:
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if len(tree) == 0:
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raise ValueError("The tree must contain at least one element")
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tree_id = tree[0].element.id
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self._upper_tree_id = tree_id
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self._lower_tree_id = tree_id
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offset = 0
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found_anchor = False
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for rendered in elements:
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if rendered.element.id == anchor_id:
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found_anchor = True
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self._upper_offset = -offset
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offset += rendered.height
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if not found_anchor:
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raise ValueError("The initial tree must contain the anchor")
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# Subtracting 1 because the lower offset is the index of the lowermost
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# message's last line, not the first line of a hypothetical message
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# below that.
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self._lower_offset = offset - 1
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def add_above(self, tree: List[RenderedElement]) -> None:
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if len(tree) == 0:
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raise ValueError("The tree must contain at least one element")
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self._upper_tree_id = tree[0].element.id
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for rendered in reversed(tree):
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self._deque.appendleft(rendered)
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self._upper_offset -= rendered.height
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# Alternative to the above for loop
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#delta = sum(map(lambda r: r.height, tree))
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#self._upper_offset -= delta
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#self._deque.extendLeft(reversed(tree))
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def add_below(self, tree: List[RenderedElement]) -> None:
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if len(tree) == 0:
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raise ValueError("The tree must contain at least one element")
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self._lower_tree_id = tree[0].element.id
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for rendered in tree:
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self._deque.append(rendered)
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self._lower_offset += rendered.height
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# Alternative to the above for loop
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#delta = sum(map(lambda r: r.height, tree))
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#self._lower_offset += delta
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#self._deque.extend(tree)
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