Joscha
96f29a49cf
Attributes can be set and deleted on sections of a MarkedUp object. Chunk attributes work like dicts (name + arbitrary value). This can be used to set color info or attach a link/URL to parts of a string, for example.
198 lines
5.1 KiB
Python
198 lines
5.1 KiB
Python
from typing import Any, Dict, List, Optional, Union
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__all__ = ["Attributes", "Chunk", "MarkedUp"]
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Attributes = Dict[str, Any]
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class Chunk:
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@staticmethod
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def join_chunks(chunks: List["Chunk"]) -> List["Chunk"]:
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if not chunks:
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return []
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new_chunks: List[Chunk] = []
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current_chunk = chunks[0]
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for chunk in chunks[1:]:
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joined_chunk = current_chunk._join(chunk)
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if joined_chunk is None:
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new_chunks.append(current_chunk)
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current_chunk = chunk
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else:
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current_chunk = joined_chunk
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new_chunks.append(current_chunk)
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return new_chunks
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# Common special methods
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def __init__(self,
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text: str,
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attributes: Attributes = {},
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) -> None:
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self._text = text
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self._attributes = dict(attributes)
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def __str__(self) -> str:
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return self.text
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def __repr__(self) -> str:
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return f"Chunk({self.text!r}, {self._attributes!r})"
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# Uncommon special methods
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def __getitem__(self, key: Union[int, slice]) -> "Chunk":
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return Chunk(self.text[key], self._attributes)
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def __len__(self) -> int:
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return len(self.text)
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# Properties
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@property
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def text(self) -> str:
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return self._text
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@property
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def attrs(self) -> Attributes:
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return dict(self._attributes)
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# Private methods
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def _join(self, chunk: "Chunk") -> Optional["Chunk"]:
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if self._attributes == chunk._attributes:
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return Chunk(self.text + chunk.text, self._attributes)
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else:
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return None
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# Public methods
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def with_attribute(self, name: str, value: Any) -> "Chunk":
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new_attributes = dict(self._attributes)
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new_attributes[name] = value
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return Chunk(self.text, new_attributes)
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def without_attribute(self, name: str) -> "Chunk":
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new_attributes = dict(self._attributes)
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# This removes the value with that key, if it exists, and does nothing
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# if it doesn't exist. (Since we give a default value, no KeyError is
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# raised if the key isn't found.)
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new_attributes.pop(name, None)
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return Chunk(self.text, new_attributes)
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class MarkedUp:
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"""
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Objects of this class are immutable and behave str-like. Supported
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operations are len, + and splicing.
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"""
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@classmethod
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def from_chunks(cls, chunks: List[Chunk]) -> "MarkedUp":
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new = cls()
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new._chunks = Chunk.join_chunks(chunks)
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return new
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# Common special methods
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def __init__(self, text: Optional[str] = None) -> None:
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self._chunks: List[Chunk] = []
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if text is not None:
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self._chunks.append(Chunk(text))
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def __str__(self) -> str:
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return "".join(map(str, self._chunks))
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def __repr__(self) -> str:
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return f"MarkedUp.from_chunks({self._chunks!r})"
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# Uncommon special methods
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def __add__(self, other: "MarkedUp") -> "MarkedUp":
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return MarkedUp.from_chunks(self._pieces + other._pieces)
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def __getitem__(self, key: Union[int, slice]) -> "MarkedUp":
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chunks: List[Chunk]
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if isinstance(key, slice):
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chunks = Chunk.join_chunks(self._slice(key))
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else:
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chunks = [self._at(key)]
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return MarkedUp.from_chunks(chunks)
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def __len__(self) -> int:
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return sum(map(len, self._chunks))
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# Properties
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@property
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def chunks(self) -> List[Chunk]:
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return list(self._chunks)
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# Private methods
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def _at(self, key: int) -> Chunk:
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if key < 0:
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key = len(self) + key
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pos = 0
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for chunk in self._chunks:
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chunk_key = key - pos
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if 0 <= chunk_key < len(chunk):
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return chunk[chunk_key]
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pos += len(chunk)
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else:
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raise KeyError
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def _slice(self, key: slice) -> List[Chunk]:
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start, stop, step = key.start, key.stop, key.step
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if start is None:
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start = 0
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elif start < 0:
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start = len(self) + start
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if stop is None:
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stop = len(self)
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elif stop < 0:
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stop = len(self) + stop
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pos = 0 # cursor position
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resulting_chunks = []
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for chunk in self._chunks:
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chunk_start = start - pos
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chunk_stop = stop - pos
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offset: Optional[int] = None
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if step is not None:
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offset = (start - pos) % step
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if chunk_stop <= 0 or chunk_start >= len(chunk):
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pass
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elif chunk_start < 0 and chunk_stop > len(chunk):
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resulting_chunks.append(chunk[offset::step])
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elif chunk_start < 0:
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resulting_chunks.append(chunk[offset:chunk_stop:step])
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elif chunk_stop > len(chunk):
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resulting_chunks.append(chunk[chunk_start::step])
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else:
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resulting_chunks.append(chunk[chunk_start:chunk_stop:step])
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pos += len(chunk)
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return resulting_chunks
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# Public methods
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def attrs(self, key: int) -> Attributes:
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return self._at(key).attrs
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