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"""
Base classes for prompt_toolkit lexers.
"""
from abc import ABCMeta, abstractmethod
from typing import Callable, Hashable, Optional
from prompt_toolkit.document import Document
from prompt_toolkit.formatted_text.base import StyleAndTextTuples
__all__ = [
"Lexer",
"SimpleLexer",
"DynamicLexer",
]
class Lexer(metaclass=ABCMeta):
"""
Base class for all lexers.
"""
@abstractmethod
def lex_document(self, document: Document) -> Callable[[int], StyleAndTextTuples]:
"""
Takes a :class:`~prompt_toolkit.document.Document` and returns a
callable that takes a line number and returns a list of
``(style_str, text)`` tuples for that line.
XXX: Note that in the past, this was supposed to return a list
of ``(Token, text)`` tuples, just like a Pygments lexer.
"""
def invalidation_hash(self) -> Hashable:
"""
When this changes, `lex_document` could give a different output.
(Only used for `DynamicLexer`.)
"""
return id(self)
class SimpleLexer(Lexer):
"""
Lexer that doesn't do any tokenizing and returns the whole input as one
token.
:param style: The style string for this lexer.
"""
def __init__(self, style: str = "") -> None:
self.style = style
def lex_document(self, document: Document) -> Callable[[int], StyleAndTextTuples]:
lines = document.lines
def get_line(lineno: int) -> StyleAndTextTuples:
"Return the tokens for the given line."
try:
return [(self.style, lines[lineno])]
except IndexError:
return []
return get_line
class DynamicLexer(Lexer):
"""
Lexer class that can dynamically returns any Lexer.
:param get_lexer: Callable that returns a :class:`.Lexer` instance.
"""
def __init__(self, get_lexer: Callable[[], Optional[Lexer]]) -> None:
self.get_lexer = get_lexer
self._dummy = SimpleLexer()
def lex_document(self, document: Document) -> Callable[[int], StyleAndTextTuples]:
lexer = self.get_lexer() or self._dummy
return lexer.lex_document(document)
def invalidation_hash(self) -> Hashable:
lexer = self.get_lexer() or self._dummy
return id(lexer)
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