94 lines
3.2 KiB
Python
94 lines
3.2 KiB
Python
"""
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Completer for a regular grammar.
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"""
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from typing import Dict, Iterable, List
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from prompt_toolkit.completion import CompleteEvent, Completer, Completion
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from prompt_toolkit.document import Document
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from .compiler import Match, _CompiledGrammar
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__all__ = [
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"GrammarCompleter",
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]
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class GrammarCompleter(Completer):
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"""
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Completer which can be used for autocompletion according to variables in
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the grammar. Each variable can have a different autocompleter.
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:param compiled_grammar: `GrammarCompleter` instance.
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:param completers: `dict` mapping variable names of the grammar to the
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`Completer` instances to be used for each variable.
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"""
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def __init__(
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self, compiled_grammar: _CompiledGrammar, completers: Dict[str, Completer]
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) -> None:
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self.compiled_grammar = compiled_grammar
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self.completers = completers
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def get_completions(
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self, document: Document, complete_event: CompleteEvent
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) -> Iterable[Completion]:
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m = self.compiled_grammar.match_prefix(document.text_before_cursor)
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if m:
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completions = self._remove_duplicates(
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self._get_completions_for_match(m, complete_event)
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)
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for c in completions:
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yield c
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def _get_completions_for_match(
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self, match: Match, complete_event: CompleteEvent
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) -> Iterable[Completion]:
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"""
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Yield all the possible completions for this input string.
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(The completer assumes that the cursor position was at the end of the
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input string.)
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"""
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for match_variable in match.end_nodes():
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varname = match_variable.varname
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start = match_variable.start
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completer = self.completers.get(varname)
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if completer:
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text = match_variable.value
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# Unwrap text.
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unwrapped_text = self.compiled_grammar.unescape(varname, text)
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# Create a document, for the completions API (text/cursor_position)
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document = Document(unwrapped_text, len(unwrapped_text))
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# Call completer
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for completion in completer.get_completions(document, complete_event):
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new_text = (
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unwrapped_text[: len(text) + completion.start_position]
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+ completion.text
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)
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# Wrap again.
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yield Completion(
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text=self.compiled_grammar.escape(varname, new_text),
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start_position=start - len(match.string),
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display=completion.display,
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display_meta=completion.display_meta,
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)
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def _remove_duplicates(self, items: Iterable[Completion]) -> List[Completion]:
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"""
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Remove duplicates, while keeping the order.
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(Sometimes we have duplicates, because the there several matches of the
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same grammar, each yielding similar completions.)
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"""
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result: List[Completion] = []
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for i in items:
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if i not in result:
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result.append(i)
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return result
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