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Diffstat (limited to 'src/prompt_toolkit/lexers/pygments.py')
| -rw-r--r-- | src/prompt_toolkit/lexers/pygments.py | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/src/prompt_toolkit/lexers/pygments.py b/src/prompt_toolkit/lexers/pygments.py new file mode 100644 index 0000000..4721d73 --- /dev/null +++ b/src/prompt_toolkit/lexers/pygments.py @@ -0,0 +1,327 @@ +""" +Adaptor classes for using Pygments lexers within prompt_toolkit. + +This includes syntax synchronization code, so that we don't have to start +lexing at the beginning of a document, when displaying a very large text. +""" +from __future__ import annotations + +import re +from abc import ABCMeta, abstractmethod +from typing import TYPE_CHECKING, Callable, Dict, Generator, Iterable, Tuple + +from prompt_toolkit.document import Document +from prompt_toolkit.filters import FilterOrBool, to_filter +from prompt_toolkit.formatted_text.base import StyleAndTextTuples +from prompt_toolkit.formatted_text.utils import split_lines +from prompt_toolkit.styles.pygments import pygments_token_to_classname + +from .base import Lexer, SimpleLexer + +if TYPE_CHECKING: + from pygments.lexer import Lexer as PygmentsLexerCls + +__all__ = [ + "PygmentsLexer", + "SyntaxSync", + "SyncFromStart", + "RegexSync", +] + + +class SyntaxSync(metaclass=ABCMeta): + """ + Syntax synchronizer. This is a tool that finds a start position for the + lexer. This is especially important when editing big documents; we don't + want to start the highlighting by running the lexer from the beginning of + the file. That is very slow when editing. + """ + + @abstractmethod + def get_sync_start_position( + self, document: Document, lineno: int + ) -> tuple[int, int]: + """ + Return the position from where we can start lexing as a (row, column) + tuple. + + :param document: `Document` instance that contains all the lines. + :param lineno: The line that we want to highlight. (We need to return + this line, or an earlier position.) + """ + + +class SyncFromStart(SyntaxSync): + """ + Always start the syntax highlighting from the beginning. + """ + + def get_sync_start_position( + self, document: Document, lineno: int + ) -> tuple[int, int]: + return 0, 0 + + +class RegexSync(SyntaxSync): + """ + Synchronize by starting at a line that matches the given regex pattern. + """ + + # Never go more than this amount of lines backwards for synchronization. + # That would be too CPU intensive. + MAX_BACKWARDS = 500 + + # Start lexing at the start, if we are in the first 'n' lines and no + # synchronization position was found. + FROM_START_IF_NO_SYNC_POS_FOUND = 100 + + def __init__(self, pattern: str) -> None: + self._compiled_pattern = re.compile(pattern) + + def get_sync_start_position( + self, document: Document, lineno: int + ) -> tuple[int, int]: + """ + Scan backwards, and find a possible position to start. + """ + pattern = self._compiled_pattern + lines = document.lines + + # Scan upwards, until we find a point where we can start the syntax + # synchronization. + for i in range(lineno, max(-1, lineno - self.MAX_BACKWARDS), -1): + match = pattern.match(lines[i]) + if match: + return i, match.start() + + # No synchronization point found. If we aren't that far from the + # beginning, start at the very beginning, otherwise, just try to start + # at the current line. + if lineno < self.FROM_START_IF_NO_SYNC_POS_FOUND: + return 0, 0 + else: + return lineno, 0 + + @classmethod + def from_pygments_lexer_cls(cls, lexer_cls: PygmentsLexerCls) -> RegexSync: + """ + Create a :class:`.RegexSync` instance for this Pygments lexer class. + """ + patterns = { + # For Python, start highlighting at any class/def block. + "Python": r"^\s*(class|def)\s+", + "Python 3": r"^\s*(class|def)\s+", + # For HTML, start at any open/close tag definition. + "HTML": r"<[/a-zA-Z]", + # For javascript, start at a function. + "JavaScript": r"\bfunction\b", + # TODO: Add definitions for other languages. + # By default, we start at every possible line. + } + p = patterns.get(lexer_cls.name, "^") + return cls(p) + + +class _TokenCache(Dict[Tuple[str, ...], str]): + """ + Cache that converts Pygments tokens into `prompt_toolkit` style objects. + + ``Token.A.B.C`` will be converted into: + ``class:pygments,pygments.A,pygments.A.B,pygments.A.B.C`` + """ + + def __missing__(self, key: tuple[str, ...]) -> str: + result = "class:" + pygments_token_to_classname(key) + self[key] = result + return result + + +_token_cache = _TokenCache() + + +class PygmentsLexer(Lexer): + """ + Lexer that calls a pygments lexer. + + Example:: + + from pygments.lexers.html import HtmlLexer + lexer = PygmentsLexer(HtmlLexer) + + Note: Don't forget to also load a Pygments compatible style. E.g.:: + + from prompt_toolkit.styles.from_pygments import style_from_pygments_cls + from pygments.styles import get_style_by_name + style = style_from_pygments_cls(get_style_by_name('monokai')) + + :param pygments_lexer_cls: A `Lexer` from Pygments. + :param sync_from_start: Start lexing at the start of the document. This + will always give the best results, but it will be slow for bigger + documents. (When the last part of the document is display, then the + whole document will be lexed by Pygments on every key stroke.) It is + recommended to disable this for inputs that are expected to be more + than 1,000 lines. + :param syntax_sync: `SyntaxSync` object. + """ + + # Minimum amount of lines to go backwards when starting the parser. + # This is important when the lines are retrieved in reverse order, or when + # scrolling upwards. (Due to the complexity of calculating the vertical + # scroll offset in the `Window` class, lines are not always retrieved in + # order.) + MIN_LINES_BACKWARDS = 50 + + # When a parser was started this amount of lines back, read the parser + # until we get the current line. Otherwise, start a new parser. + # (This should probably be bigger than MIN_LINES_BACKWARDS.) + REUSE_GENERATOR_MAX_DISTANCE = 100 + + def __init__( + self, + pygments_lexer_cls: type[PygmentsLexerCls], + sync_from_start: FilterOrBool = True, + syntax_sync: SyntaxSync | None = None, + ) -> None: + self.pygments_lexer_cls = pygments_lexer_cls + self.sync_from_start = to_filter(sync_from_start) + + # Instantiate the Pygments lexer. + self.pygments_lexer = pygments_lexer_cls( + stripnl=False, stripall=False, ensurenl=False + ) + + # Create syntax sync instance. + self.syntax_sync = syntax_sync or RegexSync.from_pygments_lexer_cls( + pygments_lexer_cls + ) + + @classmethod + def from_filename( + cls, filename: str, sync_from_start: FilterOrBool = True + ) -> Lexer: + """ + Create a `Lexer` from a filename. + """ + # Inline imports: the Pygments dependency is optional! + from pygments.lexers import get_lexer_for_filename + from pygments.util import ClassNotFound + + try: + pygments_lexer = get_lexer_for_filename(filename) + except ClassNotFound: + return SimpleLexer() + else: + return cls(pygments_lexer.__class__, sync_from_start=sync_from_start) + + def lex_document(self, document: Document) -> Callable[[int], StyleAndTextTuples]: + """ + Create a lexer function that takes a line number and returns the list + of (style_str, text) tuples as the Pygments lexer returns for that line. + """ + LineGenerator = Generator[Tuple[int, StyleAndTextTuples], None, None] + + # Cache of already lexed lines. + cache: dict[int, StyleAndTextTuples] = {} + + # Pygments generators that are currently lexing. + # Map lexer generator to the line number. + line_generators: dict[LineGenerator, int] = {} + + def get_syntax_sync() -> SyntaxSync: + "The Syntax synchronization object that we currently use." + if self.sync_from_start(): + return SyncFromStart() + else: + return self.syntax_sync + + def find_closest_generator(i: int) -> LineGenerator | None: + "Return a generator close to line 'i', or None if none was found." + for generator, lineno in line_generators.items(): + if lineno < i and i - lineno < self.REUSE_GENERATOR_MAX_DISTANCE: + return generator + return None + + def create_line_generator(start_lineno: int, column: int = 0) -> LineGenerator: + """ + Create a generator that yields the lexed lines. + Each iteration it yields a (line_number, [(style_str, text), ...]) tuple. + """ + + def get_text_fragments() -> Iterable[tuple[str, str]]: + text = "\n".join(document.lines[start_lineno:])[column:] + + # We call `get_text_fragments_unprocessed`, because `get_tokens` will + # still replace \r\n and \r by \n. (We don't want that, + # Pygments should return exactly the same amount of text, as we + # have given as input.) + for _, t, v in self.pygments_lexer.get_tokens_unprocessed(text): + # Turn Pygments `Token` object into prompt_toolkit style + # strings. + yield _token_cache[t], v + + yield from enumerate(split_lines(list(get_text_fragments())), start_lineno) + + def get_generator(i: int) -> LineGenerator: + """ + Find an already started generator that is close, or create a new one. + """ + # Find closest line generator. + generator = find_closest_generator(i) + if generator: + return generator + + # No generator found. Determine starting point for the syntax + # synchronization first. + + # Go at least x lines back. (Make scrolling upwards more + # efficient.) + i = max(0, i - self.MIN_LINES_BACKWARDS) + + if i == 0: + row = 0 + column = 0 + else: + row, column = get_syntax_sync().get_sync_start_position(document, i) + + # Find generator close to this point, or otherwise create a new one. + generator = find_closest_generator(i) + if generator: + return generator + else: + generator = create_line_generator(row, column) + + # If the column is not 0, ignore the first line. (Which is + # incomplete. This happens when the synchronization algorithm tells + # us to start parsing in the middle of a line.) + if column: + next(generator) + row += 1 + + line_generators[generator] = row + return generator + + def get_line(i: int) -> StyleAndTextTuples: + "Return the tokens for a given line number." + try: + return cache[i] + except KeyError: + generator = get_generator(i) + + # Exhaust the generator, until we find the requested line. + for num, line in generator: + cache[num] = line + if num == i: + line_generators[generator] = i + + # Remove the next item from the cache. + # (It could happen that it's already there, because of + # another generator that started filling these lines, + # but we want to synchronize these lines with the + # current lexer's state.) + if num + 1 in cache: + del cache[num + 1] + + return cache[num] + return [] + + return get_line |