syntax.py

import os.path
import platform
import textwrap
from abc import ABC, abstractmethod
from typing import Any, Dict, Iterable, List, Optional, Set, Tuple, Type, Union

from pygments.lexer import Lexer
from pygments.lexers import get_lexer_by_name, guess_lexer_for_filename
from pygments.style import Style as PygmentsStyle
from pygments.styles import get_style_by_name
from pygments.token import (
    Comment,
    Error,
    Generic,
    Keyword,
    Name,
    Number,
    Operator,
    String,
    Token,
    Whitespace,
)
from pygments.util import ClassNotFound

from rich.containers import Lines

from ._loop import loop_first
from .color import Color, blend_rgb
from .console import Console, ConsoleOptions, JustifyMethod, RenderResult
from .jupyter import JupyterMixin
from .measure import Measurement
from .segment import Segment
from .style import Style
from .text import Text

TokenType = Tuple[str, ...]

WINDOWS = platform.system() == "Windows"
DEFAULT_THEME = "monokai"

# The following styles are based on https://github.com/pygments/pygments/blob/master/pygments/formatters/terminal.py
# A few modifications were made

ANSI_LIGHT: Dict[TokenType, Style] = {
    Token: Style(),
    Whitespace: Style(color="white"),
    Comment: Style(dim=True),
    Comment.Preproc: Style(color="cyan"),
    Keyword: Style(color="blue"),
    Keyword.Type: Style(color="cyan"),
    Operator.Word: Style(color="magenta"),
    Name.Builtin: Style(color="cyan"),
    Name.Function: Style(color="green"),
    Name.Namespace: Style(color="cyan", underline=True),
    Name.Class: Style(color="green", underline=True),
    Name.Exception: Style(color="cyan"),
    Name.Decorator: Style(color="magenta", bold=True),
    Name.Variable: Style(color="red"),
    Name.Constant: Style(color="red"),
    Name.Attribute: Style(color="cyan"),
    Name.Tag: Style(color="bright_blue"),
    String: Style(color="yellow"),
    Number: Style(color="blue"),
    Generic.Deleted: Style(color="bright_red"),
    Generic.Inserted: Style(color="green"),
    Generic.Heading: Style(bold=True),
    Generic.Subheading: Style(color="magenta", bold=True),
    Generic.Prompt: Style(bold=True),
    Generic.Error: Style(color="bright_red"),
    Error: Style(color="red", underline=True),
}

ANSI_DARK: Dict[TokenType, Style] = {
    Token: Style(),
    Whitespace: Style(color="bright_black"),
    Comment: Style(dim=True),
    Comment.Preproc: Style(color="bright_cyan"),
    Keyword: Style(color="bright_blue"),
    Keyword.Type: Style(color="bright_cyan"),
    Operator.Word: Style(color="bright_magenta"),
    Name.Builtin: Style(color="bright_cyan"),
    Name.Function: Style(color="bright_green"),
    Name.Namespace: Style(color="bright_cyan", underline=True),
    Name.Class: Style(color="bright_green", underline=True),
    Name.Exception: Style(color="bright_cyan"),
    Name.Decorator: Style(color="bright_magenta", bold=True),
    Name.Variable: Style(color="bright_red"),
    Name.Constant: Style(color="bright_red"),
    Name.Attribute: Style(color="bright_cyan"),
    Name.Tag: Style(color="bright_blue"),
    String: Style(color="yellow"),
    Number: Style(color="bright_blue"),
    Generic.Deleted: Style(color="bright_red"),
    Generic.Inserted: Style(color="bright_green"),
    Generic.Heading: Style(bold=True),
    Generic.Subheading: Style(color="bright_magenta", bold=True),
    Generic.Prompt: Style(bold=True),
    Generic.Error: Style(color="bright_red"),
    Error: Style(color="red", underline=True),
}

RICH_SYNTAX_THEMES = {"ansi_light": ANSI_LIGHT, "ansi_dark": ANSI_DARK}


class SyntaxTheme(ABC):
    """Base class for a syntax theme."""

    @abstractmethod
    def get_style_for_token(self, token_type: TokenType) -> Style:
        """Get a style for a given Pygments token."""
        raise NotImplementedError  # pragma: no cover

    @abstractmethod
    def get_background_style(self) -> Style:
        """Get the background color."""
        raise NotImplementedError  # pragma: no cover


class PygmentsSyntaxTheme(SyntaxTheme):
    """Syntax theme that delegates to Pygments theme."""

    def __init__(self, theme: Union[str, Type[PygmentsStyle]]) -> None:
        self._style_cache: Dict[TokenType, Style] = {}
        if isinstance(theme, str):
            try:
                self._pygments_style_class = get_style_by_name(theme)
            except ClassNotFound:
                self._pygments_style_class = get_style_by_name("default")
        else:
            self._pygments_style_class = theme

        self._background_color = self._pygments_style_class.background_color
        self._background_style = Style(bgcolor=self._background_color)

    def get_style_for_token(self, token_type: TokenType) -> Style:
        """Get a style from a Pygments class."""
        try:
            return self._style_cache[token_type]
        except KeyError:
            try:
                pygments_style = self._pygments_style_class.style_for_token(token_type)
            except KeyError:
                style = Style.null()
            else:
                color = pygments_style["color"]
                bgcolor = pygments_style["bgcolor"]
                style = Style(
                    color="#" + color if color else "#000000",
                    bgcolor="#" + bgcolor if bgcolor else self._background_color,
                    bold=pygments_style["bold"],
                    italic=pygments_style["italic"],
                    underline=pygments_style["underline"],
                )
            self._style_cache[token_type] = style
        return style

    def get_background_style(self) -> Style:
        return self._background_style


class ANSISyntaxTheme(SyntaxTheme):
    """Syntax theme to use standard colors."""

    def __init__(self, style_map: Dict[TokenType, Style]) -> None:
        self.style_map = style_map
        self._missing_style = Style.null()
        self._background_style = Style.null()
        self._style_cache: Dict[TokenType, Style] = {}

    def get_style_for_token(self, token_type: TokenType) -> Style:
        """Look up style in the style map."""
        try:
            return self._style_cache[token_type]
        except KeyError:
            # Styles form a hierarchy
            # We need to go from most to least specific
            # e.g. ("foo", "bar", "baz") to ("foo", "bar")  to ("foo",)
            get_style = self.style_map.get
            token = tuple(token_type)
            style = self._missing_style
            while token:
                _style = get_style(token)
                if _style is not None:
                    style = _style
                    break
                token = token[:-1]
            self._style_cache[token_type] = style
            return style

    def get_background_style(self) -> Style:
        return self._background_style


class Syntax(JupyterMixin):
    """Construct a Syntax object to render syntax highlighted code.

    Args:
        code (str): Code to highlight.
        lexer (Lexer | str): Lexer to use (see https://pygments.org/docs/lexers/)
        theme (str, optional): Color theme, aka Pygments style (see https://pygments.org/docs/styles/#getting-a-list-of-available-styles). Defaults to "monokai".
        dedent (bool, optional): Enable stripping of initial whitespace. Defaults to False.
        line_numbers (bool, optional): Enable rendering of line numbers. Defaults to False.
        start_line (int, optional): Starting number for line numbers. Defaults to 1.
        line_range (Tuple[int | None, int | None], optional): If given should be a tuple of the start and end line to render.
            A value of None in the tuple indicates the range is open in that direction.
        highlight_lines (Set[int]): A set of line numbers to highlight.
        code_width: Width of code to render (not including line numbers), or ``None`` to use all available width.
        tab_size (int, optional): Size of tabs. Defaults to 4.
        word_wrap (bool, optional): Enable word wrapping.
        background_color (str, optional): Optional background color, or None to use theme color. Defaults to None.
        indent_guides (bool, optional): Show indent guides. Defaults to False.
    """

    _pygments_style_class: Type[PygmentsStyle]
    _theme: SyntaxTheme

    @classmethod
    def get_theme(cls, name: Union[str, SyntaxTheme]) -> SyntaxTheme:
        """Get a syntax theme instance."""
        if isinstance(name, SyntaxTheme):
            return name
        theme: SyntaxTheme
        if name in RICH_SYNTAX_THEMES:
            theme = ANSISyntaxTheme(RICH_SYNTAX_THEMES[name])
        else:
            theme = PygmentsSyntaxTheme(name)
        return theme

    def __init__(
        self,
        code: str,
        lexer: Union[Lexer, str],
        *,
        theme: Union[str, SyntaxTheme] = DEFAULT_THEME,
        dedent: bool = False,
        line_numbers: bool = False,
        start_line: int = 1,
        line_range: Optional[Tuple[Optional[int], Optional[int]]] = None,
        highlight_lines: Optional[Set[int]] = None,
        code_width: Optional[int] = None,
        tab_size: int = 4,
        word_wrap: bool = False,
        background_color: Optional[str] = None,
        indent_guides: bool = False,
    ) -> None:
        self.code = code
        self._lexer = lexer
        self.dedent = dedent
        self.line_numbers = line_numbers
        self.start_line = start_line
        self.line_range = line_range
        self.highlight_lines = highlight_lines or set()
        self.code_width = code_width
        self.tab_size = tab_size
        self.word_wrap = word_wrap
        self.background_color = background_color
        self.background_style = (
            Style(bgcolor=background_color) if background_color else Style()
        )
        self.indent_guides = indent_guides

        self._theme = self.get_theme(theme)

    @classmethod
    def from_path(
        cls,
        path: str,
        encoding: str = "utf-8",
        lexer: Optional[Union[Lexer, str]] = None,
        theme: Union[str, SyntaxTheme] = DEFAULT_THEME,
        dedent: bool = False,
        line_numbers: bool = False,
        line_range: Optional[Tuple[int, int]] = None,
        start_line: int = 1,
        highlight_lines: Optional[Set[int]] = None,
        code_width: Optional[int] = None,
        tab_size: int = 4,
        word_wrap: bool = False,
        background_color: Optional[str] = None,
        indent_guides: bool = False,
    ) -> "Syntax":
        """Construct a Syntax object from a file.

        Args:
            path (str): Path to file to highlight.
            encoding (str): Encoding of file.
            lexer (str | Lexer, optional): Lexer to use. If None, lexer will be auto-detected from path/file content.
            theme (str, optional): Color theme, aka Pygments style (see https://pygments.org/docs/styles/#getting-a-list-of-available-styles). Defaults to "emacs".
            dedent (bool, optional): Enable stripping of initial whitespace. Defaults to True.
            line_numbers (bool, optional): Enable rendering of line numbers. Defaults to False.
            start_line (int, optional): Starting number for line numbers. Defaults to 1.
            line_range (Tuple[int, int], optional): If given should be a tuple of the start and end line to render.
            highlight_lines (Set[int]): A set of line numbers to highlight.
            code_width: Width of code to render (not including line numbers), or ``None`` to use all available width.
            tab_size (int, optional): Size of tabs. Defaults to 4.
            word_wrap (bool, optional): Enable word wrapping of code.
            background_color (str, optional): Optional background color, or None to use theme color. Defaults to None.
            indent_guides (bool, optional): Show indent guides. Defaults to False.

        Returns:
            [Syntax]: A Syntax object that may be printed to the console
        """
        with open(path, "rt", encoding=encoding) as code_file:
            code = code_file.read()

        if not lexer:
            lexer = cls.guess_lexer(path, code=code)

        return cls(
            code,
            lexer,
            theme=theme,
            dedent=dedent,
            line_numbers=line_numbers,
            line_range=line_range,
            start_line=start_line,
            highlight_lines=highlight_lines,
            code_width=code_width,
            tab_size=tab_size,
            word_wrap=word_wrap,
            background_color=background_color,
            indent_guides=indent_guides,
        )

    @classmethod
    def guess_lexer(cls, path: str, code: Optional[str] = None) -> str:
        """Guess the alias of the Pygments lexer to use based on a path and an optional string of code.
        If code is supplied, it will use a combination of the code and the filename to determine the
        best lexer to use. For example, if the file is ``index.html`` and the file contains Django
        templating syntax, then "html+django" will be returned. If the file is ``index.html``, and no
        templating language is used, the "html" lexer will be used. If no string of code
        is supplied, the lexer will be chosen based on the file extension..

        Args:
             path (AnyStr): The path to the file containing the code you wish to know the lexer for.
             code (str, optional): Optional string of code that will be used as a fallback if no lexer
                is found for the supplied path.

        Returns:
            str: The name of the Pygments lexer that best matches the supplied path/code.
        """
        lexer: Optional[Lexer] = None
        lexer_name = "default"
        if code:
            try:
                lexer = guess_lexer_for_filename(path, code)
            except ClassNotFound:
                pass

        if not lexer:
            try:
                _, ext = os.path.splitext(path)
                if ext:
                    extension = ext.lstrip(".").lower()
                    lexer = get_lexer_by_name(extension)
            except ClassNotFound:
                pass

        if lexer:
            if lexer.aliases:
                lexer_name = lexer.aliases[0]
            else:
                lexer_name = lexer.name

        return lexer_name

    def _get_base_style(self) -> Style:
        """Get the base style."""
        default_style = self._theme.get_background_style() + self.background_style
        return default_style

    def _get_token_color(self, token_type: TokenType) -> Optional[Color]:
        """Get a color (if any) for the given token.

        Args:
            token_type (TokenType): A token type tuple from Pygments.

        Returns:
            Optional[Color]: Color from theme, or None for no color.
        """
        style = self._theme.get_style_for_token(token_type)
        return style.color

    @property
    def lexer(self) -> Optional[Lexer]:
        """The lexer for this syntax, or None if no lexer was found.

        Tries to find the lexer by name if a string was passed to the constructor.
        """

        if isinstance(self._lexer, Lexer):
            return self._lexer
        try:
            return get_lexer_by_name(
                self._lexer,
                stripnl=False,
                ensurenl=True,
                tabsize=self.tab_size,
            )
        except ClassNotFound:
            return None

    def highlight(
        self,
        code: str,
        line_range: Optional[Tuple[Optional[int], Optional[int]]] = None,
    ) -> Text:
        """Highlight code and return a Text instance.

        Args:
            code (str): Code to highlight.
            line_range(Tuple[int, int], optional): Optional line range to highlight.

        Returns:
            Text: A text instance containing highlighted syntax.
        """

        base_style = self._get_base_style()
        justify: JustifyMethod = (
            "default" if base_style.transparent_background else "left"
        )

        text = Text(
            justify=justify,
            style=base_style,
            tab_size=self.tab_size,
            no_wrap=not self.word_wrap,
        )
        _get_theme_style = self._theme.get_style_for_token

        lexer = self.lexer

        if lexer is None:
            text.append(code)
        else:
            if line_range:
                # More complicated path to only stylize a portion of the code
                # This speeds up further operations as there are less spans to process
                line_start, line_end = line_range

                def line_tokenize() -> Iterable[Tuple[Any, str]]:
                    """Split tokens to one per line."""
                    assert lexer

                    for token_type, token in lexer.get_tokens(code):
                        while token:
                            line_token, new_line, token = token.partition("\n")
                            yield token_type, line_token + new_line

                def tokens_to_spans() -> Iterable[Tuple[str, Optional[Style]]]:
                    """Convert tokens to spans."""
                    tokens = iter(line_tokenize())
                    line_no = 0
                    _line_start = line_start - 1 if line_start else 0

                    # Skip over tokens until line start
                    while line_no < _line_start:
                        _token_type, token = next(tokens)
                        yield (token, None)
                        if token.endswith("\n"):
                            line_no += 1
                    # Generate spans until line end
                    for token_type, token in tokens:
                        yield (token, _get_theme_style(token_type))
                        if token.endswith("\n"):
                            line_no += 1
                            if line_end and line_no >= line_end:
                                break

                text.append_tokens(tokens_to_spans())

            else:
                text.append_tokens(
                    (token, _get_theme_style(token_type))
                    for token_type, token in lexer.get_tokens(code)
                )
            if self.background_color is not None:
                text.stylize(f"on {self.background_color}")
        return text

    def _get_line_numbers_color(self, blend: float = 0.3) -> Color:
        background_style = self._theme.get_background_style() + self.background_style
        background_color = background_style.bgcolor
        if background_color is None or background_color.is_system_defined:
            return Color.default()
        foreground_color = self._get_token_color(Token.Text)
        if foreground_color is None or foreground_color.is_system_defined:
            return foreground_color or Color.default()
        new_color = blend_rgb(
            background_color.get_truecolor(),
            foreground_color.get_truecolor(),
            cross_fade=blend,
        )
        return Color.from_triplet(new_color)

    @property
    def _numbers_column_width(self) -> int:
        """Get the number of characters used to render the numbers column."""
        column_width = 0
        if self.line_numbers:
            column_width = len(str(self.start_line + self.code.count("\n"))) + 2
        return column_width

    def _get_number_styles(self, console: Console) -> Tuple[Style, Style, Style]:
        """Get background, number, and highlight styles for line numbers."""
        background_style = self._get_base_style()
        if background_style.transparent_background:
            return Style.null(), Style(dim=True), Style.null()
        if console.color_system in ("256", "truecolor"):
            number_style = Style.chain(
                background_style,
                self._theme.get_style_for_token(Token.Text),
                Style(color=self._get_line_numbers_color()),
                self.background_style,
            )
            highlight_number_style = Style.chain(
                background_style,
                self._theme.get_style_for_token(Token.Text),
                Style(bold=True, color=self._get_line_numbers_color(0.9)),
                self.background_style,
            )
        else:
            number_style = background_style + Style(dim=True)
            highlight_number_style = background_style + Style(dim=False)
        return background_style, number_style, highlight_number_style

    def __rich_measure__(
        self, console: "Console", options: "ConsoleOptions"
    ) -> "Measurement":
        if self.code_width is not None:
            width = self.code_width + self._numbers_column_width
            return Measurement(self._numbers_column_width, width)
        return Measurement(self._numbers_column_width, options.max_width)

    def __rich_console__(
        self, console: Console, options: ConsoleOptions
    ) -> RenderResult:

        transparent_background = self._get_base_style().transparent_background
        code_width = (
            (
                (options.max_width - self._numbers_column_width - 1)
                if self.line_numbers
                else options.max_width
            )
            if self.code_width is None
            else self.code_width
        )

        ends_on_nl = self.code.endswith("\n")
        code = self.code if ends_on_nl else self.code + "\n"
        code = textwrap.dedent(code) if self.dedent else code
        code = code.expandtabs(self.tab_size)
        text = self.highlight(code, self.line_range)

        (
            background_style,
            number_style,
            highlight_number_style,
        ) = self._get_number_styles(console)

        if not self.line_numbers and not self.word_wrap and not self.line_range:
            if not ends_on_nl:
                text.remove_suffix("\n")
            # Simple case of just rendering text
            style = (
                self._get_base_style()
                + self._theme.get_style_for_token(Comment)
                + Style(dim=True)
                + self.background_style
            )
            if self.indent_guides and not options.ascii_only:
                text = text.with_indent_guides(self.tab_size, style=style)
                text.overflow = "crop"
            if style.transparent_background:
                yield from console.render(
                    text, options=options.update(width=code_width)
                )
            else:
                syntax_lines = console.render_lines(
                    text,
                    options.update(width=code_width, height=None, justify="left"),
                    style=self.background_style,
                    pad=True,
                    new_lines=True,
                )
                for syntax_line in syntax_lines:
                    yield from syntax_line
            return

        start_line, end_line = self.line_range or (None, None)
        line_offset = 0
        if start_line:
            line_offset = max(0, start_line - 1)
        lines: Union[List[Text], Lines] = text.split("\n", allow_blank=ends_on_nl)
        if self.line_range:
            lines = lines[line_offset:end_line]

        if self.indent_guides and not options.ascii_only:
            style = (
                self._get_base_style()
                + self._theme.get_style_for_token(Comment)
                + Style(dim=True)
                + self.background_style
            )
            lines = (
                Text("\n")
                .join(lines)
                .with_indent_guides(self.tab_size, style=style)
                .split("\n", allow_blank=True)
            )

        numbers_column_width = self._numbers_column_width
        render_options = options.update(width=code_width)

        highlight_line = self.highlight_lines.__contains__
        _Segment = Segment
        padding = _Segment(" " * numbers_column_width + " ", background_style)
        new_line = _Segment("\n")

        line_pointer = "> " if options.legacy_windows else "❱ "

        for line_no, line in enumerate(lines, self.start_line + line_offset):
            if self.word_wrap:
                wrapped_lines = console.render_lines(
                    line,
                    render_options.update(height=None, justify="left"),
                    style=background_style,
                    pad=not transparent_background,
                )

            else:
                segments = list(line.render(console, end=""))
                if options.no_wrap:
                    wrapped_lines = [segments]
                else:
                    wrapped_lines = [
                        _Segment.adjust_line_length(
                            segments,
                            render_options.max_width,
                            style=background_style,
                            pad=not transparent_background,
                        )
                    ]
            if self.line_numbers:
                for first, wrapped_line in loop_first(wrapped_lines):
                    if first:
                        line_column = str(line_no).rjust(numbers_column_width - 2) + " "
                        if highlight_line(line_no):
                            yield _Segment(line_pointer, Style(color="red"))
                            yield _Segment(line_column, highlight_number_style)
                        else:
                            yield _Segment("  ", highlight_number_style)
                            yield _Segment(line_column, number_style)
                    else:
                        yield padding
                    yield from wrapped_line
                    yield new_line
            else:
                for wrapped_line in wrapped_lines:
                    yield from wrapped_line
                    yield new_line


if __name__ == "__main__":  # pragma: no cover

    import argparse
    import sys

    parser = argparse.ArgumentParser(
        description="Render syntax to the console with Rich"
    )
    parser.add_argument(
        "path",
        metavar="PATH",
        help="path to file, or - for stdin",
    )
    parser.add_argument(
        "-c",
        "--force-color",
        dest="force_color",
        action="store_true",
        default=None,
        help="force color for non-terminals",
    )
    parser.add_argument(
        "-i",
        "--indent-guides",
        dest="indent_guides",
        action="store_true",
        default=False,
        help="display indent guides",
    )
    parser.add_argument(
        "-l",
        "--line-numbers",
        dest="line_numbers",
        action="store_true",
        help="render line numbers",
    )
    parser.add_argument(
        "-w",
        "--width",
        type=int,
        dest="width",
        default=None,
        help="width of output (default will auto-detect)",
    )
    parser.add_argument(
        "-r",
        "--wrap",
        dest="word_wrap",
        action="store_true",
        default=False,
        help="word wrap long lines",
    )
    parser.add_argument(
        "-s",
        "--soft-wrap",
        action="store_true",
        dest="soft_wrap",
        default=False,
        help="enable soft wrapping mode",
    )
    parser.add_argument(
        "-t", "--theme", dest="theme", default="monokai", help="pygments theme"
    )
    parser.add_argument(
        "-b",
        "--background-color",
        dest="background_color",
        default=None,
        help="Override background color",
    )
    parser.add_argument(
        "-x",
        "--lexer",
        default="default",
        dest="lexer_name",
        help="Lexer name",
    )
    args = parser.parse_args()

    from rich.console import Console

    console = Console(force_terminal=args.force_color, width=args.width)

    if args.path == "-":
        code = sys.stdin.read()
        syntax = Syntax(
            code=code,
            lexer=args.lexer_name,
            line_numbers=args.line_numbers,
            word_wrap=args.word_wrap,
            theme=args.theme,
            background_color=args.background_color,
            indent_guides=args.indent_guides,
        )
    else:
        syntax = Syntax.from_path(
            args.path,
            lexer=args.lexer_name,
            line_numbers=args.line_numbers,
            word_wrap=args.word_wrap,
            theme=args.theme,
            background_color=args.background_color,
            indent_guides=args.indent_guides,
        )
    console.print(syntax, soft_wrap=args.soft_wrap)