live.py

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import sys
from threading import Event, RLock, Thread
from types import TracebackType
from typing import IO, Any, Callable, List, Optional, TextIO, Type, cast
 
from . import get_console
from .console import Console, ConsoleRenderable, RenderableType, RenderHook
from .control import Control
from .file_proxy import FileProxy
from .jupyter import JupyterMixin
from .live_render import LiveRender, VerticalOverflowMethod
from .screen import Screen
from .text import Text
 
 
class _RefreshThread(Thread):
    """A thread that calls refresh() at regular intervals."""
 
    def __init__(self, live: "Live", refresh_per_second: float) -> None:
        self.live = live
        self.refresh_per_second = refresh_per_second
        self.done = Event()
        super().__init__(daemon=True)
 
    def stop(self) -> None:
        self.done.set()
 
    def run(self) -> None:
        while not self.done.wait(1 / self.refresh_per_second):
            with self.live._lock:
                if not self.done.is_set():
                    self.live.refresh()
 
 
class Live(JupyterMixin, RenderHook):
    """Renders an auto-updating live display of any given renderable.
 
    Args:
        renderable (RenderableType, optional): The renderable to live display. Defaults to displaying nothing.
        console (Console, optional): Optional Console instance. Default will an internal Console instance writing to stdout.
        screen (bool, optional): Enable alternate screen mode. Defaults to False.
        auto_refresh (bool, optional): Enable auto refresh. If disabled, you will need to call `refresh()` or `update()` with refresh flag. Defaults to True
        refresh_per_second (float, optional): Number of times per second to refresh the live display. Defaults to 4.
        transient (bool, optional): Clear the renderable on exit (has no effect when screen=True). Defaults to False.
        redirect_stdout (bool, optional): Enable redirection of stdout, so ``print`` may be used. Defaults to True.
        redirect_stderr (bool, optional): Enable redirection of stderr. Defaults to True.
        vertical_overflow (VerticalOverflowMethod, optional): How to handle renderable when it is too tall for the console. Defaults to "ellipsis".
        get_renderable (Callable[[], RenderableType], optional): Optional callable to get renderable. Defaults to None.
    """
 
    def __init__(
        self,
        renderable: Optional[RenderableType] = None,
        *,
        console: Optional[Console] = None,
        screen: bool = False,
        auto_refresh: bool = True,
        refresh_per_second: float = 4,
        transient: bool = False,
        redirect_stdout: bool = True,
        redirect_stderr: bool = True,
        vertical_overflow: VerticalOverflowMethod = "ellipsis",
        get_renderable: Optional[Callable[[], RenderableType]] = None,
    ) -> None:
        assert refresh_per_second > 0, "refresh_per_second must be > 0"
        self._renderable = renderable
        self.console = console if console is not None else get_console()
        self._screen = screen
        self._alt_screen = False
 
        self._redirect_stdout = redirect_stdout
        self._redirect_stderr = redirect_stderr
        self._restore_stdout: Optional[IO[str]] = None
        self._restore_stderr: Optional[IO[str]] = None
 
        self._lock = RLock()
        self.ipy_widget: Optional[Any] = None
        self.auto_refresh = auto_refresh
        self._started: bool = False
        self.transient = True if screen else transient
 
        self._refresh_thread: Optional[_RefreshThread] = None
        self.refresh_per_second = refresh_per_second
 
        self.vertical_overflow = vertical_overflow
        self._get_renderable = get_renderable
        self._live_render = LiveRender(
            self.get_renderable(), vertical_overflow=vertical_overflow
        )
 
    @property
    def is_started(self) -> bool:
        """Check if live display has been started."""
        return self._started
 
    def get_renderable(self) -> RenderableType:
        renderable = (
            self._get_renderable()
            if self._get_renderable is not None
            else self._renderable
        )
        return renderable or ""
 
    def start(self, refresh: bool = False) -> None:
        """Start live rendering display.
 
        Args:
            refresh (bool, optional): Also refresh. Defaults to False.
        """
        with self._lock:
            if self._started:
                return
            self.console.set_live(self)
            self._started = True
            if self._screen:
                self._alt_screen = self.console.set_alt_screen(True)
            self.console.show_cursor(False)
            self._enable_redirect_io()
            self.console.push_render_hook(self)
            if refresh:
                try:
                    self.refresh()
                except Exception:
                    # If refresh fails, we want to stop the redirection of sys.stderr,
                    # so the error stacktrace is properly displayed in the terminal.
                    # (or, if the code that calls Rich captures the exception and wants to display something,
                    # let this be displayed in the terminal).
                    self.stop()
                    raise
            if self.auto_refresh:
                self._refresh_thread = _RefreshThread(self, self.refresh_per_second)
                self._refresh_thread.start()
 
    def stop(self) -> None:
        """Stop live rendering display."""
        with self._lock:
            if not self._started:
                return
            self.console.clear_live()
            self._started = False
 
            if self.auto_refresh and self._refresh_thread is not None:
                self._refresh_thread.stop()
                self._refresh_thread = None
            # allow it to fully render on the last even if overflow
            self.vertical_overflow = "visible"
            with self.console:
                try:
                    if not self._alt_screen and not self.console.is_jupyter:
                        self.refresh()
                finally:
                    self._disable_redirect_io()
                    self.console.pop_render_hook()
                    if not self._alt_screen and self.console.is_terminal:
                        self.console.line()
                    self.console.show_cursor(True)
                    if self._alt_screen:
                        self.console.set_alt_screen(False)
 
                    if self.transient and not self._alt_screen:
                        self.console.control(self._live_render.restore_cursor())
                    if self.ipy_widget is not None and self.transient:
                        self.ipy_widget.close()  # pragma: no cover
 
    def __enter__(self) -> "Live":
        self.start(refresh=self._renderable is not None)
        return self
 
    def __exit__(
        self,
        exc_type: Optional[Type[BaseException]],
        exc_val: Optional[BaseException],
        exc_tb: Optional[TracebackType],
    ) -> None:
        self.stop()
 
    def _enable_redirect_io(self) -> None:
        """Enable redirecting of stdout / stderr."""
        if self.console.is_terminal or self.console.is_jupyter:
            if self._redirect_stdout and not isinstance(sys.stdout, FileProxy):
                self._restore_stdout = sys.stdout
                sys.stdout = cast("TextIO", FileProxy(self.console, sys.stdout))
            if self._redirect_stderr and not isinstance(sys.stderr, FileProxy):
                self._restore_stderr = sys.stderr
                sys.stderr = cast("TextIO", FileProxy(self.console, sys.stderr))
 
    def _disable_redirect_io(self) -> None:
        """Disable redirecting of stdout / stderr."""
        if self._restore_stdout:
            sys.stdout = cast("TextIO", self._restore_stdout)
            self._restore_stdout = None
        if self._restore_stderr:
            sys.stderr = cast("TextIO", self._restore_stderr)
            self._restore_stderr = None
 
    @property
    def renderable(self) -> RenderableType:
        """Get the renderable that is being displayed
 
        Returns:
            RenderableType: Displayed renderable.
        """
        renderable = self.get_renderable()
        return Screen(renderable) if self._alt_screen else renderable
 
    def update(self, renderable: RenderableType, *, refresh: bool = False) -> None:
        """Update the renderable that is being displayed
 
        Args:
            renderable (RenderableType): New renderable to use.
            refresh (bool, optional): Refresh the display. Defaults to False.
        """
        if isinstance(renderable, str):
            renderable = self.console.render_str(renderable)
        with self._lock:
            self._renderable = renderable
            if refresh:
                self.refresh()
 
    def refresh(self) -> None:
        """Update the display of the Live Render."""
        with self._lock:
            self._live_render.set_renderable(self.renderablerenderable)
            if self.console.is_jupyter:  # pragma: no cover
                try:
                    from IPython.display import display
                    from ipywidgets import Output
                except ImportError:
                    import warnings
 
                    warnings.warn('install "ipywidgets" for Jupyter support')
                else:
                    if self.ipy_widget is None:
                        self.ipy_widget = Output()
                        display(self.ipy_widget)
 
                    with self.ipy_widget:
                        self.ipy_widget.clear_output(wait=True)
                        self.console.print(self._live_render.renderable)
            elif self.console.is_terminal and not self.console.is_dumb_terminal:
                with self.console:
                    self.console.print(Control())
            elif (
                not self._started and not self.transient
            ):  # if it is finished allow files or dumb-terminals to see final result
                with self.console:
                    self.console.print(Control())
 
    def process_renderables(
        self, renderables: List[ConsoleRenderable]
    ) -> List[ConsoleRenderable]:
        """Process renderables to restore cursor and display progress."""
        self._live_render.vertical_overflow = self.vertical_overflow
        if self.console.is_interactive:
            # lock needs acquiring as user can modify live_render renderable at any time unlike in Progress.
            with self._lock:
                reset = (
                    Control.home()
                    if self._alt_screen
                    else self._live_render.position_cursor()
                )
                renderables = [reset, *renderables, self._live_render]
        elif (
            not self._started and not self.transient
        ):  # if it is finished render the final output for files or dumb_terminals
            renderables = [*renderables, self._live_render]
 
        return renderables
 
 
if __name__ == "__main__":  # pragma: no cover
    import random
    import time
    from itertools import cycle
    from typing import Dict, List, Tuple
 
    from .align import Align
    from .console import Console
    from .live import Live as Live
    from .panel import Panel
    from .rule import Rule
    from .syntax import Syntax
    from .table import Table
 
    console = Console()
 
    syntax = Syntax(
        '''def loop_last(values: Iterable[T]) -> Iterable[Tuple[bool, T]]:
    """Iterate and generate a tuple with a flag for last value."""
    iter_values = iter(values)
    try:
        previous_value = next(iter_values)
    except StopIteration:
        return
    for value in iter_values:
        yield False, previous_value
        previous_value = value
    yield True, previous_value''',
        "python",
        line_numbers=True,
    )
 
    table = Table("foo", "bar", "baz")
    table.add_row("1", "2", "3")
 
    progress_renderables = [
        "You can make the terminal shorter and taller to see the live table hide"
        "Text may be printed while the progress bars are rendering.",
        Panel("In fact, [i]any[/i] renderable will work"),
        "Such as [magenta]tables[/]...",
        table,
        "Pretty printed structures...",
        {"type": "example", "text": "Pretty printed"},
        "Syntax...",
        syntax,
        Rule("Give it a try!"),
    ]
 
    examples = cycle(progress_renderables)
 
    exchanges = [
        "SGD",
        "MYR",
        "EUR",
        "USD",
        "AUD",
        "JPY",
        "CNH",
        "HKD",
        "CAD",
        "INR",
        "DKK",
        "GBP",
        "RUB",
        "NZD",
        "MXN",
        "IDR",
        "TWD",
        "THB",
        "VND",
    ]
    with Live(console=console) as live_table:
        exchange_rate_dict: Dict[Tuple[str, str], float] = {}
 
        for index in range(100):
            select_exchange = exchanges[index % len(exchanges)]
 
            for exchange in exchanges:
                if exchange == select_exchange:
                    continue
                time.sleep(0.4)
                if random.randint(0, 10) < 1:
                    console.log(next(examples))
                exchange_rate_dict[(select_exchange, exchange)] = 200 / (
                    (random.random() * 320) + 1
                )
                if len(exchange_rate_dict) > len(exchanges) - 1:
                    exchange_rate_dict.pop(list(exchange_rate_dict.keys())[0])
                table = Table(title="Exchange Rates")
 
                table.add_column("Source Currency")
                table.add_column("Destination Currency")
                table.add_column("Exchange Rate")
 
                for ((source, dest), exchange_rate) in exchange_rate_dict.items():
                    table.add_row(
                        source,
                        dest,
                        Text(
                            f"{exchange_rate:.4f}",
                            style="red" if exchange_rate < 1.0 else "green",
                        ),
                    )
 
                live_table.update(Align.center(table))