335 lines
13 KiB
Python
335 lines
13 KiB
Python
# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2024)
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import annotations
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import os
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import threading
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from pathlib import Path
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from typing import TYPE_CHECKING, Any, Callable, Final
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from streamlit import source_util
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from streamlit.logger import get_logger
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from streamlit.util import calc_md5
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from streamlit.watcher import watch_dir
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if TYPE_CHECKING:
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from streamlit.runtime.scriptrunner.script_cache import ScriptCache
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from streamlit.source_util import PageHash, PageInfo, PageName, ScriptPath
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_LOGGER: Final = get_logger(__name__)
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class PagesStrategyV1:
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"""
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Strategy for MPA v1. This strategy handles pages being set directly
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by a call to `st.navigation`. The key differences here are:
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- The pages are defined by the existence of a `pages` directory
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- We will ensure one watcher is watching the scripts in the directory.
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- Only one script runs for a full rerun.
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- We know at the beginning the intended page script to run.
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NOTE: Thread safety of the pages is handled by the source_util module
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"""
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is_watching_pages_dir: bool = False
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pages_watcher_lock = threading.Lock()
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# This is a static method because we only want to watch the pages directory
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# once on initial load.
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@staticmethod
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def watch_pages_dir(pages_manager: PagesManager):
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with PagesStrategyV1.pages_watcher_lock:
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if PagesStrategyV1.is_watching_pages_dir:
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return
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def _handle_page_changed(_path: str) -> None:
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source_util.invalidate_pages_cache()
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pages_dir = pages_manager.main_script_parent / "pages"
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watch_dir(
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str(pages_dir),
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_handle_page_changed,
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glob_pattern="*.py",
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allow_nonexistent=True,
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)
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PagesStrategyV1.is_watching_pages_dir = True
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def __init__(self, pages_manager: PagesManager, setup_watcher: bool = True):
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self.pages_manager = pages_manager
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if setup_watcher:
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PagesStrategyV1.watch_pages_dir(pages_manager)
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@property
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def initial_active_script_hash(self) -> PageHash:
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return self.pages_manager.current_page_script_hash
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def get_initial_active_script(
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self, page_script_hash: PageHash, page_name: PageName
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) -> PageInfo | None:
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pages = self.get_pages()
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if page_script_hash:
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return pages.get(page_script_hash, None)
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elif not page_script_hash and page_name:
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# If a user navigates directly to a non-main page of an app, we get
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# the first script run request before the list of pages has been
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# sent to the frontend. In this case, we choose the first script
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# with a name matching the requested page name.
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return next(
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filter(
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# There seems to be this weird bug with mypy where it
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# thinks that p can be None (which is impossible given the
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# types of pages), so we add `p and` at the beginning of
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# the predicate to circumvent this.
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lambda p: p and (p["page_name"] == page_name),
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pages.values(),
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),
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None,
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)
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# If no information about what page to run is given, default to
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# running the main page.
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# Safe because pages will at least contain the app's main page.
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main_page_info = list(pages.values())[0]
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return main_page_info
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def get_pages(self) -> dict[PageHash, PageInfo]:
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return source_util.get_pages(self.pages_manager.main_script_path)
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def register_pages_changed_callback(
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self,
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callback: Callable[[str], None],
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) -> Callable[[], None]:
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return source_util.register_pages_changed_callback(callback)
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def set_pages(self, _pages: dict[PageHash, PageInfo]) -> None:
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raise NotImplementedError("Unable to set pages in this V1 strategy")
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def get_page_script(self, _fallback_page_hash: PageHash) -> PageInfo | None:
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raise NotImplementedError("Unable to get page script in this V1 strategy")
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class PagesStrategyV2:
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"""
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Strategy for MPA v2. This strategy handles pages being set directly
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by a call to `st.navigation`. The key differences here are:
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- The pages are set directly by the user
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- The initial active script will always be the main script
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- More than one script can run in a single app run (sequentially),
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so we must keep track of the active script hash
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- We rely on pages manager to retrieve the intended page script per run
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NOTE: We don't provide any locks on the pages since the pages are not
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shared across sessions. Only the user script thread can write to
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pages and the event loop thread only reads
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"""
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def __init__(self, pages_manager: PagesManager, **kwargs):
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self.pages_manager = pages_manager
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self._pages: dict[PageHash, PageInfo] | None = None
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def get_initial_active_script(
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self, page_script_hash: PageHash, page_name: PageName
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) -> PageInfo:
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return {
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# We always run the main script in V2 as it's the common code
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"script_path": self.pages_manager.main_script_path,
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"page_script_hash": page_script_hash
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or self.pages_manager.main_script_hash, # Default Hash
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}
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@property
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def initial_active_script_hash(self) -> PageHash:
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return self.pages_manager.main_script_hash
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def get_page_script(self, fallback_page_hash: PageHash) -> PageInfo | None:
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if self._pages is None:
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return None
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if self.pages_manager.intended_page_script_hash:
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# We assume that if initial page hash is specified, that a page should
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# exist, so we check out the page script hash or the default page hash
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# as a backup
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return self._pages.get(
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self.pages_manager.intended_page_script_hash,
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self._pages.get(fallback_page_hash, None),
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)
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elif self.pages_manager.intended_page_name:
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# If a user navigates directly to a non-main page of an app, the
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# the page name can identify the page script to run
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return next(
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filter(
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# There seems to be this weird bug with mypy where it
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# thinks that p can be None (which is impossible given the
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# types of pages), so we add `p and` at the beginning of
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# the predicate to circumvent this.
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lambda p: p
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and (p["url_pathname"] == self.pages_manager.intended_page_name),
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self._pages.values(),
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),
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None,
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)
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return self._pages.get(fallback_page_hash, None)
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def get_pages(self) -> dict[PageHash, PageInfo]:
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# If pages are not set, provide the common page info where
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# - the main script path is the executing script to start
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# - the page script hash and name reflects the intended page requested
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return self._pages or {
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self.pages_manager.main_script_hash: {
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"page_script_hash": self.pages_manager.intended_page_script_hash or "",
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"page_name": self.pages_manager.intended_page_name or "",
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"icon": "",
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"script_path": self.pages_manager.main_script_path,
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}
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}
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def set_pages(self, pages: dict[PageHash, PageInfo]) -> None:
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self._pages = pages
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def register_pages_changed_callback(
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self,
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callback: Callable[[str], None],
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) -> Callable[[], None]:
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# V2 strategy does not handle any pages changed event
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return lambda: None
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class PagesManager:
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"""
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PagesManager is responsible for managing the set of pages based on the
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strategy. By default, PagesManager uses V1 which relies on the original
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assumption that there exists a `pages` directory with all the scripts.
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If the `pages` are being set directly, the strategy is switched to V2.
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This indicates someone has written an `st.navigation` call in their app
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which informs us of the pages.
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NOTE: Each strategy handles its own thread safety when accessing the pages
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"""
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DefaultStrategy: type[PagesStrategyV1 | PagesStrategyV2] = PagesStrategyV1
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def __init__(
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self,
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main_script_path: ScriptPath,
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script_cache: ScriptCache | None = None,
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**kwargs,
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):
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self._main_script_path = main_script_path
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self._main_script_hash: PageHash = calc_md5(main_script_path)
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self.pages_strategy = PagesManager.DefaultStrategy(self, **kwargs)
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self._script_cache = script_cache
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self._intended_page_script_hash: PageHash | None = None
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self._intended_page_name: PageName | None = None
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self._current_page_script_hash: PageHash = ""
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@property
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def main_script_path(self) -> ScriptPath:
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return self._main_script_path
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@property
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def main_script_parent(self) -> Path:
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return Path(self._main_script_path).parent
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@property
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def main_script_hash(self) -> PageHash:
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return self._main_script_hash
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@property
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def current_page_script_hash(self) -> PageHash:
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return self._current_page_script_hash
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@property
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def intended_page_name(self) -> PageName | None:
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return self._intended_page_name
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@property
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def intended_page_script_hash(self) -> PageHash | None:
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return self._intended_page_script_hash
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@property
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def initial_active_script_hash(self) -> PageHash:
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return self.pages_strategy.initial_active_script_hash
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@property
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def mpa_version(self) -> int:
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return 2 if isinstance(self.pages_strategy, PagesStrategyV2) else 1
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def set_current_page_script_hash(self, page_script_hash: PageHash) -> None:
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self._current_page_script_hash = page_script_hash
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def get_main_page(self) -> PageInfo:
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return {
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"script_path": self._main_script_path,
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"page_script_hash": self._main_script_hash,
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}
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def set_script_intent(
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self, page_script_hash: PageHash, page_name: PageName
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) -> None:
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self._intended_page_script_hash = page_script_hash
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self._intended_page_name = page_name
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def get_initial_active_script(
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self, page_script_hash: PageHash, page_name: PageName
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) -> PageInfo | None:
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return self.pages_strategy.get_initial_active_script(
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page_script_hash, page_name
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)
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def get_pages(self) -> dict[PageHash, PageInfo]:
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return self.pages_strategy.get_pages()
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def set_pages(self, pages: dict[PageHash, PageInfo]) -> None:
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# Manually setting the pages indicates we are using MPA v2.
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if isinstance(self.pages_strategy, PagesStrategyV1):
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if os.path.exists(self.main_script_parent / "pages"):
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_LOGGER.warning(
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"st.navigation was called in an app with a pages/ directory. This may cause unusual app behavior. You may want to rename the pages/ directory."
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)
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PagesManager.DefaultStrategy = PagesStrategyV2
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self.pages_strategy = PagesStrategyV2(self)
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self.pages_strategy.set_pages(pages)
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def get_page_script(self, fallback_page_hash: PageHash = "") -> PageInfo | None:
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# We assume the pages strategy is V2 cause this is used
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# in the st.navigation call, but we just swallow the error
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try:
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return self.pages_strategy.get_page_script(fallback_page_hash)
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except NotImplementedError:
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return None
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def register_pages_changed_callback(
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self,
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callback: Callable[[str], None],
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) -> Callable[[], None]:
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"""Register a callback to be called when the set of pages changes.
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The callback will be called with the path changed.
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"""
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return self.pages_strategy.register_pages_changed_callback(callback)
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def get_page_script_byte_code(self, script_path: str) -> Any:
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if self._script_cache is None:
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# Returning an empty string for an empty script
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return ""
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return self._script_cache.get_bytecode(script_path)
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