Add support for shiny mode magic comment

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Pending Next Release
 
+### Added
+- Added support for deploying interactive Quarto dashboards that use Shiny Express syntax.
+
 ### Changed
 
 - When deploying Shiny for Python applications on servers using a version of

pyproject.toml

@@ -8,6 +8,7 @@ readme = { file = "README.md", content-type = "text/markdown" }
 requires-python = ">=3.8"
 
 dependencies = [
+    "typing-extensions>=4.10.0",
     "six>=1.14.0",
     "pip>=10.0.0",
     "semver>=2.0.0,<3.0.0",

rsconnect/shiny_express.py

@@ -4,8 +4,10 @@
 from __future__ import annotations
 
 import ast
-from pathlib import Path
 import re
+import sys
+from pathlib import Path
+from typing import Literal, cast
 
 __all__ = ("is_express_app",)
 
@@ -39,8 +41,16 @@ def is_express_app(app: str, app_dir: str | None) -> bool:
 
     try:
         # Read the file, parse it, and look for any imports of shiny.express.
-        with open(app_path) as f:
+        with open(app_path, encoding="utf-8") as f:
             content = f.read()
+
+        # Check for magic comment in the first 1000 characters
+        forced_mode = find_magic_comment_mode(content[:1000])
+        if forced_mode == "express":
+            return True
+        elif forced_mode == "core":
+            return False
+
         tree = ast.parse(content, app_path)
         detector = DetectShinyExpressVisitor()
         detector.visit(tree)
@@ -56,25 +66,52 @@ def __init__(self):
         super().__init__()
         self.found_shiny_express_import = False
 
-    def visit_Import(self, node: ast.Import):
+    def visit_Import(self, node: ast.Import) -> None:
         if any(alias.name == "shiny.express" for alias in node.names):
             self.found_shiny_express_import = True
 
-    def visit_ImportFrom(self, node: ast.ImportFrom):
+    def visit_ImportFrom(self, node: ast.ImportFrom) -> None:
         if node.module == "shiny.express":
             self.found_shiny_express_import = True
         elif node.module == "shiny" and any(alias.name == "express" for alias in node.names):
             self.found_shiny_express_import = True
 
     # Visit top-level nodes.
-    def visit_Module(self, node: ast.Module):
+    def visit_Module(self, node: ast.Module) -> None:
         super().generic_visit(node)
 
     # Don't recurse into any nodes, so the we'll only ever look at top-level nodes.
-    def generic_visit(self, node: ast.AST):
+    def generic_visit(self, node: ast.AST) -> None:
         pass
 
 
+def find_magic_comment_mode(content: str) -> Literal["core", "express"] | None:
+    """
+    Look for a magic comment of the form "# shiny_mode: express" or "# shiny_mode:
+    core".
+
+    If a line of the form "# shiny_mode: x" is found, where "x" is not "express" or
+    "core", then a message will be printed to stderr.
+
+    Returns
+    -------
+    :
+        `"express"` if Shiny Express comment is found, `"core"` if Shiny Core comment is
+        found, and `None` if no magic comment is found.
+    """
+    m = re.search(r"^#[ \t]*shiny_mode:[ \t]*(\S*)[ \t]*$", content, re.MULTILINE)
+    if m is not None:
+        shiny_mode = cast(str, m.group(1))
+        if shiny_mode in ("express", "core"):
+            # The "type: ignore" is needed for mypy, which is used on some projects that
+            # use duplicates of this code.
+            return shiny_mode # type: ignore
+        else:
+            print(f'Invalid shiny_mode: "{shiny_mode}"', file=sys.stderr)
+
+    return None
+
+
 def escape_to_var_name(x: str) -> str:
     """
     Given a string, escape it to a valid Python variable name which contains

tests/test_shiny_express.py

@@ -0,0 +1,52 @@
+from pathlib import Path
+
+from rsconnect import shiny_express as express
+
+def test_is_express_app(tmp_path: Path):
+    tmp_file = str(tmp_path / "app.py")
+
+    def write_tmp_file(s: str):
+        with open(tmp_file, "w") as f:
+            f.write(s)
+
+    write_tmp_file("import shiny.express")
+    assert express.is_express_app(tmp_file, None)
+    # Check that it works when passing in app_path
+    assert express.is_express_app("app.py", str(tmp_path))
+
+    write_tmp_file("# comment\nimport sys\n\nimport shiny.express")
+    assert express.is_express_app(tmp_file, None)
+
+    write_tmp_file("import sys\n\nfrom shiny import App, express")
+    assert express.is_express_app(tmp_file, None)
+
+    write_tmp_file("import sys\n\nfrom shiny.express import layout, input")
+    assert express.is_express_app(tmp_file, None)
+
+    # Shouldn't find in comment
+    write_tmp_file("# import shiny.express")
+    assert not express.is_express_app(tmp_file, None)
+
+    # Shouldn't find in a string, even if it looks like an import
+    write_tmp_file('"""\nimport shiny.express\n"""')
+    assert not express.is_express_app(tmp_file, None)
+
+    # Shouldn't recurse into with, if, for, def, etc.
+    write_tmp_file("with f:\n  from shiny import express")
+    assert not express.is_express_app(tmp_file, None)
+
+    write_tmp_file("if True:\n  import shiny.express")
+    assert not express.is_express_app(tmp_file, None)
+
+    write_tmp_file("for i in range(2):\n  import shiny.express")
+    assert not express.is_express_app(tmp_file, None)
+
+    write_tmp_file("def f():\n  import shiny.express")
+    assert not express.is_express_app(tmp_file, None)
+
+    # Look for magic comment - should override import detection
+    write_tmp_file("\n#shiny_mode: core\nfrom shiny.express import ui")
+    assert not express.is_express_app(tmp_file, None)
+
+    write_tmp_file("#shiny_mode: express\nfrom shiny import ui")
+    assert express.is_express_app(tmp_file, None)