sagemathgh-39015: Meson: add sage cli
    
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes sagemath#12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes sagemath#12345". -->

Meson currently doesn't install any of the scripts in `src/bin`. This is
because
- they mostly don't make sense for meson - especially doctests, sage
packages interactions and various other developer tools shouldn't be
installed for normal users
- they rely on tricky environment variable manipulation
- they use bash and thus do not work on Windows

Here, we reimplement a very small subset of the sage cli functionality
in Python without any env hacks. At the moment only `--version`, the
interactive sage shell, `--notebook` and `-c` are implemented

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [ ] The title is concise and informative.
- [ ] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
    
URL: sagemath#39015
Reported by: Tobias Diez
Reviewer(s): Dima Pasechnik, Gonzalo Tornaría

Author: Release Manager

pyproject.toml

@@ -80,6 +80,9 @@ R = [
 file = "README.md"
 content-type = "text/markdown"
 
+[project.scripts]
+sage = "sage.cli:main"
+
 [tool.conda-lock]
 platforms = [
     'osx-64', 'linux-64', 'linux-aarch64', 'osx-arm64'

src/.relint.yml

@@ -45,7 +45,7 @@
     Sage library code should not import from sage.PAC.KAGE.all.
   pattern: 'from\s+sage(|[.](arith|categories|combinat|crypto|databases|data_structures|dynamics|ext|game_theory|games|geometry|graphs|groups|interfaces|manifolds|matrix|matroids|misc|modules|monoids|numerical|probability|quadratic_forms|quivers|rings|sat|schemes|sets|stats|symbolic|tensor)[a-z0-9_.]*|[.]libs)[.]all\s+import'
   # imports from .all are allowed in all.py; also allow in some modules that need sage.all
-  filePattern: '(.*/|)(?!(all|benchmark|dev_tools|parsing|sage_eval|explain_pickle|.*_test))[^/.]*[.](py|pyx|pxi)$'
+  filePattern: '(.*/|)(?!(all|benchmark|dev_tools|parsing|sage_eval|explain_pickle|.*_test|eval_cmd))[^/.]*[.](py|pyx|pxi)$'
 
 - name: 'namespace_pkg_all_import_2: Module-level import of .all of a namespace package'
   hint: |

src/sage/cli/__init__.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+
+import argparse
+import logging
+import sys
+
+from sage.cli.eval_cmd import EvalCmd
+from sage.cli.interactive_shell_cmd import InteractiveShellCmd
+from sage.cli.notebook_cmd import JupyterNotebookCmd
+from sage.cli.options import CliOptions
+from sage.cli.version_cmd import VersionCmd
+
+
+def main() -> int:
+    input_args = sys.argv[1:]
+    parser = argparse.ArgumentParser(
+        prog="sage",
+        description="If no command is given, starts the interactive interpreter where you can enter statements and expressions, immediately execute them and see their results.",
+    )
+    parser.add_argument(
+        "-v",
+        "--verbose",
+        action="store_true",
+        default=False,
+        help="print additional information",
+    )
+
+    VersionCmd.extend_parser(parser)
+    JupyterNotebookCmd.extend_parser(parser)
+    EvalCmd.extend_parser(parser)
+
+    if not input_args:
+        return InteractiveShellCmd(CliOptions()).run()
+
+    args = parser.parse_args(input_args)
+    options = CliOptions(**vars(args))
+
+    logging.basicConfig(level=logging.DEBUG if options.verbose else logging.INFO)
+
+    if args.command:
+        return EvalCmd(options).run()
+    elif args.notebook:
+        return JupyterNotebookCmd(options).run()
+    return InteractiveShellCmd(options).run()

src/sage/cli/__main__.py

@@ -0,0 +1,5 @@
+import sys
+
+from sage.cli import main
+
+sys.exit(main())

src/sage/cli/eval_cmd.py

@@ -0,0 +1,45 @@
+import argparse
+
+from sage.cli.options import CliOptions
+from sage.repl.preparse import preparse
+from sage.all import sage_globals
+
+
+class EvalCmd:
+    @staticmethod
+    def extend_parser(parser: argparse.ArgumentParser):
+        r"""
+        Extend the parser with the "run" command.
+
+        INPUT:
+
+        - ``parsers`` -- the parsers to extend.
+
+        OUTPUT:
+
+        - the extended parser.
+        """
+        parser.add_argument(
+            "-c",
+            "--command",
+            nargs="?",
+            help="execute the given command as sage code",
+        )
+
+    def __init__(self, options: CliOptions):
+        r"""
+        Initialize the command.
+        """
+        self.options = options
+
+    def run(self) -> int:
+        r"""
+        Execute the given command.
+        """
+        code = preparse(self.options.command)
+        try:
+            eval(compile(code, "<cmdline>", "exec"), sage_globals())
+        except Exception as e:
+            print(f"An error occurred while executing the command: {e}")
+            return 1
+        return 0

src/sage/cli/eval_cmd_test.py

@@ -0,0 +1,25 @@
+from sage.cli.eval_cmd import EvalCmd
+from sage.cli.options import CliOptions
+
+
+def test_eval_cmd_print(capsys):
+    options = CliOptions(command="print(3^33)")
+    eval_cmd = EvalCmd(options)
+
+    result = eval_cmd.run()
+    captured = capsys.readouterr()
+    assert captured.out == "5559060566555523\n"
+    assert result == 0
+
+
+def test_eval_cmd_invalid_command(capsys):
+    options = CliOptions(command="invalid_command")
+    eval_cmd = EvalCmd(options)
+
+    result = eval_cmd.run()
+    captured = capsys.readouterr()
+    assert (
+        "An error occurred while executing the command: name 'invalid_command' is not defined"
+        in captured.out
+    )
+    assert result == 1

src/sage/cli/interactive_shell_cmd.py

@@ -0,0 +1,25 @@
+from sage.cli.options import CliOptions
+
+
+class InteractiveShellCmd:
+    def __init__(self, options: CliOptions):
+        r"""
+        Initialize the command.
+        """
+        self.options = options
+
+    def run(self) -> int:
+        r"""
+        Start the interactive shell.
+        """
+        # Display startup banner. Do this before anything else to give the user
+        # early feedback that Sage is starting.
+        from sage.misc.banner import banner
+
+        banner()
+
+        from sage.repl.interpreter import SageTerminalApp
+
+        app = SageTerminalApp.instance()
+        app.initialize([])
+        return app.start()  # type: ignore

src/sage/cli/notebook_cmd.py

@@ -0,0 +1,52 @@
+import argparse
+
+from sage.cli.options import CliOptions
+
+
+class JupyterNotebookCmd:
+    @staticmethod
+    def extend_parser(parser: argparse.ArgumentParser):
+        r"""
+        Extend the parser with the Jupyter notebook command.
+
+        INPUT:
+
+        - ``parsers`` -- the parsers to extend.
+
+        OUTPUT:
+
+        - the extended parser.
+        """
+        parser.add_argument(
+            "-n",
+            "--notebook",
+            nargs="?",
+            const="jupyter",
+            choices=["jupyter", "jupyterlab"],
+            default="jupyter",
+            help="start the Jupyter notebook server (default: jupyter)",
+        )
+
+    def __init__(self, options: CliOptions):
+        r"""
+        Initialize the command.
+        """
+        self.options = options
+
+    def run(self) -> int:
+        r"""
+        Start the Jupyter notebook server.
+        """
+        if self.options.notebook == "jupyter":
+            try:
+                # notebook 6
+                from notebook.notebookapp import main
+            except ImportError:
+                # notebook 7
+                from notebook.app import main
+        elif self.options.notebook == "jupyterlab":
+            from jupyterlab.labapp import main
+        else:
+            raise ValueError(f"Unknown notebook type: {self.options.notebook}")
+
+        return main([])

src/sage/cli/notebook_cmd_test.py

@@ -0,0 +1,39 @@
+import argparse
+
+import pytest
+
+from sage.cli.notebook_cmd import JupyterNotebookCmd
+
+
+def test_jupyter_as_default():
+    parser = argparse.ArgumentParser()
+    JupyterNotebookCmd.extend_parser(parser)
+    args = parser.parse_args(["--notebook"])
+    assert args.notebook == "jupyter"
+
+
+def test_jupyter_explicitly():
+    parser = argparse.ArgumentParser()
+    JupyterNotebookCmd.extend_parser(parser)
+    args = parser.parse_args(["--notebook", "jupyter"])
+    assert args.notebook == "jupyter"
+
+
+def test_jupyterlab_explicitly():
+    parser = argparse.ArgumentParser()
+    JupyterNotebookCmd.extend_parser(parser)
+    args = parser.parse_args(["--notebook", "jupyterlab"])
+    assert args.notebook == "jupyterlab"
+
+
+def test_invalid_notebook_choice():
+    parser = argparse.ArgumentParser()
+    JupyterNotebookCmd.extend_parser(parser)
+    with pytest.raises(SystemExit):
+        parser.parse_args(["--notebook", "invalid"])
+
+
+def test_help():
+    parser = argparse.ArgumentParser()
+    JupyterNotebookCmd.extend_parser(parser)
+    assert parser.format_usage() == "usage: pytest [-h] [-n [{jupyter,jupyterlab}]]\n"

src/sage/cli/options.py

@@ -0,0 +1,17 @@
+from dataclasses import dataclass
+
+
+@dataclass
+class CliOptions:
+    """
+    A TypedDict for command-line interface options.
+    """
+
+    """Indicates whether verbose output is enabled."""
+    verbose: bool = False
+
+    """The notebook type to start."""
+    notebook: str = "jupyter"
+
+    """The command to execute."""
+    command: str | None = None