Add setuptools entry point

pyproject.toml

@@ -84,6 +84,9 @@ dev = ["pytest>=6", "pytest-cov", "pytest-timeout"]
 [project.scripts]
 shtab = "shtab.main:main"
 
+[project.entry-points."setuptools.finalize_distribution_options"]
+generate = "shtab.setuptools:generate_completions"
+
 [tool.flake8]
 max_line_length = 99
 extend_ignore = ["E261", "P101"]

shtab/setuptools.py

@@ -0,0 +1,80 @@
+"""A entry point for setuptools."""
+import io
+import os
+import sys
+from contextlib import redirect_stdout, suppress
+from importlib import import_module
+from importlib.metadata import EntryPoint, EntryPoints
+from typing import Callable
+
+from setuptools import Distribution
+
+try:
+    import tomllib as tomli
+except ImportError:
+    import tomli
+
+
+def get_stdout(function: Callable) -> str:
+    """Get stdout."""
+    string = io.StringIO()
+    with redirect_stdout(string), suppress(SystemExit):
+        function()
+    string.seek(0)
+    content = string.read()
+    return content
+
+
+def generate_completions(distribution: Distribution) -> None:
+    """Generate completions."""
+    # Get entry_points from setup.py
+    entry_points = getattr(distribution, "entry_points")
+    if entry_points is None:
+        entry_points = EntryPoints()
+    entry_points = entry_points.select(group="console_scripts")
+    # Get entry_points from setup.cfg
+    if len(entry_points) == 0 and os.path.isfile("setup.cfg"):
+        import configparser
+
+        parser = configparser.ConfigParser()
+        parser.read(["setup.cfg"], encoding="utf-8")
+        _entry_points = parser.get("metadata", "entry_points", fallback=None)
+        if isinstance(_entry_points, dict):
+            console_scripts = _entry_points.get("console_scripts", [])
+            for console_script in console_scripts:
+                k, _, v = console_script.partition("=")
+                entry_points += [
+                    EntryPoint(name=k.strip(), group="console_scripts", value=v.strip())]
+    # Get entry_points from pyproject.toml
+    if len(entry_points) == 0 and os.path.isfile("pyproject.toml"):
+        with open("pyproject.toml", "rb") as f:
+            pyproject = tomli.load(f)
+        scripts = pyproject.get("project", {}).get("scripts", {})
+        if isinstance(scripts, dict):
+            for k, v in scripts.items():
+                entry_points += [EntryPoint(name=k, group="scripts", value=v)]
+
+    cwd = os.getcwd()
+    # https://setuptools.pypa.io/en/latest/userguide/package_discovery.html#flat-layout
+    sys.path.insert(0, cwd)
+    # https://setuptools.pypa.io/en/latest/userguide/package_discovery.html#src-layout
+    sys.path.insert(0, os.path.join(cwd, "src"))
+    for entry_point in entry_points:
+        # entry_point.value can be 'module_path:function_name[extra1, extra2]'
+        path = entry_point.value.split("[")[0]
+        module_path, _, function_name = path.rpartition(":")
+        module = import_module(module_path)
+        function = vars(module).get(function_name)
+        prog = entry_point.name
+        shells = {"bash": prog, "zsh": "_" + prog, "tcsh": prog + ".csh"}
+        os.makedirs("sdist", exist_ok=True)
+        argv = sys.argv
+        for shell, filename in shells.items():
+            sys.argv = [prog, "--print-completion", shell]
+            # bash, zsh, tcsh only use `\n`
+            content = get_stdout(function).replace("\r\n", "\n") # type: ignore
+            if content == "":
+                continue
+            with open(os.path.join("sdist", filename), "w", newline="") as f:
+                f.write(content)
+        sys.argv = argv