feat(tui): add curses interface

nvitop/tui/library/curses/__init__.py

@@ -3,6 +3,108 @@
 
 # pylint: disable=missing-module-docstring
 
-from curses import *  # noqa: F403 # pylint: disable=redefined-builtin
+from typing import TYPE_CHECKING as _TYPE_CHECKING
 
 from nvitop.tui.library.curses import ascii  # pylint: disable=redefined-builtin
+
+
+try:
+    from curses import *  # noqa: F403 # pylint: disable=redefined-builtin
+except ImportError:
+    from nvitop.tui.library.curses._curses import *  # noqa: F403 # pylint: disable=redefined-builtin
+
+    # Copied from the CPython repository.
+    # https://github.com/python/cpython/blob/HEAD/Lib/curses/__init__.py
+
+    # Some constants, most notably the ACS_* ones, are only added to the C
+    # _curses module's dictionary after initscr() is called.  (Some
+    # versions of SGI's curses don't define values for those constants
+    # until initscr() has been called.)  This wrapper function calls the
+    # underlying C initscr(), and then copies the constants from the
+    # _curses module to the curses package's dictionary.  Don't do 'from
+    # curses import *' if you'll be needing the ACS_* constants.
+
+    def initscr():
+        import os
+        import sys
+
+        import nvitop.tui.library.curses as curses
+        import nvitop.tui.library.curses._curses as _curses
+
+        # we call setupterm() here because it raises an error
+        # instead of calling exit() in error cases.
+        setupterm(term=os.getenv('TERM', 'unknown'), fd=sys.__stdout__.fileno())
+        stdscr = _curses.initscr()
+        for key, value in _curses.__dict__.items():
+            if key.startswith('ACS_') or key in ('LINES', 'COLS'):
+                setattr(curses, key, value)
+
+        return stdscr
+
+    # This is a similar wrapper for start_color(), which adds the COLORS and
+    # COLOR_PAIRS variables which are only available after start_color() is
+    # called.
+
+    def start_color():
+        import nvitop.tui.library.curses as curses
+        import nvitop.tui.library.curses._curses as _curses
+
+        retval = _curses.start_color()
+        if hasattr(_curses, 'COLORS'):
+            curses.COLORS = _curses.COLORS
+        if hasattr(_curses, 'COLOR_PAIRS'):
+            curses.COLOR_PAIRS = _curses.COLOR_PAIRS
+        return retval
+
+    # Wrapper for the entire curses-based application.  Runs a function which
+    # should be the rest of your curses-based application.  If the application
+    # raises an exception, wrapper() will restore the terminal to a sane state so
+    # you can read the resulting traceback.
+
+    def wrapper(func, /, *args, **kwds):
+        """Wrapper function that initializes curses and calls another function,
+        restoring normal keyboard/screen behavior on error.
+
+        The callable object 'func' is then passed the main window 'stdscr'
+        as its first argument, followed by any other arguments passed to
+        wrapper().
+        """
+
+        try:
+            # Initialize curses
+            stdscr = initscr()
+
+            # Turn off echoing of keys, and enter cbreak mode,
+            # where no buffering is performed on keyboard input
+            noecho()
+            cbreak()
+
+            # In keypad mode, escape sequences for special keys
+            # (like the cursor keys) will be interpreted and
+            # a special value like curses.KEY_LEFT will be returned
+            stdscr.keypad(1)
+
+            # Start color, too.  Harmless if the terminal doesn't have
+            # color; user can test with has_color() later on.  The try/catch
+            # works around a minor bit of over-conscientiousness in the curses
+            # module -- the error return from C start_color() is ignorable.
+            try:
+                start_color()
+            except:  # noqa: B001,E722,RUF100
+                pass
+
+            return func(stdscr, *args, **kwds)
+        finally:
+            # Set everything back to normal
+            if 'stdscr' in locals():
+                stdscr.keypad(0)
+                echo()
+                nocbreak()
+                endwin()
+
+
+if _TYPE_CHECKING:
+    try:
+        from curses import window as CursesWindow  # noqa: N812
+    except ImportError:
+        from nvitop.tui.library.curses._curses import CursesWindow