initial commit with color test

.gitignore

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+/.mypy_cache

.pre-commit-config.yaml

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+repos:
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.2.3
+    hooks:
+    -   id: trailing-whitespace
+    -   id: end-of-file-fixer
+    -   id: check-docstring-first
+    -   id: check-yaml
+    -   id: debug-statements
+    -   id: double-quote-string-fixer
+    -   id: name-tests-test
+    -   id: requirements-txt-fixer
+-   repo: https://gitlab.com/pycqa/flake8
+    rev: 3.7.8
+    hooks:
+    -   id: flake8
+-   repo: https://github.com/pre-commit/mirrors-autopep8
+    rev: v1.4.4
+    hooks:
+    -   id: autopep8
+-   repo: https://github.com/asottile/reorder_python_imports
+    rev: v1.6.0
+    hooks:
+    -   id: reorder-python-imports
+        args: [--py3-plus]
+-   repo: https://github.com/asottile/add-trailing-comma
+    rev: v1.4.1
+    hooks:
+    -   id: add-trailing-comma
+        args: [--py36-plus]
+-   repo: https://github.com/asottile/pyupgrade
+    rev: v1.21.0
+    hooks:
+    -   id: pyupgrade
+        args: [--py36-plus]
+-   repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v0.711
+    hooks:
+    -   id: mypy

babi.py

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+import _curses
+import argparse
+import curses
+from typing import Dict
+from typing import Tuple
+
+
+def _get_color_pair_mapping() -> Dict[Tuple[int, int], int]:
+    ret = {}
+    i = 0
+    for bg in range(-1, 16):
+        for fg in range(bg, 16):
+            ret[(fg, bg)] = i
+            i += 1
+    return ret
+
+
+COLORS = _get_color_pair_mapping()
+del _get_color_pair_mapping
+
+
+def _has_colors() -> bool:
+    # https://github.com/python/typeshed/pull/3115
+    return curses.has_colors and curses.COLORS >= 16  # type: ignore
+
+
+def _color(fg: int, bg: int) -> int:
+    if _has_colors():
+        if bg > fg:
+            return curses.A_REVERSE | curses.color_pair(COLORS[(bg, fg)])
+        else:
+            return curses.color_pair(COLORS[(fg, bg)])
+    else:
+        if bg > fg:
+            return curses.A_REVERSE | curses.color_pair(0)
+        else:
+            return curses.color_pair(0)
+
+
+def _init_colors(stdscr: '_curses._CursesWindow') -> None:
+    curses.use_default_colors()
+    if not _has_colors():
+        return
+    for (fg, bg), pair in COLORS.items():
+        if pair == 0:  # cannot reset pair 0
+            continue
+        curses.init_pair(pair, fg, bg)
+
+
+def _color_test(stdscr: '_curses._CursesWindow') -> None:
+    maxy, maxx = stdscr.getmaxyx()
+    if maxy < 16 or maxx < 64:
+        raise SystemExit('--color-test needs a window of at least 64 x 16')
+
+    x = y = 0
+    for fg in range(-1, 16):
+        for bg in range(-1, 16):
+            if bg > fg:
+                s = f'*{COLORS[bg, fg]:3}'
+            else:
+                s = f' {COLORS[fg, bg]:3}'
+            stdscr.addstr(y, x, s, _color(fg, bg))
+            x += 4
+        y += 1
+        x = 0
+
+
+def c_main(stdscr: '_curses._CursesWindow', args: argparse.Namespace) -> None:
+    _init_colors(stdscr)
+    if args.color_test:
+        _color_test(stdscr)
+    stdscr.getch()
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--color-test', action='store_true')
+    args = parser.parse_args()
+    curses.wrapper(c_main, args)
+    return 0
+
+
+if __name__ == '__main__':
+    exit(main())