Fix input line wrapping bug (#6)

On most terminals, line wrapping would not work properly when using the input function with GNU readline and color escape codes. This PR adds special delimiters around the escape codes, signaling to readline that these are non-visible characters and un-confusing its line wrapping functionality.

Author: velovix

brainframe/cli/print_utils.py

@@ -20,6 +20,14 @@ class Color(Enum):
     UNDERLINE = "\033[4m"
 
 
+# These delimiters tell GNU readline that any characters between them are
+# non-visible. These should be put before and after ASCII escape codes. Without
+# these, escape codes mess up readline's text wrapping support.
+# See: https://superuser.com/a/301355
+_NON_VISIBLE_START = "\001"
+_NON_VISIBLE_END = "\002"
+
+
 def ask_yes_no(message_id, **kwargs) -> bool:
     """Prompts the user with a yes or no question. The default value is yes.
 
@@ -80,7 +88,13 @@ def print_color(message, color: Color, **kwargs) -> None:
 
 def input_color(message, color: Color) -> str:
     color = _check_no_color(color)
-    return input(f"{color.value}{message}{Color.END.value}")
+    # See https://superuser.com/a/301355 for why these non-visible delimiters
+    # are necessary for input()
+    return input(
+        f"{_NON_VISIBLE_START}{color.value}{_NON_VISIBLE_END}"
+        f"{message}"
+        f"{_NON_VISIBLE_START}{Color.END.value}{_NON_VISIBLE_END}"
+    )
 
 
 def _check_no_color(color: Color) -> Color:
@@ -108,3 +122,7 @@ def _check_no_color(color: Color) -> Color:
                                         Installer
 
 """
+
+# Importing readline has the side-effect of augmenting the `input` function
+# with GNU readline features.
+_ = readline