1 files changed, 328 insertions, 0 deletions
diff --git a/src/prompt_toolkit/utils.py b/src/prompt_toolkit/utils.py
new file mode 100644
index 0000000..4ceded3
--- /dev/null
+++ b/src/prompt_toolkit/utils.py
@@ -0,0 +1,328 @@
+import os
+import signal
+import sys
+import threading
+from collections import deque
+from typing import (
+    Callable,
+    ContextManager,
+    Deque,
+    Dict,
+    Generator,
+    Generic,
+    List,
+    Optional,
+    TypeVar,
+    Union,
+)
+
+from wcwidth import wcwidth
+
+__all__ = [
+    "Event",
+    "DummyContext",
+    "get_cwidth",
+    "suspend_to_background_supported",
+    "is_conemu_ansi",
+    "is_windows",
+    "in_main_thread",
+    "get_bell_environment_variable",
+    "get_term_environment_variable",
+    "take_using_weights",
+    "to_str",
+    "to_int",
+    "AnyFloat",
+    "to_float",
+    "is_dumb_terminal",
+]
+
+# Used to ensure sphinx autodoc does not try to import platform-specific
+# stuff when documenting win32.py modules.
+SPHINX_AUTODOC_RUNNING = "sphinx.ext.autodoc" in sys.modules
+
+_Sender = TypeVar("_Sender", covariant=True)
+
+
+class Event(Generic[_Sender]):
+    """
+    Simple event to which event handlers can be attached. For instance::
+
+        class Cls:
+            def __init__(self):
+                # Define event. The first parameter is the sender.
+                self.event = Event(self)
+
+        obj = Cls()
+
+        def handler(sender):
+            pass
+
+        # Add event handler by using the += operator.
+        obj.event += handler
+
+        # Fire event.
+        obj.event()
+    """
+
+    def __init__(
+        self, sender: _Sender, handler: Optional[Callable[[_Sender], None]] = None
+    ) -> None:
+        self.sender = sender
+        self._handlers: List[Callable[[_Sender], None]] = []
+
+        if handler is not None:
+            self += handler
+
+    def __call__(self) -> None:
+        "Fire event."
+        for handler in self._handlers:
+            handler(self.sender)
+
+    def fire(self) -> None:
+        "Alias for just calling the event."
+        self()
+
+    def add_handler(self, handler: Callable[[_Sender], None]) -> None:
+        """
+        Add another handler to this callback.
+        (Handler should be a callable that takes exactly one parameter: the
+        sender object.)
+        """
+        # Add to list of event handlers.
+        self._handlers.append(handler)
+
+    def remove_handler(self, handler: Callable[[_Sender], None]) -> None:
+        """
+        Remove a handler from this callback.
+        """
+        if handler in self._handlers:
+            self._handlers.remove(handler)
+
+    def __iadd__(self, handler: Callable[[_Sender], None]) -> "Event[_Sender]":
+        """
+        `event += handler` notation for adding a handler.
+        """
+        self.add_handler(handler)
+        return self
+
+    def __isub__(self, handler: Callable[[_Sender], None]) -> "Event[_Sender]":
+        """
+        `event -= handler` notation for removing a handler.
+        """
+        self.remove_handler(handler)
+        return self
+
+
+class DummyContext(ContextManager[None]):
+    """
+    (contextlib.nested is not available on Py3)
+    """
+
+    def __enter__(self) -> None:
+        pass
+
+    def __exit__(self, *a: object) -> None:
+        pass
+
+
+class _CharSizesCache(Dict[str, int]):
+    """
+    Cache for wcwidth sizes.
+    """
+
+    LONG_STRING_MIN_LEN = 64  # Minimum string length for considering it long.
+    MAX_LONG_STRINGS = 16  # Maximum number of long strings to remember.
+
+    def __init__(self) -> None:
+        super().__init__()
+        # Keep track of the "long" strings in this cache.
+        self._long_strings: Deque[str] = deque()
+
+    def __missing__(self, string: str) -> int:
+        # Note: We use the `max(0, ...` because some non printable control
+        #       characters, like e.g. Ctrl-underscore get a -1 wcwidth value.
+        #       It can be possible that these characters end up in the input
+        #       text.
+        result: int
+        if len(string) == 1:
+            result = max(0, wcwidth(string))
+        else:
+            result = sum(self[c] for c in string)
+
+        # Store in cache.
+        self[string] = result
+
+        # Rotate long strings.
+        # (It's hard to tell what we can consider short...)
+        if len(string) > self.LONG_STRING_MIN_LEN:
+            long_strings = self._long_strings
+            long_strings.append(string)
+
+            if len(long_strings) > self.MAX_LONG_STRINGS:
+                key_to_remove = long_strings.popleft()
+                if key_to_remove in self:
+                    del self[key_to_remove]
+
+        return result
+
+
+_CHAR_SIZES_CACHE = _CharSizesCache()
+
+
+def get_cwidth(string: str) -> int:
+    """
+    Return width of a string. Wrapper around ``wcwidth``.
+    """
+    return _CHAR_SIZES_CACHE[string]
+
+
+def suspend_to_background_supported() -> bool:
+    """
+    Returns `True` when the Python implementation supports
+    suspend-to-background. This is typically `False' on Windows systems.
+    """
+    return hasattr(signal, "SIGTSTP")
+
+
+def is_windows() -> bool:
+    """
+    True when we are using Windows.
+    """
+    return sys.platform == "win32"  # Not 'darwin' or 'linux2'
+
+
+def is_windows_vt100_supported() -> bool:
+    """
+    True when we are using Windows, but VT100 escape sequences are supported.
+    """
+    if sys.platform == "win32":
+        # Import needs to be inline. Windows libraries are not always available.
+        from prompt_toolkit.output.windows10 import is_win_vt100_enabled
+
+        return is_win_vt100_enabled()
+
+    return False
+
+
+def is_conemu_ansi() -> bool:
+    """
+    True when the ConEmu Windows console is used.
+    """
+    return sys.platform == "win32" and os.environ.get("ConEmuANSI", "OFF") == "ON"
+
+
+def in_main_thread() -> bool:
+    """
+    True when the current thread is the main thread.
+    """
+    return threading.current_thread().__class__.__name__ == "_MainThread"
+
+
+def get_bell_environment_variable() -> bool:
+    """
+    True if env variable is set to true (true, TRUE, TrUe, 1).
+    """
+    value = os.environ.get("PROMPT_TOOLKIT_BELL", "true")
+    return value.lower() in ("1", "true")
+
+
+def get_term_environment_variable() -> str:
+    "Return the $TERM environment variable."
+    return os.environ.get("TERM", "")
+
+
+_T = TypeVar("_T")
+
+
+def take_using_weights(
+    items: List[_T], weights: List[int]
+) -> Generator[_T, None, None]:
+    """
+    Generator that keeps yielding items from the items list, in proportion to
+    their weight. For instance::
+
+        # Getting the first 70 items from this generator should have yielded 10
+        # times A, 20 times B and 40 times C, all distributed equally..
+        take_using_weights(['A', 'B', 'C'], [5, 10, 20])
+
+    :param items: List of items to take from.
+    :param weights: Integers representing the weight. (Numbers have to be
+                    integers, not floats.)
+    """
+    assert len(items) == len(weights)
+    assert len(items) > 0
+
+    # Remove items with zero-weight.
+    items2 = []
+    weights2 = []
+    for item, w in zip(items, weights):
+        if w > 0:
+            items2.append(item)
+            weights2.append(w)
+
+    items = items2
+    weights = weights2
+
+    # Make sure that we have some items left.
+    if not items:
+        raise ValueError("Did't got any items with a positive weight.")
+
+    #
+    already_taken = [0 for i in items]
+    item_count = len(items)
+    max_weight = max(weights)
+
+    i = 0
+    while True:
+        # Each iteration of this loop, we fill up until by (total_weight/max_weight).
+        adding = True
+        while adding:
+            adding = False
+
+            for item_i, item, weight in zip(range(item_count), items, weights):
+                if already_taken[item_i] < i * weight / float(max_weight):
+                    yield item
+                    already_taken[item_i] += 1
+                    adding = True
+
+        i += 1
+
+
+def to_str(value: Union[Callable[[], str], str]) -> str:
+    "Turn callable or string into string."
+    if callable(value):
+        return to_str(value())
+    else:
+        return str(value)
+
+
+def to_int(value: Union[Callable[[], int], int]) -> int:
+    "Turn callable or int into int."
+    if callable(value):
+        return to_int(value())
+    else:
+        return int(value)
+
+
+AnyFloat = Union[Callable[[], float], float]
+
+
+def to_float(value: AnyFloat) -> float:
+    "Turn callable or float into float."
+    if callable(value):
+        return to_float(value())
+    else:
+        return float(value)
+
+
+def is_dumb_terminal(term: Optional[str] = None) -> bool:
+    """
+    True if this terminal type is considered "dumb".
+
+    If so, we should fall back to the simplest possible form of line editing,
+    without cursor positioning and color support.
+    """
+    if term is None:
+        return is_dumb_terminal(os.environ.get("TERM", ""))
+
+    return term.lower() in ["dumb", "unknown"]