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readline.dg
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readline.dg
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import '/os'
import '/re'
import '/time'
import '/math'
import '/fcntl'
import '/struct'
import '/select'
import '/termios'
import '/contextlib'
import '/collections'
#: ANSI character DFA. Matches either a single character or a complete control sequence.
#:
#: Sequence :: Re
#:
Sequence = re.compile r'''(?sx)\033(?:
\[.*?[@-~] # ANSI CSI: standard escape sequences.
|\]\d+;.*?\007 # ANSI OSC: e.g. sets the title of an XTerm-like VT.
|[NO]. # ANSI SS2/SS3: alternate character sets.
)|(.)'''
#: A sequence of characters considered by the real GNU readline to be zero-length.
ZeroLengthSequence = re.compile r'''\001.*?\002'''
Key = subclass object where
DEL_ASCII = '\x7f' # This is actually used as Backspace. Probably.
DEL_ANSI = '\033[3~' # *This* is Delete.
INSERT = '\033[2~'
PAGE_UP = '\033[5~'
PAGE_DOWN = '\033[6~'
UP = '\033[A'
DOWN = '\033[B'
RIGHT = '\033[C'
LEFT = '\033[D'
HOME = '\033[H'
END = '\033[F'
HOME_ALT = '\033OH' # Non-standard sequences?
END_ALT = '\033OF'
# Control sequence = ASCII name [= known name] = value
CONTROL_A = SOH = HOME_CTRL = '\x01'
CONTROL_B = STX = LEFT_CTRL = '\x02'
CONTROL_C = ETX = SIGINT = '\x03' # only usable via `enable_jobs = False`
CONTROL_D = EOF = '\x04'
CONTROL_E = ENQ = END_CTRL = '\x05'
CONTROL_F = ACK = RIGHT_CTRL = '\x06'
CONTROL_G = BEL = ALARM = '\x07'
CONTROL_H = BS = DEL_CTRL = '\x08'
CONTROL_I = TAB = '\x09'
CONTROL_J = LF = ENTER = '\x0a'
CONTROL_K = VT = CUT_END = '\x0b'
CONTROL_L = FF = NEWPAGE = '\x0c'
# Control+M = '\r' is unusable due to automatic line break conversion.
CONTROL_N = SO = DOWN_CTRL = '\x0e'
CONTROL_O = SI = CUT_START = '\x0f'
CONTROL_P = DLE = UP_CTRL = '\x10'
CONTROL_Q = DC1 = XON = '\x11' # only usable via `enable_flowctl = False`
CONTROL_R = DC2 = SEARCH = '\x12'
CONTROL_S = DC3 = XOFF = '\x13' # only usable via `enable_flowctl = False`
CONTROL_T = DC4 = '\x14'
CONTROL_U = NAK = '\x15'
CONTROL_V = SYN = '\x16'
CONTROL_W = ETB = '\x17'
CONTROL_X = CAN = CANCEL = '\x18'
CONTROL_Y = EM = PASTE = '\x19'
CONTROL_Z = SUB = SUSPEND = '\x1a' # only usable via `enable_jobs = False`
Color = subclass object where
FG = subclass object where
black = '\033[30m{}\033[39m'.format
red = '\033[31m{}\033[39m'.format
green = '\033[32m{}\033[39m'.format
yellow = '\033[33m{}\033[39m'.format
blue = '\033[34m{}\033[39m'.format
magenta = '\033[35m{}\033[39m'.format
cyan = '\033[36m{}\033[39m'.format
white = '\033[37m{}\033[39m'.format
BG = subclass object where
black = '\033[40m{}\033[49m'.format
red = '\033[41m{}\033[49m'.format
green = '\033[42m{}\033[49m'.format
yellow = '\033[43m{}\033[49m'.format
blue = '\033[44m{}\033[49m'.format
magenta = '\033[45m{}\033[49m'.format
cyan = '\033[46m{}\033[49m'.format
white = '\033[47m{}\033[49m'.format
Teletype = subclass object where
#: Various TTY-related functions.
#:
#: input :: TextIOBase -- 'r'-mode TTY.
#: output :: TextIOBase -- 'w'-mode TTY.
#:
__init__ = @input @output @name: None ~>
not @input .isatty! => raise $ IOError 'input: not a tty'
not @output.isatty! => raise $ IOError 'output: not a tty'
None
read = ~> @input.read
write = ~> @output.write
flush = ~> @output.flush!
#: Return true iff input is a single non-control character.
#:
#: printable :: str -> bool
#:
printable = classmethod $ data ~> if
len data == 0 => True
len data == 1 => 32 <= ord data < 127 or 160 <= ord data
#: Enter the raw mode of a TTY: disable line buffering, echo, etc.
#:
#: * `jobctl`: whether to enable Ctrl+C (SIGINT) and Ctrl+Z (SIGSTOP).
#: * `flowctl`: whether to enable Ctrl+S (XOFF) and Ctrl+Q (XON).
#:
#: where "enable" means the default behavior. That is, pass `False` to bind your
#: own actions on these combos. Otherwise, they won't even reach the application.
#:
#: raw :: bool bool -> context NoneType
#:
raw = contextlib.contextmanager $ jobctl flowctl ~>
old = termios.tcgetattr @input
new = termios.tcgetattr @input
new !! 0 &= ~(termios.ISTRIP | termios.IXON)
new !! 3 &= ~(termios.ECHO | termios.ICANON | termios.IEXTEN | termios.ISIG)
new !! 6 !! termios.VMIN = 0 # This makes `read` non-blocking.
new !! 6 !! termios.VTIME = 0
if flowctl => new !! 0 |= termios.IXON
if jobctl => new !! 3 |= termios.ISIG
except _ => yield $ termios.tcsetattr @input termios.TCSADRAIN new
finally => termios.tcsetattr @input termios.TCSAFLUSH old
#: Find out how much stuff this TTY can display at once.
#:
#: size :: (int, int) -- (height, width) in characters
#:
size = ~> struct.unpack 'hh' $ fcntl.ioctl @output termios.TIOCGWINSZ '1234'
#: Read at most a line from a TTY (blocking until at least a character is available.)
#:
#: buffer :: float -> iter str
#:
buffer = timeout ~>
x = @input.readline!
x == '' =>
has_data = fst $ if timeout => select.select [@input] [] [] timeout
otherwise => select.select [@input] [] []
x = @input.readline!
x == '' and has_data => raise $ IOError 'input channel closed'
map (x -> x.group!) $ Sequence.finditer x
#: Move the caret `y` characters down and `x` characters to the right.
#:
#: relmove :: int int -> a
#:
relmove = y x ~> @write $ (+)
if y > 0 => '\033[{}B'.format y
y < 0 => '\033[{}A'.format (-y)
otherwise => '' # If `y` is 0, terminals might assume 1.
if x > 0 => '\033[{}C'.format x
x < 0 => '\033[{}D'.format (-x)
otherwise => ''
#: Erase everything from the cursor to the end of the screen.
#:
#: erase :: a
#:
erase = ~> @write '\033[J'
ReadlineState = subclass object where
#: A readline input state.
#:
#: Defines stuff such as the current buffer contents, caret position, etc.
#:
__init__ = @prompt @buffer @position @cache ~> None
#: Move the caret to the right.
#:
#: right :: int -> ReadlineState
#:
right = i ~> ReadlineState @prompt @buffer (@position + i `min` len @buffer) @cache
#: Move the caret to the left.
#:
#: left :: int -> ReadlineState
#:
left = i ~> ReadlineState @prompt @buffer (@position - i `max` 0) @cache
#: Insert a string into the buffer, move the caret if necessary.
#:
#: insert :: int str -> ReadlineState
#:
insert = i d ~> if
i < 0 => @insert 0 $ d !! slice (-i) None
otherwise => ReadlineState @prompt
(+)
@buffer !! slice None i + d
@buffer !! slice i None
@position + len d * (i <= @position)
@cache
#: Erase the characters at position `i`, move the caret accordingly.
#:
#: erase :: int (Optional int) -> ReadlineState
#:
erase = i length: 1 ~> if
i < 0 => @erase 0 $ length + i
otherwise => ReadlineState @prompt
(+)
@buffer !! slice None i
@buffer !! slice (i + length) None
@position - (length `min` @position - i `max` 0)
@cache
Readline = subclass object where
__init__ = *: args **: kwargs ~>
@tty = Teletype *: args **: kwargs
# In case subclasses decide to override keybindings, make sure
# they don't add them to the global mapping.
@bindings = @bindings.copy!
@bindings !! Key.CONTROL_L = state ->
state = @erase state
@tty.write '\033[H\033[J'
state
None
#: A mapping of keys to state modificators. Note that a key may be
#: either a character or an ANSI sequence.
#:
#: bindings :: dict str (ReadlineState -> ReadlineState)
#:
bindings = dict'
Key.ENTER, state -> raise $ StopIteration state.buffer
Key.RIGHT, state -> state.right 1
Key.RIGHT_CTRL, state -> state.right 1
Key.LEFT, state -> state.left 1
Key.LEFT_CTRL, state -> state.left 1
Key.END, state -> state.right $ len state.buffer
Key.END_ALT, state -> state.right $ len state.buffer
Key.END_CTRL, state -> state.right $ len state.buffer
Key.HOME, state -> state.left state.position
Key.HOME_ALT, state -> state.left state.position
Key.HOME_CTRL, state -> state.left state.position
Key.DEL_ANSI, state -> state.erase state.position
Key.DEL_ASCII, state -> state.erase $ state.position - 1
Key.DEL_CTRL, state -> state.erase $ state.position - 1
Key.EOF, state -> if
state.buffer => state.erase state.position
otherwise => raise EOFError
#: Whether to enable ^C and ^Z. Disallows the use of `Key.SIGINT` and `Key.SUSPEND`.
#:
#: enable_jobs :: bool
#:
enable_jobs = True
#: Whether to enable XON/XOFF, whatever that means. Disables `Key.XON` and `Key.XOFF`.
#:
#: enable_flowctl :: bool
#:
enable_flowctl = False
#: Default line preprocessor. Does nothing.
#:
#: This method is called whenever an updated display is required.
#: Its only argument is the buffer, and the return value should
#: be an ANSI-escaped string to display. This could be used,
#: for example, to implement syntax highlighting.
#:
#: NOTE: this method must NOT change the apparent length of a string.
#: Otherwise, the caret will appear in the wrong position.
#:
#: preprocess :: str -> str
#:
preprocess = ln ~> ln
#: Read a line from a TTY while displaying a preview on another TTY.
#:
#: If the prompt is a function, it will be called with the current
#: `ReadlineState` whenever the display is updated.
#:
#: input :: (Either str (ReadlineState -> str)) (Optional float) -> str
#:
input = prompt timeout: 0 buffer: '' position: 0 ~>
with @tty.raw @enable_jobs @enable_flowctl => except
err =>
start = time.time!
state = ReadlineState prompt buffer position {}
while True =>
passed = min timeout $ time.time! - start
passed >= timeout > 0 => raise $ BlockingIOError state
@update state
for c in @tty.buffer (timeout - passed) => if
@bindings.get c => state = (@bindings !! c) state
@tty.printable c => state = state.insert state.position c
otherwise => @tty.write Key.ALARM
err :: StopIteration => err.value
finally => @finalize state
#: Write a preview of a line buffer onto a TTY. Writing stuff to output afterwards
#: will mess with the prompt; call `erase` or `finalize` first.
#:
#: update :: ReadlineState -> ReadlineState
#:
update = state ~>
@erase state
prefix = if
state.prompt :: collections.Callable => state.prompt state
otherwise => str state.prompt
prelen = len $ ZeroLengthSequence.sub '' prefix
wh, ww = @tty.size
h, w = prelen + len state.buffer `divmod` ww
y, x = prelen + state.position `divmod` ww
@tty.write $ if
h < wh => prefix + @preprocess state.buffer
otherwise => ''.join
where
# Not enough lines to display everything, let's try another approach.
# We'll only show the `ww - 1` characters closest to the cursor.
offset = prelen + state.position
start = max (offset - (ww - 1 >> 1)) 0
end = min (offset + (ww - 1 >> 1)) (prelen + len state.buffer)
# And again, to ensure that we show `ww - 1` characters
# even if the cursor is at either end of the buffer.
end = min (max end $ start + ww - 1) (prelen + len state.buffer)
start = max (min start $ end - ww + 1) 0
y, x := 0, offset - start
h, w := 0, end - start
c = 0
for m in Sequence.finditer (prefix + @preprocess state.buffer) => if
m.group 1 => start < (c += 1) <= end => yield $ m.group 0
# Include all ANSI escapes in the output to ensure that
# all resets work as intended.
otherwise => yield $ m.group 0
# Some TTYs don't create a new line if the output fits the window exactly;
# the problem is, we still have to show the cursor, but there's no space.
# So we need to create a new line to put it on manually.
h != 0 and w == 0 => @tty.write '\n\r'
@tty.relmove (y - h) (x - w)
@tty.flush
# `erase` will use that info to locate the start of the buffer.
# FIXME this value may become invalid if the terminal rewraps on resize.
state.cache !! 'offset' = y, x
state
#: Completely erase the prompt and the input buffer from the screen.
#:
#: erase :: ReadlineState -> ReadlineState
#:
erase = state ~>
y, x = state.cache.pop 'offset' (0, 0)
@tty.relmove (-y) (-x)
@tty.erase
state
#: Make sure the prompt does not interfere with further output to the TTY.
#:
#: finalize :: ReadlineState -> ReadlineState
#:
finalize = state ~>
@erase state
prefix = if
state.prompt :: collections.Callable => state.prompt state
otherwise => str state.prompt
@tty.write $ prefix + @preprocess state.buffer + '\n\r'
@tty.flush
state
History = subclass Readline where
#: A mix-in that enables history navigation with up and down arrows.
#:
#: history :: [str] -- a list of previously entered lines
#:
__init__ = *: args **: kwargs ~>
(super History self).__init__ *: args **: kwargs
@history = list!
@bindings.update $ dict'
Key.UP, @history_prev
Key.UP_CTRL, @history_prev
Key.DOWN, @history_next
Key.DOWN_CTRL, @history_next
None
#: Switch to the previous history entry, if any. The contents of the buffer are lost.
#:
#: history_prev :: ReadlineState -> ReadlineState
#:
history_prev = state ~>
i = state.cache.get 'history' -1
if i <= -len @history => @tty.write Key.ALARM
otherwise =>
state = state.erase 0 $ len state.buffer
state = state.insert 0 $ @history !! (i - 1)
state.cache !! 'history' = i - 1
state
#: Switch to the next history entry, if any. The contents of the buffer are lost.
#:
#: history_next :: ReadlineState -> ReadlineState
#:
history_next = state ~>
i = state.cache.get 'history' -1
if i >= -1 => @tty.write Key.ALARM
otherwise =>
state = state.erase 0 $ len state.buffer
state = state.insert 0 $ @history !! (i + 1)
state.cache !! 'history' = i + 1
state
input = *: args **: kwargs ~> result where
@history.append ''
@history !! -1 = result = (super History self).input *: args **: kwargs
@history !! -1 or @history !!~ -1
Completer = subclass Readline where
completion_keys = [Key.TAB]
completion_regex = re.compile r'\w+'
#: A mix-in that enables basic completion.
#:
#: completion_keys :: [str] -- the keys on which to trigger completion.
#: completion_regex :: Re -- a regex that matches all completable words.
#:
__init__ = *: args **: kwargs ~>
(super Completer self).__init__ *: args **: kwargs
for k in @completion_keys => @bindings !! k = @complete_event
None
#: Handle a completion event. Default implementation calls `complete_buffer`
#: and either substitutes the incomplete word for a result or outputs the list
#: with `display_completions`.
#:
#: complete_event :: ReadlineState -> ReadlineState
#:
complete_event = state ~>
@tty.write Key.ALARM
start, length, cmps = @complete_buffer state.buffer state.position
if len cmps == 1 => state = state.erase start length |>.insert start (head cmps)
len cmps != 0 =>
prefix = ''.join $ map fst $ takewhile (cs -> len (set cs) == 1) $ zip *: cmps
# e.g. if all possible completions for `a` are `abc1`, `abc2`, and `abc3`,
# this will automatically insert `abc` after displaying the list.
state = @finalize state |>.erase start length |>.insert start prefix
@display_completions cmps
state
#: Find the word to complete and get the list of possible completions.
#: Returns a (start index, length, completions) tuple.
#:
#: complete_buffer :: str int -> (int, int, [str])
#:
complete_buffer = buf at ~> except
err => m = next $ filter (m -> m.start! <= at <= m.end!) $ @completion_regex.finditer buf
err is None => m.start!, m.end! - m.start!, @complete_word m.group!
err :: StopIteration => 0, 0, []
#: Fetch the list of possible completions for a word.
#:
#: complete_word :: str -> [str]
#:
complete_word = word ~> ["Completer.complete_word", "not", "implemented"]
#: Format and display a list of multiple possible completions.
#:
#: display_completions :: [str] -> a
#:
display_completions = cmps ~>
maxlen = max $ map len cmps
width = @tty.size !! 1 // (maxlen + 1)
height = math.ceil $ len cmps / width
for y in range height =>
for x in range y (len cmps `min` y + width * height) height =>
@tty.write ' '
@tty.write $ (cmps !! x).ljust maxlen
@tty.write '\n'