cpython/Lib/_pyrepl/reader.py at 513a14864c0b5d1bcbb1356af68aabc63b9e687c · DinoV/cpython

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# Antonio Cuni

# Armin Rigo

# Permission to use, copy, modify, and distribute this software and

# its documentation for any purpose is hereby granted without fee,

# provided that the above copyright notice appear in all copies and

# that both that copyright notice and this permission notice appear in

# supporting documentation.

# THE AUTHOR MICHAEL HUDSON DISCLAIMS ALL WARRANTIES WITH REGARD TO

# THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY

# AND FITNESS, IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL,

# INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER

# RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF

# CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN

# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

from __future__ import annotations

from contextlib import contextmanager

from dataclasses import dataclass, field, fields

import unicodedata

from _colorize import can_colorize, ANSIColors # type: ignore[import-not-found]

from . import commands, console, input

from .utils import ANSI_ESCAPE_SEQUENCE, wlen

from .trace import trace

# types

Command = commands.Command

if False:

from typing import Callable

from .types import Callback, SimpleContextManager, KeySpec, CommandName

CalcScreen = Callable[[], list[str]]

def disp_str(buffer: str) -> tuple[str, list[int]]:

"""disp_str(buffer:string) -> (string, [int])

Return the string that should be the printed represenation of

|buffer| and a list detailing where the characters of |buffer|

get used up. E.g.:

>>> disp_str(chr(3))

('^C', [1, 0])

"""

b: list[int] = []

s: list[str] = []

for c in buffer:

if ord(c) > 128 and unicodedata.category(c).startswith("C"):

c = r"\u%04x" % ord(c)

s.append(c)

b.append(wlen(c))

b.extend([0] * (len(c) - 1))

return "".join(s), b

# syntax classes:

SYNTAX_WHITESPACE, SYNTAX_WORD, SYNTAX_SYMBOL = range(3)

def make_default_syntax_table() -> dict[str, int]:

# XXX perhaps should use some unicodedata here?

st: dict[str, int] = {}

for c in map(chr, range(256)):

st[c] = SYNTAX_SYMBOL

for c in [a for a in map(chr, range(256)) if a.isalnum()]:

st[c] = SYNTAX_WORD

st["\n"] = st[" "] = SYNTAX_WHITESPACE

return st

def make_default_commands() -> dict[CommandName, type[Command]]:

result: dict[CommandName, type[Command]] = {}

for v in vars(commands).values():

if isinstance(v, type) and issubclass(v, Command) and v.__name__[0].islower():

result[v.__name__] = v

result[v.__name__.replace("_", "-")] = v

return result

default_keymap: tuple[tuple[KeySpec, CommandName], ...] = tuple(

[

(r"\C-a", "beginning-of-line"),

(r"\C-b", "left"),

(r"\C-c", "interrupt"),

(r"\C-d", "delete"),

(r"\C-e", "end-of-line"),

(r"\C-f", "right"),

(r"\C-g", "cancel"),

(r"\C-h", "backspace"),

(r"\C-j", "accept"),

(r"\<return>", "accept"),

(r"\C-k", "kill-line"),

(r"\C-l", "clear-screen"),

(r"\C-m", "accept"),

(r"\C-t", "transpose-characters"),

(r"\C-u", "unix-line-discard"),

(r"\C-w", "unix-word-rubout"),

(r"\C-x\C-u", "upcase-region"),

(r"\C-y", "yank"),

(r"\C-z", "suspend"),

(r"\M-b", "backward-word"),

(r"\M-c", "capitalize-word"),

(r"\M-d", "kill-word"),

(r"\M-f", "forward-word"),

(r"\M-l", "downcase-word"),

(r"\M-t", "transpose-words"),

(r"\M-u", "upcase-word"),

(r"\M-y", "yank-pop"),

(r"\M--", "digit-arg"),

(r"\M-0", "digit-arg"),

(r"\M-1", "digit-arg"),

(r"\M-2", "digit-arg"),

(r"\M-3", "digit-arg"),

(r"\M-4", "digit-arg"),

(r"\M-5", "digit-arg"),

(r"\M-6", "digit-arg"),

(r"\M-7", "digit-arg"),

(r"\M-8", "digit-arg"),

(r"\M-9", "digit-arg"),

# (r'\M-\n', 'insert-nl'),

("\\\\", "self-insert"),

(r"\x1b[200~", "enable_bracketed_paste"),

(r"\x1b[201~", "disable_bracketed_paste"),

]

+ [(c, "self-insert") for c in map(chr, range(32, 127)) if c != "\\"]

+ [(c, "self-insert") for c in map(chr, range(128, 256)) if c.isalpha()]

+ [

(r"\<up>", "up"),

(r"\<down>", "down"),

(r"\<left>", "left"),

(r"\C-\<left>", "backward-word"),

(r"\<right>", "right"),

(r"\C-\<right>", "forward-word"),

(r"\<delete>", "delete"),

(r"\<backspace>", "backspace"),

(r"\M-\<backspace>", "backward-kill-word"),

(r"\<end>", "end-of-line"), # was 'end'

(r"\<home>", "beginning-of-line"), # was 'home'

(r"\<f1>", "help"),

(r"\<f2>", "show-history"),

(r"\<f3>", "paste-mode"),

(r"\EOF", "end"), # the entries in the terminfo database for xterms

(r"\EOH", "home"), # seem to be wrong. this is a less than ideal

# workaround

]

)

@dataclass(slots=True)

class Reader:

"""The Reader class implements the bare bones of a command reader,

handling such details as editing and cursor motion. What it does

not support are such things as completion or history support -

these are implemented elsewhere.

Instance variables of note include:

* buffer:

A *list* (*not* a string at the moment :-) containing all the

characters that have been entered.

* console:

Hopefully encapsulates the OS dependent stuff.

* pos:

A 0-based index into 'buffer' for where the insertion point

is.

* screeninfo:

Ahem. This list contains some info needed to move the

insertion point around reasonably efficiently.

* cxy, lxy:

the position of the insertion point in screen ...

* syntax_table:

Dictionary mapping characters to 'syntax class'; read the

emacs docs to see what this means :-)

* commands:

Dictionary mapping command names to command classes.

* arg:

The emacs-style prefix argument. It will be None if no such

argument has been provided.

* dirty:

True if we need to refresh the display.

* kill_ring:

The emacs-style kill-ring; manipulated with yank & yank-pop

* ps1, ps2, ps3, ps4:

prompts. ps1 is the prompt for a one-line input; for a

multiline input it looks like:

ps2> first line of input goes here

ps3> second and further

ps3> lines get ps3

...

ps4> and the last one gets ps4

As with the usual top-level, you can set these to instances if

you like; str() will be called on them (once) at the beginning

of each command. Don't put really long or newline containing

strings here, please!

This is just the default policy; you can change it freely by

overriding get_prompt() (and indeed some standard subclasses

do).

* finished:

handle1 will set this to a true value if a command signals

that we're done.

"""

console: console.Console

## state

buffer: list[str] = field(default_factory=list)

pos: int = 0

ps1: str = "->> "

ps2: str = "/>> "

ps3: str = "|.. "

ps4: str = R"\__ "

kill_ring: list[list[str]] = field(default_factory=list)

msg: str = ""

arg: int | None = None

dirty: bool = False

finished: bool = False

paste_mode: bool = False

in_bracketed_paste: bool = False

commands: dict[str, type[Command]] = field(default_factory=make_default_commands)

last_command: type[Command] | None = None

syntax_table: dict[str, int] = field(default_factory=make_default_syntax_table)

msg_at_bottom: bool = True

keymap: tuple[tuple[str, str], ...] = ()

input_trans: input.KeymapTranslator = field(init=False)

input_trans_stack: list[input.KeymapTranslator] = field(default_factory=list)

screen: list[str] = field(default_factory=list)

screeninfo: list[tuple[int, list[int]]] = field(init=False)

cxy: tuple[int, int] = field(init=False)

lxy: tuple[int, int] = field(init=False)

calc_screen: CalcScreen = field(init=False)

scheduled_commands: list[str] = field(default_factory=list)

def __post_init__(self) -> None:

# Enable the use of `insert` without a `prepare` call - necessary to

# facilitate the tab completion hack implemented for

# <https://bugs.python.org/issue25660>.

self.keymap = self.collect_keymap()

self.input_trans = input.KeymapTranslator(

self.keymap, invalid_cls="invalid-key", character_cls="self-insert"

)

self.screeninfo = [(0, [])]

self.cxy = self.pos2xy()

self.lxy = (self.pos, 0)

self.calc_screen = self.calc_complete_screen

def collect_keymap(self) -> tuple[tuple[KeySpec, CommandName], ...]:

return default_keymap

def append_to_screen(self) -> list[str]:

new_screen = self.screen.copy() or ['']

new_character = self.buffer[-1]

new_character_len = wlen(new_character)

last_line_len = wlen(new_screen[-1])

if last_line_len + new_character_len >= self.console.width: # We need to wrap here

new_screen[-1] += '\\'

self.screeninfo[-1][1].append(1)

new_screen.append(self.buffer[-1])

self.screeninfo.append((0, [new_character_len]))

else:

new_screen[-1] += self.buffer[-1]

self.screeninfo[-1][1].append(new_character_len)

self.cxy = self.pos2xy()

# Reset the function that is used for completing the screen

self.calc_screen = self.calc_complete_screen

return new_screen

def calc_complete_screen(self) -> list[str]:

"""The purpose of this method is to translate changes in

self.buffer into changes in self.screen. Currently it rips

everything down and starts from scratch, which whilst not

especially efficient is certainly simple(r).

"""

lines = self.get_unicode().split("\n")

screen: list[str] = []

screeninfo: list[tuple[int, list[int]]] = []

pos = self.pos

for ln, line in enumerate(lines):

ll = len(line)

if 0 <= pos <= ll:

if self.msg and not self.msg_at_bottom:

for mline in self.msg.split("\n"):

screen.append(mline)

screeninfo.append((0, []))

self.lxy = pos, ln

prompt = self.get_prompt(ln, ll >= pos >= 0)

while "\n" in prompt:

pre_prompt, _, prompt = prompt.partition("\n")

screen.append(pre_prompt)

screeninfo.append((0, []))

pos -= ll + 1

prompt, lp = self.process_prompt(prompt)

l, l2 = disp_str(line)

wrapcount = (wlen(l) + lp) // self.console.width

if wrapcount == 0:

screen.append(prompt + l)

screeninfo.append((lp, l2))

else:

i = 0

while l:

prelen = lp if i == 0 else 0

index_to_wrap_before = 0

column = 0

for character_width in l2:

if column + character_width >= self.console.width - prelen:

break

index_to_wrap_before += 1

column += character_width

pre = prompt if i == 0 else ""

if len(l) > index_to_wrap_before:

post = "\\"

after = [1]

else:

post = ""

after = []

screen.append(pre + l[:index_to_wrap_before] + post)

screeninfo.append((prelen, l2[:index_to_wrap_before] + after))

l = l[index_to_wrap_before:]

l2 = l2[index_to_wrap_before:]

i += 1

self.screeninfo = screeninfo

self.cxy = self.pos2xy()

if self.msg and self.msg_at_bottom:

for mline in self.msg.split("\n"):

screen.append(mline)

screeninfo.append((0, []))

return screen

def process_prompt(self, prompt: str) -> tuple[str, int]:

"""Process the prompt.

This means calculate the length of the prompt. The character \x01

and \x02 are used to bracket ANSI control sequences and need to be

excluded from the length calculation. So also a copy of the prompt

is returned with these control characters removed."""

# The logic below also ignores the length of common escape

# sequences if they were not explicitly within \x01...\x02.

# They are CSI (or ANSI) sequences ( ESC [ ... LETTER )

out_prompt = ""

l = wlen(prompt)

pos = 0

while True:

s = prompt.find("\x01", pos)

if s == -1:

break

e = prompt.find("\x02", s)

if e == -1:

break

# Found start and end brackets, subtract from string length

l = l - (e - s + 1)

keep = prompt[pos:s]

l -= sum(map(wlen, ANSI_ESCAPE_SEQUENCE.findall(keep)))

out_prompt += keep + prompt[s + 1 : e]

pos = e + 1

keep = prompt[pos:]

l -= sum(map(wlen, ANSI_ESCAPE_SEQUENCE.findall(keep)))

out_prompt += keep

return out_prompt, l

def bow(self, p: int | None = None) -> int:

"""Return the 0-based index of the word break preceding p most

immediately.

p defaults to self.pos; word boundaries are determined using

self.syntax_table."""

if p is None:

p = self.pos

st = self.syntax_table

b = self.buffer

p -= 1

while p >= 0 and st.get(b[p], SYNTAX_WORD) != SYNTAX_WORD:

p -= 1

while p >= 0 and st.get(b[p], SYNTAX_WORD) == SYNTAX_WORD:

p -= 1

return p + 1

def eow(self, p: int | None = None) -> int:

"""Return the 0-based index of the word break following p most

immediately.

p defaults to self.pos; word boundaries are determined using

self.syntax_table."""

if p is None:

p = self.pos

st = self.syntax_table

b = self.buffer

while p < len(b) and st.get(b[p], SYNTAX_WORD) != SYNTAX_WORD:

p += 1

while p < len(b) and st.get(b[p], SYNTAX_WORD) == SYNTAX_WORD:

p += 1

return p

def bol(self, p: int | None = None) -> int:

"""Return the 0-based index of the line break preceding p most

immediately.

p defaults to self.pos."""

if p is None:

p = self.pos

b = self.buffer

p -= 1

while p >= 0 and b[p] != "\n":

p -= 1

return p + 1

def eol(self, p: int | None = None) -> int:

"""Return the 0-based index of the line break following p most

immediately.

p defaults to self.pos."""

if p is None:

p = self.pos

b = self.buffer

while p < len(b) and b[p] != "\n":

p += 1

return p

def max_column(self, y: int) -> int:

"""Return the last x-offset for line y"""

return self.screeninfo[y][0] + sum(self.screeninfo[y][1])

def max_row(self) -> int:

return len(self.screeninfo) - 1

def get_arg(self, default: int = 1) -> int:

"""Return any prefix argument that the user has supplied,

returning 'default' if there is None. Defaults to 1.

"""

if self.arg is None:

return default

return self.arg

def get_prompt(self, lineno: int, cursor_on_line: bool) -> str:

"""Return what should be in the left-hand margin for line

'lineno'."""

if self.arg is not None and cursor_on_line:

prompt = f"(arg: {self.arg}) "

elif self.paste_mode:

prompt = "(paste) "

elif "\n" in self.buffer:

if lineno == 0:

prompt = self.ps2

elif self.ps4 and lineno == self.buffer.count("\n"):

prompt = self.ps4

else:

prompt = self.ps3

else:

prompt = self.ps1

if can_colorize():

prompt = f"{ANSIColors.BOLD_MAGENTA}{prompt}{ANSIColors.RESET}"

return prompt

def push_input_trans(self, itrans: input.KeymapTranslator) -> None:

self.input_trans_stack.append(self.input_trans)

self.input_trans = itrans

def pop_input_trans(self) -> None:

self.input_trans = self.input_trans_stack.pop()

def setpos_from_xy(self, x: int, y: int) -> None:

"""Set pos according to coordinates x, y"""

pos = 0

i = 0

while i < y:

prompt_len, character_widths = self.screeninfo[i]

offset = len(character_widths) - character_widths.count(0)

in_wrapped_line = prompt_len + sum(character_widths) >= self.console.width

if in_wrapped_line:

pos += offset - 1 # -1 cause backslash is not in buffer

else:

pos += offset + 1 # +1 cause newline is in buffer

i += 1

j = 0

cur_x = self.screeninfo[i][0]

while cur_x < x:

if self.screeninfo[i][1][j] == 0:

continue

cur_x += self.screeninfo[i][1][j]

j += 1

pos += 1

self.pos = pos

def pos2xy(self) -> tuple[int, int]:

"""Return the x, y coordinates of position 'pos'."""

# this *is* incomprehensible, yes.

y = 0

pos = self.pos

assert 0 <= pos <= len(self.buffer)

if pos == len(self.buffer):

y = len(self.screeninfo) - 1

p, l2 = self.screeninfo[y]

return p + sum(l2) + l2.count(0), y

for p, l2 in self.screeninfo:

l = len(l2) - l2.count(0)

in_wrapped_line = p + sum(l2) >= self.console.width

offset = l - 1 if in_wrapped_line else l # need to remove backslash

if offset >= pos:

break

if p + sum(l2) >= self.console.width:

pos -= l - 1 # -1 cause backslash is not in buffer

else:

pos -= l + 1 # +1 cause newline is in buffer

y += 1

return p + sum(l2[:pos]), y

def insert(self, text: str | list[str]) -> None:

"""Insert 'text' at the insertion point."""

self.buffer[self.pos : self.pos] = list(text)

self.pos += len(text)

self.dirty = True

def update_cursor(self) -> None:

"""Move the cursor to reflect changes in self.pos"""

self.cxy = self.pos2xy()

self.console.move_cursor(*self.cxy)

def after_command(self, cmd: Command) -> None:

"""This function is called to allow post command cleanup."""

if getattr(cmd, "kills_digit_arg", True):

if self.arg is not None:

self.dirty = True

self.arg = None

def prepare(self) -> None:

"""Get ready to run. Call restore when finished. You must not

write to the console in between the calls to prepare and

restore."""

try:

self.console.prepare()

self.arg = None

self.finished = False

del self.buffer[:]

self.pos = 0

self.dirty = True

self.last_command = None

self.calc_screen()

except BaseException:

self.restore()

raise

while self.scheduled_commands:

cmd = self.scheduled_commands.pop()

self.do_cmd((cmd, []))

def last_command_is(self, cls: type) -> bool:

if not self.last_command:

return False

return issubclass(cls, self.last_command)

def restore(self) -> None:

"""Clean up after a run."""

self.console.restore()

@contextmanager

def suspend(self) -> SimpleContextManager:

"""A context manager to delegate to another reader."""

prev_state = {f.name: getattr(self, f.name) for f in fields(self)}

try:

self.restore()

yield

finally:

for arg in ("msg", "ps1", "ps2", "ps3", "ps4", "paste_mode"):

setattr(self, arg, prev_state[arg])

self.prepare()

def finish(self) -> None:

"""Called when a command signals that we're finished."""

pass

def error(self, msg: str = "none") -> None:

self.msg = "! " + msg + " "

self.dirty = True

self.console.beep()

def update_screen(self) -> None:

if self.dirty:

self.refresh()

def refresh(self) -> None:

"""Recalculate and refresh the screen."""

# this call sets up self.cxy, so call it first.

self.screen = self.calc_screen()

self.console.refresh(self.screen, self.cxy)

self.dirty = False

def do_cmd(self, cmd: tuple[str, list[str]]) -> None:

"""`cmd` is a tuple of "event_name" and "event", which in the current

implementation is always just the "buffer" which happens to be a list

of single-character strings."""

trace("received command {cmd}", cmd=cmd)

if isinstance(cmd[0], str):

command_type = self.commands.get(cmd[0], commands.invalid_command)

elif isinstance(cmd[0], type):

command_type = cmd[0]

else:

return # nothing to do

command = command_type(self, *cmd) # type: ignore[arg-type]

command.do()

self.after_command(command)

if self.dirty and not self.in_bracketed_paste:

self.refresh()

else:

self.update_cursor()

if not isinstance(cmd, commands.digit_arg):

self.last_command = command_type

self.finished = bool(command.finish)

if self.finished:

self.console.finish()

self.finish()

def handle1(self, block: bool = True) -> bool:

"""Handle a single event. Wait as long as it takes if block

is true (the default), otherwise return False if no event is

pending."""

if self.msg:

self.msg = ""

self.dirty = True

while True:

event = self.console.get_event(block)

if not event: # can only happen if we're not blocking

return False

translate = True

if event.evt == "key":

self.input_trans.push(event)

elif event.evt == "scroll":

self.refresh()

elif event.evt == "resize":

self.refresh()

else:

translate = False

if translate:

cmd = self.input_trans.get()

else:

cmd = [event.evt, event.data]

if cmd is None:

if block:

continue

else:

return False

self.do_cmd(cmd)

return True

def push_char(self, char: int | bytes) -> None:

self.console.push_char(char)

self.handle1(block=False)

def readline(self, startup_hook: Callback | None = None) -> str:

"""Read a line. The implementation of this method also shows

how to drive Reader if you want more control over the event

loop."""

self.prepare()

try:

if startup_hook is not None:

startup_hook()

self.refresh()

while not self.finished:

self.handle1()

return self.get_unicode()

finally:

self.restore()

def bind(self, spec: KeySpec, command: CommandName) -> None:

self.keymap = self.keymap + ((spec, command),)

self.input_trans = input.KeymapTranslator(

self.keymap, invalid_cls="invalid-key", character_cls="self-insert"

)

def get_unicode(self) -> str:

"""Return the current buffer as a unicode string."""

return "".join(self.buffer)

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