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@jonathanslenders @randy3k @delirious-lettuce @38elements @haridsv @Carreau @asmeurer
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Data structures for the Buffer.
It holds the text, cursor position, history, etc...
import asyncio
import os
import re
import shlex
import subprocess
import tempfile
from asyncio import Task, ensure_future
from enum import Enum
from functools import wraps
from typing import (
from .application.current import get_app
from .application.run_in_terminal import run_in_terminal
from .auto_suggest import AutoSuggest, Suggestion
from .cache import FastDictCache
from .clipboard import ClipboardData
from .completion import (
from .document import Document
from .filters import FilterOrBool, to_filter
from .history import History, InMemoryHistory
from .search import SearchDirection, SearchState
from .selection import PasteMode, SelectionState, SelectionType
from .utils import Event, to_str
from .validation import ValidationError, Validator
__all__ = [
class EditReadOnlyBuffer(Exception):
" Attempt editing of read-only :class:`.Buffer`. "
class ValidationState(Enum):
" The validation state of a buffer. This is set after the validation. "
class CompletionState:
Immutable class that contains a completion state.
def __init__(self, original_document: 'Document',
completions: Optional[List['Completion']] = None,
complete_index: Optional[int] = None):
#: Document as it was when the completion started.
self.original_document = original_document
#: List of all the current Completion instances which are possible at
#: this point.
self.completions = completions or []
#: Position in the `completions` array.
#: This can be `None` to indicate "no completion", the original text.
self.complete_index = complete_index # Position in the `_completions` array.
def __repr__(self) -> str:
return '%s(%r, <%r> completions, index=%r)' % (
self.original_document, len(self.completions), self.complete_index)
def go_to_index(self, index: Optional[int]) -> None:
Create a new :class:`.CompletionState` object with the new index.
When `index` is `None` deselect the completion.
if self.completions:
assert index is None or 0 <= index < len(self.completions)
self.complete_index = index
def new_text_and_position(self) -> Tuple[str, int]:
Return (new_text, new_cursor_position) for this completion.
if self.complete_index is None:
return self.original_document.text, self.original_document.cursor_position
original_text_before_cursor = self.original_document.text_before_cursor
original_text_after_cursor = self.original_document.text_after_cursor
c = self.completions[self.complete_index]
if c.start_position == 0:
before = original_text_before_cursor
before = original_text_before_cursor[:c.start_position]
new_text = before + c.text + original_text_after_cursor
new_cursor_position = len(before) + len(c.text)
return new_text, new_cursor_position
def current_completion(self) -> Optional['Completion']:
Return the current completion, or return `None` when no completion is
if self.complete_index is not None:
return self.completions[self.complete_index]
return None
_QUOTED_WORDS_RE = re.compile(r"""(\s+|".*?"|'.*?')""")
class YankNthArgState:
For yank-last-arg/yank-nth-arg: Keep track of where we are in the history.
def __init__(self, history_position: int = 0, n: int = -1,
previous_inserted_word: str = ''):
self.history_position = history_position
self.previous_inserted_word = previous_inserted_word
self.n = n
def __repr__(self) -> str:
return '%s(history_position=%r, n=%r, previous_inserted_word=%r)' % (
self.__class__.__name__, self.history_position, self.n,
BufferEventHandler = Callable[['Buffer'], None]
BufferAcceptHandler = Callable[['Buffer'], bool]
class Buffer:
The core data structure that holds the text and cursor position of the
current input line and implements all text manipulations on top of it. It
also implements the history, undo stack and the completion state.
:param completer: :class:`~prompt_toolkit.completion.Completer` instance.
:param history: :class:`~prompt_toolkit.history.History` instance.
:param tempfile_suffix: The tempfile suffix (extension) to be used for the
"open in editor" function. For a Python REPL, this would be ".py", so
that the editor knows the syntax highlighting to use. This can also be
a callable that returns a string.
:param name: Name for this buffer. E.g. DEFAULT_BUFFER. This is mostly
useful for key bindings where we sometimes prefer to refer to a buffer
by their name instead of by reference.
:param accept_handler: Called when the buffer input is accepted. (Usually
when the user presses `enter`.) The accept handler receives this
`Buffer` as input and should return True when the buffer text should be
kept instead of calling reset.
In case of a `PromptSession` for instance, we want to keep the text,
because we will exit the application, and only reset it during the next
:param on_text_changed: When the buffer text changes. (Callable on None.)
:param on_text_insert: When new text is inserted. (Callable on None.)
:param on_cursor_position_changed: When the cursor moves. (Callable on None.)
:param on_completions_changed: When the completions were changed. (Callable on None.)
:param on_suggestion_set: When an auto-suggestion text has been set. (Callable on None.)
:param complete_while_typing: :class:`~prompt_toolkit.filters.Filter`
or `bool`. Decide whether or not to do asynchronous autocompleting while
:param validate_while_typing: :class:`~prompt_toolkit.filters.Filter`
or `bool`. Decide whether or not to do asynchronous validation while
:param enable_history_search: :class:`~prompt_toolkit.filters.Filter` or
`bool` to indicate when up-arrow partial string matching is enabled. It
is advised to not enable this at the same time as
`complete_while_typing`, because when there is an autocompletion found,
the up arrows usually browse through the completions, rather than
through the history.
:param read_only: :class:`~prompt_toolkit.filters.Filter`. When True,
changes will not be allowed.
:param multiline: :class:`~prompt_toolkit.filters.Filter` or `bool`. When
not set, pressing `Enter` will call the `accept_handler`. Otherwise,
pressing `Esc-Enter` is required.
def __init__(self,
completer: Optional[Completer] = None,
auto_suggest: Optional[AutoSuggest] = None,
history: Optional[History] = None,
validator: Optional[Validator] = None,
tempfile_suffix: Union[str, Callable[[], str]] = '',
name: str = '',
complete_while_typing: FilterOrBool = False,
validate_while_typing: FilterOrBool = False,
enable_history_search: FilterOrBool = False,
document: Optional[Document] = None,
accept_handler: Optional[BufferAcceptHandler] = None,
read_only: FilterOrBool = False,
multiline: FilterOrBool = True,
on_text_changed: Optional[BufferEventHandler] = None,
on_text_insert: Optional[BufferEventHandler] = None,
on_cursor_position_changed: Optional[BufferEventHandler] = None,
on_completions_changed: Optional[BufferEventHandler] = None,
on_suggestion_set: Optional[BufferEventHandler] = None):
# Accept both filters and booleans as input.
enable_history_search = to_filter(enable_history_search)
complete_while_typing = to_filter(complete_while_typing)
validate_while_typing = to_filter(validate_while_typing)
read_only = to_filter(read_only)
multiline = to_filter(multiline)
self.completer = completer or DummyCompleter()
self.auto_suggest = auto_suggest
self.validator = validator
self.tempfile_suffix = tempfile_suffix = name
self.accept_handler = accept_handler
# Filters. (Usually, used by the key bindings to drive the buffer.)
self.complete_while_typing = complete_while_typing
self.validate_while_typing = validate_while_typing
self.enable_history_search = enable_history_search
self.read_only = read_only
self.multiline = multiline
# Text width. (For wrapping, used by the Vi 'gq' operator.)
self.text_width = 0
#: The command buffer history.
# Note that we shouldn't use a lazy 'or' here. bool(history) could be
# False when empty.
self.history = InMemoryHistory() if history is None else history
self.__cursor_position = 0
# Events
self.on_text_changed: Event['Buffer'] = Event(self, on_text_changed)
self.on_text_insert: Event['Buffer'] = Event(self, on_text_insert)
self.on_cursor_position_changed: Event['Buffer'] = Event(self, on_cursor_position_changed)
self.on_completions_changed: Event['Buffer'] = Event(self, on_completions_changed)
self.on_suggestion_set: Event['Buffer'] = Event(self, on_suggestion_set)
# Document cache. (Avoid creating new Document instances.)
self._document_cache: FastDictCache[Tuple[str, int, Optional[SelectionState]], Document] = \
FastDictCache(Document, size=10)
# Create completer / auto suggestion / validation coroutines.
self._async_suggester = self._create_auto_suggest_coroutine()
self._async_completer = self._create_completer_coroutine()
self._async_validator = self._create_auto_validate_coroutine()
# Reset other attributes.
# Attach callback for new history entries.
def new_history_item(sender: History) -> None:
# Insert the new string into `_working_lines`.
self._working_lines.insert(0, self.history.get_strings()[0])
self.__working_index += 1
def __repr__(self) -> str:
if len(self.text) < 15:
text = self.text
text = self.text[:12] + '...'
return '<Buffer(name=%r, text=%r) at %r>' % (, text, id(self))
def reset(self, document: Optional[Document] = None,
append_to_history: bool = False) -> None:
:param append_to_history: Append current input to history first.
if append_to_history:
document = document or Document()
self.__cursor_position = document.cursor_position
# `ValidationError` instance. (Will be set when the input is wrong.)
self.validation_error: Optional[ValidationError] = None
self.validation_state: Optional[ValidationState] = ValidationState.UNKNOWN
# State of the selection.
self.selection_state: Optional[SelectionState] = None
# Multiple cursor mode. (When we press 'I' or 'A' in visual-block mode,
# we can insert text on multiple lines at once. This is implemented by
# using multiple cursors.)
self.multiple_cursor_positions: List[int] = []
# When doing consecutive up/down movements, prefer to stay at this column.
self.preferred_column: Optional[int] = None
# State of complete browser
# For interactive completion through Ctrl-N/Ctrl-P.
self.complete_state: Optional[CompletionState] = None
# State of Emacs yank-nth-arg completion.
self.yank_nth_arg_state: Optional[YankNthArgState] = None # for yank-nth-arg.
# Remember the document that we had *right before* the last paste
# operation. This is used for rotating through the kill ring.
self.document_before_paste: Optional[Document] = None
# Current suggestion.
self.suggestion: Optional[Suggestion] = None
# The history search text. (Used for filtering the history when we
# browse through it.)
self.history_search_text: Optional[str] = None
# Undo/redo stacks (stack of `(text, cursor_position)`).
self._undo_stack: List[Tuple[str, int]] = []
self._redo_stack: List[Tuple[str, int]] = []
#: The working lines. Similar to history, except that this can be
#: modified. The user can press arrow_up and edit previous entries.
#: Ctrl-C should reset this, and copy the whole history back in here.
#: Enter should process the current command and append to the real
#: history.
self._working_lines = self.history.get_strings()[:]
self.__working_index = len(self._working_lines) - 1
# <getters/setters>
def _set_text(self, value: str) -> bool:
""" set text at current working_index. Return whether it changed. """
working_index = self.working_index
working_lines = self._working_lines
original_value = working_lines[working_index]
working_lines[working_index] = value
# Return True when this text has been changed.
if len(value) != len(original_value):
# For Python 2, it seems that when two strings have a different
# length and one is a prefix of the other, Python still scans
# character by character to see whether the strings are different.
# (Some benchmarking showed significant differences for big
# documents. >100,000 of lines.)
return True
elif value != original_value:
return True
return False
def _set_cursor_position(self, value: int) -> bool:
""" Set cursor position. Return whether it changed. """
original_position = self.__cursor_position
self.__cursor_position = max(0, value)
return value != original_position
def text(self) -> str:
return self._working_lines[self.working_index]
def text(self, value: str) -> None:
Setting text. (When doing this, make sure that the cursor_position is
valid for this text. text/cursor_position should be consistent at any time,
otherwise set a Document instead.)
# Ensure cursor position remains within the size of the text.
if self.cursor_position > len(value):
self.cursor_position = len(value)
# Don't allow editing of read-only buffers.
if self.read_only():
raise EditReadOnlyBuffer()
changed = self._set_text(value)
if changed:
# Reset history search text.
# (Note that this doesn't need to happen when working_index
# changes, which is when we traverse the history. That's why we
# don't do this in `self._text_changed`.)
self.history_search_text = None
def cursor_position(self) -> int:
return self.__cursor_position
def cursor_position(self, value: int) -> None:
Setting cursor position.
assert isinstance(value, int)
# Ensure cursor position is within the size of the text.
if value > len(self.text):
value = len(self.text)
if value < 0:
value = 0
changed = self._set_cursor_position(value)
if changed:
def working_index(self) -> int:
return self.__working_index
def working_index(self, value: int) -> None:
if self.__working_index != value:
self.__working_index = value
# Make sure to reset the cursor position, otherwise we end up in
# situations where the cursor position is out of the bounds of the
# text.
self.cursor_position = 0
def _text_changed(self) -> None:
# Remove any validation errors and complete state.
self.validation_error = None
self.validation_state = ValidationState.UNKNOWN
self.complete_state = None
self.yank_nth_arg_state = None
self.document_before_paste = None
self.selection_state = None
self.suggestion = None
self.preferred_column = None
# fire 'on_text_changed' event.
# Input validation.
# (This happens on all change events, unlike auto completion, also when
# deleting text.)
if self.validator and self.validate_while_typing():
def _cursor_position_changed(self) -> None:
# Remove any complete state.
# (Input validation should only be undone when the cursor position
# changes.)
self.complete_state = None
self.yank_nth_arg_state = None
self.document_before_paste = None
# Unset preferred_column. (Will be set after the cursor movement, if
# required.)
self.preferred_column = None
# Note that the cursor position can change if we have a selection the
# new position of the cursor determines the end of the selection.
# fire 'on_cursor_position_changed' event.
def document(self) -> Document:
Return :class:`~prompt_toolkit.document.Document` instance from the
current text, cursor position and selection state.
return self._document_cache[
self.text, self.cursor_position, self.selection_state]
def document(self, value: Document) -> None:
Set :class:`~prompt_toolkit.document.Document` instance.
This will set both the text and cursor position at the same time, but
atomically. (Change events will be triggered only after both have been set.)
def set_document(self, value: Document, bypass_readonly: bool = False) -> None:
Set :class:`~prompt_toolkit.document.Document` instance. Like the
``document`` property, but accept an ``bypass_readonly`` argument.
:param bypass_readonly: When True, don't raise an
:class:`.EditReadOnlyBuffer` exception, even
when the buffer is read-only.
.. warning::
When this buffer is read-only and `bypass_readonly` was not passed,
the `EditReadOnlyBuffer` exception will be caught by the
`KeyProcessor` and is silently suppressed. This is important to
keep in mind when writing key bindings, because it won't do what
you expect, and there won't be a stack trace. Use try/finally
around this function if you need some cleanup code.
# Don't allow editing of read-only buffers.
if not bypass_readonly and self.read_only():
raise EditReadOnlyBuffer()
# Set text and cursor position first.
text_changed = self._set_text(value.text)
cursor_position_changed = self._set_cursor_position(value.cursor_position)
# Now handle change events. (We do this when text/cursor position is
# both set and consistent.)
if text_changed:
self.history_search_text = None
if cursor_position_changed:
def is_returnable(self) -> bool:
True when there is something handling accept.
return bool(self.accept_handler)
# End of <getters/setters>
def save_to_undo_stack(self, clear_redo_stack: bool = True) -> None:
Safe current state (input text and cursor position), so that we can
restore it by calling undo.
# Safe if the text is different from the text at the top of the stack
# is different. If the text is the same, just update the cursor position.
if self._undo_stack and self._undo_stack[-1][0] == self.text:
self._undo_stack[-1] = (self._undo_stack[-1][0], self.cursor_position)
self._undo_stack.append((self.text, self.cursor_position))
# Saving anything to the undo stack, clears the redo stack.
if clear_redo_stack:
self._redo_stack = []
def transform_lines(self, line_index_iterator: Iterable[int],
transform_callback: Callable[[str], str]) -> str:
Transforms the text on a range of lines.
When the iterator yield an index not in the range of lines that the
document contains, it skips them silently.
To uppercase some lines::
new_text = transform_lines(range(5,10), lambda text: text.upper())
:param line_index_iterator: Iterator of line numbers (int)
:param transform_callback: callable that takes the original text of a
line, and return the new text for this line.
:returns: The new text.
# Split lines
lines = self.text.split('\n')
# Apply transformation
for index in line_index_iterator:
lines[index] = transform_callback(lines[index])
except IndexError:
return '\n'.join(lines)
def transform_current_line(
self, transform_callback: Callable[[str], str]) -> None:
Apply the given transformation function to the current line.
:param transform_callback: callable that takes a string and return a new string.
document = self.document
a = document.cursor_position + document.get_start_of_line_position()
b = document.cursor_position + document.get_end_of_line_position()
self.text = (
document.text[:a] +
transform_callback(document.text[a:b]) +
def transform_region(self, from_: int, to: int,
transform_callback: Callable[[str], str]) -> None:
Transform a part of the input string.
:param from_: (int) start position.
:param to: (int) end position.
:param transform_callback: Callable which accepts a string and returns
the transformed string.
assert from_ < to
self.text = ''.join([
self.text[:from_] +
transform_callback(self.text[from_:to]) +
def cursor_left(self, count: int = 1) -> None:
self.cursor_position += self.document.get_cursor_left_position(count=count)
def cursor_right(self, count: int = 1) -> None:
self.cursor_position += self.document.get_cursor_right_position(count=count)
def cursor_up(self, count: int = 1) -> None:
""" (for multiline edit). Move cursor to the previous line. """
original_column = self.preferred_column or self.document.cursor_position_col
self.cursor_position += self.document.get_cursor_up_position(
count=count, preferred_column=original_column)
# Remember the original column for the next up/down movement.
self.preferred_column = original_column
def cursor_down(self, count: int = 1) -> None:
""" (for multiline edit). Move cursor to the next line. """
original_column = self.preferred_column or self.document.cursor_position_col
self.cursor_position += self.document.get_cursor_down_position(
count=count, preferred_column=original_column)
# Remember the original column for the next up/down movement.
self.preferred_column = original_column
def auto_up(self, count: int = 1,
go_to_start_of_line_if_history_changes: bool = False) -> None:
If we're not on the first line (of a multiline input) go a line up,
otherwise go back in history. (If nothing is selected.)
if self.complete_state:
elif self.document.cursor_position_row > 0:
elif not self.selection_state:
# Go to the start of the line?
if go_to_start_of_line_if_history_changes:
self.cursor_position += self.document.get_start_of_line_position()
def auto_down(self, count: int = 1,
go_to_start_of_line_if_history_changes: bool = False) -> None:
If we're not on the last line (of a multiline input) go a line down,
otherwise go forward in history. (If nothing is selected.)
if self.complete_state:
elif self.document.cursor_position_row < self.document.line_count - 1:
elif not self.selection_state:
# Go to the start of the line?
if go_to_start_of_line_if_history_changes:
self.cursor_position += self.document.get_start_of_line_position()
def delete_before_cursor(self, count: int = 1) -> str:
Delete specified number of characters before cursor and return the
deleted text.
assert count >= 0
deleted = ''
if self.cursor_position > 0:
deleted = self.text[self.cursor_position - count:self.cursor_position]
new_text = self.text[:self.cursor_position - count] + self.text[self.cursor_position:]
new_cursor_position = self.cursor_position - len(deleted)
# Set new Document atomically.
self.document = Document(new_text, new_cursor_position)
return deleted
def delete(self, count: int = 1) -> str:
Delete specified number of characters and Return the deleted text.
if self.cursor_position < len(self.text):
deleted = self.document.text_after_cursor[:count]
self.text = self.text[:self.cursor_position] + \
self.text[self.cursor_position + len(deleted):]
return deleted
return ''
def join_next_line(self, separator: str = ' ') -> None:
Join the next line to the current one by deleting the line ending after
the current line.
if not self.document.on_last_line:
self.cursor_position += self.document.get_end_of_line_position()
# Remove spaces.
self.text = (self.document.text_before_cursor + separator +
self.document.text_after_cursor.lstrip(' '))
def join_selected_lines(self, separator: str = ' ') -> None:
Join the selected lines.
assert self.selection_state
# Get lines.
from_, to = sorted([self.cursor_position, self.selection_state.original_cursor_position])
before = self.text[:from_]
lines = self.text[from_:to].splitlines()
after = self.text[to:]
# Replace leading spaces with just one space.
lines = [l.lstrip(' ') + separator for l in lines]
# Set new document.
self.document = Document(text=before + ''.join(lines) + after,
cursor_position=len(before + ''.join(lines[:-1])) - 1)
def swap_characters_before_cursor(self) -> None:
Swap the last two characters before the cursor.
pos = self.cursor_position
if pos >= 2:
a = self.text[pos - 2]
b = self.text[pos - 1]
self.text = self.text[:pos - 2] + b + a + self.text[pos:]
def go_to_history(self, index: int) -> None:
Go to this item in the history.
if index < len(self._working_lines):
self.working_index = index
self.cursor_position = len(self.text)
def complete_next(self, count: int = 1,
disable_wrap_around: bool = False) -> None:
Browse to the next completions.
(Does nothing if there are no completion.)
index: Optional[int]
if self.complete_state:
completions_count = len(self.complete_state.completions)
if self.complete_state.complete_index is None:
index = 0
elif self.complete_state.complete_index == completions_count - 1:
index = None
if disable_wrap_around:
index = min(completions_count - 1, self.complete_state.complete_index + count)
def complete_previous(
self, count: int = 1, disable_wrap_around: bool = False) -> None:
Browse to the previous completions.
(Does nothing if there are no completion.)
index: Optional[int]
if self.complete_state:
if self.complete_state.complete_index == 0:
index = None
if disable_wrap_around:
elif self.complete_state.complete_index is None:
index = len(self.complete_state.completions) - 1
index = max(0, self.complete_state.complete_index - count)
def cancel_completion(self) -> None:
Cancel completion, go back to the original text.
if self.complete_state:
self.complete_state = None
def _set_completions(self, completions: List[Completion]) -> CompletionState:
Start completions. (Generate list of completions and initialize.)
By default, no completion will be selected.
self.complete_state = CompletionState(
# Trigger event. This should eventually invalidate the layout.
return self.complete_state
def start_history_lines_completion(self) -> None:
Start a completion based on all the other lines in the document and the
found_completions: Set[str] = set()
completions = []
# For every line of the whole history, find matches with the current line.
current_line = self.document.current_line_before_cursor.lstrip()
for i, string in enumerate(self._working_lines):
for j, l in enumerate(string.split('\n')):
l = l.strip()
if l and l.startswith(current_line):
# When a new line has been found.
if l not in found_completions:
# Create completion.
if i == self.working_index:
display_meta = "Current, line %s" % (j + 1)
display_meta = "History %s, line %s" % (i + 1, j + 1)
def go_to_completion(self, index: Optional[int]) -> None:
Select a completion from the list of current completions.
assert self.complete_state
# Set new completion
state = self.complete_state
# Set text/cursor position
new_text, new_cursor_position = state.new_text_and_position()
self.document = Document(new_text, new_cursor_position)
# (changing text/cursor position will unset complete_state.)
self.complete_state = state
def apply_completion(self, completion: Completion) -> None:
Insert a given completion.
# If there was already a completion active, cancel that one.
if self.complete_state:
self.complete_state = None
# Insert text from the given completion.
def _set_history_search(self) -> None:
Set `history_search_text`.
(The text before the cursor will be used for filtering the history.)
if self.enable_history_search():
if self.history_search_text is None:
self.history_search_text = self.document.text_before_cursor
self.history_search_text = None
def _history_matches(self, i: int) -> bool:
True when the current entry matches the history search.
(when we don't have history search, it's also True.)
return (self.history_search_text is None or
def history_forward(self, count: int = 1) -> None:
Move forwards through the history.
:param count: Amount of items to move forward.
# Go forward in history.
found_something = False
for i in range(self.working_index + 1, len(self._working_lines)):
if self._history_matches(i):
self.working_index = i
count -= 1
found_something = True
if count == 0:
# If we found an entry, move cursor to the end of the first line.
if found_something:
self.cursor_position = 0
self.cursor_position += self.document.get_end_of_line_position()
def history_backward(self, count: int = 1) -> None:
Move backwards through history.
# Go back in history.
found_something = False
for i in range(self.working_index - 1, -1, -1):
if self._history_matches(i):
self.working_index = i
count -= 1
found_something = True
if count == 0:
# If we move to another entry, move cursor to the end of the line.
if found_something:
self.cursor_position = len(self.text)
def yank_nth_arg(self, n: Optional[int] = None,
_yank_last_arg: bool = False) -> None:
Pick nth word from previous history entry (depending on current
`yank_nth_arg_state`) and insert it at current position. Rotate through
history if called repeatedly. If no `n` has been given, take the first
argument. (The second word.)
:param n: (None or int), The index of the word from the previous line
to take.
assert n is None or isinstance(n, int)
history_strings = self.history.get_strings()
if not len(history_strings):
# Make sure we have a `YankNthArgState`.
if self.yank_nth_arg_state is None:
state = YankNthArgState(n=-1 if _yank_last_arg else 1)
state = self.yank_nth_arg_state
if n is not None:
state.n = n
# Get new history position.
new_pos = state.history_position - 1
if -new_pos > len(history_strings):
new_pos = -1
# Take argument from line.
line = history_strings[new_pos]
words = [w.strip() for w in _QUOTED_WORDS_RE.split(line)]
words = [w for w in words if w]
word = words[state.n]
except IndexError:
word = ''
# Insert new argument.
if state.previous_inserted_word:
# Save state again for next completion. (Note that the 'insert'
# operation from above clears `self.yank_nth_arg_state`.)
state.previous_inserted_word = word
state.history_position = new_pos
self.yank_nth_arg_state = state
def yank_last_arg(self, n: Optional[int] = None) -> None:
Like `yank_nth_arg`, but if no argument has been given, yank the last
word by default.
self.yank_nth_arg(n=n, _yank_last_arg=True)
def start_selection(
selection_type: SelectionType = SelectionType.CHARACTERS) -> None:
Take the current cursor position as the start of this selection.
self.selection_state = SelectionState(self.cursor_position, selection_type)
def copy_selection(self, _cut: bool = False) -> ClipboardData:
Copy selected text and return :class:`.ClipboardData` instance.
Notice that this doesn't store the copied data on the clipboard yet.
You can store it like this:
.. code:: python
data = buffer.copy_selection()
new_document, clipboard_data = self.document.cut_selection()
if _cut:
self.document = new_document
self.selection_state = None
return clipboard_data
def cut_selection(self) -> ClipboardData:
Delete selected text and return :class:`.ClipboardData` instance.
return self.copy_selection(_cut=True)
def paste_clipboard_data(
self, data: ClipboardData,
paste_mode: PasteMode = PasteMode.EMACS,
count: int = 1) -> None:
Insert the data from the clipboard.
assert isinstance(data, ClipboardData)
assert paste_mode in (PasteMode.VI_BEFORE, PasteMode.VI_AFTER, PasteMode.EMACS)
original_document = self.document
self.document = self.document.paste_clipboard_data(data, paste_mode=paste_mode, count=count)
# Remember original document. This assignment should come at the end,
# because assigning to 'document' will erase it.
self.document_before_paste = original_document
def newline(self, copy_margin: bool = True) -> None:
Insert a line ending at the current position.
if copy_margin:
self.insert_text('\n' + self.document.leading_whitespace_in_current_line)
def insert_line_above(self, copy_margin: bool = True) -> None:
Insert a new line above the current one.
if copy_margin:
insert = self.document.leading_whitespace_in_current_line + '\n'
insert = '\n'
self.cursor_position += self.document.get_start_of_line_position()
self.cursor_position -= 1
def insert_line_below(self, copy_margin: bool = True) -> None:
Insert a new line below the current one.
if copy_margin:
insert = '\n' + self.document.leading_whitespace_in_current_line
insert = '\n'
self.cursor_position += self.document.get_end_of_line_position()
def insert_text(self, data: str, overwrite: bool = False,
move_cursor: bool = True, fire_event: bool = True) -> None:
Insert characters at cursor position.
:param fire_event: Fire `on_text_insert` event. This is mainly used to
trigger autocompletion while typing.
# Original text & cursor position.
otext = self.text
ocpos = self.cursor_position
# In insert/text mode.
if overwrite:
# Don't overwrite the newline itself. Just before the line ending,
# it should act like insert mode.
overwritten_text = otext[ocpos:ocpos + len(data)]
if '\n' in overwritten_text:
overwritten_text = overwritten_text[:overwritten_text.find('\n')]
text = otext[:ocpos] + data + otext[ocpos + len(overwritten_text):]
text = otext[:ocpos] + data + otext[ocpos:]
if move_cursor:
cpos = self.cursor_position + len(data)
cpos = self.cursor_position
# Set new document.
# (Set text and cursor position at the same time. Otherwise, setting
# the text will fire a change event before the cursor position has been
# set. It works better to have this atomic.)
self.document = Document(text, cpos)
# Fire 'on_text_insert' event.
if fire_event: # XXX: rename to `start_complete`.
# Only complete when "complete_while_typing" is enabled.
if self.completer and self.complete_while_typing():
# Call auto_suggest.
if self.auto_suggest:
def undo(self) -> None:
# Pop from the undo-stack until we find a text that if different from
# the current text. (The current logic of `save_to_undo_stack` will
# cause that the top of the undo stack is usually the same as the
# current text, so in that case we have to pop twice.)
while self._undo_stack:
text, pos = self._undo_stack.pop()
if text != self.text:
# Push current text to redo stack.
self._redo_stack.append((self.text, self.cursor_position))
# Set new text/cursor_position.
self.document = Document(text, cursor_position=pos)
def redo(self) -> None:
if self._redo_stack:
# Copy current state on undo stack.
# Pop state from redo stack.
text, pos = self._redo_stack.pop()
self.document = Document(text, cursor_position=pos)
def validate(self, set_cursor: bool = False) -> bool:
Returns `True` if valid.
:param set_cursor: Set the cursor position, if an error was found.
# Don't call the validator again, if it was already called for the
# current input.
if self.validation_state != ValidationState.UNKNOWN:
return self.validation_state == ValidationState.VALID
# Call validator.
if self.validator:
except ValidationError as e:
# Set cursor position (don't allow invalid values.)
if set_cursor:
self.cursor_position = min(max(0, e.cursor_position), len(self.text))
self.validation_state = ValidationState.INVALID
self.validation_error = e
return False
# Handle validation result.
self.validation_state = ValidationState.VALID
self.validation_error = None
return True
async def _validate_async(self) -> None:
Asynchronous version of `validate()`.
This one doesn't set the cursor position.
We have both variants, because a synchronous version is required.
Handling the ENTER key needs to be completely synchronous, otherwise
stuff like type-ahead is going to give very weird results. (People
could type input while the ENTER key is still processed.)
An asynchronous version is required if we have `validate_while_typing`
while True:
# Don't call the validator again, if it was already called for the
# current input.
if self.validation_state != ValidationState.UNKNOWN:
# Call validator.
error = None
document = self.document
if self.validator:
await self.validator.validate_async(self.document)
except ValidationError as e:
error = e
# If the document changed during the validation, try again.
if self.document != document:
# Handle validation result.
if error:
self.validation_state = ValidationState.INVALID
self.validation_state = ValidationState.VALID
self.validation_error = error
get_app().invalidate() # Trigger redraw (display error).
def append_to_history(self) -> None:
Append the current input to the history.
# Save at the tail of the history. (But don't if the last entry the
# history is already the same.)
if self.text:
history_strings = self.history.get_strings()
if not len(history_strings) or history_strings[-1] != self.text:
def _search(self, search_state: SearchState,
include_current_position: bool = False,
count: int = 1) -> Optional[Tuple[int, int]]:
Execute search. Return (working_index, cursor_position) tuple when this
search is applied. Returns `None` when this text cannot be found.
assert count > 0
text = search_state.text
direction = search_state.direction
ignore_case = search_state.ignore_case()
def search_once(working_index: int, document: Document) -> Optional[Tuple[int, Document]]:
Do search one time.
Return (working_index, document) or `None`
if direction == SearchDirection.FORWARD:
# Try find at the current input.
new_index = document.find(
text, include_current_position=include_current_position,
if new_index is not None:
return (working_index,
Document(document.text, document.cursor_position + new_index))
# No match, go forward in the history. (Include len+1 to wrap around.)
# (Here we should always include all cursor positions, because
# it's a different line.)
for i in range(working_index + 1, len(self._working_lines) + 1):
i %= len(self._working_lines)
document = Document(self._working_lines[i], 0)
new_index = document.find(text, include_current_position=True,
if new_index is not None:
return (i, Document(document.text, new_index))
# Try find at the current input.
new_index = document.find_backwards(
text, ignore_case=ignore_case)
if new_index is not None:
return (working_index,
Document(document.text, document.cursor_position + new_index))
# No match, go back in the history. (Include -1 to wrap around.)
for i in range(working_index - 1, -2, -1):
i %= len(self._working_lines)
document = Document(self._working_lines[i], len(self._working_lines[i]))
new_index = document.find_backwards(
text, ignore_case=ignore_case)
if new_index is not None:
return (i, Document(document.text, len(document.text) + new_index))
return None
# Do 'count' search iterations.
working_index = self.working_index
document = self.document
for _ in range(count):
result = search_once(working_index, document)
if result is None:
return None # Nothing found.
working_index, document = result
return (working_index, document.cursor_position)
def document_for_search(self, search_state: SearchState) -> Document:
Return a :class:`~prompt_toolkit.document.Document` instance that has
the text/cursor position for this search, if we would apply it. This
will be used in the
:class:`~prompt_toolkit.layout.BufferControl` to display feedback while
search_result = self._search(search_state, include_current_position=True)
if search_result is None:
return self.document
working_index, cursor_position = search_result
# Keep selection, when `working_index` was not changed.
if working_index == self.working_index:
selection = self.selection_state
selection = None
return Document(self._working_lines[working_index],
cursor_position, selection=selection)
def get_search_position(
self, search_state: SearchState,
include_current_position: bool = True, count: int = 1) -> int:
Get the cursor position for this search.
(This operation won't change the `working_index`. It's won't go through
the history. Vi text objects can't span multiple items.)
search_result = self._search(
search_state, include_current_position=include_current_position, count=count)
if search_result is None:
return self.cursor_position
working_index, cursor_position = search_result
return cursor_position
def apply_search(self, search_state: SearchState,
include_current_position: bool = True,
count: int = 1) -> None:
Apply search. If something is found, set `working_index` and
search_result = self._search(
search_state, include_current_position=include_current_position, count=count)
if search_result is not None:
working_index, cursor_position = search_result
self.working_index = working_index
self.cursor_position = cursor_position
def exit_selection(self) -> None:
self.selection_state = None
def open_in_editor(self, validate_and_handle: bool = False) -> 'asyncio.Task[None]':
Open code in editor.
This returns a future, and runs in a thread executor.
if self.read_only():
raise EditReadOnlyBuffer()
# Write to temporary file
descriptor, filename = tempfile.mkstemp(to_str(self.tempfile_suffix))
os.write(descriptor, self.text.encode('utf-8'))
async def run() -> None:
# Open in editor
# (We need to use `run_in_terminal`, because not all editors go to
# the alternate screen buffer, and some could influence the cursor
# position.)
succes = await run_in_terminal(
lambda: self._open_file_in_editor(filename), in_executor=True)
# Read content again.
if succes:
with open(filename, 'rb') as f:
text ='utf-8')
# Drop trailing newline. (Editors are supposed to add it at the
# end, but we don't need it.)
if text.endswith('\n'):
text = text[:-1]
self.document = Document(
# Accept the input.
if validate_and_handle:
# Clean up temp file.
return get_app().create_background_task(run())
def _open_file_in_editor(self, filename: str) -> bool:
Call editor executable.
Return True when we received a zero return code.
# If the 'VISUAL' or 'EDITOR' environment variable has been set, use that.
# Otherwise, fall back to the first available editor that we can find.
visual = os.environ.get('VISUAL')
editor = os.environ.get('EDITOR')
editors = [
# Order of preference.
for e in editors:
if e:
# Use 'shlex.split()', because $VISUAL can contain spaces
# and quotes.
returncode = + [filename])
return returncode == 0
except OSError:
# Executable does not exist, try the next one.
return False
def start_completion(
select_first: bool = False,
select_last: bool = False,
insert_common_part: bool = False,
complete_event: Optional[CompleteEvent] = None) -> None:
Start asynchronous autocompletion of this buffer.
(This will do nothing if a previous completion was still in progress.)
# Only one of these options can be selected.
assert select_first + select_last + insert_common_part <= 1
complete_event=complete_event or CompleteEvent(completion_requested=True)))
def _create_completer_coroutine(self) -> Callable[..., Awaitable[None]]:
Create function for asynchronous autocompletion.
(This consumes the asynchronous completer generator, which possibly
runs the completion algorithm in another thread.)
def completion_does_nothing(document: Document, completion: Completion) -> bool:
Return `True` if applying this completion doesn't have any effect.
(When it doesn't insert any new text.
text_before_cursor = document.text_before_cursor
replaced_text = text_before_cursor[
len(text_before_cursor) + completion.start_position:]
return replaced_text == completion.text
async def async_completer(
select_first: bool = False,
select_last: bool = False,
insert_common_part: bool = False,
complete_event: Optional[CompleteEvent] = None) -> None:
document = self.document
complete_event = complete_event or CompleteEvent(text_inserted=True)
# Don't complete when we already have completions.
if self.complete_state or not self.completer:
# Create an empty CompletionState.
complete_state = CompletionState(original_document=self.document)
self.complete_state = complete_state
def proceed() -> bool:
""" Keep retrieving completions. Input text has not yet changed
while generating completions. """
return self.complete_state == complete_state
async for completion in self.completer.get_completions_async(document, complete_event):
# If the input text changes, abort.
if not proceed():
completions = complete_state.completions
# When there is only one completion, which has nothing to add, ignore it.
if (len(completions) == 1 and
completion_does_nothing(document, completions[0])):
del completions[:]
# Set completions if the text was not yet changed.
if proceed():
# When no completions were found, or when the user selected
# already a completion by using the arrow keys, don't do anything.
if not self.complete_state or self.complete_state.complete_index is not None:
# When there are no completions, reset completion state anyway.
if not completions:
self.complete_state = None
# Render the ui if the completion menu was shown
# it is needed especially if there is one completion and it was deleted.
# Select first/last or insert common part, depending on the key
# binding. (For this we have to wait until all completions are
# loaded.)
if select_first:
elif select_last:
self.go_to_completion(len(completions) - 1)
elif insert_common_part:
common_part = get_common_complete_suffix(document, completions)
if common_part:
# Insert the common part, update completions.
if len(completions) > 1:
# (Don't call `async_completer` again, but
# recalculate completions. See:
completions[:] = [
for c in completions]
self.complete_state = None
# When we were asked to insert the "common"
# prefix, but there was no common suffix but
# still exactly one match, then select the
# first. (It could be that we have a completion
# which does * expansion, like '*.py', with
# exactly one match.)
if len(completions) == 1:
# If the last operation was an insert, (not a delete), restart
# the completion coroutine.
if self.document.text_before_cursor == document.text_before_cursor:
return # Nothing changed.
if self.document.text_before_cursor.startswith(document.text_before_cursor):
raise _Retry
return async_completer
def _create_auto_suggest_coroutine(self) -> Callable[[], Awaitable[None]]:
Create function for asynchronous auto suggestion.
(This can be in another thread.)
async def async_suggestor() -> None:
document = self.document
# Don't suggest when we already have a suggestion.
if self.suggestion or not self.auto_suggest:
suggestion = await self.auto_suggest.get_suggestion_async(self, document)
# Set suggestion only if the text was not yet changed.
if self.document == document:
# Set suggestion and redraw interface.
self.suggestion = suggestion
# Otherwise, restart thread.
raise _Retry
return async_suggestor
def _create_auto_validate_coroutine(self) -> Callable[[], Awaitable[None]]:
Create a function for asynchronous validation while typing.
(This can be in another thread.)
async def async_validator() -> None:
await self._validate_async()
return async_validator
def validate_and_handle(self) -> None:
Validate buffer and handle the accept action.
valid = self.validate(set_cursor=True)
# When the validation succeeded, accept the input.
if valid:
if self.accept_handler:
keep_text = self.accept_handler(self)
keep_text = False
if not keep_text:
_T = TypeVar('_T', bound=Callable[..., Awaitable])
def _only_one_at_a_time(coroutine: _T) -> _T:
Decorator that only starts the coroutine only if the previous call has
finished. (Used to make sure that we have only one autocompleter, auto
suggestor and validator running at a time.)
When the coroutine raises `_Retry`, it is restarted.
running = False
async def new_coroutine(*a: Any, **kw: Any) -> Any:
nonlocal running
# Don't start a new function, if the previous is still in progress.
if running:
running = True
while True:
await coroutine(*a, **kw)
except _Retry:
return None
running = False
return cast(_T, new_coroutine)
class _Retry(Exception):
" Retry in `_only_one_at_a_time`. "
def indent(buffer: Buffer, from_row: int, to_row: int, count: int = 1) -> None:
Indent text of a :class:`.Buffer` object.
current_row = buffer.document.cursor_position_row
line_range = range(from_row, to_row)
# Apply transformation.
new_text = buffer.transform_lines(line_range, lambda l: ' ' * count + l)
buffer.document = Document(
Document(new_text).translate_row_col_to_index(current_row, 0))
# Go to the start of the line.
buffer.cursor_position += buffer.document.get_start_of_line_position(after_whitespace=True)
def unindent(buffer: Buffer, from_row: int, to_row: int, count: int = 1) -> None:
Unindent text of a :class:`.Buffer` object.
current_row = buffer.document.cursor_position_row
line_range = range(from_row, to_row)
def transform(text: str) -> str:
remove = ' ' * count
if text.startswith(remove):
return text[len(remove):]
return text.lstrip()
# Apply transformation.
new_text = buffer.transform_lines(line_range, transform)
buffer.document = Document(
Document(new_text).translate_row_col_to_index(current_row, 0))
# Go to the start of the line.
buffer.cursor_position += buffer.document.get_start_of_line_position(after_whitespace=True)
def reshape_text(buffer: Buffer, from_row: int, to_row: int) -> None:
Reformat text, taking the width into account.
`to_row` is included.
(Vi 'gq' operator.)
lines = buffer.text.splitlines(True)
lines_before = lines[:from_row]
lines_after = lines[to_row + 1:]
lines_to_reformat = lines[from_row:to_row + 1]
if lines_to_reformat:
# Take indentation from the first line.
match ='^\s*', lines_to_reformat[0])
length = match.end() if match else 0 # `match` can't be None, actually.
indent = lines_to_reformat[0][:length].replace('\n', '')
# Now, take all the 'words' from the lines to be reshaped.
words = ''.join(lines_to_reformat).split()
# And reshape.
width = (buffer.text_width or 80) - len(indent)
reshaped_text = [indent]
current_width = 0
for w in words:
if current_width:
if len(w) + current_width + 1 > width:
current_width = 0
reshaped_text.append(' ')
current_width += 1
current_width += len(w)
if reshaped_text[-1] != '\n':
# Apply result.
buffer.document = Document(
text=''.join(lines_before + reshaped_text + lines_after),
cursor_position=len(''.join(lines_before + reshaped_text)))
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