Permalink
Fetching contributors…
Cannot retrieve contributors at this time
434 lines (364 sloc) 15.1 KB
# encoding: utf-8
"""This module provides 'sequence awareness'."""
# std imports
import functools
import textwrap
import math
import re
# local
from blessed._capabilities import CAPABILITIES_CAUSE_MOVEMENT
# 3rd party
import wcwidth
import six
__all__ = ('Sequence', 'SequenceTextWrapper', 'iter_parse', 'measure_length')
class Termcap(object):
"""Terminal capability of given variable name and pattern."""
def __init__(self, name, pattern, attribute):
"""
Class initializer.
:arg str name: name describing capability.
:arg str pattern: regular expression string.
:arg str attribute: :class:`~.Terminal` attribute used to build
this terminal capability.
"""
self.name = name
self.pattern = pattern
self.attribute = attribute
self._re_compiled = None
def __repr__(self):
# pylint: disable=redundant-keyword-arg
return '<Termcap {self.name}:{self.pattern!r}>'.format(self=self)
@property
def named_pattern(self):
# pylint: disable=redundant-keyword-arg
return '(?P<{self.name}>{self.pattern})'.format(self=self)
@property
def re_compiled(self):
if self._re_compiled is None:
self._re_compiled = re.compile(self.pattern)
return self._re_compiled
@property
def will_move(self):
"""Whether capability causes cursor movement."""
return self.name in CAPABILITIES_CAUSE_MOVEMENT
def horizontal_distance(self, text):
"""
Horizontal carriage adjusted by capability, may be negative.
:rtype: int
:arg str text: for capabilities *parm_left_cursor*,
*parm_right_cursor*, provide the matching sequence
text, its interpreted distance is returned.
:returns: 0 except for matching '
"""
value = {
'cursor_left': -1,
'backspace': -1,
'cursor_right': 1,
'tab': 8,
'ascii_tab': 8,
}.get(self.name, None)
if value is not None:
return value
unit = {
'parm_left_cursor': -1,
'parm_right_cursor': 1
}.get(self.name, None)
if unit is not None:
value = int(self.re_compiled.match(text).group(1))
return unit * value
return 0
# pylint: disable=too-many-arguments
@classmethod
def build(cls, name, capability, attribute, nparams=0,
numeric=99, match_grouped=False, match_any=False,
match_optional=False):
r"""
Class factory builder for given capability definition.
:arg str name: Variable name given for this pattern.
:arg str capability: A unicode string representing a terminal
capability to build for. When ``nparams`` is non-zero, it
must be a callable unicode string (such as the result from
``getattr(term, 'bold')``.
:arg attribute: The terminfo(5) capability name by which this
pattern is known.
:arg int nparams: number of positional arguments for callable.
:arg bool match_grouped: If the numeric pattern should be
grouped, ``(\d+)`` when ``True``, ``\d+`` default.
:arg bool match_any: When keyword argument ``nparams`` is given,
*any* numeric found in output is suitable for building as
pattern ``(\d+)``. Otherwise, only the first matching value of
range *(numeric - 1)* through *(numeric + 1)* will be replaced by
pattern ``(\d+)`` in builder.
:arg bool match_optional: When ``True``, building of numeric patterns
containing ``(\d+)`` will be built as optional, ``(\d+)?``.
"""
_numeric_regex = r'\d+'
if match_grouped:
_numeric_regex = r'(\d+)'
if match_optional:
_numeric_regex = r'(\d+)?'
numeric = 99 if numeric is None else numeric
# basic capability attribute, not used as a callable
if nparams == 0:
return cls(name, re.escape(capability), attribute)
# a callable capability accepting numeric argument
_outp = re.escape(capability(*(numeric,) * nparams))
if not match_any:
for num in range(numeric - 1, numeric + 2):
if str(num) in _outp:
pattern = _outp.replace(str(num), _numeric_regex)
return cls(name, pattern, attribute)
if match_grouped:
pattern = re.sub(r'(\d+)', _numeric_regex, _outp)
else:
pattern = re.sub(r'\d+', _numeric_regex, _outp)
return cls(name, pattern, attribute)
class SequenceTextWrapper(textwrap.TextWrapper):
"""This docstring overridden."""
def __init__(self, width, term, **kwargs):
"""
Class initializer.
This class supports the :meth:`~.Terminal.wrap` method.
"""
self.term = term
textwrap.TextWrapper.__init__(self, width, **kwargs)
def _wrap_chunks(self, chunks):
"""
Sequence-aware variant of :meth:`textwrap.TextWrapper._wrap_chunks`.
This simply ensures that word boundaries are not broken mid-sequence,
as standard python textwrap would incorrectly determine the length
of a string containing sequences, and may also break consider sequences
part of a "word" that may be broken by hyphen (``-``), where this
implementation corrects both.
"""
lines = []
if self.width <= 0 or not isinstance(self.width, int):
raise ValueError(
"invalid width {0!r}({1!r}) (must be integer > 0)"
.format(self.width, type(self.width)))
term = self.term
drop_whitespace = not hasattr(self, 'drop_whitespace'
) or self.drop_whitespace
chunks.reverse()
while chunks:
cur_line = []
cur_len = 0
if lines:
indent = self.subsequent_indent
else:
indent = self.initial_indent
width = self.width - len(indent)
if drop_whitespace and (
Sequence(chunks[-1], term).strip() == '' and lines):
del chunks[-1]
while chunks:
chunk_len = Sequence(chunks[-1], term).length()
if cur_len + chunk_len <= width:
cur_line.append(chunks.pop())
cur_len += chunk_len
else:
break
if chunks and Sequence(chunks[-1], term).length() > width:
self._handle_long_word(chunks, cur_line, cur_len, width)
if drop_whitespace and (
cur_line and Sequence(cur_line[-1], term).strip() == ''):
del cur_line[-1]
if cur_line:
lines.append(indent + u''.join(cur_line))
return lines
def _handle_long_word(self, reversed_chunks, cur_line, cur_len, width):
"""Sequence-aware :meth:`textwrap.TextWrapper._handle_long_word`.
This simply ensures that word boundaries are not broken mid-sequence,
as standard python textwrap would incorrectly determine the length
of a string containing sequences, and may also break consider sequences
part of a "word" that may be broken by hyphen (``-``), where this
implementation corrects both.
"""
# Figure out when indent is larger than the specified width, and make
# sure at least one character is stripped off on every pass
if width < 1:
space_left = 1
else:
space_left = width - cur_len
# If we're allowed to break long words, then do so: put as much
# of the next chunk onto the current line as will fit.
if self.break_long_words:
term = self.term
chunk = reversed_chunks[-1]
idx = nxt = 0
for text, _ in iter_parse(term, chunk):
nxt += len(text)
if Sequence(chunk[:nxt], term).length() > space_left:
break
idx = nxt
cur_line.append(chunk[:idx])
reversed_chunks[-1] = chunk[idx:]
# Otherwise, we have to preserve the long word intact. Only add
# it to the current line if there's nothing already there --
# that minimizes how much we violate the width constraint.
elif not cur_line:
cur_line.append(reversed_chunks.pop())
# If we're not allowed to break long words, and there's already
# text on the current line, do nothing. Next time through the
# main loop of _wrap_chunks(), we'll wind up here again, but
# cur_len will be zero, so the next line will be entirely
# devoted to the long word that we can't handle right now.
SequenceTextWrapper.__doc__ = textwrap.TextWrapper.__doc__
class Sequence(six.text_type):
"""
A "sequence-aware" version of the base :class:`str` class.
This unicode-derived class understands the effect of escape sequences
of printable length, allowing a properly implemented :meth:`rjust`,
:meth:`ljust`, :meth:`center`, and :meth:`length`.
"""
def __new__(cls, sequence_text, term):
"""
Class constructor.
:arg sequence_text: A string that may contain sequences.
:arg blessed.Terminal term: :class:`~.Terminal` instance.
"""
new = six.text_type.__new__(cls, sequence_text)
new._term = term
return new
def ljust(self, width, fillchar=u' '):
"""
Return string containing sequences, left-adjusted.
:arg int width: Total width given to right-adjust ``text``. If
unspecified, the width of the attached terminal is used (default).
:arg str fillchar: String for padding right-of ``text``.
:returns: String of ``text``, right-aligned by ``width``.
:rtype: str
"""
rightside = fillchar * int(
(max(0.0, float(width - self.length()))) / float(len(fillchar)))
return u''.join((self, rightside))
def rjust(self, width, fillchar=u' '):
"""
Return string containing sequences, right-adjusted.
:arg int width: Total width given to right-adjust ``text``. If
unspecified, the width of the attached terminal is used (default).
:arg str fillchar: String for padding left-of ``text``.
:returns: String of ``text``, right-aligned by ``width``.
:rtype: str
"""
leftside = fillchar * int(
(max(0.0, float(width - self.length()))) / float(len(fillchar)))
return u''.join((leftside, self))
def center(self, width, fillchar=u' '):
"""
Return string containing sequences, centered.
:arg int width: Total width given to center ``text``. If
unspecified, the width of the attached terminal is used (default).
:arg str fillchar: String for padding left and right-of ``text``.
:returns: String of ``text``, centered by ``width``.
:rtype: str
"""
split = max(0.0, float(width) - self.length()) / 2
leftside = fillchar * int(
(max(0.0, math.floor(split))) / float(len(fillchar)))
rightside = fillchar * int(
(max(0.0, math.ceil(split))) / float(len(fillchar)))
return u''.join((leftside, self, rightside))
def length(self):
r"""
Return the printable length of string containing sequences.
Strings containing ``term.left`` or ``\b`` will cause "overstrike",
but a length less than 0 is not ever returned. So ``_\b+`` is a
length of 1 (displays as ``+``), but ``\b`` alone is simply a
length of 0.
Some characters may consume more than one cell, mainly those CJK
Unified Ideographs (Chinese, Japanese, Korean) defined by Unicode
as half or full-width characters.
"""
# because control characters may return -1, "clip" their length to 0.
clip = functools.partial(max, 0)
return sum(clip(wcwidth.wcwidth(w_char))
for w_char in self.strip_seqs())
# we require ur"" for the docstring, but it is not supported by all
# python versions.
if length.__doc__ is not None:
length.__doc__ += (
u"""
For example:
>>> from blessed import Terminal
>>> from blessed.sequences import Sequence
>>> term = Terminal()
>>> msg = term.clear + term.red(u'コンニチハ'), term
>>> Sequence(msg).length()
10
.. note:: Although accounted for, strings containing sequences such
as ``term.clear`` will not give accurate returns, it is not
considered lengthy (a length of 0).
""")
def strip(self, chars=None):
"""
Return string of sequences, leading, and trailing whitespace removed.
:arg str chars: Remove characters in chars instead of whitespace.
:rtype: str
"""
return self.strip_seqs().strip(chars)
def lstrip(self, chars=None):
"""
Return string of all sequences and leading whitespace removed.
:arg str chars: Remove characters in chars instead of whitespace.
:rtype: str
"""
return self.strip_seqs().lstrip(chars)
def rstrip(self, chars=None):
"""
Return string of all sequences and trailing whitespace removed.
:arg str chars: Remove characters in chars instead of whitespace.
:rtype: str
"""
return self.strip_seqs().rstrip(chars)
def strip_seqs(self):
"""
Return ``text`` stripped of only its terminal sequences.
:rtype: str
"""
gen = iter_parse(self._term, self.padd())
return u''.join(text for text, cap in gen if not cap)
def padd(self):
"""
Return non-destructive horizontal movement as destructive spacing.
:rtype: str
"""
outp = ''
for text, cap in iter_parse(self._term, self):
if not cap:
outp += text
continue
value = cap.horizontal_distance(text)
if value > 0:
outp += ' ' * value
elif value < 0:
outp = outp[:value]
else:
outp += text
return outp
def iter_parse(term, text):
"""
Generator yields (text, capability) for characters of ``text``.
value for ``capability`` may be ``None``, where ``text`` is
:class:`str` of length 1. Otherwise, ``text`` is a full
matching sequence of given capability.
"""
for match in re.finditer(term._caps_compiled_any, text):
name = match.lastgroup
value = match.group(name)
if name == 'MISMATCH':
yield (value, None)
else:
yield value, term.caps[name]
def measure_length(text, term):
"""
.. deprecated:: 1.12.0.
:rtype: int
"""
try:
text, capability = next(iter_parse(term, text))
if capability:
return len(text)
except StopIteration:
return 0
return 0