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Issue #18725: The textwrap module now supports truncating multiline text.

This commit is contained in:
Serhiy Storchaka 2013-10-15 21:22:54 +03:00
parent bc2bfa6b68
commit acc9f3fb16
4 changed files with 165 additions and 58 deletions
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28
Doc/library/textwrap.rst
View File

@ -250,6 +250,22 @@ hyphenated words; only then will long words be broken if necessary, unless
was to always allow breaking hyphenated words.
.. attribute:: max_lines
(default: ``None``) If not ``None``, then the text be will truncated to
*max_lines* lines.
.. versionadded:: 3.4
.. attribute:: placeholder
(default: ``' [...]'``) String that will be appended to the last line of
text if it will be truncated.
.. versionadded:: 3.4
:class:`TextWrapper` also provides some public methods, analogous to the
module-level convenience functions:
@ -266,15 +282,3 @@ hyphenated words; only then will long words be broken if necessary, unless
Wraps the single paragraph in *text*, and returns a single string
containing the wrapped paragraph.
.. function:: shorten(text, *, placeholder=" [...]")
Collapse and truncate the given text to fit in :attr:`width`
characters.
The text first has its whitespace collapsed. If it then fits in
:attr:`width`, it is returned as-is. Otherwise, as many words
as possible are joined and then the *placeholder* is appended.
.. versionadded:: 3.4

105
Lib/test/test_textwrap.py
View File

@ -42,10 +42,6 @@ class BaseTestCase(unittest.TestCase):
"\nexpected %r\n"
"but got %r" % (expect, result))
def check_shorten(self, text, width, expect, **kwargs):
result = shorten(text, width, **kwargs)
self.check(result, expect)
class WrapTestCase(BaseTestCase):
@ -433,6 +429,90 @@ What a mess!
self.check_wrap(text, 7, ["aa \xe4\xe4-", "\xe4\xe4"])
class MaxLinesTestCase(BaseTestCase):
text = "Hello there, how are you this fine day? I'm glad to hear it!"
def test_simple(self):
self.check_wrap(self.text, 12,
["Hello [...]"],
max_lines=0)
self.check_wrap(self.text, 12,
["Hello [...]"],
max_lines=1)
self.check_wrap(self.text, 12,
["Hello there,",
"how [...]"],
max_lines=2)
self.check_wrap(self.text, 13,
["Hello there,",
"how are [...]"],
max_lines=2)
self.check_wrap(self.text, 80, [self.text], max_lines=1)
self.check_wrap(self.text, 12,
["Hello there,",
"how are you",
"this fine",
"day? I'm",
"glad to hear",
"it!"],
max_lines=6)
def test_spaces(self):
# strip spaces before placeholder
self.check_wrap(self.text, 12,
["Hello there,",
"how are you",
"this fine",
"day? [...]"],
max_lines=4)
# placeholder at the start of line
self.check_wrap(self.text, 6,
["Hello",
"[...]"],
max_lines=2)
# final spaces
self.check_wrap(self.text + ' ' * 10, 12,
["Hello there,",
"how are you",
"this fine",
"day? I'm",
"glad to hear",
"it!"],
max_lines=6)
def test_placeholder(self):
self.check_wrap(self.text, 12,
["Hello..."],
max_lines=1,
placeholder='...')
self.check_wrap(self.text, 12,
["Hello there,",
"how are..."],
max_lines=2,
placeholder='...')
# long placeholder and indentation
with self.assertRaises(ValueError):
wrap(self.text, 16, initial_indent=' ',
max_lines=1, placeholder=' [truncated]...')
with self.assertRaises(ValueError):
wrap(self.text, 16, subsequent_indent=' ',
max_lines=2, placeholder=' [truncated]...')
self.check_wrap(self.text, 16,
[" Hello there,",
" [truncated]..."],
max_lines=2,
initial_indent=' ',
subsequent_indent=' ',
placeholder=' [truncated]...')
self.check_wrap(self.text, 16,
[" [truncated]..."],
max_lines=1,
initial_indent=' ',
subsequent_indent=' ',
placeholder=' [truncated]...')
self.check_wrap(self.text, 80, [self.text], placeholder='.' * 1000)
class LongWordTestCase (BaseTestCase):
def setUp(self):
self.wrapper = TextWrapper()
@ -493,6 +573,14 @@ How *do* you spell that odd word, anyways?
result = wrap(self.text, width=30, break_long_words=0)
self.check(result, expect)
def test_max_lines_long(self):
self.check_wrap(self.text, 12,
['Did you say ',
'"supercalifr',
'agilisticexp',
'[...]'],
max_lines=4)
class IndentTestCases(BaseTestCase):
@ -782,6 +870,10 @@ class IndentTestCase(unittest.TestCase):
class ShortenTestCase(BaseTestCase):
def check_shorten(self, text, width, expect, **kwargs):
result = shorten(text, width, **kwargs)
self.check(result, expect)
def test_simple(self):
# Simple case: just words, spaces, and a bit of punctuation
text = "Hello there, how are you this fine day? I'm glad to hear it!"
@ -825,10 +917,9 @@ class ShortenTestCase(BaseTestCase):
self.check_shorten("hello world! ", 10, "[...]")
def test_width_too_small_for_placeholder(self):
wrapper = TextWrapper(width=8)
wrapper.shorten("x" * 20, placeholder="(......)")
shorten("x" * 20, width=8, placeholder="(......)")
with self.assertRaises(ValueError):
wrapper.shorten("x" * 20, placeholder="(.......)")
shorten("x" * 20, width=8, placeholder="(.......)")
def test_first_word_too_long_but_placeholder_fits(self):
self.check_shorten("Helloo", 5, "[...]")

88
Lib/textwrap.py
View File

@ -19,8 +19,6 @@ __all__ = ['TextWrapper', 'wrap', 'fill', 'dedent', 'indent']
# since 0xa0 is not in range(128).
_whitespace = '\t\n\x0b\x0c\r '
_default_placeholder = ' [...]'
class TextWrapper:
"""
Object for wrapping/filling text. The public interface consists of
@ -64,6 +62,10 @@ class TextWrapper:
compound words.
drop_whitespace (default: true)
Drop leading and trailing whitespace from lines.
max_lines (default: None)
Truncate wrapped lines.
placeholder (default: ' [...]')
Append to the last line of truncated text.
"""
unicode_whitespace_trans = {}
@ -106,7 +108,10 @@ class TextWrapper:
break_long_words=True,
drop_whitespace=True,
break_on_hyphens=True,
tabsize=8):
tabsize=8,
*,
max_lines=None,
placeholder=' [...]'):
self.width = width
self.initial_indent = initial_indent
self.subsequent_indent = subsequent_indent
@ -117,6 +122,8 @@ class TextWrapper:
self.drop_whitespace = drop_whitespace
self.break_on_hyphens = break_on_hyphens
self.tabsize = tabsize
self.max_lines = max_lines
self.placeholder = placeholder
# -- Private methods -----------------------------------------------
@ -225,6 +232,13 @@ class TextWrapper:
lines = []
if self.width <= 0:
raise ValueError("invalid width %r (must be > 0)" % self.width)
if self.max_lines is not None:
if self.max_lines > 1:
indent = self.subsequent_indent
else:
indent = self.initial_indent
if len(indent) + len(self.placeholder.lstrip()) > self.width:
raise ValueError("placeholder too large for max width")
# Arrange in reverse order so items can be efficiently popped
# from a stack of chucks.
@ -267,15 +281,41 @@ class TextWrapper:
# fit on *any* line (not just this one).
if chunks and len(chunks[-1]) > width:
self._handle_long_word(chunks, cur_line, cur_len, width)
cur_len = sum(map(len, cur_line))
# If the last chunk on this line is all whitespace, drop it.
if self.drop_whitespace and cur_line and cur_line[-1].strip() == '':
cur_len -= len(cur_line[-1])
del cur_line[-1]
# Convert current line back to a string and store it in list
# of all lines (return value).
if cur_line:
lines.append(indent + ''.join(cur_line))
if (self.max_lines is None or
len(lines) + 1 < self.max_lines or
(not chunks or
self.drop_whitespace and
len(chunks) == 1 and
not chunks[0].strip()) and cur_len <= width):
# Convert current line back to a string and store it in
# list of all lines (return value).
lines.append(indent + ''.join(cur_line))
else:
while cur_line:
if (cur_line[-1].strip() and
cur_len + len(self.placeholder) <= width):
cur_line.append(self.placeholder)
lines.append(indent + ''.join(cur_line))
break
cur_len -= len(cur_line[-1])
del cur_line[-1]
else:
if lines:
prev_line = lines[-1].rstrip()
if (len(prev_line) + len(self.placeholder) <=
self.width):
lines[-1] = prev_line + self.placeholder
break
lines.append(indent + self.placeholder.lstrip())
break
return lines
@ -308,36 +348,6 @@ class TextWrapper:
"""
return "\n".join(self.wrap(text))
def shorten(self, text, *, placeholder=_default_placeholder):
"""shorten(text: str) -> str
Collapse and truncate the given text to fit in 'self.width' columns.
"""
max_length = self.width
if max_length < len(placeholder.strip()):
raise ValueError("placeholder too large for max width")
sep = ' '
sep_len = len(sep)
parts = []
cur_len = 0
chunks = self._split_chunks(text)
for chunk in chunks:
if not chunk.strip():
continue
chunk_len = len(chunk) + sep_len if parts else len(chunk)
if cur_len + chunk_len > max_length:
break
parts.append(chunk)
cur_len += chunk_len
else:
# No truncation necessary
return sep.join(parts)
max_truncated_length = max_length - len(placeholder)
while parts and cur_len > max_truncated_length:
last = parts.pop()
cur_len -= len(last) + sep_len
return (sep.join(parts) + placeholder).strip()
# -- Convenience interface ---------------------------------------------
@ -366,7 +376,7 @@ def fill(text, width=70, **kwargs):
w = TextWrapper(width=width, **kwargs)
return w.fill(text)
def shorten(text, width, *, placeholder=_default_placeholder, **kwargs):
def shorten(text, width, **kwargs):
"""Collapse and truncate the given text to fit in the given width.
The text first has its whitespace collapsed. If it then fits in
@ -378,8 +388,8 @@ def shorten(text, width, *, placeholder=_default_placeholder, **kwargs):
>>> textwrap.shorten("Hello world!", width=11)
'Hello [...]'
"""
w = TextWrapper(width=width, **kwargs)
return w.shorten(text, placeholder=placeholder)
w = TextWrapper(width=width, max_lines=1, **kwargs)
return w.fill(' '.join(text.strip().split()))
# -- Loosely related functionality -------------------------------------

2
Misc/NEWS
View File

@ -42,6 +42,8 @@ Core and Builtins
Library
-------
- Issue #18725: The textwrap module now supports truncating multiline text.
- Issue #18776: atexit callbacks now display their full traceback when they
raise an exception.