Text::Autoformat(3) User Contributed Perl Documentation Text::Autoformat(3)NAMEText::Autoformat - Automatic text wrapping and reformatting
VERSION
This document describes version 1.669002 of Text::AutoformatSYNOPSIS
# Minimal use: read from STDIN, format to STDOUT...
use Text::Autoformat;
autoformat;
# In-memory formatting...
$formatted = autoformat $rawtext;
# Configuration...
$formatted = autoformat $rawtext, { %options };
# Margins (1..72 by default)...
$formatted = autoformat $rawtext, { left=>8, right=>70 };
# Justification (left by default)...
$formatted = autoformat $rawtext, { justify => 'left' };
$formatted = autoformat $rawtext, { justify => 'right' };
$formatted = autoformat $rawtext, { justify => 'full' };
$formatted = autoformat $rawtext, { justify => 'centre' };
# Filling (does so by default)...
$formatted = autoformat $rawtext, { fill=>0 };
# Squeezing whitespace (does so by default)...
$formatted = autoformat $rawtext, { squeeze=>0 };
# Select appropriate tabspacing (default is 8 spaces per tab):
$formatted = autoformat $rawtext, { tabspace=>4 };
# Case conversions...
$formatted = autoformat $rawtext, { case => 'lower' };
$formatted = autoformat $rawtext, { case => 'upper' };
$formatted = autoformat $rawtext, { case => 'sentence' };
$formatted = autoformat $rawtext, { case => 'title' };
$formatted = autoformat $rawtext, { case => 'highlight' };
# Selective reformatting
$formatted = autoformat $rawtext, { ignore=>qr/^\t/ };
BACKGROUND
The problem
Perl plaintext formatters just aren't smart enough. Given a typical
piece of plaintext in need of formatting:
In comp.lang.perl.misc you wrote:
: > <CN = Clooless Noobie> writes:
: > CN> PERL sux because:
: > CN> * It doesn't have a switch statement and you have to put $
: > CN>signs in front of everything
: > CN> * There are too many OR operators: having |, || and 'or'
: > CN>operators is confusing
: > CN> * VB rools, yeah!!!!!!!!!
: > CN> So anyway, how can I stop reloads on a web page?
: > CN> Email replies only, thanks - I don't read this newsgroup.
: >
: > Begone, sirrah! You are a pathetic, Bill-loving, microcephalic
: > script-infant.
: Sheesh, what's with this group - ask a question, get toasted! And how
: *dare* you accuse me of Ianuphilia!
both the venerable Unix fmt tool and Perl's standard Text::Wrap module
produce:
In comp.lang.perl.misc you wrote: : > <CN = Clooless Noobie>
writes: : > CN> PERL sux because: : > CN> * It doesn't
have a switch statement and you have to put $ : > CN>signs in
front of everything : > CN> * There are too many OR
operators: having |, || and 'or' : > CN>operators is confusing
: > CN> * VB rools, yeah!!!!!!!!! : > CN> So anyway, how
can I stop reloads on a web page? : > CN> Email replies only,
thanks - I don't read this newsgroup. : > : > Begone, sirrah!
You are a pathetic, Bill-loving, microcephalic : >
script-infant. : Sheesh, what's with this group - ask a
question, get toasted! And how : *dare* you accuse me of
Ianuphilia!
Other formatting modules -- such as Text::Correct and Text::Format --
provide more control over their output, but produce equally poor
results when applied to arbitrary input. They simply don't understand
the structural conventions of the text they're reformatting.
The solution
The Text::Autoformat module provides a subroutine named "autoformat"
that wraps text to specified margins. However, "autoformat" reformats
its input by analysing the text's structure, so it wraps the above
example like so:
In comp.lang.perl.misc you wrote:
: > <CN = Clooless Noobie> writes:
: > CN> PERL sux because:
: > CN> * It doesn't have a switch statement and you
: > CN> have to put $ signs in front of everything
: > CN> * There are too many OR operators: having |, ||
: > CN> and 'or' operators is confusing
: > CN> * VB rools, yeah!!!!!!!!! So anyway, how can I
: > CN> stop reloads on a web page? Email replies
: > CN> only, thanks - I don't read this newsgroup.
: >
: > Begone, sirrah! You are a pathetic, Bill-loving,
: > microcephalic script-infant.
: Sheesh, what's with this group - ask a question, get toasted!
: And how *dare* you accuse me of Ianuphilia!
Note that the various quoting conventions have been observed. In fact,
their structure has been used to determine where some paragraphs begin.
Furthermore "autoformat" correctly distinguished between the leading
'*' bullets of the nested list (which were outdented) and the leading
emphatic '*' of "*dare*" (which was inlined).
DESCRIPTION
Paragraphs
The fundamental task of the "autoformat" subroutine is to identify and
rearrange independent paragraphs in a text. Paragraphs typically
consist of a series of lines containing at least one non-whitespace
character, followed by one or more lines containing only optional
whitespace. This is a more liberal definition than many other
formatters use: most require an empty line to terminate a paragraph.
Paragraphs may also be denoted by bulleting, numbering, or quoting (see
the following sections).
Once a paragraph has been isolated, "autoformat" fills and re-wraps its
lines according to the margins that are specified in its argument list.
These are placed after the text to be formatted, in a hash reference:
$tidied = autoformat($messy, {left=>20, right=>60});
By default, "autoformat" uses a left margin of 1 (first column) and a
right margin of 72.
You can also control whether (and how) "autoformat" breaks words at the
end of a line, using the 'break' option:
# Turn off all hyphenation
use Text::Autoformat qw(autoformat break_wrap);
$tidied = autoformat($messy, {break=>break_wrap});
# Default hyphenation
use Text::Autoformat qw(autoformat break_at);
$tidied = autoformat($messy, {break=>break_at('-')});
# Use TeX::Hyphen module's hyphenation (module must be installed)
use Text::Autoformat qw(autoformat break_TeX);
$tidied = autoformat($messy, {break=>break_TeX});
Normally, "autoformat" only reformats the first paragraph it
encounters, and leaves the remainder of the text unaltered. This
behaviour is useful because it allows a one-liner invoking the
subroutine to be mapped onto a convenient keystroke in a text editor,
to provide one-paragraph-at-a-time reformatting:
% cat .exrc
map f !Gperl -MText::Autoformat -e'autoformat'
(Note that to facilitate such one-liners, if "autoformat" is called in
a void context without any text data, it takes its text from "STDIN"
and writes its result to "STDOUT").
To enable "autoformat" to rearrange the entire input text at once, the
"all" argument is used:
$tidied_all = autoformat($messy, {left=>20, right=>60, all=>1});
"autoformat" can also be directed to selectively reformat paragraphs,
using the "ignore" argument:
$tidied_some = autoformat($messy, {ignore=>qr/^[ \t]/});
The value for "ignore" may be a "qr"'d regex, a subroutine reference,
or the special string 'indented'.
If a regex is specified, any paragraph whose original text matches that
regex will not be reformatted (i.e. it will be printed verbatim).
If a subroutine is specified, that subroutine will be called once for
each paragraph (with $_ set to the paragraph's text). The subroutine is
expected to return a true or false value. If it returns true, the
paragraph will not be reformatted.
If the value of the "ignore" option is the string 'indented',
"autoformat" will ignore any paragraph in which every line begins with
a whitespace.
You may also specify multiple "ignore" options by including them in an
array-ref:
$tidied_mesg = autoformat($messy, {ignore=>[qr/1/,'indented']});
One other special case of ignorance is ignoring mail headers and
signature. This option is specified using the "mail" argument:
$tidied_mesg = autoformat($messy_mesg, {mail=>1});
Note that the "ignore" or "mail" options automatically imply "all".
Bulleting and (re-)numbering
Often plaintext will include lists that are either:
* bulleted,
* simply numbered (i.e. 1., 2., 3., etc.), or
* hierarchically numbered (1, 1.1, 1.2, 1.3, 2, 2.1. and so forth).
In such lists, each bulleted item is implicitly a separate paragraph,
and is formatted individually, with the appropriate indentation:
* bulleted,
* simply numbered (i.e. 1., 2., 3.,
etc.), or
* hierarchically numbered (1, 1.1,
1.2, 1.3, 2, 2.1. and so forth).
More importantly, if the points are numbered, the numbering is checked
and reordered. For example, a list whose points have been rearranged:
1. Analyze problem
3. Design algorithm
1. Code solution
5. Test
4. Ship
would be renumbered automatically by "autoformat":
1. Analyze problem
2. Design algorithm
3. Code solution
4. Test
5. Ship
The same reordering would be performed if the "numbering" was by
letters ("a." "b." "c." etc.) or Roman numerals ("i." "ii." "iii.)" or
by some combination of these ("1a." "1b." "2a." "2b." etc.) Handling
disordered lists of letters and Roman numerals presents an interesting
challenge. A list such as:
A. Put cat in box.
D. Close lid.
E. Activate Geiger counter.
should be reordered as "A." "B." "C.," whereas:
I. Put cat in box.
D. Close lid.
XLI. Activate Geiger counter.
should be reordered "I." "II." "III."
The "autoformat" subroutine solves this problem by always interpreting
alphabetic bullets as being letters, unless the full list consists only
of valid Roman numerals, at least one of which is two or more
characters long.
Note that renumbering starts at the first number actually given, rather
than restarting at the first possible number. To renumber from 1 (or
A.) you must change the first numbered bullet to that.
If automatic renumbering isn't wanted, just specify the 'renumber'
option with a false value.
Note that normal numbers above 1000 at the start of a line are no
longer considered to be paragraph numbering. Numbered paragraphs
running that high are exceptionally rare, and much rarer than
paragraphs that look like these:
Although it has long been popular (especially in the year
2001) to point out that we now live in the Future, many
of the promised miracles of Future Life have failed to
eventuate. This is a new phenomenon (it didn't happen in
1001) because the idea that the future might be different
is a new phenomenon.
which the former numbering rules caused to be formatted like this:
Although it has long been popular (especially in the year
2001) to point out that we now live in the Future, many of the
promised miracles of Future Life have failed to eventuate.
This is a new phenomenon (it didn't happen in
2002) because the idea that the future might be different is a
new phenomenon.
but which are now formatted:
Although it has long been popular (especially in the year 2001)
to point out that we now live in the Future, many of the
promised miracles of Future Life have failed to eventuate. This
is a new phenomenon (it didn't happen in 1001) because the idea
that the future might be different is a new phenomenon.
If you want numbers less than 1000 (or other characters strings
currently treated as bullets) to be ignored in this way, you can turn
of list formatting entirely by setting the 'lists' option to a false
value.
You can also select which kinds of lists are recognized, by using a
string as the value of lists:
# Don't recognize Roman numerals or alphabetics as list markers...
autoformat { lists => 'number, bullet' }, $text;
# Don't recognize bullets or numbers as list markers...
autoformat { lists => 'roman, alpha' }, $text;
# Recognize everything except Roman numerals as list markers...
autoformat { lists => 'number, bullet, alpha' }, $text;
The string should contain one or more of the following words: "number",
"bullet", "alpha", "roman". "autoformat()" will ignore any list type
that doesn't appear in the 'lists' string.
Quoting
Another case in which contiguous lines may be interpreted as belonging
to different paragraphs, is where they are quoted with distinct
quoters. For example:
: > CN> So anyway, how can I stop reloads on a web page? Email
: > CN> replies only, thanks - I don't read this newsgroup.
: > Begone, sirrah! You are a pathetic, Bill-loving,
: > microcephalic script-infant.
: Sheesh, what's with this group - ask a question, get toasted!
: And how *dare* you accuse me of Ianuphilia!
"autoformat" recognizes the various quoting conventions used in this
example and treats it as three paragraphs to be independently
reformatted.
Block quotations present a different challenge. A typical formatter
would render the following quotation:
"We are all of us in the gutter, but some of us are looking at
the stars"
-- Oscar Wilde
like so:
"We are all of us in the gutter, but some of us are looking at
the stars" -- Oscar Wilde
"autoformat" recognizes the quotation structure by matching the
following regular expression against the text component of each
paragraph:
/ \A(\s*) # leading whitespace for quotation (["']|``) # opening
quotemark (.*) # quotation (''|\2) # closing quotemark \s*?\n #
trailing whitespace after quotation (\1[ ]+) # leading
whitespace for attribution
# (must be indented more than
# quotation)
(--|-) # attribution introducer ([^\n]*?\n) # first
attribution line ((\5[^\n]*?$)*) # other attribution lines
# (indented no less than first line)
\s*\Z # optional whitespace to end of paragraph /xsm
When reformatted (see below), the indentation and the attribution
structure will be preserved:
"We are all of us in the gutter, but some of us are looking
at the stars"
-- Oscar Wilde
Widow control
Note that in the last example, "autoformat" broke the line at column
68, four characters earlier than it should have. It did so because, if
the full margin width had been used, the formatting would have left the
last two words by themselves on an oddly short last line:
"We are all of us in the gutter, but some of us are looking at
the stars"
This phenomenon is known as "widowing" and is heavily frowned upon in
typesetting circles. It looks ugly in plaintext too, so "autoformat"
avoids it by stealing extra words from earlier lines in a paragraph, so
as to leave enough for a reasonable last line. The heuristic used is
that final lines must be at least 10 characters long (though this
number may be adjusted by passing a "widow => minlength" argument to
"autoformat").
If the last line is too short, the paragraph's right margin is reduced
by one column, and the paragraph is reformatted. This process iterates
until either the last line exceeds nine characters or the margins have
been narrowed by 10% of their original separation. In the latter case,
the reformatter gives up and uses its original formatting.
Justification
The "autoformat" subroutine also takes a named argument: "{justify =>
type}", which specifies how each paragraph is to be justified. The
options are: 'left' (the default), "'right'," 'centre' (or 'center'),
and 'full'. These act on the complete paragraph text (but not on any
quoters before that text). For example, with 'right' justification:
R3> Now is the Winter of our discontent made
R3> glorious Summer by this son of York. And all
R3> the clouds that lour'd upon our house In the
R3> deep bosom of the ocean buried.
Full justification is interesting in a fixed-width medium like
plaintext because it usually results in uneven spacing between words.
Typically, formatters provide this by distributing the extra spaces
into the first available gaps of each line:
R3> Now is the Winter of our discontent made
R3> glorious Summer by this son of York. And all
R3> the clouds that lour'd upon our house In
R3> the deep bosom of the ocean buried.
This produces a rather jarring visual effect, so "autoformat" reverses
the strategy and inserts extra spaces at the end of lines:
R3> Now is the Winter of our discontent made
R3> glorious Summer by this son of York. And all
R3> the clouds that lour'd upon our house In
R3> the deep bosom of the ocean buried.
Most readers find this less disconcerting.
Implicit centring
Even if explicit centring is not specified, "autoformat" will attempt
to automatically detect centred paragraphs and preserve their
justification. It does this by examining each line of the paragraph and
asking: "if this line were part of a centred paragraph, where would the
centre line have been?"
The answer can be determined by adding the length of leading whitespace
before the first word, plus half the length of the full set of words on
the line. That is, for a single line:
$line =~ /^(\s*)(.*?)(\s*)$/ $centre =
length($1)+0.5*length($2);
By making the same estimate for every line, and then comparing the
estimates, it is possible to deduce whether all the lines are centred
with respect to the same axis of symmetry (with an allowance of X1 to
cater for the inevitable rounding when the centre positions of even-
length rows were originally computed). If a common axis of symmetry is
detected, "autoformat" assumes that the lines are supposed to be
centred, and switches to centre-justification mode for that paragraph.
Note that this behaviour can to switched off entirely by setting the
"autocentre" argument false.
Case transformations
The "autoformat" subroutine can also optionally perform case
conversions on the text it processes. The "{case => type}" argument
allows the user to specify five different conversions:
'upper'
This mode unconditionally converts every letter in the reformatted
text to upper-case;
'lower'
This mode unconditionally converts every letter in the reformatted
text to lower-case;
'sentence'
This mode attempts to generate correctly-cased sentences from the
input text. That is, the first letter after a sentence-terminating
punctuator is converted to upper-case. Then, each subsequent word
in the sentence is converted to lower-case, unless that word is
originally mixed-case or contains punctuation. For example, under
"{case => 'sentence'}":
'POVERTY, MISERY, ETC. are the lot of the PhD candidate. alas!'
becomes:
'Poverty, misery, etc. are the lot of the PhD candidate. Alas!'
Note that "autoformat" is clever enough to recognize that the
period after abbreviations such as "etc." is not a sentence
terminator.
If the argument is specified as 'sentence ' (with one or more
trailing whitespace characters) those characters are used to
replace the single space that appears at the end of the sentence.
For example, "autoformat($text, {case=>'sentence '}") would
produce:
'Poverty, misery, etc. are the lot of the PhD candidate. Alas!'
'title'
This mode behaves like 'sentence' except that the first letter of
every word is capitalized:
'What I Did On My Summer Vacation In Monterey'
'highlight'
This mode behaves like 'title' except that trivial words are not
capitalized:
'What I Did on my Summer Vacation in Monterey'
Selective reformatting
You can select which paragraphs "autoformat" actually reformats (or,
rather, those it doesn't reformat) using the "ignore" flag.
For example:
# Reformat all paras except those containing "verbatim"...
print autoformat { all => 1, ignore => qr/verbatim/i }, $text;
# Reformat all paras except those less that 3 lines long...
print autoformat { all => 1, ignore => sub { tr/\n/\n/ < 3
} }, $text;
# Reformat all paras except those that are indented...
print autoformat { all => 1, ignore => qr/^\s/m }, $text;
# Reformat all paras except those that are indented (easier)...
print autoformat { all => 1, ignore => 'indented' }, $text;
Handling tabs
Text::Autoformat replaces any tabs in the text it's formatting with the
appropriate number of spaces (using Text::Tabs to do its dirty work).
It normally assumes that each tab is equivalent to 8 space characters,
but you can change that default using the 'tabspace' option:
print autoformat { tabspace => 4 }, $text;
SEE ALSO
The Text::Reform module
AUTHOR
Damian Conway (damian@conway.org)
BUGS
There are undoubtedly serious bugs lurking somewhere in code this funky
:-) Bug reports and other feedback are most welcome.
LICENCE AND COPYRIGHT
Copyright (c) 1997-2007, Damian Conway "<DCONWAY@CPAN.org>". All rights
reserved.
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself. See perlartistic.
DISCLAIMER OF WARRANTY
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT
WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER
PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND,
EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
NECESSARY SERVICING, REPAIR, OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
perl v5.14.1 2011-06-20 Text::Autoformat(3)
