oracular (3) Text::Autoformat.3pm.gz
NAME
Text::Autoformat - Automatic text wrapping and reformatting
VERSION
This document describes version 1.72 of Text::Autoformat
SYNOPSIS
# 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' };
$formatted = autoformat $rawtext, { case => \&my_case_func };
# 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' }, $text;
The string should contain one or more of the following words: "number", "bullet", "alpha", "roman".
"autoformat()" will ignore any list type that doesn't appear in the 'lists' string.
Quoting
Another case in which contiguous lines may be interpreted as belonging to different paragraphs, is where
they are quoted with distinct quoters. For example:
: > CN> So anyway, how can I stop reloads on a web page? Email
: > CN> replies only, thanks - I don't read this newsgroup.
: > Begone, sirrah! You are a pathetic, Bill-loving,
: > microcephalic script-infant.
: Sheesh, what's with this group - ask a question, get toasted!
: And how *dare* you accuse me of Ianuphilia!
"autoformat" recognizes the various quoting conventions used in this example and treats it as three
paragraphs to be independently reformatted.
You may also override the default set of recognized quoters by specifying a 'quoter' argument when
calling "autoformat()". For example, to format lines such as:
// This is a comment
// in the standard C(++)
// comment-to-EOL
// format
specify:
autoformat($text, { quoter =E<gt> qr{//} })
Instead of completely replacing the existing set of quoters, you can extend them by specifying a pattern
that includes the metasequence "<QUOTER>", which is then replaced by the module's standard pattern for
quoters. So, for example, to add "//" to the set of existing quoters:
autoformat($text, { quoter =E<gt> qr{//|<QUOTER>} })
Block quotations present a different challenge. A typical formatter would render the following quotation:
"We are all of us in the gutter, but some of us are looking at
the stars"
-- Oscar Wilde
like so:
"We are all of us in the gutter, but some of us are looking at
the stars" -- Oscar Wilde
"autoformat" recognizes the quotation structure by matching the following regular expression against the
text component of each paragraph:
/ \A(\s*) # leading whitespace for quotation (["']|``) # opening
quotemark (.*) # quotation (''|\2) # closing quotemark \s*?\n #
trailing whitespace after quotation (\1[ ]+) # leading
whitespace for attribution
# (must be indented more than
# quotation)
(--|-) # attribution introducer ([^\n]*?\n) # first
attribution line ((\5[^\n]*?$)*) # 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($2);
By making the same estimate for every line, and then comparing the estimates, it is possible to deduce
whether all the lines are centred with respect to the same axis of symmetry (with an allowance of ±1 to
cater for the inevitable rounding when the centre positions of even-length rows were originally
computed). If a common axis of symmetry is detected, "autoformat" assumes that the lines are supposed to
be centred, and switches to centre-justification mode for that paragraph.
Note that this behaviour can to switched off entirely by setting the "autocentre" argument false.
Case transformations
The "autoformat" subroutine can also optionally perform case conversions on the text it processes. The
"{case => type}" argument allows the user to specify six different conversions:
'upper'
This mode unconditionally converts every letter in the reformatted text to upper-case;
'lower'
This mode unconditionally converts every letter in the reformatted text to lower-case;
'sentence'
This mode attempts to generate correctly-cased sentences from the input text. That is, the first
letter after a sentence-terminating punctuator is converted to upper-case. Then, each subsequent word
in the sentence is converted to lower-case, unless that word is originally mixed-case or contains
punctuation. For example, under "{case => 'sentence'}":
'POVERTY, MISERY, ETC. are the lot of the PhD candidate. alas!'
becomes:
'Poverty, misery, etc. are the lot of the PhD candidate. Alas!'
Note that "autoformat" is clever enough to recognize that the period after abbreviations such as
"etc." is not a sentence terminator.
If the argument is specified as 'sentence ' (with one or more trailing whitespace characters) those
characters are used to replace the single space that appears at the end of the sentence. For example,
"autoformat($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'
"sub{...}"
If the argument for 'case' is a subroutine reference, that subroutine is applied to each word and the
result replaces the word in the text.
For example, to convert a string to hostage-case:
my $ransom_note = sub {
return join "", # ^ Reconcatenate
map {/[aeiou]/i ? lc : uc} # | uPPeR aND LoWeR each
split //, # | Break into chars
shift; # | Take argument
};
$text = autoformat($text, {case => $ransom_note });
# "FoR eXaMPLe, To CoNVeRT a STRiNG To HoSTaGe-CaSe:"
Or to highlight particular words:
my @SPECIAL = qw( perl camel wall );
sub highlight_specials {
my ($word) = @_;
return $word ~~ @SPECIAL ? uc($word) : $word;
}
$text = autoformat($text, {case => \&highlight_specials});
# "It is easier for a CAMEL to pass through a WALL of PERL..."
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
Text::Reform - provides functions for manual text wrapping and reformatting.
Text::Aligner - provides a single function for justifying strings according to various styles.
Text::Format - a class that provides methods for formatting text in various ways.
Data::Formatter::Text - format various Perl data structures as text, in different ways according to the
type of data.
REPOSITORY
<https://github.com/neilb/Text-Autoformat>
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
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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
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