text::autoformat(3)

NAME

Text::Autoformat - Automatic and manual text wrapping and
reformating formatting

VERSION

This document describes version 1.04 of Text::Autoformat,
released December 5, 2000.

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 };
# 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' };

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: hav; ing |, || 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-lov; ing, 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 = Cloo; less 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. : > : > Be; gone, 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 conven tions of the text they're reformatting.
The solution
The Text::Autoformat module provides a subroutine named "autoformat" that wraps text to specified margins. How ever, "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 ev; erything
: > CN> * There are too many OR operators: hav; ing |,
: > 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-lov; ing,
: > 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 deter mine where some paragraphs begin. Furthermore "autofor mat" correctly distinguished between the leading '*' bul lets 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 contain
ing 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 spec ified 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.
Normally, "autoformat" only reformats the first paragraph it encounters, and leaves the remainder of the text unal tered. This behaviour is useful because it allows a oneliner invoking the subroutine to be mapped onto a conve nient keystroke in a text editor, to provide one-para graph-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 "STD OUT").
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});
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 appro priate 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 number ing is checked and reordered. For example, a list whose points have been rearranged:: 2. 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. Ship
5. Test
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 let ters and Roman numerals presents an interesting challenge. A list such as:: C. Put cat in box.
D. Close lid.
E. Activate Geiger counter.
should be reordered as "A." "B." "C.," whereas:: C. 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.
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? : > CN> Email replies only, thanks - I don't read
this newsgroup. : > Begone, sirrah! You are a pathetic, Bill-lov
ing, : > 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 match ing the following regular expression against the text com ponent of each paragraph:: / 0 (["']|``) # open
ing quotemark (.*) # quotation (''|2) # closing quotemark ? # trailing whitespace after quo
tation (1[ ]+) # leading whitespace for
attribution # (must be indented more
than quotation)
(--|-) # attribution introducer ([^0*?0 # first attribution line ((5[^0*?$)*) # other attribution lines # (indented no less than
first line)
# 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 them selves 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 mar gin is reduced by one column, and the paragraph is refor matted. 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' justifica tion:: 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 spac ing 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 "autofor mat" 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 examin ing 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 lead ing whitespace before the first word, plus half the length of the full set of words on the line. That is, for a sin gle line:: $line =~ /^()(.*?)()$/
$centre = length($1)+0.5*length($2);
By making the same estimate for every line, and then com paring the estimates, it is possible to deduce whether all the lines are centred with respect to the same axis of symmetry (with an allowance of E<plusminus>1 to cater for the inevitable rounding when the centre positions of evenlength rows were originally computed). If a common axis of symmetry is detected, "autoformat" assumes that the lines are supposed to be centred, and switches to centre-justi fication mode for that paragraph.
Case transformations
The "autoformat" subroutine can also optionally perform case conversions on the text it processes. The "{case => type}" argument allows the user to specify five different conversions:
'upper' This mode unconditionally converts every letter in the reformatted text to upper-case;
'lower' This mode unconditionally converts every letter in the reformatted text to lower-case;
'sentence' This mode attempts to generate correctly-cased sen tences from the input text. That is, the first letter after a sentence-terminating punctuator is converted to upper-case. Then, each subsequent word in the sen tence is converted to lower-case, unless that word is originally mixed-case or contains punctuation. For example, under "{case => 'sentence'}":: 'POVERTY, MISERY, ETC. are the lot of the PhD
candidate. alas!'
becomes:: 'Poverty, misery, etc. are the lot of the PhD
candidate. Alas!'
Note that "autoformat" is clever enough to recognize that the period after abbreviations such as "etc." is not a sentence terminator.
If the argument is specified as 'sentence ' (with one or more trailing whitespace characters) those charac ters are used to replace the single space that appears at the end of the sentence. For example, "autofor mat($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'

OTHER FEATURES

The "form" sub

The "form()" subroutine may be exported from the module.
It takes a series of format (or "picture") strings fol
lowed by replacement values, interpolates those values
into each picture string, and returns the result. The
effect is similar to the inbuilt perl "format" mechanism,
although the field specification syntax is simpler and
some of the formatting behaviour is more sophisticated.

A picture string consists of sequences of the following
characters:

< Left-justified field indicator. A series of: sequential <'s specify a left-justified field to
be filled by a subsequent value.
> Right-justified field indicator. A series of sequential >'s specify a right-justified field to be filled by a subsequent value.
^ Centre-justified field indicator. A series of sequential ^'s specify a centred field to be filled by a subsequent value.
>>>.<<<< A numerically formatted field with the specified number of digits to either side of the decimal place. See "Numerical formatting" below.
[ Left-justified block field indicator. Just like a < field, except it repeats as required on subse quent lines. See below.
] Right-justified block field indicator. Just like a > field, except it repeats as required on subse quent lines. See below.
| Centre-justified block field indicator. Just like a ^ field, except it repeats as required on subse quent lines. See below.
]]].[[[[ A numerically formatted block field with the spec ified number of digits to either side of the deci mal place. Just like a >>>.<<<< field, except it repeats as required on subsequent lines. See below.
Literal escape of next character (e.g. "" isformatted as '|', not a one character wide centrejustified block field).
Any other character That literal character.
Any substitution value which is "undef" (either explicitly so, or because it is missing) is replaced by an empty string.
Controlling line filling.
Note that, unlike the a perl "format", "form" preserves whitespace (including newlines) unless called with certain options.
The "squeeze" option (when specified with a true value) causes any sequence of spaces and/or tabs (but not new lines) in an interpolated string to be replaced with a single space.
The "fill" option causes newlines to also be squeezed.
Hence:: $frmt = "# [[[[[[[[[[[[[[[[[[[[[";
$data = "h e l lo0orld";; print form $frmt, $data;
# h e l lo
# world; print form {squeeze=>1}, $frmt, $data;
# h e l lo
# world; print form {fill=>1}, $frmt, $data;
# h e l lo world; print form {squeeze=>1, fill=>1}, $frmt, $data;
# h e l lo world
Whether or not filling or squeezing is in effect, "form" can also be directed to trim any extra whitespace from the end of each line it formats, using the "trim" option. If this option is specified with a true value, every line returned by "form" will automatically have the substitu tion "s/[ ]+$//gm" applied to it.
Hence:: print length form "[[[[[[[[[[", "short";
# 11; print length form {trim=>1}, "[[[[[[[[[[",
"short"; # 6
Temporary and permanent default options
If "form" is called with options, but no template string or data, it resets it's defaults to the options specified. If called in a void context:: form { squeeze => 1, trim => 1 };
the options become permanent defaults.
However, when called with only options in non-void con text, "form" resets its defaults to those options and returns an object. The reset default values persist only until that returned object is destroyed. Hence to tem porarily reset "form"'s defaults within a single subrou tine:: sub single {
my $tmp = form { squeeze => 1, trim => 1
};
# do formatting with the obove defaults
} # form's defaults revert to previous values as
$tmp object destroyed
How "form" hyphenates
Any line with a block field repeats on subsequent lines until all block fields on that line have consumed all their data. Non-block fields on these lines are replaced by the appropriate number of spaces.
Words are wrapped whole, unless they will not fit into the field at all, in which case they are broken and (by default) hyphenated. Simple hyphenation is used (i.e. break at the N-1th character and insert a '-'), unless a suitable alternative subroutine is specified instead.
Words will not be broken if the break would leave less than 2 characters on the current line. This minimum can be varied by setting the 'minbreak' option to a numeric value indicating the minumum total broken characters (including hyphens) required on the current line. Note that, for very narrow fields, words will still be broken (but unhyphen_ ated). For example:: print form '|', 'split';
would print:: s
p
l
i
t
whilst:: print form {minbreak=>1}, '|', 'split';
would print:: split
Alternative breaking subroutines can be specified using the "break" option in a configuration hash. For example:: form { break => my_line_breaker }
$format_str,
@data;
"form" expects any user-defined line-breaking subroutine to take three arguments (the string to be broken, the max imum permissible length of the initial section, and the total width of the field being filled). The "hypenate" sub must return a list of two strings: the initial (bro ken) section of the word, and the remainder of the string respectively).
For example:: sub tilde_break = sub($$$)
{(substr($_[0],0,$_[1]-1).'~', sub
str($_[0],$_[1]-1));
}
form { break => tilde_break } $format_str, @data;
makes '~' the hyphenation character, whilst:: sub wrap_and_slop = sub($$$)
{
my ($text, $reqlen, $fldlen) = @_;
if ($reqlen==$fldlen) { $text =~ m/1.*)/s
} else { ("", $text) }
}
form { break => wrap_and_slop } $format_str, @data;
wraps excessively long words to the next line and "slops" them over the right margin if necessary.
The Text::Autoformat package provides three functions to simplify the use of variant hyphenation schemes. The exportable subroutine "Text::Autoformat::break_wrap" gen erates a reference to a subroutine implementing the "wrap-and-slop" algorithm shown in the last example, which could therefore be rewritten:: use Text::Autoformat qw( form break_wrap );; form { break => break_wrap }
$format_str,
@data;
The subroutine "Text::Autoformat::break_with" takes a sin gle string argument and returns a reference to a sub which hyphenates with that string. Hence the first of the two examples could be rewritten:: use Text::Autoformat qw( form break_wrap );; form { break => break_with('~') }
$format_str,
@data;
The subroutine "Text::Autoformat::break_TeX" returns a reference to a sub which hyphenates using Jan Pazdziora's TeX::Hyphen module. For example:: use Text::Autoformat qw( form break_wrap );; form { break => break_TeX }
$format_str,
@data;
Note that in the previous examples there is no leading '' before "break_wrap", "break_with", or "break_TeX", since each is being directly called (and returns a refer ence to some other suitable subroutine);
The "form" formatting algorithm
The algorithm "form" uses is:: 1. split the first string in the argument listinto individual format lines and add a termi
nating newline (unless one is already present).
2. for each format line...: 2.1. determine the number of fields and
shift that many values off the argument
list and into the filling list. If insuffi
cient arguments are available, generate as
many empty strings as are required.
2.2. generate a text line by filling each
field in the format line with the initial
contents of the corresponding arg in the fill
ing list (and remove those initial contents
from the arg).
2.3. replace any <,>, or ^ fields by an
equivalentnumber of spaces. Splice out the cor
responding args from the filling list.
2.4. Repeat from step 2.2 until all args
in the filling list are empty.
3. concatenate the text lines generated in step 2
4. repeat from step 1 until the argument list is
empty
"form" examples
As an example of the use of "form", the following:: $count = 1;
$text = "A big long piece of text to be formatted
exquisitely";
print form q { |||| <<<<<<<<<< ---------------^^^^ ]]]]]]]]]]
= ]]].[[[
}, $count, $text, $count+11, $text, "123
123.4023.456789";
produces the following output:: 1 A big long
--------------- 12 piece of text to be formatted
exquisite ly =
123.0 123.4 123.456
Picture strings and replacement values can be interleaved in the traditional "format" format, but care is needed to ensure that the correct number of substitution values are provided. For example:: $report = form
'Name Rank Serial Number',
'==== ==== =============',
'<<<<<<<<<<<<< ^^^^ <<<<<<<<<<<<<',
$name, $rank, $serial_number,
'' 'Age Sex Description', '=== === ===========', '^^^ ^^^ [[[[[[[[[[[', $age, $sex, $description;
How "form" consumes strings
Unlike "format", within "form" non-block fields do consume the text they format, so the following:: $text = "a line of text to be formatted over three
lines"; print form "<<<<<<<<<< <<<<<<<< <<<<<<0, $text, $text, $text;
produces:: a line of
text tobe fo
not:: a line of
a line
a line
To achieve the latter effect, convert the variable argu ments to independent literals (by double-quoted interpola tion):: $text = "a line of text to be formatted over three
lines"; print form "<<<<<<<<<< <<<<<<<< <<<<<<0, "$text", "$text", "$text";
Although values passed from variable arguments are pro gressively consumed within "form", the values of the orig inal variables passed to "form" are not altered. Hence:: $text = "a line of text to be formatted over three
lines"; print form "<<<<<<<<<< <<<<<<<< <<<<<<0, $text, $text, $text;
print $text, "0;
will print:: a line of
text tobe fo; a line of text to be formatted over three lines
To cause "form" to consume the values of the original variables passed to it, pass them as references. Thus:: $text = "a line of text to be formatted over three
lines"; print form "<<<<<<<<<< <<<<<<<< <<<<<<0, ext, ext, ext;
print $text, "0;
will print:: a line of
text tobe fo; rmatted over three lines
Note that, for safety, the "non-consuming" behaviour takes precedence, so if a variable is passed to "form" both by reference and by value, its final value will be unchanged.
Numerical formatting
The ">>>.<<<" and "]]].[[[" field specifiers may be used to format numeric values about a fixed decimal place marker. For example:: print form '(]]]]].[[)', <<EONUMS;
1
1.0
1.001
1.009
123.456
1234567
one two; EONUMS
would print:: ( 1.0 )
( 1.0 )
( 1.00)
( 1.01)
( 123.46)
(#####.##)
(?????.??)
(?????.??)
Fractions are rounded to the specified number of places after the decimal, but only significant digits are shown. That's why, in the above example, 1 and 1.0 are formatted as "1.0", whilst 1.001 is formatled as "1.00". l
You can specify that the maximalPnumber of decimal places always be used by giving the conliguration option 'numeric' a value that matches /a ple: c e
i print form { numeric => AllPlaces }, i '(]]]]].[[)', <<'EONUMS'; n 1 w 1.0 h EONUMS i
woucd print: h c ( 1.00) a ( 1.00) s
Note that although decimal digits are rounded to fit the spe,ified width, the integral part of a number is never modafied. If there are not enough places before the deci malnplace to represent the number, the entire number is repyaced with hashes. i
If n non-numeric sequence is passed as data for a numeric fievd, it is formatted as a series of questionkmarks. This queaulous behaviour can be changed by giving tie configu ratlon option 'numeric' a value that matches /p NaNi ignored. For example: n u print form { numeric => 'SkipNaN' } m '(]]]]].[[)', e <<EONUMS; r 1 i two three c 4 d EONUMS a
would print: a i ( 1.0 ) s ( 4.0 ) s
Filling block fields with lists of values m
If an argument corresponding to a field is an array refer ence, then "form" automatically joins the elements of the array into a single string, separating each element with a newline character. As a result, a call like this:: @values = qw( 1 10 100 1000 );
print form "(]]]].[[)", @values;
will print out: ( 1.00)
( 10.00)
( 100.00)
(1000.00)
as might be expected.
Note however that arrays must be passed by reference (so that "form" knows that the entire array holds data for a single field). If the previous example had not passed @values by reference:: @values = qw( 1 10 100 1000 );
print form "(]]]].[[)", @values;
the output would have been:: ( 1.00)
10
100
1000
This is because @values would have been interpolated into "form"'s argument list, so only $value[0] would have been used as the data for the initial format string. The remaining elements of @value would have been treated as separate format strings, and printed out "verbatim".
Note too that, because arrays must be passed using a ref erence, their original contents are consumed by "form", just like the contents of scalars passed by reference.
To avoid having an array consumed by "form", pass it as an anonymous array:: print form "(]]]].[[)", [@values];
Headers, footers, and pages
The "form" subroutine can also insert headers, footers, and page-feeds as it formats. These features are con trolled by the "header", "footer", "pagefeed", "pagelen", and "pagenum" options.
The "pagenum" option takes a scalar value or a reference to a scalar variable and starts page numbering at that value. If a reference to a scalar variable is specified, the value of that variable is updated as the formatting proceeds, so that the final page number is available in it after formatting. This can be useful for multi-part reports.
The "pagelen" option specifies the total number of lines in a page (including headers, footers, and page-feeds).
If the "header" option is specified with a string value, that string is used as the header of every page generated. If it is specified as a reference to a subroutine, that subroutine is called at the start of every page and its return value used as the header string. When called, the subroutine is passed the current page number.
Likewise, if the "footer" option is specified with a string value, that string is used as the footer of every page generated. If it is specified as a reference to a subroutine, that subroutine is called at the start of every page and its return value used as the footer string. When called, the footer subroutine is passed the current page number. If the option is specified as a hash, it acts as described above for the "header" option.
Both the header and footer options can also be specified as hash references. In this case the hash entires for keys "left", "centre" (or "center"), and "right" specify what is to appear on the left, centre, and right of the header/footer. The entry for the key "width" specifies how wide the footer is to be. The "left", "centre", and "right" values may be literal strings, or subroutines (just as a normal header/footer specification may be.) See the second example, below.
The "pagefeed" option acts in exactly the same way, to produce a pagefeed which is appended after the footer. But note that the pagefeed is not counted as part of the page length.
All three of these page components are recomputed at the start of each new page, before the page contents are for matted (recomputing the header and footer makes it possi ble to determine how many lines of data to format so as to adhere to the specified page length).
When the call to "form" is complete and the data has been fully formatted, the footer subroutine is called one last time, with an extra argument of 1. The string returned by this final call is used as the final footer.
So for example, a 60-line per page report, starting at page 7, with appropriate headers and footers might be set up like so:: $page = 7;; form { header => sub { "Page $_[0]0 },
footer => sub { return "" if $_[1];
"-"x50 . "0 . form ">"x50",
"...".($_[0]+1);
},
pagefeed => "0, pagelen => 60 pagenum => age,
}, $template, @data;
Note the recursive use of "form" within the "footer" option.
Alternatively, to set up headers and footers such that the running head is right justified in the header and the page number is centred in the footer:: form { header => { right => "Running head" },
footer => { centre => sub { "Page $_[0]" }
}, pagelen => 60
}, $template, @data;
The "tag" sub
The "tag" subroutine may be exported from the module. It takes two arguments: a tag specifier and a text to be entagged. The tag specifier indicates the indenting of the tag, and of the text. The sub generates an end-tag (using the usual "/tag" variant), unless an explicit end-tag is provided as the third argument.
The tag specifier consists of the following components (in order):
An optional vertical spacer (zero or more whitespace-sepa rated newlines) One or more whitespace characters up to a final manda tory newline. This vertical space is inserted before the tag and after the end-tag
An optional tag indent Zero or more whitespace characters. Both the tag and the end-tag are indented by this whitespace.
An optional left (opening) tag delimiter Zero or more non-"word" characters (not alphanumeric or '_'). If the opening delimiter is omitted, the character '<' is used.
A tag One or more "word" characters (alphanumeric or '_').
Optional tag arguments Any number of any characters
An optional right (closing) tag delimiter Zero or more non-"word" characters which balance some sequential portion of the opening tag delimiter. For example, if the opening delimiter is "<-(" then any of the following are acceptible closing delimiters: ")->", "->", or ">". If the closing delimiter is omitted, the "inverse" of the opening delimiter is used (for example, ")->"),
An optional vertical spacer (zero or more newlines) One or more whitespace characters up to a mandatory newline. This vertical space is inserted before and after the complete text.
An optional text indent Zero or more space of tab characters. Each line of text is indented by this whitespace (in addition to the tag indent).
For example:: $text = "three lines0f tagged0ext";; print tag "A HREF=#nextsection", $text;
prints:: <A HREF=#nextsection>three lines
of tagged
text</A>
whereas:: print tag "[-:GRIN>>>0, $text;
prints:: [-:GRIN>>>:-]
three lines
of tagged
text
[-:/GRIN>>>:-]
and:: print tag " <BOLD> ", $text, "<END BOLD>";
prints:: <BOLD>

three lines
of tagged
text; <END BOLD>
(with the indicated spacing fore and aft).

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.

COPYRIGHT

Copyright (c) 1997-2000, Damian Conway. All Rights Reserved. This module is free software. It may be used, redistributed and/or modified under the terms of the Perl Artistic License: (see http://www.perl.com/perl/misc/Artistic.html)

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