summaryrefslogtreecommitdiff
path: root/lib/Automake/Wrap.pm
blob: 0aa42e17d330a2f4a8b59000dcf6ffcd5ccd9d80 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
# Copyright (C) 2003-2013 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

package Automake::Wrap;

use 5.006;
use strict;

require Exporter;
use vars '@ISA', '@EXPORT_OK';
@ISA = qw/Exporter/;
@EXPORT_OK = qw/wrap makefile_wrap/;

=head1 NAME

Automake::Wrap - a paragraph formatter

=head1 SYNOPSIS

  use Automake::Wrap 'wrap', 'makefile_wrap';

  print wrap ($first_ident, $next_ident, $end_of_line, $max_length,
              @values);

  print makefile_wrap ("VARIABLE = ", "    ", @values);

=head1 DESCRIPTION

This modules provide facility to format list of strings.  It is
comparable to Perl's L<Text::Wrap>, however we can't use L<Text::Wrap>
because some versions will abort when some word to print exceeds the
maximum length allowed.  (Ticket #17141, fixed in Perl 5.8.0.)

=head2 Functions

=over 4

=cut

# _tab_length ($TXT)
# ------------------
# Compute the length of TXT, counting tab characters as 8 characters.
sub _tab_length($)
{
  my ($txt) = @_;
  my $len = length ($txt);
  $len += 7 * ($txt =~ tr/\t/\t/);
  return $len;
}

=item C<wrap ($head, $fill, $eol, $max_len, @values)>

Format C<@values> as a block of text that starts with C<$head>,
followed by the strings in C<@values> separated by spaces or by
C<"$eol\n$fill"> so that the length of each line never exceeds
C<$max_len>.

The C<$max_len> constraint is ignored for C<@values> items which
are too big to fit alone one a line.

The constructed paragraph is C<"\n">-terminated.

=cut

sub wrap($$$$@)
{
  my ($head, $fill, $eol, $max_len, @values) = @_;

  my $result = $head;
  my $column = _tab_length ($head);

  my $fill_len = _tab_length ($fill);
  my $eol_len = _tab_length ($eol);

  my $not_first_word = 0;

  foreach (@values)
    {
      my $len = _tab_length ($_);

      # See if the new variable fits on this line.
      # (The + 1 is for the space we add in front of the value.).
      if ($column + $len + $eol_len + 1 > $max_len
	  # Do not break before the first word if it does not fit on
	  # the next line anyway.
	  && ($not_first_word || $fill_len + $len + $eol_len + 1 <= $max_len))
	{
	  # Start a new line.
	  $result .= "$eol\n" . $fill;
	  $column = $fill_len;
	}
      elsif ($not_first_word)
	{
	  # Add a space only if result does not already end
	  # with a space.
	  $_ = " $_" if $result =~ /\S\z/;
	  ++$len;
	}
      $result .= $_;
      $column += $len;
      $not_first_word = 1;
    }

  $result .= "\n";
  return $result;
}


=item C<makefile_wrap ($head, $fill, @values)>

Format C<@values> in a way which is suitable for F<Makefile>s.
This is comparable to C<wrap>, except C<$eol> is known to
be C<" \\">, and the maximum length has been hardcoded to C<72>.

A space is appended to C<$head> when this is not already
the case.

This can be used to format variable definitions or dependency lines.

  makefile_wrap ('VARIABLE =', "\t", @values);
  makefile_wrap ('rule:', "\t", @dependencies);

=cut

sub makefile_wrap ($$@)
{
  my ($head, $fill, @values) = @_;
  if (@values)
    {
      $head .= ' ' if $head =~ /\S\z/;
      return wrap $head, $fill, " \\", 72, @values;
    }
  return "$head\n";
}


1;

### Setup "GNU" style for perl-mode and cperl-mode.
## Local Variables:
## perl-indent-level: 2
## perl-continued-statement-offset: 2
## perl-continued-brace-offset: 0
## perl-brace-offset: 0
## perl-brace-imaginary-offset: 0
## perl-label-offset: -2
## cperl-indent-level: 2
## cperl-brace-offset: 0
## cperl-continued-brace-offset: 0
## cperl-label-offset: -2
## cperl-extra-newline-before-brace: t
## cperl-merge-trailing-else: nil
## cperl-continued-statement-offset: 2
## End: