#! /usr/bin/gawk -f

# CVS version control block - do not edit manually
#  $RCSfile: bibfile-reformat-pages,v $
#  $Revision: 1.4 $
#  $Date: 2004/09/27 13:54:47 $
#  $Source: /home/cvs/papers/sty/bibfile-reformat-pages,v $

# bibfile-reformat-pages - put file.bib page ranges into uniform style
# Copyright (C) 2004  Barak A. Pearlmutter <barak@cs.may.ie>

# 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 of the License, or (at
# your option) any later version.  You can find a copy of this license
# at http://www.fsf.org/copyleft/gpl.html, or in the file COPYING, or
# on Debian systems in /usr/share/common-licenses/GPL, or by writing
# to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
# Boston, MA  02111-1307  USA

# 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.

function usage()
{
  print "Usage: bibfile-reformat-pages [abbrev=1] [separator=X] [files.bib or stdin]";
  print;
  print "Summary: reformat the \"pages=\" bits of a .bib file.";
  print;
  print "Version: '$RCSfile: bibfile-reformat-pages,v $ $Revision: 1.4 $";
  print;
  print "Description:";
  print;
  print "  Passes through input file or stdin, which is assumed to be a bibtex";
  print "  .bib file, changing page ranges to a uniform format.  The converted";
  print "  file is sent to standard output.  Vacuous ranges are always compressed,";
  print "  so 1234-1234 becomes just 1234.  Blanks around in the range separator";
  print "  are always squeezed out, so \"12 - 34 \" becomes \"12-34\".  Ranges are";
  print "  by default put into expanded style, so 1234-56 becomes 1234-1256, but";
  print "  if the abbrev=1 option is given the conversion is reversed and 1234-1256";
  print "  is instead abbreviated to 1234-56.  The range separator \"-\" or \"--\"";
  print "  is preserved, unless a separator=- or separator=-- option is given in";
  print"   which case they are homogenised.";
  print;
  print "  Efforts, albeit not exhaustive ones, are taken to only modify \"pages=\"";
  print "  lines and to err on the side of caution (first, do no harm).";
  print;
  print "Options:";
  print;
  print "  -h           Print this help message and exit";
  print "  abbrev=1     Abbreviate page ranges instead of unabbreviating them";
  print "  separator=X  Replaces page range separators with X, which must be - or --.";
  print;
  print "Examples:";
  print;
  print "  bibfile-reformat-pages abbrev=0 separator=-- foo.bib > foo-new.bib";
  print "  diff foo.bib foo-new.bib";
  print "  mv foo-new.bib foo.bib";
  print;
  print "  bibfile-reformat-pages foo.bib > foo-new.bib";
  print;
  print "  bibfile-reformat-pages < foo.bib > foo-new.bib";
  print;
  print "  bibfile-reformat-pages abbrev=1 separator=- foo.bib > foo-new.bib";
  print;
  print "Useful commands for testing:";
  print;
  print "  bibfile-reformat-pages foo.bib | diff foo.bib - | more"
  print "  for f in *.bib; do echo $f; bibfile-reformat-pages <$f | diff $f -; done";
  print "  find . -name '*.bib' | xargs bibfile-reformat-pages | egrep pages | more";
}

BEGIN {
  if ( ARGV[1] == "-h" || ARGV[1] ~ /^--?help$/ ) {
    usage();
    exit;
  }
  IGNORECASE=1;
  abbrev=0;			# avoid uninitialised variable warning
  separator=0;			# avoid uninitialised variable warning
}

## Would code as "if" in BEGIN, but var=x opts processed after BEGIN.
(separator && !(separator ~ /^--?$/)) {
  print "error: illegal option separator=" separator > "/dev/stderr";
  print "  valid values: \"-\" or \"--\"." > "/dev/stderr";
  close("/dev/stderr");
  exit 1;
}

function high_page_unabbrev(lo, hi)
{
  llo = length(lo);
  lhi = length(hi);
  if (llo > lhi)
    hi = substr(lo, 1, llo-lhi) hi;
  return hi;
}

function numsame(x, y)
{
  i = 1;
  while (1)
    {
      xc = substr(x, i, 1);
      yc = substr(y, i, 1);
      if (!xc || !yc || xc != yc)
	return i-1;
      i += 1;
    }
}

function high_page_abbrev(lo, hi)
{
  hi = high_page_unabbrev(lo, hi);
  llo = length(lo);
  lhi = length(hi);
  if (llo == lhi) {
    k = numsame(lo, hi);
    if ( k > 0 )
      hi = substr(hi, 1+k);
  }
  return hi;
}

match($0,
      /^([[:blank:]]*pages[[:blank:]]*=[^[:digit:]]*)([[:digit:]]+)[[:blank:]]*(--?)[[:blank:]]*([[:digit:]]+)([^[:digit:]]*)$/,
      a) {
  low = a[2];
  sep = a[3];
  high = a[4];
  high = high_page_unabbrev(low, high);	# put into canonical (unabbrev) form
  if (low == high) {
    print a[1] low a[5];	# 123-123 becomes just 123
  } else {
    if (abbrev) high = high_page_abbrev(low, high);
    if (separator) sep=separator;
    print a[1] low sep high a[5];
  }
  next;
}

{
  print;
}