update-copyright: much ado about intervals

* build-aux/update-copyright: Implement and document
UPDATE_COPYRIGHT_USE_INTERVALS to control expansion and collapse
of copyright year intervals.
Also, document UPDATE_COPYRIGHT_YEAR.
* tests/test-update-copyright.sh: Test it.

1 files changed, 35 insertions, 16 deletions

diff --git a/build-aux/update-copyright b/build-aux/update-copyright
index fb1c7d2b79..d8445fee08 100755
--- a/build-aux/update-copyright
+++ b/build-aux/update-copyright
@@ -1,7 +1,7 @@
 #!/usr/bin/perl -0777 -pi
 # Update an FSF copyright year list to include the current year.
 
-my $VERSION = '2009-08-14.02:23'; # UTC
+my $VERSION = '2009-08-14.05:03'; # UTC
 
 # Copyright (C) 2009 Free Software Foundation, Inc.
 #
@@ -92,6 +92,16 @@ my $VERSION = '2009-08-14.02:23'; # UTC
 #      within the FSF copyright statement.
 #   7. Each copyright year is 2 or 4 digits, and years are separated by
 #      commas or dashes.  Whitespace may occur after commas.
+#
+# Environment variables:
+#
+#   1. If UPDATE_COPYRIGHT_USE_INTERVALS=1, every series of consecutive
+#      copyright years (such as 90, 1991, 1992-2007, 2008) in an updated
+#      FSF copyright statement is collapsed to a single interval (such
+#      as 1990-2008).  If unset or set to 0, all existing copyright year
+#      intervals are expanded.
+#   2. For testing purposes, you can set the assumed current year in
+#      UPDATE_COPYRIGHT_YEAR.
 
 use strict;
 use warnings;
@@ -138,7 +148,7 @@ while (/(^|\n)(.{0,$prefix_max})$copyright_re/g)
     $holder_re =~ s/\s/$ws_re/g;
     my $stmt_remainder_re =
       "(?:$ws_re$circle_c_re)?"
-      . "$ws_re(?:(?:\\d\\d)?\\d\\d(,$ws_re?|-))*"
+      . "$ws_re(?:(?:\\d\\d)?\\d\\d(?:,$ws_re?|-))*"
       . "((?:\\d\\d)?\\d\\d)$ws_re$holder_re";
     if (/\G$stmt_remainder_re/)
       {
@@ -151,8 +161,7 @@ if (defined $stmt_re)
   {
     /$stmt_re/ or die; # Should never die.
     my $stmt = $1;
-    my $sep = $2 ? $2 : "";
-    my $final_year_orig = $3;
+    my $final_year_orig = $2;
 
     # Handle two-digit year numbers like "98" and "99".
     my $final_year = $final_year_orig;
@@ -162,18 +171,7 @@ if (defined $stmt_re)
     if ($final_year != $this_year)
       {
         # Update the year.
-        if ($sep eq '-' && $final_year + 1 == $this_year)
-          {
-            $stmt =~ s/$final_year_orig/$this_year/;
-          }
-        elsif ($sep ne '-' && $final_year + 1 == $this_year)
-          {
-            $stmt =~ s/$final_year_orig/$final_year-$this_year/;
-          }
-        else
-          {
-            $stmt =~ s/$final_year_orig/$final_year, $this_year/;
-          }
+        $stmt =~ s/$final_year_orig/$final_year, $this_year/;
 
         # Normalize all whitespace including newline-prefix sequences.
         $stmt =~ s/$ws_re/ /g;
@@ -184,6 +182,27 @@ if (defined $stmt_re)
         # Convert 2-digit to 4-digit years.
         $stmt =~ s/(\b\d\d\b)/19$1/g;
 
+        # Make the use of intervals consistent.
+        if (!$ENV{UPDATE_COPYRIGHT_USE_INTERVALS})
+          {
+            $stmt =~ s/(\d{4})-(\d{4})/join(', ', $1..$2)/eg;
+          }
+        else
+          {
+            $stmt =~
+              s/
+                (\d{4})
+                (?:
+                  (,\ |-)
+                  ((??{
+                    if    ($2 eq '-') { '\d{4}'; }
+                    elsif (!$3)       { $1 + 1;  }
+                    else              { $3 + 1;  }
+                  }))
+                )+
+              /$1-$3/gx;
+          }
+
         # Format within margin.
         my $stmt_wrapped;
         my $text_margin = $margin - length($prefix);