turn the script into a modulino for ease of testing

Co-authored-by: Eric Herman <[email protected]>

Author: book

Porting/merge-deltas.pl

@@ -75,7 +75,7 @@ sub inject_items
         my $from = next_header_pos( $delta, 2, $delta_pos );
         my $to   = next_header_pos( $delta, 1, $from ) - 1;
 
-        # inject them at the end of the section
+        # inject them before the next =head2 (or the end of the section)
         $master_pos = next_header_pos( $master, 2, $master_pos )
           // next_header_pos( $master, 1, $master_pos );
         splice @$master, $master_pos, 0, $delta->@[ $from .. $to ];
@@ -278,48 +278,17 @@ ( $tree )
     return join '', $handler->{$name}->( $directive, $attr, @nodes );
 }
 
-# MAIN PROGRAM
-
-# argument processing
-my $version = shift;
-die "Usage: $0 <version>\n  version is required\n"
-  unless $version;
-die "$version does not look like a stable Perl version\n"
-  unless $version =~ /\A5\.[0-9]{1,2}[02468]\z/;
-
-# the previous version
-my $previous = join '.', '5', ( split /\./, $version )[1] - 2;
-
-# the version number used for delta
-# TODO: this should be computable
-my $tag_stable = $version =~ tr/.//dr;
-my $tag_devel  = $tag_stable - 1;
-
 # Note: the parser can only be used *once* per file
-sub tree_for ($file) {
+sub tree_for ($string) {
     my $parser = Pod::Simple::SimpleTree->new;
     $parser->keep_encoding_directive(1);
     $parser->preserve_whitespace(1);
     $parser->accept_targets('*');          # for & begin/end
     $parser->_output_is_for_JustPod(1);    # for ~bracket_count
-    $parser->parse_file($file)->root;
+    $parser->parse_string_document($string)->root;
 }
 
-# the current, unfinished, delta will be used to produce the final document
-my $main_delta = 'pod/perldelta.pod';
-
-# load the template
-my $master = tree_for($main_delta);
-
-# loop over all the development deltas
-for my $file_tree (
-    map [ $_->[0], tree_for( $_->[0] ) ],
-    sort { $b->[1] <=> $a->[1] }
-    map [ $_, m{pod/perl$tag_devel([0-9]+)delta\.pod}g ],
-    glob "pod/perl$tag_devel*delta.pod"
-  )
-{
-    my ( $file, $delta ) = @$file_tree;
+sub merge_into ( $master, $delta, $file ) {
 
     # loop over the =head1 sections
     for my $title (
@@ -335,8 +304,54 @@ ($file)
     }
 }
 
-# save the result
-open my $fh, '>', $main_delta
-  or die "Can't open $main_delta for writing: $!";
-print $fh as_pod($master);
+# poor man's slurp
+sub slurp { return do { local @ARGV = @_; local $/; <> } }
+
+# MAIN PROGRAM
+
+sub main (@argv) {
+
+    # argument processing
+    my $version = shift @argv;
+    die "Usage: $0 <version>\n  version is required\n"
+      unless $version;
+    die "$version does not look like a stable Perl version\n"
+      unless $version =~ /\A5\.[0-9]{1,2}[02468]\z/;
+
+    # the previous version
+    my $previous = join '.', '5', ( split /\./, $version )[1] - 2;
+
+    # the version number used for delta
+    # TODO: this should be computable
+    my $tag_stable = $version =~ tr/.//dr;
+    my $tag_devel  = $tag_stable - 1;
+
+    # the current, unfinished, delta will be used to produce the final document
+    my $main_delta = 'pod/perldelta.pod';
+
+    # load the template
+    my $master = tree_for( slurp($main_delta) );
+
+    # loop over all the development deltas
+    for my $file_tree (
+        map [ $_->[0], tree_for( slurp( $_->[0] ) ) ],
+        sort { $b->[1] <=> $a->[1] }
+        map [ $_, m{pod/perl$tag_devel([0-9]+)delta\.pod}g ],
+        glob "pod/perl$tag_devel*delta.pod"
+      )
+    {
+        my ( $file, $delta ) = @$file_tree;
+        merge_into( $master, $delta, $file );
+    }
+
+    # save the result
+    open my $fh, '>', $main_delta
+      or die "Can't open $main_delta for writing: $!";
+    print $fh as_pod($master);
+
+    return 0;
+}
+
+# make it easier to test
+exit main( @ARGV ) unless caller;