ParseXS: refactor: add Node::global_cpp_line

(This commit is part of a series which will extend the AST parse tree
from just representing individual XSUBs to representing the whole XS
file.)

This node stores a single "#foo BAR" C preprocessor line which appears
within the XS part of an XS file, and which is in global (file) scope
(as opposed to being within code in an XSUB or BOOT).

Author: iabyn

dist/ExtUtils-ParseXS/lib/ExtUtils/ParseXS.pm

@@ -438,20 +438,17 @@ sub process_file {
 
  PARAGRAPH:
   while ($self->fetch_para()) {
+
     # Process and emit any initial C-preprocessor lines and blank
     # lines.  Also, keep track of #if/#else/#endif nesting, updating:
     #    $self->{XS_parse_stack}
     #    $self->{XS_parse_stack_top_if_idx}
     #    $self->{bootcode_early}
     #    $self->{bootcode_later}
-
     while (@{ $self->{line} } && $self->{line}->[0] !~ /^[^\#]/) {
-      my $ln = shift(@{ $self->{line} });
-      print $ln, "\n";
-      next unless $ln =~ /^\#\s*((if)(?:n?def)?|elsif|else|endif)\b/;
-      my $statement = $+;
-      # update global tracking of #if/#else etc
-      $self->analyze_preprocessor_statement($statement);
+      my $node = ExtUtils::ParseXS::Node::global_cpp_line->new();
+      $node->parse($self);
+      $node->as_code($self);
     }
 
     next PARAGRAPH unless @{ $self->{line} };

dist/ExtUtils-ParseXS/lib/ExtUtils/ParseXS/Node.pm

@@ -685,6 +685,45 @@ sub as_code {
 }
 
 
+# ======================================================================
+
+package ExtUtils::ParseXS::Node::global_cpp_line;
+
+# AST node representing a single C-preprocessor line in file (global)
+# scope. (A "single" line can actually include embedded "\\\n"'s from line
+# continuations).
+
+BEGIN { $build_subclass->(
+    'cpp_line',  # the text of the "#  foo" CPP line
+)};
+
+sub parse {
+    my __PACKAGE__        $self   = shift;
+    my ExtUtils::ParseXS  $pxs    = shift;
+
+    $self->SUPER::parse($pxs); # set file/line_no
+
+    my $ln = $self->{cpp_line} = shift(@{$pxs->{line}});
+
+    # Update global tracking of *conditional* CPP directives;s
+    # i.e. #if/#else etc
+
+    return 1 unless $ln =~ /^\#\s*((if)(?:n?def)?|elsif|else|endif)\b/;
+    my $directive = $+; # one of "if", "elsif", "else", "endif"
+    $pxs->analyze_preprocessor_statement($directive);
+
+    1;
+}
+
+
+sub as_code {
+    my __PACKAGE__        $self   = shift;
+    my ExtUtils::ParseXS  $pxs    = shift;
+
+    print $self->{cpp_line}, "\n";
+}
+
+
 # ======================================================================
 
 package ExtUtils::ParseXS::Node::xsub;