ParseXS: refactor: fetch_para(): invert if

change

    if (cond) {
        ... lots lines ...
    }

to

    if (!cond) {
        goto read_next_line;
    }
    ... lots lines ...

  read_next_line:

which might be considered a bit regressive in a 'goto considered
harmful' sort of way, but will will help with further refactoring,
and emphasises that the current input line is discarded if the condition
isn't met (i.e. it strips out code comments, which wasn't obvious).

Author: iabyn

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

@@ -662,18 +662,14 @@ sub fetch_para {
       return 1;
     }
 
-    my $final;
-
-    # Process this line unless it looks like a '#', comment
-
-    if ($self->{lastline} !~ /^\s*#/ # not a CPP directive
+    if ($self->{lastline} =~ /^\s*#/
            # CPP directives:
            #   ANSI:    if ifdef ifndef elif else endif define undef
            #              line error pragma
            #   gcc:    warning include_next
            #   obj-c:  import
            #   others: ident (gcc notes that some cpps have this one)
-        || $self->{lastline} =~ /^\#[ \t]*
+        && $self->{lastline} !~ /^\#[ \t]*
                                   (?:
                                         (?:if|ifn?def|elif|else|endif|elifn?def|
                                            define|undef|pragma|error|
@@ -683,14 +679,22 @@ sub fetch_para {
                                         \s* ["<] .* [>"]
                                  )
                                 /x
-    )
-    {
+    ) {
+      # A line starting with # but not a CPP directive?
+      # Must be a code comment. Skip it.
+      goto read_next_line;
+    }
+
+    # A general line: process it
+
+    my $final;
+
       # Blank line followed by char in column 1. Start of next XSUB?
       last if    $self->{lastline} =~ /^\S/
               && @{ $self->{line} }
               && $self->{line}->[-1] eq "";
 
-      # processes CPP conditionals
+      # analyse CPP conditionals
       if ($self->{lastline}
             =~/^#[ \t]*(if|ifn?def|elif|else|endif|elifn?def)\b/)
       {
@@ -721,8 +725,9 @@ sub fetch_para {
 
       push(@{ $self->{line} }, $self->{lastline});
       push(@{ $self->{line_no} }, $self->{lastline_no});
-    } # end of processing non-comment lines
 
+
+  read_next_line:
     # Read next line and continuation lines
     last unless defined($self->{lastline} = readline($self->{in_fh}));
     $self->{lastline_no} = $.;