Meta/indent-cpp-directive: C preprocessor directive indentation rules

indent-cpp-directive.perl

@@ -0,0 +1,32 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+my $indent_level = -1;
+
+sub emit {
+	my $indent = $indent_level <= 0 ? "" : " " x $indent_level;
+	printf "#%s%s", $indent, $_;
+}
+
+while (<>) {
+	unless (s/^\s*#\s*//) {
+		print;
+		next;
+	}
+
+	if (/^if/) {
+		emit($_);
+		$indent_level++;
+	} elsif (/^el/) {
+		$indent_level--;
+		emit($_);
+		$indent_level++;
+	} elsif (/^endif/) {
+		$indent_level--;
+		emit($_);
+	} else {
+		emit($_);
+	}
+}