use a perl script for mixed_language_module_map_extender

tools/mixed_language_module_map_extender/BUILD

@@ -4,6 +4,6 @@ licenses(["notice"])
 
 sh_binary(
     name = "mixed_language_module_map_extender",
-    srcs = ["mixed_language_module_map_extender.sh"],
+    srcs = ["mixed_language_module_map_extender.pl"],
     visibility = ["//visibility:public"],
 )

tools/mixed_language_module_map_extender/mixed_language_module_map_extender.pl

@@ -0,0 +1,90 @@
+#! /usr/bin/env perl
+# ============================================================================ #
+# 
+# This script processes a C Family module map file to adjust header paths.
+# 
+# USAGE: mixed_language_module_map_extender.pl <output>                  \
+#                                              <modulemap>               \
+#                                              <module_name>             \
+#                                              <swift_generated_header>
+# 
+# 
+# ============================================================================ #
+
+use strict;
+use warnings;
+use File::Spec;
+
+# Check arguments
+if ( @ARGV != 4 ||
+     ( @ARGV == 1 && ( $ARGV[0] eq '-h' || $ARGV[0] eq "--help" ) )
+   )
+  {
+    my $msg = "USAGE: $0 <output> <modulemap> <module_name> " .
+              "<swift_generated_header>\n";
+    if ( @ARGV == 1 )
+      {
+        print STDERR $msg;
+        exit 0;
+      }
+    else
+      {
+        die $msg;
+      }
+  }
+
+my ( $output, $modulemap, $module_name, $swift_generated_header ) = @ARGV;
+
+# Get absolute paths for directories
+my $modulemap_dir = File::Spec->rel2abs(
+     ( File::Spec->splitpath( $modulemap ) )[1]
+   );
+my $output_dir = File::Spec->rel2abs( ( File::Spec->splitpath( $output ) )[1] );
+
+# Open input and output files
+open( my $in_fh, '<', $modulemap ) or
+    die "Cannot open input file '$modulemap': $!\n";
+
+open( my $out_fh, '>', $output ) or
+    die "Cannot open output file '$output': $!\n";
+
+
+# Process each line of the module map
+while ( my $line = <$in_fh> )
+  {
+    # Match header declarations with optional modifiers
+    # ( private, textual, umbrella )
+    if ( $line =~ /^(\s*(?:private\s+|textual\s+|umbrella\s+)*)
+                   header\s+"([^"]+)"(.*)$/x
+       )
+    {
+      my ( $prefix, $header_path, $suffix ) = ( $1, $2, $3 );
+
+      # Convert header path to absolute, then to relative from output directory
+      my $original_header_abs = File::Spec->rel2abs(
+        $header_path
+      , $modulemap_dir
+      );
+      my $new_header_rel = File::Spec->abs2rel(
+        $original_header_abs
+      , $output_dir
+      );
+
+      print $out_fh "${prefix}header \"$new_header_rel\"$suffix\n";
+    }
+  else
+    {
+      print $out_fh $line;
+    }
+  }
+
+# Add Swift submodule
+print $out_fh "\n";
+print $out_fh "module \"$module_name\".Swift {\n";
+print $out_fh "    header \"$swift_generated_header\"\n";
+print $out_fh "\n";
+print $out_fh "    requires objc\n";
+print $out_fh "}\n";
+
+close( $in_fh );
+close( $out_fh );