JSON export/import in generate-bindings.pl

Source/bindings/scripts/IRToFromJSON.pm

+# Copyright (C) 2013 Google Inc. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+# Library to convert the Perl Intermediate Representation (IR) of IDLs
+# to and from JSON, for:
+# 1. Modularity between frontend parser and backend code generator;
+# 2. Porting to Python, so can connect Perl scripts and Python scripts.
+
+package IRToFromJSON;
+
+use strict;
+use warnings;
+
+require Exporter;
+use vars qw(@ISA @EXPORT_OK);
+@ISA = qw(Exporter);
+@EXPORT_OK = qw(IRToJSON);
+
+use JSON -convert_blessed_universally;  # IR contains blessed references
+
+sub IRToJSON

[haraken, 2013/06/03 06:49:14]

Nit: I don't want to make one file just for one method (even temporary!). Can
you write this in generate-bindings.pl?

[Nils Barth (inactive), 2013/06/03 07:27:16]

Agreed that this looks a bit silly now (it's not worth all the boilerplate to
avoid putting a 10-line function in generate-bindings), but the import code is
going to be significantly longer and messier.

This is because JSON is a POD, but our Perl data structure is an object, so
there's a lot of undoing the serialization.

You can see what's involved in importing to Python (60 lines), where we're just
pruning the excess Perl info:
https://codereview.chromium.org/15959019/diff/2001/Source/bindings/scripts/bl...
I anticipate it'll be about 80 lines of Perl, due to restoring the objects
(blessing etc.) -- we have to make sure the imported JSON is *exactly* the same
as the original Perl.

Basically I expect this to get much longer and messier, and wanted to plan ahead
to reduce churn in generate-bindings.pl.

If you'd prefer, I can put this initially in generate-bindings.pl, and then if
the import code is long (as I expect), we can factor it out.

+{
+    my $document = shift;
+    my $json = JSON->new->utf8;
+    $json = $json->allow_blessed->convert_blessed();
+    my $json_text= $json->encode($document);
+    return $json_text;
+}
+
+1;