Fix missing introspection data for libtracker-sparql (when using Meson)

Up til now only the Tracker.SparqlConnection and Tracker.SparqlBuilder
resources were introspectable. This is because we only used the
introspection output from `valac`, but other bits of libtracker-sparql
have since been added that are written in C.

There seems to be no way to generate a single .gir for a combined C and
Vala codebase, so instead I have written a simple `g-ir-merge` script
which can combine two different namespaces into a single .gir.

This is currently tested and working with the Meson build instructions.
It would be possible to implement this for the Autotools build
instructions as well.

https://bugzilla.gnome.org/show_bug.cgi?id=782091

2 files changed, 173 insertions, 1 deletions

diff --git a/utils/Makefile.am b/utils/Makefile.am
index caf0f72f4..88dcffd10 100644
--- a/utils/Makefile.am
+++ b/utils/Makefile.am
@@ -9,4 +9,4 @@ if HAVE_TRACKER_RESDUMP
 SUBDIRS += tracker-resdump
 endif
 
-EXTRA_DIST = meson.build
+EXTRA_DIST = meson.build g-ir-merge/g-ir-merge
diff --git a/utils/g-ir-merge/g-ir-merge b/utils/g-ir-merge/g-ir-merge
new file mode 100755
index 000000000..45ed5f535
--- /dev/null
+++ b/utils/g-ir-merge/g-ir-merge
@@ -0,0 +1,172 @@
+#!/usr/bin/python3
+#
+# Copyright 2017, Sam Thursfield <sam@afuera.me.uk>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+# Boston, MA  02110-1301, USA.
+
+
+'''g-ir-merge: combine multiple GObject Introspection namespaces together.
+
+This tool exists to solve a problem in Tracker: we have code for
+libtracker-sparql written in both C and Vala. It's not possible to generate
+a single .gir for all of this code as `g-ir-scanner` can't deal with Vala's
+generated .c code, and `valac` only handles .vala code.
+
+The only workable solution seems to be to generate two different .gir files
+and manually combine them. Thankfully it's not too difficult to do this.
+
+For more discussion, see: https://bugzilla.gnome.org/show_bug.cgi?id=782091
+
+'''
+
+
+import argparse
+import sys
+from xml.etree import ElementTree
+
+CORE_NAMESPACE = 'http://www.gtk.org/introspection/core/1.0'
+C_NAMESPACE = 'http://www.gtk.org/introspection/c/1.0'
+GLIB_NAMESPACE = 'http://www.gtk.org/introspection/glib/1.0'
+
+def argument_parser():
+    parser = argparse.ArgumentParser(
+        description="Merge .gir repositories together.")
+
+    parser.add_argument('--namespace', '-n', metavar='NAMESPACE_NAME', type=str, required=True,
+                        help="name for combined .gir namespace")
+    parser.add_argument('--nsversion', metavar='NAMESPACE_VERSION', type=str, required=True,
+                        help="version for combined .gir namespace")
+
+    parser.add_argument('--c-include', metavar='C_INCLUDES', type=list,
+                        help="override list of C includes")
+
+    parser.add_argument('files', metavar="GIR_FILE", type=str, nargs='+',
+                        help="input .gir file")
+    return parser
+
+
+def parse_inputs(files):
+    '''Read the important contents from one or more .gir files and return all.
+
+    This does no post-processing of the data, it simply returns everything
+    including any duplicate or contradictory info.
+
+    '''
+    ns = {
+        'core': CORE_NAMESPACE,
+        'c': C_NAMESPACE
+    }
+
+    includes = []
+    namespaces = []
+    c_includes = []
+
+    for file in files:
+        gi_repository = ElementTree.parse(file).getroot()
+
+        for gi_include in gi_repository.findall('core:include', ns):
+            includes.append(gi_include)
+
+        for gi_namespace in gi_repository.findall('core:namespace', ns):
+            namespaces.append(gi_namespace)
+
+        for gi_c_include in gi_repository.findall('c:include', ns):
+            c_includes.append(gi_c_include)
+
+    return includes, namespaces, c_includes
+
+
+def merge_includes(all_includes):
+    merged = {}
+    for element in all_includes:
+        name = element.get('name')
+        version = element.get('version')
+        if name not in merged:
+            merged[name] = element
+    return merged.values()
+
+
+def merge_namespaces(all_namespaces):
+    identifier_prefixes = set()
+    symbol_prefixes = set()
+    shared_libraries = set()
+
+    contents = []
+
+    for element in all_namespaces:
+        if element.get('c:identifier_prefixes', None):
+            identifier_prefixes.update(element.get('c:identifier_prefixes').split(','))
+        if element.get('c:symbol_prefixes', None):
+            symbol_prefixes.update(element.get('c:symbol_prefixes').split(','))
+        identifier_prefixes.update(element.get('c:prefix', []))
+        symbol_prefixes.update(element.get('c:prefix', []))
+
+        if element.get('shared-library', None):
+            shared_libraries.update(element.get('shared-library', '').split(','))
+
+        contents.extend(element)
+
+    return (contents,
+            ','.join(sorted(identifier_prefixes)),
+            ','.join(sorted(symbol_prefixes)),
+            ','.join(sorted(shared_libraries)))
+
+
+def create_repository(namespace_name, namespace_version, shared_libraries,
+                      c_identifier_prefixes, c_symbol_prefixes, includes, namespace_contents):
+    '''Create a new GI repository with a single namespace.'''
+    ElementTree.register_namespace('', CORE_NAMESPACE)
+    ElementTree.register_namespace('c', C_NAMESPACE)
+    ElementTree.register_namespace('glib', GLIB_NAMESPACE)
+    gir_version = '1.2'
+
+    repository = ElementTree.Element('repository', attrib={'version': gir_version})
+    repository.extend(includes)
+
+    namespace = ElementTree.SubElement(repository, 'namespace', attrib={
+            'name': namespace_name,
+            'version': namespace_version,
+            'shared-library': shared_libraries,
+            'c:identifier-prefixes': c_identifier_prefixes,
+            'c:symbol-prefixes': c_symbol_prefixes,
+        })
+    namespace.extend(namespace_contents)
+
+    return repository
+
+
+def main():
+    args = argument_parser().parse_args()
+
+    all_includes, all_namespaces, all_c_includes = parse_inputs(args.files)
+
+    includes = merge_includes(all_includes)
+
+    namespace_contents, identifier_prefixes, symbol_prefixes, shared_libraries \
+        = merge_namespaces(all_namespaces)
+
+    repository = create_repository(args.namespace, args.nsversion, shared_libraries,
+                                   identifier_prefixes, symbol_prefixes,
+                                   includes, namespace_contents)
+
+    print(ElementTree.tostring(repository, encoding="unicode"))
+
+
+try:
+    main()
+except RuntimeError as e:
+    sys.stderr.write("{}\n".format(e))
+    sys.exit(1)