moc: add -M<key=value> to ease static qml plugin linking

A module plugin in qml belongs to a URI/namespace. This
uri is resolved run-time by QtDeclarative by knowing the
path of the qmldir that references the plugin.
For static plugins this becomes a problem, since we lost
the information regarding which plugin belongs to which
qmldir, since a static plugin has no file path.

To avoid pushing the responsibility of clarifying this
onto the application developer, it is better to embed this
information into the meta data of the plugins themselves.
Since this information can be resolved by the
build system, a new option to moc has been added:
-M<key=value>
that will let you add meta tags to the meta data from
the command line to each class that has an IID specified.
For the URI case, we can then e.g do:
-Muri=QtQuick.Controls -Muri=QtQuick.Controls.Private

Change-Id: I81a156660148fc94db6f3cac0473e9e1c8458c58
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/src/tools/moc/main.cpp b/src/tools/moc/main.cpp
index 999cae0e60..98472792f8 100644
--- a/src/tools/moc/main.cpp
+++ b/src/tools/moc/main.cpp
@@ -242,6 +242,11 @@ int runMoc(int argc, char **argv)
     undefineOption.setValueName(QStringLiteral("macro"));
     parser.addOption(undefineOption);
 
+    QCommandLineOption metadataOption(QStringLiteral("M"));
+    metadataOption.setDescription(QStringLiteral("Add key/value pair to plugin meta data"));
+    metadataOption.setValueName(QStringLiteral("key=value"));
+    parser.addOption(metadataOption);
+
     QCommandLineOption noIncludeOption(QStringLiteral("i"));
     noIncludeOption.setDescription(QStringLiteral("Do not generate an #include statement."));
     parser.addOption(noIncludeOption);
@@ -385,6 +390,24 @@ int runMoc(int argc, char **argv)
         moc.filename = filename.toLocal8Bit();
     }
 
+    foreach (const QString &md, parser.values(metadataOption)) {
+        int split = md.indexOf(QLatin1Char('='));
+        QString key = md.left(split);
+        QString value = md.mid(split + 1);
+
+        if (split == -1 || key.isEmpty() || value.isEmpty()) {
+            error("missing key or value for option '-M'");
+        } else if (key.indexOf(QLatin1Char('.')) != -1) {
+            // Don't allow keys with '.' for now, since we might need this
+            // format later for more advanced meta data API
+            error("A key cannot contain the letter '.' for option '-M'");
+        } else {
+            QJsonArray array = moc.metaArgs.value(key);
+            array.append(value);
+            moc.metaArgs.insert(key, array);
+        }
+    }
+
     moc.currentFilenames.push(filename.toLocal8Bit());
     moc.includes = pp.includes;