[libcalamares] Add a TranslatedString class to locale/

- While QObject::tr and gettext give us translations **most** of the
   time via the translation mechanism, we sometimes have strings
   embedded in configuration files that need to be shown to people
   as well. Follow the .desktop style in handling this.
 - A key's value **might** be translated; use `key[lang]` for the
   translation into one of the languages that Calamares understands.
   Code that expects a translated (human-readable) string in a configuration
   file can use TranslatedString to collect all the translations of a
   given key, so that it displays the right string from the configuration
   when needed.

src/libcalamares/CMakeLists.txt

@@ -34,6 +34,7 @@ set( libSources
     locale/Label.cpp
     locale/LabelModel.cpp
     locale/Lookup.cpp
+    locale/TranslatableConfiguration.cpp
 
     # Partition service
     partition/PartitionSize.cpp

src/libcalamares/locale/TranslatableConfiguration.cpp

@@ -0,0 +1,67 @@
+/* === This file is part of Calamares - <https://github.com/calamares> ===
+ *
+ *   Copyright 2019, Adriaan de Groot <groot@kde.org>
+ *
+ *   Calamares 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 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   Calamares 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 Calamares. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "TranslatableConfiguration.h"
+
+#include "LabelModel.h"
+
+#include "utils/Logger.h"
+#include "utils/Variant.h"
+
+#include <QRegularExpression>
+#include <QRegularExpressionMatch>
+
+namespace CalamaresUtils
+{
+namespace Locale
+{
+TranslatedString::TranslatedString(const QString& string)
+{
+    m_strings[QString()]=string;
+}
+TranslatedString::TranslatedString(const QVariantMap& map, const QString& key)
+{
+    // Get the un-decorated value for the key
+    QString value = CalamaresUtils::getString( map, key );
+    if ( value.isEmpty() )
+    {
+        value = key;
+    }
+    m_strings[QString()] = value;
+    
+    for ( auto it = m_strings.constKeyValueBegin(); it != m_strings.constKeyValueEnd(); ++it )
+    {
+        QString subkey = (*it).first;
+        if ( subkey == key )
+        {
+            // Already obtained, above
+        }
+        else if ( subkey.startsWith( key ) )
+        {
+            QRegularExpressionMatch match;
+            if ( subkey.indexOf( QRegularExpression("\\[([a-zA-Z_@]*)\\]"), 0, &match ) > 0 )
+            {
+                QString language = match.captured(1);
+                cDebug() << "Found translation" << key << '[' << language << ']';
+            }
+        }
+    }
+}
+
+}  // namespace Locale
+}  // namespace CalamaresUtils

src/libcalamares/locale/TranslatableConfiguration.h

@@ -0,0 +1,54 @@
+/* === This file is part of Calamares - <https://github.com/calamares> ===
+ *
+ *   Copyright 2019, Adriaan de Groot <groot@kde.org>
+ *
+ *   Calamares 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 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   Calamares 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 Calamares. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LOCALE_TRANSLATABLECONFIGURATION_H
+#define LOCALE_TRANSLATABLECONFIGURATION_H
+
+#include "DllMacro.h"
+
+#include <QLocale>
+#include <QMap>
+#include <QVariant>
+
+namespace CalamaresUtils
+{
+namespace Locale
+{
+    /** @brief A human-readable string from a configuration file
+     * 
+     * The configuration files can contain human-readable strings,
+     * but those need their own translations and are not supported
+     * by QObject::tr or anything else.
+     */
+    class DLLEXPORT TranslatedString
+    {
+    public:
+        /** @brief Get all the translations connected to @p key
+         */
+        TranslatedString( const QVariantMap& map, const QString& key );
+        /** @brief Not-actually-translated string.
+         */
+        TranslatedString( const QString& string );
+    private:
+        // Maps locale name to human-readable string, "" is English
+        QMap< QString, QString > m_strings;
+    };
+}  // namespace Locale
+}  // namespace CalamaresUtils
+
+#endif