Refactored conversion routines used in the Typesystem class and the Variant class into an own class, implemented missing conversion from string to integer/double, implemented proper JSON serialization of variants

1 files changed, 72 insertions, 0 deletions

diff --git a/src/core/common/VariantConverter.hpp b/src/core/common/VariantConverter.hpp
new file mode 100644
index 0000000..b683083
--- /dev/null
+++ b/src/core/common/VariantConverter.hpp
@@ -0,0 +1,72 @@
+/*
+    Ousía
+    Copyright (C) 2014, 2015  Benjamin Paaßen, Andreas Stöckel
+
+    This program 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.
+
+    This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _OUSIA_VARIANT_CONVERTER_HPP_
+#define _OUSIA_VARIANT_CONVERTER_HPP_
+
+namespace ousia {
+
+// Forward declaration
+class Variant;
+class Logger;
+
+/**
+ * The VariantConverter class is used to convert a variant to a certain
+ * prespecified type. The functions ensure that the variant has the requested
+ * type, even if the conversion fails.
+ */
+class VariantConverter {
+
+public:
+	/**
+	 * Enumeration used to define the mode of conversion -- either only safe
+	 * conversions (without any data loss) are performed, or all possible
+	 * conversions are tried (with possible data loss).
+	 */
+	enum class Mode {
+		SAFE, ALL
+	};
+
+	/**
+	 * Makes sure the given variant is a boolean. If the "mode" parameter is
+	 * set to Mode::SAFE, only booleans can be converted to booleans. For all
+	 * other types the conversion fails. If "mode" is set to Mode::ALL, nullptr
+	 * values and zero numeric values are treated as "false", all other values
+	 * are treated as "true".
+	 *
+	 * @param var is instance of the Variant class that should be converted to
+	 * the requested type.
+	 * @param logger is a reference to the logger instance into which messages
+	 * should be logged.
+	 * @param mode is the conversion mode. See method description for the exact
+	 * effect.
+	 */
+	static bool toBool(Variant &var, Logger &logger, Mode mode = Mode::SAFE);
+
+	static bool toInt(Variant &var, Logger &logger, Mode mode = Mode::SAFE);
+
+	static bool toDouble(Variant &var, Logger &logger, Mode mode = Mode::SAFE);
+
+	static bool toString(Variant &var, Logger &logger, Mode mode = Mode::SAFE);
+
+};
+
+}
+
+#endif /* _OUSIA_VARIANT_CONVERTER_HPP_ */
+