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+/* vim: set sw=4 sts=4 et foldmethod=syntax : */
+
+/*
+ * Copyright (c) 2005, 2006 Ciaran McCreesh <ciaranm@gentoo.org>
+ *
+ * This file is part of the Paludis package manager. Paludis is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU General
+ * Public License version 2, as published by the Free Software Foundation.
+ *
+ * Paludis 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, write to the Free Software Foundation, Inc., 59 Temple
+ * Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef PALUDIS_GUARD_PALUDIS_VALIDATED_HH
+#define PALUDIS_GUARD_PALUDIS_VALIDATED_HH 1
+
+#include <ostream>
+#include <paludis/util/comparison_policy.hh>
+
+namespace paludis
+{
+ /**
+ * A Validated wraps a particular class instance, ensuring that it always
+ * meets certain validation criteria.
+ */
+ template <typename ValidatedDataType_, typename Validator_>
+ class Validated : public ComparisonPolicy<
+ Validated<ValidatedDataType_, Validator_>,
+ comparison_mode::FullComparisonTag,
+ comparison_method::CompareByMemberTag<ValidatedDataType_> >
+ {
+ private:
+ ValidatedDataType_ _value;
+
+ public:
+ /**
+ * Copy constructor (no validation needed).
+ */
+ Validated(const Validated<ValidatedDataType_, Validator_> & other) :
+ ComparisonPolicy<
+ Validated<ValidatedDataType_, Validator_>,
+ comparison_mode::FullComparisonTag,
+ comparison_method::CompareByMemberTag<ValidatedDataType_> >
+ (other),
+ _value(other._value)
+ {
+ }
+
+ /**
+ * Constructor (validation needed).
+ */
+ explicit Validated(const ValidatedDataType_ & value) :
+ ComparisonPolicy<
+ Validated<ValidatedDataType_, Validator_>,
+ comparison_mode::FullComparisonTag,
+ comparison_method::CompareByMemberTag<ValidatedDataType_> >
+ (&Validated<ValidatedDataType_, Validator_>::_value),
+ _value(value)
+ {
+ Validator_::validate(_value);
+ }
+
+ /**
+ * Assignment (no validation needed).
+ */
+ const Validated<ValidatedDataType_, Validator_> & operator=
+ (const Validated<ValidatedDataType_,Validator_> & other)
+ {
+ _value = other._value;
+ return *this;
+ }
+
+ /**
+ * Fetch to our ValidatedDataType_. This should not be a cast
+ * operator to avoid problems with ambiguous comparison operators.
+ */
+ const ValidatedDataType_ & data() const
+ {
+ return _value;
+ }
+ };
+
+ /**
+ * Writing a Validated instance to a stream is done by its data.
+ */
+ template <typename D_, typename V_>
+ std::ostream &
+ operator<< (std::ostream & s, const Validated<D_, V_> & v)
+ {
+ s << v.data();
+ return s;
+ }
+}
+
+#endif