add boost on mac

macx64/include/boost/histogram/axis/polymorphic_bin.hpp

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+// Copyright 2018 Hans Dembinski
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_HISTOGRAM_AXIS_POLYMORPHIC_BIN_HPP
+#define BOOST_HISTOGRAM_AXIS_POLYMORPHIC_BIN_HPP
+
+#include <boost/histogram/detail/meta.hpp>
+#include <type_traits>
+
+namespace boost {
+namespace histogram {
+namespace axis {
+
+/**
+  Holds the bin data of a axis::variant.
+
+  The interface is a superset of the `value_bin_view` and `interval_bin_view`
+  classes. The methods value() and lower() return the same number. For a value bin,
+  upper() and lower() and center() return the same number, width() returns zero.
+
+  This is not a view like interval_bin_view or value_bin_view for two reasons.
+  - Sequential calls to lower() and upper() would have to each loop through
+    the variant types. This is likely to be slower than filling all the data in
+    one loop.
+  - polymorphic_bin may be created from a temporary instance of axis::variant,
+    like in the call histogram::axis(0). Storing a reference to the axis would
+    result in a dangling reference. Rather than specialing the code to handle
+    this, it seems easier to just use a value instead of a view here.
+*/
+template <typename RealType>
+class polymorphic_bin {
+  using value_type = RealType;
+
+public:
+  polymorphic_bin(value_type lower, value_type upper)
+      : lower_or_value_(lower), upper_(upper) {}
+
+  /// Implicitly convert to bin value (for axis with discrete values).
+  operator const value_type&() const noexcept { return lower_or_value_; }
+
+  /// Return lower edge of bin.
+  value_type lower() const noexcept { return lower_or_value_; }
+  /// Return upper edge of bin.
+  value_type upper() const noexcept { return upper_; }
+  /// Return center of bin.
+  value_type center() const noexcept { return 0.5 * (lower() + upper()); }
+  /// Return width of bin.
+  value_type width() const noexcept { return upper() - lower(); }
+
+  template <typename BinType>
+  bool operator==(const BinType& rhs) const noexcept {
+    return equal_impl(detail::has_method_lower<BinType>(), rhs);
+  }
+
+  template <typename BinType>
+  bool operator!=(const BinType& rhs) const noexcept {
+    return !operator==(rhs);
+  }
+
+  /// Return true if bin is discrete.
+  bool is_discrete() const noexcept { return lower_or_value_ == upper_; }
+
+private:
+  bool equal_impl(std::true_type, const polymorphic_bin& rhs) const noexcept {
+    return lower_or_value_ == rhs.lower_or_value_ && upper_ == rhs.upper_;
+  }
+
+  template <typename BinType>
+  bool equal_impl(std::true_type, const BinType& rhs) const noexcept {
+    return lower() == rhs.lower() && upper() == rhs.upper();
+  }
+
+  template <typename BinType>
+  bool equal_impl(std::false_type, const BinType& rhs) const noexcept {
+    return is_discrete() && static_cast<value_type>(*this) == rhs;
+  }
+
+  const value_type lower_or_value_, upper_;
+};
+
+} // namespace axis
+} // namespace histogram
+} // namespace boost
+
+#endif