Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 151 insertions, 0 deletions

diff --git a/src/boost/libs/yap/perf/lazy_vector_perf.cpp b/src/boost/libs/yap/perf/lazy_vector_perf.cpp
new file mode 100644
index 000000000..e40990501
--- /dev/null
+++ b/src/boost/libs/yap/perf/lazy_vector_perf.cpp
@@ -0,0 +1,151 @@
+// Copyright (C) 2016-2018 T. Zachary Laine
+//
+// 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)
+//[ lazy_vector
+// Defining this allows the assignment below of an expression to a double
+// without writing any specific code to do so.
+#include <boost/yap/expression.hpp>
+
+#include <algorithm>
+#include <cassert>
+#include <iostream>
+#include <vector>
+
+
+template<boost::yap::expr_kind Kind, typename Tuple>
+struct lazy_vector_expr;
+
+
+// This transform turns a terminal of std::vector<double> into a terminal
+// containing the nth double in that vector.  Think of it as turning our
+// expression of vectors into an expression of scalars.
+struct take_nth
+{
+    boost::yap::terminal<lazy_vector_expr, double> operator()(
+        boost::yap::terminal<lazy_vector_expr, std::vector<double>> const &
+            expr);
+
+    std::size_t n;
+};
+
+// A custom expression template that defines lazy + and - operators that
+// produce expressions, and an eager [] operator that returns the nth element
+// of the expression.
+//[ lazy_vector_decl
+template<boost::yap::expr_kind Kind, typename Tuple>
+struct lazy_vector_expr
+{
+    static const boost::yap::expr_kind kind = Kind;
+
+    Tuple elements;
+
+    // Note that this does not return an expression; it is greedily evaluated.
+    auto operator[](std::size_t n) const;
+};
+
+BOOST_YAP_USER_BINARY_OPERATOR(plus, lazy_vector_expr, lazy_vector_expr)
+BOOST_YAP_USER_BINARY_OPERATOR(minus, lazy_vector_expr, lazy_vector_expr)
+//]
+
+template<boost::yap::expr_kind Kind, typename Tuple>
+auto lazy_vector_expr<Kind, Tuple>::operator[](std::size_t n) const
+{
+    return boost::yap::evaluate(boost::yap::transform(*this, take_nth{n}));
+}
+
+boost::yap::terminal<lazy_vector_expr, double> take_nth::operator()(
+    boost::yap::terminal<lazy_vector_expr, std::vector<double>> const & expr)
+{
+    double x = boost::yap::value(expr)[n];
+    // This move is something of a hack.  The move indicates that the terminal
+    // should keep the value of x (since, being an rvalue, it may be a
+    // temporary), rather than a reference to x.  See the "How Expression
+    // Operands Are Treated" section of the tutorial for details.
+    return boost::yap::make_terminal<lazy_vector_expr, double>(std::move(x));
+}
+
+// In order to define the += operator with the semantics we want, it's
+// convenient to derive a terminal type from a terminal instantiation of
+// lazy_vector_expr.  note that we could have written a template
+// specialization here instead -- either one would work.  That would of course
+// have required more typing.
+struct lazy_vector : lazy_vector_expr<
+                         boost::yap::expr_kind::terminal,
+                         boost::hana::tuple<std::vector<double>>>
+{
+    lazy_vector() {}
+
+    explicit lazy_vector(std::vector<double> && vec)
+    {
+        elements = boost::hana::tuple<std::vector<double>>(std::move(vec));
+    }
+
+    template<boost::yap::expr_kind Kind, typename Tuple>
+    lazy_vector & operator+=(lazy_vector_expr<Kind, Tuple> const & rhs)
+    {
+        std::vector<double> & this_vec = boost::yap::value(*this);
+        for (int i = 0, size = (int)this_vec.size(); i < size; ++i) {
+            this_vec[i] += rhs[i];
+        }
+        return *this;
+    }
+};
+
+lazy_vector v1{std::vector<double>(4, 1.0)};
+lazy_vector v2{std::vector<double>(4, 2.0)};
+lazy_vector v3{std::vector<double>(4, 3.0)};
+
+double get_d1_with_yap()
+{
+    double retval = (v2 + v3)[2];
+    return retval;
+}
+
+double get_d1_by_hand()
+{
+    std::vector<double> & v2_ref = boost::yap::value(v2);
+    std::vector<double> & v3_ref = boost::yap::value(v3);
+    double retval = v2_ref[2] + v3_ref[2];
+    return retval;
+}
+
+void update_v1_with_yap() { v1 += v2 - v3; }
+
+void update_v1_by_hand()
+{
+    std::vector<double> & v1_ref = boost::yap::value(v1);
+    std::vector<double> & v2_ref = boost::yap::value(v2);
+    std::vector<double> & v3_ref = boost::yap::value(v3);
+    for (int i = 0, size = (int)v1_ref.size(); i < size; ++i) {
+        v1_ref[i] += v2_ref[i] - v3_ref[i];
+    }
+}
+
+int main()
+{
+    double d1_1 = get_d1_with_yap();
+    std::cout << d1_1 << "\n";
+
+    double d1_2 = get_d1_by_hand();
+    std::cout << d1_2 << "\n";
+
+    update_v1_with_yap();
+    std::cout << '{' << v1[0] << ',' << v1[1] << ',' << v1[2] << ',' << v1[3]
+              << '}' << "\n";
+
+    boost::yap::value(v1) = std::vector<double>(4, 1.0);
+
+    update_v1_by_hand();
+    std::cout << '{' << v1[0] << ',' << v1[1] << ',' << v1[2] << ',' << v1[3]
+              << '}' << "\n";
+
+    // This expression is disallowed because it does not conform to the
+    // implicit grammar.  operator+= is only defined on terminals, not
+    // arbitrary expressions.
+    // (v2 + v3) += v1;
+
+    return 0;
+}
+//]