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Add support for alternate transform function syntax, a la Boost.Proto, using the new tag types.

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Zach Laine
2016-11-29 17:36:17 -06:00
parent 5c3688a1c3
commit a4ea007d59
3 changed files with 327 additions and 14 deletions
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99
test/user_expression_transform_3.cpp
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@@ -29,17 +29,74 @@ namespace user {
number naxpy (number a, number x, number y)
{ return number{a.value * x.value + y.value + 10.0}; }
struct eval_xform
struct empty_xform {};
struct eval_xform_tag
{
decltype(auto) operator() (term<user::number> const & expr)
{ return expr.value(); }
decltype(auto) operator() (bp17::terminal_tag, user::number const & n)
{ return n; }
};
struct plus_to_minus_xform
struct eval_xform_expr
{
decltype(auto) operator() (term<user::number> const & expr)
{ return ::boost::proto17::value(expr); }
};
struct eval_xform_both
{
decltype(auto) operator() (bp17::terminal_tag, user::number const & n)
{ return n; }
decltype(auto) operator() (term<user::number> const & expr)
{
throw std::logic_error("Oops! Picked the wrong overload!");
return ::boost::proto17::value(expr);
}
};
struct plus_to_minus_xform_tag
{
decltype(auto) operator() (bp17::plus_tag, user::number const & lhs, user::number const & rhs)
{
return bp17::make_expression<bp17::expr_kind::minus>(
term<user::number>{lhs},
term<user::number>{rhs}
);
}
};
struct plus_to_minus_xform_expr
{
template <typename Expr1, typename Expr2>
decltype(auto) operator() (bp17::expression<bp17::expr_kind::plus, bh::tuple<Expr1, Expr2>> const & expr)
{ return bp17::make_expression<bp17::expr_kind::minus>(expr.left(), expr.right()); }
{
return bp17::make_expression<bp17::expr_kind::minus>(
::boost::proto17::left(expr),
::boost::proto17::right(expr)
);
}
};
struct plus_to_minus_xform_both
{
decltype(auto) operator() (bp17::plus_tag, user::number const & lhs, user::number const & rhs)
{
return bp17::make_expression<bp17::expr_kind::minus>(
term<user::number>{lhs},
term<user::number>{rhs}
);
}
template <typename Expr1, typename Expr2>
decltype(auto) operator() (bp17::expression<bp17::expr_kind::plus, bh::tuple<Expr1, Expr2>> const & expr)
{
throw std::logic_error("Oops! Picked the wrong overload!");
return bp17::make_expression<bp17::expr_kind::minus>(
::boost::proto17::left(expr),
::boost::proto17::right(expr)
);
}
};
decltype(auto) naxpy_eager_nontemplate_xform (
@@ -125,8 +182,24 @@ TEST(user_expression_transform_3, test_user_expression_transform_3)
EXPECT_EQ(result.value, 1);
}
auto transformed_expr = transform(expr, user::eval_xform{});
{
auto transformed_expr = transform(expr, user::empty_xform{});
user::number result = evaluate(transformed_expr);
EXPECT_EQ(result.value, 1);
}
{
auto transformed_expr = transform(expr, user::eval_xform_tag{});
EXPECT_EQ(transformed_expr.value, 1);
}
{
auto transformed_expr = transform(expr, user::eval_xform_expr{});
EXPECT_EQ(transformed_expr.value, 1);
}
{
auto transformed_expr = transform(expr, user::eval_xform_both{});
EXPECT_EQ(transformed_expr.value, 1);
}
}
@@ -138,8 +211,20 @@ TEST(user_expression_transform_3, test_user_expression_transform_3)
EXPECT_EQ(result.value, 45);
}
auto transformed_expr = transform(expr, user::plus_to_minus_xform{});
{
auto transformed_expr = transform(expr, user::plus_to_minus_xform_tag{});
user::number result = evaluate(transformed_expr);
EXPECT_EQ(result.value, 39);
}
{
auto transformed_expr = transform(expr, user::plus_to_minus_xform_expr{});
user::number result = evaluate(transformed_expr);
EXPECT_EQ(result.value, 39);
}
{
auto transformed_expr = transform(expr, user::plus_to_minus_xform_both{});
user::number result = evaluate(transformed_expr);
EXPECT_EQ(result.value, 39);
}