Fix SDim case for .size(), .empty()

* ra/expr.hh (dimv_size): Don't assume Dim.
  (dimv_empty): New function.
* ra/arrays.hh (View, Container): Reuse dimv_empty().
  (shared_borrowing): Handle SDim case for rank 1.

Author: lloda

box/SConstruct

@@ -50,7 +50,7 @@ env.Prepend(CPPPATH=['..', '.'],
             LINKFLAGS=raflags['LINKFLAGS'])
 
 [ra.to_test_ra(env, variant_dir)(example)
- for example in ['tuple-construct', 'iterator-as-ravel', 'view']]
+ for example in ['tuple-construct', 'iterator-as-ravel']]
 
 if not top['skip_summary']:
     atexit.register(lambda: ra.print_summary(GetBuildFailures, 'ra/box'))

box/view.cc

@@ -116,9 +116,9 @@ struct View: public ViewBase<Dimv_>
     constexpr static dim_t step(auto k) requires (RAC(k, step)) { return simv[k].step; }
     constexpr dim_t step(int k) const requires (!(RAC(k, step))) { return dimv[k].step; }
     consteval static dim_t size() requires (CT) { return dimv_size(simv); }
-    consteval static bool empty() requires (CT) { return any(0==map(&Dim::len, simv)); }
+    consteval static bool empty() requires (CT) { return dimv_empty(simv); }
     constexpr dim_t size() const requires (!CT) { return dimv_size(dimv); }
-    constexpr bool empty() const requires (!CT) { return any(0==map(&Dim::len, dimv)); }
+    constexpr bool empty() const requires (!CT) { return dimv_empty(dimv); }
     constexpr View() requires (!CT) {} // used by Container constructors
     constexpr View(Dimv && dimv, P cp) requires (!CT && !std::is_reference_v<Dimv>): ViewBase<Dimv>(std::move(dimv)), cp(cp) {} // cannot assign dimv later
     constexpr View(Dimv const & dimv, P cp) requires (!CT): ViewBase<Dimv>(dimv), cp(cp) {} // cannot assign dimv later
@@ -280,7 +280,7 @@ struct Container
     constexpr static dim_t step(auto k) requires (RAC(k, step)) { return simv[k].step; }
     constexpr dim_t step(int k) const requires (!(RAC(k, step))) { return dimv[k].step; }
     constexpr dim_t size() const { return dimv_size(dimv); }
-    constexpr bool empty() const { return any(0==map(&Dim::len, dimv)); }
+    constexpr bool empty() const { return dimv_empty(dimv); }
 #undef RAC
     constexpr auto data(this auto && sf) { return storage_traits<Store>::data(sf.store); }
     constexpr auto view() { return View<T *, Dimv const &>(dimv, data()); }
@@ -367,7 +367,7 @@ shared_borrowing(Slice auto & s)
     using T = value_t<decltype(s)>;
     Shared<T, rank_s(s)> a;
     a.store = std::shared_ptr<T>(s.data(), [](T *){});
-    a.dimv = s.dimv;
+    if constexpr (1==rank_s(s)) { a.dimv[0] = s.dimv[0]; } else { a.dimv = s.dimv; } // [Dimv] = [SDim] etc.
     return a;
 }
 

ra/arrays.hh

@@ -223,7 +223,8 @@ filldimv(Iterator auto && p, auto & dv)
 }
 
 consteval auto c_dimv(auto lv) { std::array<Dim, ra::size(lv)> dv; filldimv(ra::iter(lv), dv); return dv; };
-constexpr dim_t dimv_size(auto const & dv) { dim_t s=1; for (Dim d: dv) { if (d.len<0) return d.len; else s*=d.len; } return s; }
+constexpr dim_t dimv_size(auto const & dv) { dim_t s=1; for (auto const & d: dv) { if (d.len<0) return d.len; else s*=d.len; } return s; }
+constexpr bool dimv_empty(auto const & dv) { for (auto const & d: dv) { if (0==d.len) return true; } return false; }
 
 constexpr rank_t rank_sum(rank_t a, rank_t b) { return ANY==a || ANY==b ? ANY : a+b; }
 constexpr rank_t rank_diff(rank_t a, rank_t b) { return ANY==a || ANY==b ? ANY : a-b; }

ra/expr.hh

@@ -1,5 +1,5 @@
 // -*- mode: c++; coding: utf-8 -*-
-// ra/test - View with custom dimv and generalized iter(Slice).
+// ra/test - View with custom dimv and iter(general Slice).
 
 // (c) Daniel Llorens - 2026
 // This library is free software; you can redistribute it and/or modify it under
@@ -12,9 +12,29 @@
 
 using std::cout, std::endl;
 
+template <class P, int R>
+auto ctad(ra::ViewBig<P, R> const & a)
+{
+    return std::make_tuple<sizeof(std::remove_pointer_t<P>), R>;
+}
+
 int main()
 {
     ra::TestRecorder tr(std::cout);
+#if 0 // FIXME
+    tr.section("CTAD for ViewBig");
+    {
+        ra::Big<float, 1> a({10}, 0.);
+        auto [xa, ya] = ctad(a());
+        tr.test_eq(sizeof(float), xa);
+        tr.test_eq(1, ya);
+        ra::Big<double, 2> b({3, 3}, 0.);
+        auto [xb, yb] = ctad(b());
+        tr.test_eq(sizeof(double), xb);
+        tr.test_eq(2, yb);
+    }
+#endif
+    tr.section("Custom dimv and iter(general Slice)");
     {
         int x[6] = { 1, 2, 3, 4, 5, 6 };
         auto v = ra::viewptr(x);

test/ra-17.cc

@@ -92,6 +92,15 @@ int main()
         tr.test(aa.empty());
         tr.test(a.begin()==a.end());
     }
+    tr.section("empty()/size() corner case");
+    {
+        ra::Big<int, 1> a = {};
+        ra::Big<int, 1> b = { 1, 2, 3 };
+        tr.test(a.empty());
+        tr.test(!b.empty());
+        tr.test_eq(0, a.size());
+        tr.test_eq(3, b.size());
+    }
     tr.section("foreign vectors from std::");
     {
         tr.info("adapted std::array has static size").test_eq(3, size_s(ra::iter(std::array {1, 2, 0})));