ring: add simple statically sized ring buffer

1 files changed, 93 insertions, 0 deletions

diff --git a/test/ring.cc b/test/ring.cc
new file mode 100644
index 0000000..a42efaa
--- /dev/null
+++ b/test/ring.cc
@@ -0,0 +1,93 @@
+#include <ring.h>
+
+#include <cstdio>
+
+#define LOG    \
+  if (false) { \
+  } else       \
+    puts(__PRETTY_FUNCTION__)
+
+/// A helper sruct to count instances, copy- and move constructions.
+struct m {
+  m() {
+    LOG;
+    ++cnt;
+  }
+  ~m() {
+    LOG;
+    --cnt;
+  }
+  m(const m&) {
+    LOG;
+    ++cnt;
+    ++cpy;
+  }
+  m(m&&) noexcept {
+    LOG;
+    ++cnt;
+    ++mov;
+  }
+  m& operator=(const m&) = delete;
+  m& operator=(m&&) = delete;
+
+  static std::size_t cnt;
+  static std::size_t mov;
+  static std::size_t cpy;
+};
+
+std::size_t m::cnt = 0;
+std::size_t m::mov = 0;
+std::size_t m::cpy = 0;
+
+int main() {
+  {
+    ring<m, 8> r;
+
+    assert(r.size() == 0);
+    assert(r.is_empty());
+    assert(!r.is_full());
+
+    for (int i = 0; i < 10; ++i) {
+      bool ok = r.emplace();
+      i < 8 ? assert(ok) : assert(!ok);
+    }
+
+    assert(r.size() == 8);
+    assert(!r.is_empty());
+    assert(r.is_full());
+
+#if __cplusplus >= 201703L
+    auto v = r.take();
+    assert(v.has_value());
+
+    assert(r.size() == 7);
+    assert(!r.is_empty());
+    assert(!r.is_full());
+#endif
+
+    assert(m::cnt == 8);
+  }
+
+  assert(m::cnt == 0);
+
+  m::mov = 0;
+  m::cpy = 0;
+  {
+    ring<m, 8> r;
+
+    // Move construct m from an m rvalue reference.
+    assert(m::mov == 0);
+    r.push(m{});
+    assert(m::mov == 1);
+
+    // Copy construct m from an m lvalue reference.
+    m m;
+    assert(m::cpy == 0);
+    r.push(m);
+    assert(m::cpy == 1);
+
+    assert(m::cnt == 3);
+  }
+
+  assert(m::cnt == 0);
+}