feat(data): SPSC ring buffer, incremental min/max LOD pyramid, series types

tests/harness.hpp

@@ -35,6 +35,23 @@ struct Failure {
   std::string msg;
 };
 
+/// Compares two doubles within `eps`. `PLOT_CHECK_NEAR(a, b)` leaves it to the
+/// default below; pass an explicit tolerance for computed values.
+inline constexpr double kNearEps = 1e-9;
+
+inline void check_near(double a, double b, double eps, const char* file, int line,
+                       const char* lhs, const char* rhs) {
+  if (!(std::fabs(a - b) <= eps)) {
+    throw Failure{std::string(file) + ":" + std::to_string(line) + " CHECK_NEAR(" + lhs + ", " +
+                  rhs + ") got " + std::to_string(a) + " vs " + std::to_string(b)};
+  }
+}
+
+inline void check_near(double a, double b, const char* file, int line, const char* lhs,
+                       const char* rhs) {
+  check_near(a, b, kNearEps, file, line, lhs, rhs);
+}
+
 inline int run_all() {
   int failed = 0;
   for (auto& c : cases()) {
@@ -64,11 +81,5 @@ inline int run_all() {
                                 " CHECK(" #cond ")"};                                       \
   } while (0)
 
-#define PLOT_CHECK_NEAR(a, b, eps)                                                          \
-  do {                                                                                      \
-    const double _a = (a), _b = (b);                                                        \
-    if (!(std::fabs(_a - _b) <= (eps)))                                                      \
-      throw ::plottest::Failure{std::string(__FILE__) + ":" + std::to_string(__LINE__) +     \
-                                " CHECK_NEAR(" #a ", " #b ") got " + std::to_string(_a) +    \
-                                " vs " + std::to_string(_b)};                               \
-  } while (0)
+#define PLOT_CHECK_NEAR(a, b, ...)                                                          \
+  ::plottest::check_near((a), (b) __VA_OPT__(,) __VA_ARGS__, __FILE__, __LINE__, #a, #b)