Reqrite project as BEd specific.

src/internal/address/resolve.cc

@@ -0,0 +1,40 @@
+#include "bed.h"
+#include "internal/address/address.h"
+
+namespace bed::internal::address {
+uint64_t Address::resolve(BEd &ctx) {
+  uint64_t result = std::visit(
+    [&](auto const &addr) -> uint64_t {
+      uint64_t line = 0;
+
+      using T = std::decay_t<decltype(addr)>;
+
+      if constexpr (std::is_same_v<T, std::monostate>) {
+        throw address_error("empty address");
+      } else if constexpr (std::is_same_v<T, None>) {
+        throw address_error("no address");
+      } else if constexpr (std::is_same_v<T, Current>) {
+        line = ctx.active->line;
+      } else if constexpr (std::is_same_v<T, Last>) {
+        line = ctx.active->vase.lines();
+      } else if constexpr (std::is_same_v<T, Number>) {
+        line = addr.i;
+      } else {
+        throw ed_error("Unhandled address given.");
+      }
+
+      if (offset < 0 && line < (uint64_t)-offset)
+        throw address_error("Can't have negative addresses");
+      line += offset;
+
+      if (line > ctx.active->vase.lines())
+        throw address_error("Line number too high.");
+
+      return line;
+    },
+    base
+  );
+
+  return result + offset;
+}
+}; // namespace bed::internal::address