[Lua] Apply Namer to Lua (#7171)

* Apply Namer to Lua bfbs code gen

* refactor namer into IdlNamer to keep idl includes separate

* remove commented out code

* added bfbs_namer

* remove Enum case

* add to bazel

src/idl_namer.h

@@ -0,0 +1,114 @@
+#ifndef FLATBUFFERS_IDL_NAMER
+#define FLATBUFFERS_IDL_NAMER
+
+#include "flatbuffers/idl.h"
+#include "namer.h"
+
+namespace flatbuffers {
+
+// Provides Namer capabilities to types defined in the flatbuffers IDL.
+class IdlNamer : public Namer {
+ public:
+  explicit IdlNamer(Config config, std::set<std::string> keywords)
+      : Namer(config, std::move(keywords)) {}
+
+  using Namer::Constant;
+  using Namer::Directories;
+  using Namer::Field;
+  using Namer::File;
+  using Namer::Function;
+  using Namer::Method;
+  using Namer::Namespace;
+  using Namer::NamespacedType;
+  using Namer::ObjectType;
+  using Namer::Type;
+  using Namer::Variable;
+  using Namer::Variant;
+
+  // Types are always structs or enums so we can only expose these two
+  // overloads.
+  std::string Type(const StructDef &d) const { return Type(d.name); }
+  std::string Type(const EnumDef &d) const { return Type(d.name); }
+
+  std::string Function(const Definition &s) const { return Function(s.name); }
+
+  std::string Field(const FieldDef &s) const { return Field(s.name); }
+
+  std::string Variable(const FieldDef &s) const { return Variable(s.name); }
+
+  std::string Variable(const StructDef &s) const { return Variable(s.name); }
+
+  std::string Variant(const EnumVal &s) const { return Variant(s.name); }
+
+  std::string EnumVariant(const EnumDef &e, const EnumVal &v) const {
+    return Type(e) + config_.enum_variant_seperator + Variant(v);
+  }
+
+  std::string ObjectType(const StructDef &d) const {
+    return ObjectType(d.name);
+  }
+  std::string ObjectType(const EnumDef &d) const { return ObjectType(d.name); }
+
+  std::string Namespace(const struct Namespace &ns) const {
+    return Namespace(ns.components);
+  }
+
+  std::string NamespacedType(const Definition &def) const {
+    return NamespacedString(def.defined_namespace, Type(def.name));
+  }
+
+  std::string NamespacedObjectType(const Definition &def) const {
+    return NamespacedString(def.defined_namespace, ObjectType(def.name));
+  }
+
+  std::string Directories(const struct Namespace &ns,
+                          SkipDir skips = SkipDir::None) const {
+    return Directories(ns.components, skips);
+  }
+
+  // Legacy fields do not really follow the usual config and should be
+  // considered for deprecation.
+
+  std::string LegacyRustNativeVariant(const EnumVal &v) const {
+    return ConvertCase(EscapeKeyword(v.name), Case::kUpperCamel);
+  }
+
+  std::string LegacyRustFieldOffsetName(const FieldDef &field) const {
+    return "VT_" + ConvertCase(EscapeKeyword(field.name), Case::kAllUpper);
+  }
+
+  // TODO(caspern): What's up with this case style?
+  std::string LegacySwiftVariant(const EnumVal &ev) const {
+    auto name = ev.name;
+    if (isupper(name.front())) {
+      std::transform(name.begin(), name.end(), name.begin(), CharToLower);
+    }
+    return EscapeKeyword(ConvertCase(name, Case::kLowerCamel));
+  }
+
+ private:
+  std::string NamespacedString(const struct Namespace *ns,
+                               const std::string &str) const {
+    std::string ret;
+    if (ns != nullptr) { ret += Namespace(ns->components); }
+    if (!ret.empty()) ret += config_.namespace_seperator;
+    return ret + str;
+  }
+};
+
+// This is a temporary helper function for code generators to call until all
+// flag-overriding logic into flatc.cpp
+inline Namer::Config WithFlagOptions(const Namer::Config &input,
+                                     const IDLOptions &opts,
+                                     const std::string &path) {
+  Namer::Config result = input;
+  result.object_prefix = opts.object_prefix;
+  result.object_suffix = opts.object_suffix;
+  result.output_path = path;
+  result.filename_suffix = opts.filename_suffix;
+  return result;
+}
+
+}  // namespace flatbuffers
+
+#endif  // FLATBUFFERS_IDL_NAMER