1 files changed, 123 insertions, 0 deletions
diff --git a/modules/codec/args.h b/modules/codec/args.h
new file mode 100644
index 0000000..6bb75a2
--- /dev/null
+++ b/modules/codec/args.h
@@ -0,0 +1,123 @@
+#pragma once
+
+#include "schema.h"
+
+namespace saw {
+namespace encode {
+struct Args {};
+}
+
+namespace schema {
+template<typename InnerSchemaStruct, typename InnerSchemaTuple>
+using Args = Struct<
+	Member<String, "program">,
+	Member<InnerSchemaStruct, "args">,
+	Member<InnerSchemaTuple, "positionals">
+>;
+}
+
+template<typename T>
+class data<T, encode::Args> {
+	static_assert(always_false<T>,"Not supported. Use the schema::Args alias or check how it's defined.");
+};
+
+template<typename... Str, string_literal... Lits, typename... Tup>
+class data<schema::Args<schema::Struct<schema::Member<Str,Lits>...>, schema::Tuple<Tup...>>, encode::Args> {
+private:
+	char** argv_;
+	int argc_;
+public:
+	data(char** argv, int argc):
+		argv_{argv},
+		argc_{argc}
+	{}
+
+	size_t size() const {
+		if(argc_ < 0){
+			return 0;
+		}
+
+		static_assert(sizeof(int) <= sizeof(size_t), "size_t is smaller than int");
+
+		return static_cast<size_t>(argc_);
+	}
+
+	std::string_view arg_view(size_t i){
+		if(i < size()){
+			return std::string_view{argv_[i]};
+		}
+		return "";
+	}
+};
+
+namespace impl {
+template<typename T, typename ToDec>
+struct args_decode {
+	static_assert(always_false<T,ToDec>, "Not supported");
+};
+
+template<typename... Str, string_literal... Lits, typename... Tup, typename ToDec>
+struct args_decode<schema::Args<schema::Struct<schema::Member<Str,Lits>...>,schema::Tuple<Tup...>>,ToDec> {
+	using Schema = schema::Args<
+		schema::Struct<schema::Member<Str,Lits>...>,
+		schema::Tuple<Tup...>
+	>;
+
+	static error_or<void> decode(data<Schema, encode::Args>& from, data<Schema,ToDec>& to){
+		if(from.size() == 0){
+			return make_error<err::invalid_state>();
+		}
+
+		to.get<"program">().set(std::string{from.arg_view(0)});
+		std::size_t tuple_pos = 0;
+		for(size_t i = 1; i < from.size(); ++i){
+			auto view = from.arg_view(i);
+			if(view.starts_with("--")){
+				view.remove_prefix(std::min(2u, view.size()));
+				++i;
+
+				if( i >= from.size() ){
+					return make_error<err::invalid_state>();
+				}
+
+				auto value_view = from.arg_view(i);
+
+				auto eov = decode_struct_member<0>(to.get<"args">(), view, value_view);
+				if(eov.is_error()){
+					return eov;
+				}
+			} else {
+				auto eov = decode_tuple_member<0>(to.get<"positionals">(), view);
+				if(eov.is_error()){
+					return eov;
+				}
+				++tuple_pos;
+			}
+		}
+
+		if(tuple_pos != sizeof...(Tup)){
+			return make_error<err::invalid_state>();
+		}
+
+		return void_t{};
+	}
+};
+}
+
+template<typename Schema>
+class codec<Schema, encode::Args> {
+public:
+	template<typename ToDec>
+	error_or<void> decode(data<Schema, encode::Args>& from, data<Schema, ToDec>& to){
+		struct name_and_value {
+			std::string name;
+			std::string value;
+		};
+		std::string program;
+		std::vector<name_and_value> navs;
+		std::vector<std::string> positionals;
+
+		return void_t{};
+	}
+};
+}