From 0b2d95b65e363e2ff3e1747a0035137c46d20751 Mon Sep 17 00:00:00 2001
From: Claudius 'keldu' Holeksa <mail@keldu.de>
Date: Sun, 18 Aug 2024 18:57:32 +0200
Subject: Adding comments to decoding failures

---
 modules/codec-json/c++/json.tmpl.hpp | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/modules/codec-json/c++/json.tmpl.hpp b/modules/codec-json/c++/json.tmpl.hpp
index d17c02d..8dbee8c 100644
--- a/modules/codec-json/c++/json.tmpl.hpp
+++ b/modules/codec-json/c++/json.tmpl.hpp
@@ -528,7 +528,7 @@ struct json_decode<schema::Primitive<T,N>, ToDecode> {
 			typename native_data_type<Schema>::type result;
 			auto fc_result = std::from_chars(num_view.data(), num_view.data() + num_view.size(), result);
 			if(fc_result.ec != std::errc{}){
-				return make_error<err::invalid_state>();
+				return make_error<err::invalid_state>("Couldn't decode Primitive Value");
 			}
 
 			to.set(result);
@@ -666,7 +666,7 @@ struct json_decode<schema::Struct<schema::Member<T,Lits>...>, ToDecode> {
 			constexpr static string_literal Literal = parameter_key_pack_type<i, Lits...>::literal;
 			if(search_name == Literal.view()){
 				if(fields[i]){
-					return make_error<err::invalid_state>();
+					return make_error<err::invalid_state>("Duplicate entry in Struct");
 				}
 				fields[i] = true;
 				auto eov = json_decode<Type, ToDecode>::decode(buff, to.template get<Literal>());
@@ -677,7 +677,7 @@ struct json_decode<schema::Struct<schema::Member<T,Lits>...>, ToDecode> {
 				decode_field_search<i+1>(buff, to, fields, search_name);
 			}
 		}else {
-			return make_error<err::invalid_state>();
+			return make_error<err::invalid_state>("Field in Struct not found");
 		}
 		return void_t{};
 	}
@@ -694,7 +694,7 @@ struct json_decode<schema::Struct<schema::Member<T,Lits>...>, ToDecode> {
 				return make_error<err::buffer_exhausted>();
 			}
 			if(buff.read() != ':'){
-				return make_error<err::invalid_state>();
+				return make_error<err::invalid_state>("Field separator in Struct expected");
 			}
 			buff.read_advance(1);
 			json_helper::skip_whitespace(buff);
@@ -717,13 +717,13 @@ struct json_decode<schema::Struct<schema::Member<T,Lits>...>, ToDecode> {
 				// If not all fields are set, the dataset is incomplete
 				for(auto& iter : fields){
 					if(!iter){
-						return make_error<err::invalid_state>();
+						return make_error<err::invalid_state>("Not all fields were set");
 					}
 				}
 				buff.read_advance(1);
 				return void_t{};
 			}else{
-				return make_error<err::invalid_state>();
+				return make_error<err::invalid_state>("Struct Separator ',' or Struct '}' ending expected");
 			}
 			json_helper::skip_whitespace(buff);
 			if(buff.read_composite_length() == 0){
@@ -738,7 +738,7 @@ struct json_decode<schema::Struct<schema::Member<T,Lits>...>, ToDecode> {
 		std::fill(found_fields.begin(), found_fields.end(), false);
 
 		SAW_ASSERT(buff.read() == '{'){
-			return make_error<err::invalid_state>();
+			return make_error<err::invalid_state>("Expected Struct beginning '{'");
 		}
 		buff.read_advance(1);
 		json_helper::skip_whitespace(buff);
@@ -749,7 +749,7 @@ struct json_decode<schema::Struct<schema::Member<T,Lits>...>, ToDecode> {
 		// Check if there are no elements present in the JSON Struct
 		if(buff.read() == '}'){
 			if(sizeof...(T) > 0){
-				return make_error<err::invalid_state>();
+				return make_error<err::invalid_state>("Expected Struct ending '}'");
 			}
 			buff.read_advance(1);
 			return void_t{};
@@ -773,7 +773,7 @@ struct json_decode<schema::Tuple<T...>, ToDecode> {
 		if constexpr (i < sizeof...(T)){
 			if constexpr ( i > 0 ){
 				if(buff.read() != ','){
-					return make_error<err::invalid_state>();
+					return make_error<err::invalid_state>("Expected ',' in Tuple");
 				}
 				buff.read_advance(1);
 				json_helper::skip_whitespace(buff);
@@ -798,7 +798,7 @@ struct json_decode<schema::Tuple<T...>, ToDecode> {
 			}
 		}else{
 			if(buff.read() != ']'){
-				return make_error<err::invalid_state>();
+				return make_error<err::invalid_state>("Expected Tuple Ending ']'");
 			}
 			buff.read_advance(1);
 		}
@@ -888,7 +888,7 @@ struct json_decode<schema::Array<T,D>, ToDecode> {
 			if(log_dim){
 				dims[Level] = index[Level];
 			}else if (dims[Level] != index[Level]){
-				return make_error<err::invalid_state>();
+				return make_error<err::invalid_state>("Not matching Array endings");
 			}
 		}
 		return void_t{};
-- 
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