From 858bf359b8357bfe32f9f6b8b0713165db3d1799 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Renault?= <clement@meilisearch.com>
Date: Tue, 22 Oct 2019 16:02:02 +0200
Subject: [PATCH] Make possible to convert recursive object into strings

---
 meilidb-core/src/serde/convert_to_string.rs | 72 +++++++++++++++++++--
 meilidb-core/src/serde/indexer.rs           |  6 +-
 2 files changed, 70 insertions(+), 8 deletions(-)

diff --git a/meilidb-core/src/serde/convert_to_string.rs b/meilidb-core/src/serde/convert_to_string.rs
index 2f1fe0ca1..718bd1bf2 100644
--- a/meilidb-core/src/serde/convert_to_string.rs
+++ b/meilidb-core/src/serde/convert_to_string.rs
@@ -12,8 +12,8 @@ impl ser::Serializer for ConvertToString {
     type SerializeTuple = ser::Impossible<Self::Ok, Self::Error>;
     type SerializeTupleStruct = ser::Impossible<Self::Ok, Self::Error>;
     type SerializeTupleVariant = ser::Impossible<Self::Ok, Self::Error>;
-    type SerializeMap = ser::Impossible<Self::Ok, Self::Error>;
-    type SerializeStruct = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeMap = MapConvertToString;
+    type SerializeStruct = StructConvertToString;
     type SerializeStructVariant = ser::Impossible<Self::Ok, Self::Error>;
 
     fn serialize_bool(self, _value: bool) -> Result<Self::Ok, Self::Error> {
@@ -169,7 +169,9 @@ impl ser::Serializer for ConvertToString {
     }
 
     fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
-        Err(SerializerError::UnserializableType { type_name: "map" })
+        Ok(MapConvertToString {
+            text: String::new(),
+        })
     }
 
     fn serialize_struct(
@@ -177,8 +179,8 @@ impl ser::Serializer for ConvertToString {
         _name: &'static str,
         _len: usize,
     ) -> Result<Self::SerializeStruct, Self::Error> {
-        Err(SerializerError::UnserializableType {
-            type_name: "struct",
+        Ok(StructConvertToString {
+            text: String::new(),
         })
     }
 
@@ -194,3 +196,63 @@ impl ser::Serializer for ConvertToString {
         })
     }
 }
+
+pub struct MapConvertToString {
+    text: String,
+}
+
+impl ser::SerializeMap for MapConvertToString {
+    type Ok = String;
+    type Error = SerializerError;
+
+    fn serialize_key<T: ?Sized>(&mut self, key: &T) -> Result<(), Self::Error>
+    where
+        T: ser::Serialize,
+    {
+        let text = key.serialize(ConvertToString)?;
+        self.text.push_str(&text);
+        self.text.push_str(" ");
+        Ok(())
+    }
+
+    fn serialize_value<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
+    where
+        T: ser::Serialize,
+    {
+        let text = value.serialize(ConvertToString)?;
+        self.text.push_str(&text);
+        Ok(())
+    }
+
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Ok(self.text)
+    }
+}
+
+pub struct StructConvertToString {
+    text: String,
+}
+
+impl ser::SerializeStruct for StructConvertToString {
+    type Ok = String;
+    type Error = SerializerError;
+
+    fn serialize_field<T: ?Sized>(
+        &mut self,
+        key: &'static str,
+        value: &T,
+    ) -> Result<(), Self::Error>
+    where
+        T: ser::Serialize,
+    {
+        let value = value.serialize(ConvertToString)?;
+        self.text.push_str(key);
+        self.text.push_str(" ");
+        self.text.push_str(&value);
+        Ok(())
+    }
+
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Ok(self.text)
+    }
+}
diff --git a/meilidb-core/src/serde/indexer.rs b/meilidb-core/src/serde/indexer.rs
index 04d24a63a..49c91252d 100644
--- a/meilidb-core/src/serde/indexer.rs
+++ b/meilidb-core/src/serde/indexer.rs
@@ -20,7 +20,7 @@ impl<'a> ser::Serializer for Indexer<'a> {
     type SerializeTupleStruct = ser::Impossible<Self::Ok, Self::Error>;
     type SerializeTupleVariant = ser::Impossible<Self::Ok, Self::Error>;
     type SerializeMap = MapIndexer<'a>;
-    type SerializeStruct = StructSerializer<'a>;
+    type SerializeStruct = StructIndexer<'a>;
     type SerializeStructVariant = ser::Impossible<Self::Ok, Self::Error>;
 
     fn serialize_bool(self, _value: bool) -> Result<Self::Ok, Self::Error> {
@@ -302,14 +302,14 @@ impl<'a> ser::SerializeMap for MapIndexer<'a> {
     }
 }
 
-pub struct StructSerializer<'a> {
+pub struct StructIndexer<'a> {
     attribute: SchemaAttr,
     document_id: DocumentId,
     indexer: &'a mut RawIndexer,
     texts: Vec<String>,
 }
 
-impl<'a> ser::SerializeStruct for StructSerializer<'a> {
+impl<'a> ser::SerializeStruct for StructIndexer<'a> {
     type Ok = Option<usize>;
     type Error = SerializerError;