Add token object function for retrieving the token metadata

Signed-off-by: Mic Bowman <mic.bowman@intel.com>

Author: cmickeyb

exchange-contract/exchange/contracts/token_object.cpp

@@ -47,6 +47,38 @@ const std::string capability_generation_key("capability_generation_key");
 
 static ww::exchange::LedgerStore ledger_store("token_ledger");
 
+// -----------------------------------------------------------------
+// NAME: get_token_metadata
+//
+// Pulls the stored token metadata (which is a serialized JSON object),
+// verifies the schema of the metadata, and returns it in the
+// token_metadata parameter. The expectation is that this function
+// will be called by token classes that specialize token behavior.
+// -----------------------------------------------------------------
+bool ww::exchange::token_object::get_token_metadata(
+    const std::string& schema,
+    ww::value::Object& token_metadata)
+{
+    std::string serialized_token_metadata;
+    ERROR_IF_NOT(token_object_store.get(token_metadata_key, serialized_token_metadata),
+                 "unexpected error: failed to get token metadata");
+
+    ww::value::Object deserialized_token_metadata;
+    ERROR_IF_NOT(deserialized_token_metadata.deserialize(serialized_token_metadata.c_str()),
+                 "unexpected error: failed to deserialized token metadata");
+
+    ww::value::Object token_metadata_schema;
+    ERROR_IF_NOT(token_metadata_schema.deserialize(schema.c_str()),
+                 "unexpected error: failed to deserialize token metadata schema");
+
+    ERROR_IF_NOT(deserialized_token_metadata.validate_schema(token_metadata_schema),
+                 "unexpected error: token metadata does not match schema");
+
+    token_metadata.set(deserialized_token_metadata);
+    return true;
+}
+
+
 // -----------------------------------------------------------------
 // METHOD: initialize_contract
 // -----------------------------------------------------------------

exchange-contract/exchange/token_object.h

@@ -76,6 +76,10 @@ namespace token_object
         const ww::value::Object& parameters,
         ww::value::Object& capability_result);
 
+    bool get_token_metadata(
+        const std::string& schema,
+        ww::value::Object& token_metadata);
+
 }; // token_object
 }; // exchange
 }; // ww