ircd::json: Add prepend/append tools for arrays.

include/ircd/json/json.h

@@ -43,6 +43,9 @@ namespace ircd::json
 // Convenience toolset for higher level operations.
 namespace ircd::json
 {
+	strung append(const array &, const string_view &val);
+	strung prepend(const array &, const string_view &val);
+
 	void merge(stack::object &out, const vector &);
 	strung remove(const object &, const string_view &key);
 	strung remove(const object &, const size_t &index);

ircd/json.cc

@@ -838,6 +838,53 @@ ircd::json::merge(stack::object &out,
 	top.compose(*out.s);
 }
 
+ircd::json::strung
+ircd::json::prepend(const array &s,
+                    const string_view &val)
+{
+	if(unlikely(!empty(s) && type(s) != type::ARRAY))
+		throw type_error
+		{
+			"Cannot prepend value into JSON of type %s",
+			reflect(type(s))
+		};
+
+	size_t ctr{0}, i{0};
+	auto &b(value_buffer);
+
+	b.at(ctr++) = val;
+	for(const string_view &v : s)
+		b.at(ctr++) = v;
+
+	return strung
+	{
+		b.data(), b.data() + ctr
+	};
+}
+
+ircd::json::strung
+ircd::json::append(const array &s,
+                   const string_view &val)
+{
+	if(unlikely(!empty(s) && type(s) != type::ARRAY))
+		throw type_error
+		{
+			"Cannot append value into JSON of type %s",
+			reflect(type(s))
+		};
+
+	size_t ctr{0}, i{0};
+	auto &b(value_buffer);
+	for(const string_view &v : s)
+		b.at(ctr++) = v;
+
+	b.at(ctr++) = val;
+	return strung
+	{
+		b.data(), b.data() + ctr
+	};
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 // json/stack.h