Support for parsing JSON schemas with references.

lib/Schema.js

@@ -96,7 +96,7 @@ Schema.session = session
 
 Schema.fromJS = def()
 
-Schema.fromJSON = def()
+Schema.fromJSON = Schema.session(def())
 
 
 Schema.extend = function(descriptor) {

lib/extensions/Schema.js

@@ -36,3 +36,43 @@ function renewing(ref) {
 }
 
 Schema.self = schema.self = renewing(new SchemaReference())
+
+Schema.fromJSON.def(function(sch) {
+  if (sch.id == null && sch['$ref'] == null) return
+
+  var id, session = Schema.session
+
+  if (!session.deserialized) session.deserialized = { references: {}, subscribers: {} }
+
+  if (sch.id != null) {
+    // This schema can be referenced in the future with the given ID
+    id = sch.id
+
+    // Deserializing:
+    delete sch.id
+    var schemaObject = Schema.fromJSON(sch)
+    sch.id = id
+
+    // Storing the schema object and notifying subscribers
+    session.deserialized.references[id] = schemaObject
+    ;(session.deserialized.subscribers[id] || []).forEach(function(callback) {
+      callback(schemaObject)
+    })
+
+    return schemaObject
+
+  } else {
+    // Referencing a schema given somewhere else with the given ID
+    id = sch['$ref']
+
+    // If the referenced schema is already known, we are ready
+    if (session.deserialized.references[id]) return session.deserialized.references[id]
+
+    // If not, returning a reference, and when the schema gets known, resolving the reference
+    if (!session.deserialized.subscribers[id]) session.deserialized.subscribers[id] = []
+    var reference = new SchemaReference()
+    session.deserialized.subscribers[id].push(reference.resolve.bind(reference))
+
+    return reference
+  }
+})