class JsonSchema::DocumentStore

reference to the top-level schema before doing anything else.
that have already happened and handles cyclic dependencies. Store a
Each URI tuple also contains a pointer map that helps speed up expansions
that we’ve seen in the schema.
The document store helps resolve URI-based JSON pointers by storing IDs

def add_schema(schema) 

def add_schema(schema)
  raise ArgumentError, "can't add nil URI" if schema.uri.nil?
  uri = schema.uri.chomp('#')
  @schema_map[uri] = schema
end

def each 

def each
  @schema_map.each { |k, v| yield(k, v) }
end

def initialize 

def initialize
  @schema_map = {}
end

def lookup_schema(uri) 

def lookup_schema(uri)
  uri = uri.chomp('#')
  @schema_map[uri]
end