// Facts encodes the schema as facts. This is primarily used for programmatically
// creating a schema and then writing the facts to storage for later use.
func (s *Schema) Facts() origins.Facts {
var (
err error
attr *Attribute
fact *origins.Fact
facts origins.Facts
buf = origins.NewBuffer(nil)
entity *origins.Ident
)
for _, attr = range s.attrs {
entity = &origins.Ident{
Domain: attr.Domain,
Name: attr.Name,
}
if facts, err = origins.Reflect(attr); err != nil {
panic(err)
}
for _, fact = range facts {
fact.Domain = s.Domain
fact.Entity = entity
// Fill in the defaults.
if fact.Attribute.Domain == "" {
fact.Attribute.Domain = fact.Domain
}
buf.Write(fact)
}
}
return buf.Facts()
}
// defaults fills in the default values for the fact.
func (tx *Transaction) defaults(f *origins.Fact) error {
if f.Domain == "" {
if tx.options.DefaultDomain == "" {
return ErrNoDomain
}
f.Domain = tx.options.DefaultDomain
}
// Default to fact domain.
if f.Entity.Domain == "" {
f.Entity.Domain = f.Domain
}
if f.Attribute.Domain == "" {
f.Attribute.Domain = f.Domain
}
// Set fact time to the transaction time if flagged to do so.
if f.Time.IsZero() && tx.options.SetDefaultTime {
f.Time = tx.StartTime
}
return nil
}
// unmarshalFact decodes a fact from it's binary representation. The domain and
// transaction ID are passed in since they are not encoded with the fact itself.
// This is because facts are stored relative to a domain and a transaction.
func unmarshalFact(m *ProtoFact, b []byte, d string, t uint64, f *origins.Fact) error {
m.Reset()
if err := proto.Unmarshal(b, m); err != nil {
return err
}
f.Domain = d
f.Transaction = t
f.Entity = &origins.Ident{
Domain: m.GetEntityDomain(),
Name: m.GetEntity(),
}
f.Attribute = &origins.Ident{
Domain: m.GetAttributeDomain(),
Name: m.GetAttribute(),
}
f.Value = &origins.Ident{
Domain: m.GetValueDomain(),
Name: m.GetValue(),
}
f.Time = chrono.MicroTime(m.GetTime())
if m.GetAdded() {
f.Operation = origins.Assertion
} else {
f.Operation = origins.Retraction
}
return nil
}
// macro takes a fact and resolves the macro.
func (tx *Transaction) macro(fact *origins.Fact) error {
// Do not process facts for the macros themselves.
if fact.Domain == origins.MacrosDomain {
return nil
}
// Entity-based macro.
if fact.Entity.Domain == origins.MacrosDomain {
switch fact.Entity.Name {
// Facts about the domain.
case "domain":
fact.Entity.Name = fact.Domain
fact.Domain = origins.DomainsDomain
fact.Entity.Domain = ""
// Facts about the transaction.
case "tx":
fact.Domain = origins.TransactionsDomain
fact.Entity.Domain = ""
fact.Entity.Name = fmt.Sprint(tx.ID)
default:
return fmt.Errorf("transactor(%d): unknown entity macro: %s", tx.ID, fact.Entity.Name)
}
}
// Value-based macro.
if fact.Value.Domain == origins.MacrosDomain {
switch fact.Value.Name {
// Set the value to the transaction time.
case "now":
fact.Value.Domain = ""
fact.Value.Name = tx.StartTime.String()
// Set the value to the transaction entity.
case "tx":
fact.Value.Domain = origins.TransactionsDomain
fact.Value.Name = fmt.Sprint(tx.ID)
default:
return fmt.Errorf("transactor(%s): unknown value macro: %s", tx.ID, fact.Value.Name)
}
}
return nil
}