refactor: group migration graph logic

migration_graph.go

@@ -5,6 +5,15 @@ import (
 	"fmt"
 )
 
+type MigrationGraph struct {
+	// Reference to the root of the graph.
+	Root *Migration
+	// Name to struct mapping of all migrations part of the graph.
+	Migrations map[string]Migration
+	// Mapping of all migrations to their parent, if any.
+	parentage map[string]*Migration
+}
+
 func NewMigrationGraph() MigrationGraph {
 	return MigrationGraph{Migrations: map[string]Migration{}, parentage: map[string]*Migration{}}
 }

models.go

@@ -11,15 +11,6 @@ type Migration struct {
 	Run      bool
 }
 
-type MigrationGraph struct {
-	// Reference to the root of the graph.
-	Root *Migration
-	// Name to struct mapping of all migrations part of the graph.
-	Migrations map[string]Migration
-	// Mapping of all migrations to their parent, if any.
-	parentage map[string]*Migration
-}
-
 type DB interface {
 	Execute(sql string) error
 }