1 files changed, 82 insertions, 0 deletions
diff --git a/vendor/github.com/authzed/spicedb/internal/namespace/aliasing.go b/vendor/github.com/authzed/spicedb/internal/namespace/aliasing.go
new file mode 100644
index 0000000..adbaa94
--- /dev/null
+++ b/vendor/github.com/authzed/spicedb/internal/namespace/aliasing.go
@@ -0,0 +1,82 @@
+package namespace
+
+import (
+	"sort"
+
+	"github.com/authzed/spicedb/pkg/schema"
+)
+
+// computePermissionAliases computes a map of aliases between the various permissions in a
+// namespace. A permission is considered an alias if it *directly* refers to another permission
+// or relation without any other form of expression.
+func computePermissionAliases(typeDefinition *schema.ValidatedDefinition) (map[string]string, error) {
+	aliases := map[string]string{}
+	done := map[string]struct{}{}
+	unresolvedAliases := map[string]string{}
+
+	for _, rel := range typeDefinition.Namespace().Relation {
+		// Ensure the relation has a rewrite...
+		if rel.GetUsersetRewrite() == nil {
+			done[rel.Name] = struct{}{}
+			continue
+		}
+
+		// ... with a union ...
+		union := rel.GetUsersetRewrite().GetUnion()
+		if union == nil {
+			done[rel.Name] = struct{}{}
+			continue
+		}
+
+		// ... with a single child ...
+		if len(union.Child) != 1 {
+			done[rel.Name] = struct{}{}
+			continue
+		}
+
+		// ... that is a computed userset.
+		computedUserset := union.Child[0].GetComputedUserset()
+		if computedUserset == nil {
+			done[rel.Name] = struct{}{}
+			continue
+		}
+
+		// If the aliased item is a relation, then we've found the alias target.
+		aliasedPermOrRel := computedUserset.GetRelation()
+		if !typeDefinition.IsPermission(aliasedPermOrRel) {
+			done[rel.Name] = struct{}{}
+			aliases[rel.Name] = aliasedPermOrRel
+			continue
+		}
+
+		// Otherwise, add the permission to the working set.
+		unresolvedAliases[rel.Name] = aliasedPermOrRel
+	}
+
+	for len(unresolvedAliases) > 0 {
+		startingCount := len(unresolvedAliases)
+		for relName, aliasedPermission := range unresolvedAliases {
+			if _, ok := done[aliasedPermission]; ok {
+				done[relName] = struct{}{}
+
+				if alias, ok := aliases[aliasedPermission]; ok {
+					aliases[relName] = alias
+				} else {
+					aliases[relName] = aliasedPermission
+				}
+				delete(unresolvedAliases, relName)
+				continue
+			}
+		}
+		if len(unresolvedAliases) == startingCount {
+			keys := make([]string, 0, len(unresolvedAliases))
+			for key := range unresolvedAliases {
+				keys = append(keys, key)
+			}
+			sort.Strings(keys)
+			return nil, NewPermissionsCycleErr(typeDefinition.Namespace().Name, keys)
+		}
+	}
+
+	return aliases, nil
+}