Replace expressions engine (#133)

internal/model/anchors.go

@@ -0,0 +1,30 @@
+package model
+
+import (
+	"errors"
+
+	"gopkg.in/yaml.v3"
+)
+
+// Assumes there is no cycle ensured via test TestVerifyCycleIsInvalid
+func resolveAliases(node *yaml.Node) error {
+	switch node.Kind {
+	case yaml.AliasNode:
+		aliasTarget := node.Alias
+		if aliasTarget == nil {
+			return errors.New("unresolved alias node")
+		}
+		*node = *aliasTarget
+		if err := resolveAliases(node); err != nil {
+			return err
+		}
+
+	case yaml.DocumentNode, yaml.MappingNode, yaml.SequenceNode:
+		for _, child := range node.Content {
+			if err := resolveAliases(child); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}