From 99c38d9e8158747cb9d170efdf99cf22ffb539e3 Mon Sep 17 00:00:00 2001
From: Bevan Arps <bevan.arps@microsoft.com>
Date: Mon, 5 Jul 2021 11:32:51 +1200
Subject: [PATCH] Convert direction from an enum into a discriminated union

---
 hack/generator/pkg/conversions/direction.go | 45 +++++++++++++++++++--
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/hack/generator/pkg/conversions/direction.go b/hack/generator/pkg/conversions/direction.go
index 1a80f64b273..1f27723396b 100644
--- a/hack/generator/pkg/conversions/direction.go
+++ b/hack/generator/pkg/conversions/direction.go
@@ -5,12 +5,49 @@
 
 package conversions
 
+import (
+	"github.com/Azure/azure-service-operator/hack/generator/pkg/astmodel"
+)
+
 // Direction specifies the direction of conversion we're implementing with this function
-type Direction int
+type Direction interface {
+	// SelectString returns one of the provided strings, depending on the direction of conversion
+	SelectString(from string, to string) string
+	// SelectType returns one of the provided types, depending on the direction of conversion
+	SelectType(from astmodel.Type, to astmodel.Type) astmodel.Type
+}
 
-const (
+var (
 	// ConvertFrom indicates the conversion is from the passed 'other', populating the receiver with properties from the other
-	ConvertFrom = Direction(1)
+	ConvertFrom Direction = &ConvertFromDirection{}
 	// ConvertTo indicates the conversion is to the passed 'other', populating the other with properties from the receiver
-	ConvertTo = Direction(2)
+	ConvertTo Direction = &ConvertToDirection{}
 )
+
+type ConvertFromDirection struct{}
+
+var _ Direction = &ConvertFromDirection{}
+
+// SelectString returns the string for conversion FROM
+func (dir *ConvertFromDirection) SelectString(fromString string, _ string) string {
+	return fromString
+}
+
+// SelectType returns the type for conversion FROM
+func (dir *ConvertFromDirection) SelectType(fromType astmodel.Type, _ astmodel.Type) astmodel.Type {
+	return fromType
+}
+
+type ConvertToDirection struct{}
+
+var _ Direction = &ConvertToDirection{}
+
+// SelectString returns the string for conversion TO
+func (dir *ConvertToDirection) SelectString(_ string, toValue string) string {
+	return toValue
+}
+
+// SelectType returns the type for conversion TO
+func (dir *ConvertToDirection) SelectType(_ astmodel.Type, toType astmodel.Type) astmodel.Type {
+	return toType
+}