Implement ALTER TYPE RENAME VALUE / ADD VALUE (#433)

* postgresql: Implement ALTER TYPE RENAME/ADD VALUE

* catalog: Implement ALTER TYPE RENAME/ADD VALUE

This is a backport of the implementation from sql/catalog.

Author: kyleconroy

internal/catalog/build.go

@@ -99,6 +99,56 @@ func Update(c *pg.Catalog, stmt nodes.Node) error {
 
 	switch n := raw.Stmt.(type) {
 
+	case nodes.AlterEnumStmt:
+		fqn, err := ParseList(n.TypeName)
+		if err != nil {
+			return err
+		}
+		schema, exists := c.Schemas[fqn.Schema]
+		if !exists {
+			return wrap(pg.ErrorSchemaDoesNotExist(fqn.Schema), raw.StmtLocation)
+		}
+		typ, exists := schema.Types[fqn.Rel]
+		if !exists {
+			return wrap(pg.ErrorRelationDoesNotExist(fqn.Rel), raw.StmtLocation)
+		}
+		enum, ok := typ.(pg.Enum)
+		if !ok {
+			return wrap(pg.ErrorRelationDoesNotExist(fqn.Rel), raw.StmtLocation)
+		}
+		oldIndex := -1
+		newIndex := -1
+		for i, val := range enum.Vals {
+			if n.OldVal != nil && val == *n.OldVal {
+				oldIndex = i
+			}
+			if n.NewVal != nil && val == *n.NewVal {
+				newIndex = i
+			}
+		}
+		if n.OldVal != nil {
+			// RENAME TYPE
+			if oldIndex < 0 {
+				return fmt.Errorf("type %s does not have value %s", fqn.Rel, *n.OldVal)
+			}
+			if newIndex >= 0 {
+				return fmt.Errorf("type %s already has value %s", fqn.Rel, *n.NewVal)
+			}
+			enum.Vals[oldIndex] = *n.NewVal
+			schema.Types[fqn.Rel] = enum
+		} else {
+			// ADD VALUE
+			if newIndex >= 0 {
+				if !n.SkipIfNewValExists {
+					return fmt.Errorf("type %s already has value %s", fqn.Rel, *n.NewVal)
+				} else {
+					return nil
+				}
+			}
+			enum.Vals = append(enum.Vals, *n.NewVal)
+			schema.Types[fqn.Rel] = enum
+		}
+
 	case nodes.AlterObjectSchemaStmt:
 		switch n.ObjectType {
 

internal/catalog/build_test.go

@@ -45,6 +45,43 @@ func TestUpdate(t *testing.T) {
 				},
 			},
 		},
+		{
+			`
+			CREATE TYPE status AS ENUM ('open', 'closed');
+			ALTER TYPE status RENAME VALUE 'closed' TO 'shut';
+			`,
+			pg.Catalog{
+				Schemas: map[string]pg.Schema{
+					"public": {
+						Types: map[string]pg.Type{
+							"status": pg.Enum{
+								Name: "status",
+								Vals: []string{"open", "shut"},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			`
+			CREATE TYPE status AS ENUM ('open', 'closed');
+			ALTER TYPE status ADD VALUE 'unknown';
+			ALTER TYPE status ADD VALUE IF NOT EXISTS 'unknown';
+			`,
+			pg.Catalog{
+				Schemas: map[string]pg.Schema{
+					"public": {
+						Types: map[string]pg.Type{
+							"status": pg.Enum{
+								Name: "status",
+								Vals: []string{"open", "closed", "unknown"},
+							},
+						},
+					},
+				},
+			},
+		},
 		{
 			"CREATE TABLE venues ();",
 			pg.Catalog{
@@ -240,6 +277,27 @@ func TestUpdate(t *testing.T) {
 				},
 			},
 		},
+		/*
+			{
+				`
+				CREATE TYPE status AS ENUM ('open', 'closed');
+				ALTER TYPE status RENAME VALUE 'closed' TO 'shut';
+				`,
+				pg.Catalog{
+					Schemas: map[string]pg.Schema{
+						"public": {
+							Types: map[string]pg.Type{
+								"status": pg.Enum{
+									Name: "status",
+									Vals: []string{"open", "shut"},
+								},
+							},
+							Tables: map[string]pg.Table{},
+						},
+					},
+				},
+			},
+		*/
 		{
 			`
 			CREATE TABLE venues ();