Support SCHEMA DDL statements (#179)

* Implement CREATE SCHEMA and DROP SCHEMA statements

* Update testdata

Author: apstndb

ast/ast.go

@@ -60,6 +60,8 @@ type Statement interface {
 // - https://cloud.google.com/spanner/docs/reference/standard-sql/dml-syntax
 
 func (QueryStatement) isStatement()     {}
+func (CreateSchema) isStatement()       {}
+func (DropSchema) isStatement()         {}
 func (CreateDatabase) isStatement()     {}
 func (AlterDatabase) isStatement()      {}
 func (CreateTable) isStatement()        {}
@@ -297,6 +299,8 @@ type DDL interface {
 //
 // - https://cloud.google.com/spanner/docs/reference/standard-sql/data-definition-language
 
+func (CreateSchema) isDDL()       {}
+func (DropSchema) isDDL()         {}
 func (CreateDatabase) isDDL()     {}
 func (AlterDatabase) isDDL()      {}
 func (CreateTable) isDDL()        {}
@@ -1765,6 +1769,30 @@ type OptionsDef struct {
 	Value Expr
 }
 
+// CreateSchema is CREATE SCHEMA statement node.
+//
+//	CREATE SCHEMA {{.Name | sql}}
+type CreateSchema struct {
+	// pos = Create
+	// end = Name.end
+
+	Create token.Pos // position of "CREATE" keyword
+
+	Name *Ident
+}
+
+// DropSchema is DROP SCHEMA statement node.
+//
+//	DROP SCHEMA {{.Name | sql}}
+type DropSchema struct {
+	// pos = Drop
+	// end = Name.end
+
+	Drop token.Pos // position of "DROP" keyword
+
+	Name *Ident
+}
+
 // CreateDatabase is CREATE DATABASE statement node.
 //
 //	CREATE DATABASE {{.Name | sql}}

ast/pos.go

@@ -786,6 +786,10 @@ func (c *CreateDatabase) SQL() string {
 	return "CREATE DATABASE " + c.Name.SQL()
 }
 
+func (s *CreateSchema) SQL() string { return "CREATE SCHEMA " + s.Name.SQL() }
+
+func (s *DropSchema) SQL() string { return "DROP SCHEMA " + s.Name.SQL() }
+
 func (d *AlterDatabase) SQL() string {
 	return "ALTER DATABASE " + d.Name.SQL() + " SET " + d.Options.SQL()
 }

ast/sql.go

@@ -2299,6 +2299,8 @@ func (p *Parser) parseDDL() ast.DDL {
 	case p.Token.Kind == "CREATE":
 		p.nextToken()
 		switch {
+		case p.Token.IsKeywordLike("SCHEMA"):
+			return p.parseCreateSchema(pos)
 		case p.Token.IsKeywordLike("DATABASE"):
 			return p.parseCreateDatabase(pos)
 		case p.Token.IsKeywordLike("TABLE"):
@@ -2341,6 +2343,8 @@ func (p *Parser) parseDDL() ast.DDL {
 	case p.Token.IsKeywordLike("DROP"):
 		p.nextToken()
 		switch {
+		case p.Token.IsKeywordLike("SCHEMA"):
+			return p.parseDropSchema(pos)
 		case p.Token.IsKeywordLike("TABLE"):
 			return p.parseDropTable(pos)
 		case p.Token.IsKeywordLike("INDEX"):
@@ -2377,6 +2381,24 @@ func (p *Parser) parseDDL() ast.DDL {
 	panic(p.errorfAtToken(&p.Token, "expected pseudo keyword: ALTER, DROP, but: %s", p.Token.AsString))
 }
 
+func (p *Parser) parseCreateSchema(pos token.Pos) *ast.CreateSchema {
+	p.expectKeywordLike("SCHEMA")
+	name := p.parseIdent()
+	return &ast.CreateSchema{
+		Create: pos,
+		Name:   name,
+	}
+}
+
+func (p *Parser) parseDropSchema(pos token.Pos) *ast.DropSchema {
+	p.expectKeywordLike("SCHEMA")
+	name := p.parseIdent()
+	return &ast.DropSchema{
+		Drop: pos,
+		Name: name,
+	}
+}
+
 func (p *Parser) parseCreateDatabase(pos token.Pos) *ast.CreateDatabase {
 	p.expectKeywordLike("DATABASE")
 	name := p.parseIdent()

parser.go

@@ -0,0 +1 @@
+CREATE SCHEMA sch1

testdata/input/ddl/create_schema.sql

@@ -0,0 +1 @@
+DROP SCHEMA sch1

testdata/input/ddl/drop_schema.sql

@@ -0,0 +1,14 @@
+--- create_schema.sql
+CREATE SCHEMA sch1
+--- AST
+&ast.CreateSchema{
+  Create: 0,
+  Name:   &ast.Ident{
+    NamePos: 14,
+    NameEnd: 18,
+    Name:    "sch1",
+  },
+}
+
+--- SQL
+CREATE SCHEMA sch1

testdata/result/ddl/create_schema.sql.txt

@@ -0,0 +1,14 @@
+--- drop_schema.sql
+DROP SCHEMA sch1
+--- AST
+&ast.DropSchema{
+  Drop: 0,
+  Name: &ast.Ident{
+    NamePos: 12,
+    NameEnd: 16,
+    Name:    "sch1",
+  },
+}
+
+--- SQL
+DROP SCHEMA sch1

testdata/result/ddl/drop_schema.sql.txt

@@ -0,0 +1,14 @@
+--- create_schema.sql
+CREATE SCHEMA sch1
+--- AST
+&ast.CreateSchema{
+  Create: 0,
+  Name:   &ast.Ident{
+    NamePos: 14,
+    NameEnd: 18,
+    Name:    "sch1",
+  },
+}
+
+--- SQL
+CREATE SCHEMA sch1

testdata/result/statement/create_schema.sql.txt

@@ -0,0 +1,14 @@
+--- drop_schema.sql
+DROP SCHEMA sch1
+--- AST
+&ast.DropSchema{
+  Drop: 0,
+  Name: &ast.Ident{
+    NamePos: 12,
+    NameEnd: 16,
+    Name:    "sch1",
+  },
+}
+
+--- SQL
+DROP SCHEMA sch1