Merge PR cloudspannerecosystem#368: feat: support DROP VIEW IF EXISTS

Author: apstndb

ast/ast.go

@@ -2832,12 +2832,13 @@ type CreateView struct {
 
 // DropView is DROP VIEW statement node.
 //
-//	DROP VIEW {{.Name | sql}}
+//	DROP VIEW {{if .IfExists}}IF EXISTS{{end}} {{.Name | sql}}
 type DropView struct {
 	// pos = Drop
 	// end = Name.end
 
-	Drop token.Pos
+	Drop     token.Pos
+	IfExists bool
 
 	Name *Path
 }

ast/sql.go

@@ -860,7 +860,9 @@ func (c *CreateView) SQL() string {
 		" SQL SECURITY " + string(c.SecurityType) + " AS " + c.Query.SQL()
 }
 
-func (d *DropView) SQL() string { return "DROP VIEW " + d.Name.SQL() }
+func (d *DropView) SQL() string {
+	return "DROP VIEW " + strOpt(d.IfExists, "IF EXISTS ") + d.Name.SQL()
+}
 
 func (c *ColumnDef) SQL() string {
 	return c.Name.SQL() + " " + c.Type.SQL() +

parser.go

@@ -3485,11 +3485,13 @@ func (p *Parser) parseCreateView(pos token.Pos, orReplace bool) *ast.CreateView
 
 func (p *Parser) parseDropView(pos token.Pos) *ast.DropView {
 	p.expectKeywordLike("VIEW")
+	ifExists := p.parseIfExists()
 	name := p.parsePath()
 
 	return &ast.DropView{
-		Drop: pos,
-		Name: name,
+		Drop:     pos,
+		IfExists: ifExists,
+		Name:     name,
 	}
 }
 

testdata/input/ddl/drop_view_if_exists.sql

@@ -0,0 +1 @@
+DROP VIEW IF EXISTS SingersView

testdata/result/ddl/drop_view_if_exists.sql.txt

@@ -0,0 +1,19 @@
+--- drop_view_if_exists.sql
+DROP VIEW IF EXISTS SingersView
+
+--- AST
+&ast.DropView{
+  IfExists: true,
+  Name:     &ast.Path{
+    Idents: []*ast.Ident{
+      &ast.Ident{
+        NamePos: 20,
+        NameEnd: 31,
+        Name:    "SingersView",
+      },
+    },
+  },
+}
+
+--- SQL
+DROP VIEW IF EXISTS SingersView

testdata/result/statement/drop_view_if_exists.sql.txt

@@ -0,0 +1,19 @@
+--- drop_view_if_exists.sql
+DROP VIEW IF EXISTS SingersView
+
+--- AST
+&ast.DropView{
+  IfExists: true,
+  Name:     &ast.Path{
+    Idents: []*ast.Ident{
+      &ast.Ident{
+        NamePos: 20,
+        NameEnd: 31,
+        Name:    "SingersView",
+      },
+    },
+  },
+}
+
+--- SQL
+DROP VIEW IF EXISTS SingersView