Break out ast.go into multiple files (#506)

* sql/ast: Export ast.go into individual files

* Fix package name and go fmt

* Use correct build tags for compiler

Author: kyleconroy

internal/compiler/engine.go

@@ -1,3 +1,5 @@
+// +build exp
+
 package compiler
 
 import (

internal/compiler/runtime/parse.go

@@ -1,3 +1,5 @@
+// +build exp
+
 package runtime
 
 import (

internal/sql/ast/alter_table_cmd.go

@@ -0,0 +1,22 @@
+package ast
+
+type AlterTableType int
+
+const (
+	AT_AddColumn AlterTableType = iota
+	AT_AlterColumnType
+	AT_DropColumn
+	AT_DropNotNull
+	AT_SetNotNull
+)
+
+type AlterTableCmd struct {
+	Subtype   AlterTableType
+	Name      *string
+	Def       *ColumnDef
+	MissingOk bool
+}
+
+func (n *AlterTableCmd) Pos() int {
+	return 0
+}

internal/sql/ast/alter_table_set_schema_stmt.go

@@ -0,0 +1,10 @@
+package ast
+
+type AlterTableSetSchemaStmt struct {
+	Table     *TableName
+	NewSchema *string
+}
+
+func (n *AlterTableSetSchemaStmt) Pos() int {
+	return 0
+}

internal/sql/ast/alter_table_stmt.go

@@ -0,0 +1,11 @@
+package ast
+
+type AlterTableStmt struct {
+	Table *TableName
+	Cmds  *List
+	// MissingOk bool
+}
+
+func (n *AlterTableStmt) Pos() int {
+	return 0
+}

internal/sql/ast/alter_type_add_value_stmt.go

@@ -0,0 +1,11 @@
+package ast
+
+type AlterTypeAddValueStmt struct {
+	Type               *TypeName
+	NewValue           *string
+	SkipIfNewValExists bool
+}
+
+func (n *AlterTypeAddValueStmt) Pos() int {
+	return 0
+}

internal/sql/ast/alter_type_rename_value_stmt.go

@@ -0,0 +1,11 @@
+package ast
+
+type AlterTypeRenameValueStmt struct {
+	Type     *TypeName
+	OldValue *string
+	NewValue *string
+}
+
+func (n *AlterTypeRenameValueStmt) Pos() int {
+	return 0
+}