union.go

// Copyright 2015 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
//
// Author: Peter Mattis (peter@cockroachlabs.com)

// This code was derived from https://github.com/youtube/vitess.
//
// Copyright 2012, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file

package parser

import (
	"bytes"
	"fmt"
)

// UnionClause represents a UNION statement.
type UnionClause struct {
	Type        UnionType
	Left, Right *Select
	All         bool
}

// UnionType represents one of the three set operations in sql.
type UnionType int

// Union.Type
const (
	UnionOp UnionType = iota
	IntersectOp
	ExceptOp
)

var unionTypeName = [...]string{
	UnionOp:     "UNION",
	IntersectOp: "INTERSECT",
	ExceptOp:    "EXCEPT",
}

func (i UnionType) String() string {
	if i < 0 || i > UnionType(len(unionTypeName)-1) {
		return fmt.Sprintf("UnionType(%d)", i)
	}
	return unionTypeName[i]
}

// Format implements the NodeFormatter interface.
func (node *UnionClause) Format(buf *bytes.Buffer, f FmtFlags) {
	FormatNode(buf, f, node.Left)
	buf.WriteByte(' ')
	buf.WriteString(node.Type.String())
	if node.All {
		buf.WriteString(" ALL")
	}
	buf.WriteByte(' ')
	FormatNode(buf, f, node.Right)
}