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window.go
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window.go
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// Copyright 2023 Dolthub, Inc.
//
// 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.
package ast
import (
"fmt"
vitess "github.com/dolthub/vitess/go/vt/sqlparser"
"github.com/dolthub/doltgresql/postgres/parser/sem/tree"
)
// nodeWindow handles *tree.Window nodes.
func nodeWindow(node tree.Window) (vitess.Window, error) {
if len(node) == 0 {
return nil, nil
}
windows := make(vitess.Window, len(node))
for i, def := range node {
windowDef, err := nodeWindowDef(def)
if err != nil {
return nil, err
}
windows[i] = windowDef
}
return windows, nil
}
// nodeWindowDef handles *tree.WindowDef nodes.
func nodeWindowDef(node *tree.WindowDef) (*vitess.WindowDef, error) {
if node == nil {
return nil, nil
}
partitionBy, err := nodeExprs(node.Partitions)
if err != nil {
return nil, err
}
orderBy, err := nodeOrderBy(node.OrderBy)
if err != nil {
return nil, err
}
var frame *vitess.Frame
if node.Frame != nil {
var unit vitess.FrameUnit
switch node.Frame.Mode {
case tree.RANGE:
unit = vitess.RangeUnit
case tree.ROWS:
unit = vitess.RowsUnit
case tree.GROUPS:
return nil, fmt.Errorf("GROUPS is not yet supported")
default:
return nil, fmt.Errorf("unknown window frame mode")
}
var bounds [2]*vitess.FrameBound
for i, bound := range []*tree.WindowFrameBound{node.Frame.Bounds.StartBound, node.Frame.Bounds.EndBound} {
if bound == nil {
continue
}
var boundType vitess.BoundType
switch bound.BoundType {
case tree.UnboundedPreceding:
boundType = vitess.UnboundedPreceding
case tree.OffsetPreceding:
boundType = vitess.ExprPreceding
case tree.CurrentRow:
boundType = vitess.CurrentRow
case tree.OffsetFollowing:
boundType = vitess.ExprFollowing
case tree.UnboundedFollowing:
boundType = vitess.UnboundedFollowing
default:
return nil, fmt.Errorf("unknown window frame bound type")
}
boundExpr, err := nodeExpr(bound.OffsetExpr)
if err != nil {
return nil, err
}
bounds[i] = &vitess.FrameBound{
Expr: boundExpr,
Type: boundType,
}
}
frame = &vitess.Frame{
Unit: unit,
Extent: &vitess.FrameExtent{
Start: bounds[0],
End: bounds[1],
},
}
}
return &vitess.WindowDef{
Name: vitess.NewColIdent(string(node.Name)),
NameRef: vitess.NewColIdent(string(node.RefName)),
PartitionBy: partitionBy,
OrderBy: orderBy,
Frame: frame,
}, nil
}