/
project.go
74 lines (65 loc) · 1.76 KB
/
project.go
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// Copyright 2023 Sneller, 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 plan
import (
"strings"
"github.com/SnellerInc/sneller/expr"
"github.com/SnellerInc/sneller/ion"
"github.com/SnellerInc/sneller/vm"
)
// Project is a plan Op that
// projects and re-names fields
type Project struct {
Nonterminal
Using []expr.Binding
}
func (p *Project) exec(dst vm.QuerySink, src *Input, ep *ExecParams) error {
proj, err := vm.NewProjection(ep.rewriteBind(p.Using), dst)
if err != nil {
return err
}
return p.From.exec(proj, src, ep)
}
func (p *Project) encode(dst *ion.Buffer, st *ion.Symtab, ep *ExecParams) error {
dst.BeginStruct(-1)
settype("project", dst, st)
dst.BeginField(st.Intern("project"))
encodeBindings(p.Using, dst, st, ep)
dst.EndStruct()
return nil
}
func (p *Project) SetField(f ion.Field) error {
switch f.Label {
case "project":
bind, err := expr.DecodeBindings(f.Datum)
if err != nil {
return err
}
p.Using = bind
default:
return errUnexpectedField
}
return nil
}
func (p *Project) String() string {
var out strings.Builder
out.WriteString("PROJECT ")
for i := range p.Using {
out.WriteString(expr.ToString(&p.Using[i]))
if i != len(p.Using)-1 {
out.WriteString(", ")
}
}
return out.String()
}