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set.go
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set.go
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// Copyright 2020-2021 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 plan
import (
"fmt"
"strings"
"github.com/Ciyfly/FakerMysql/sql"
"github.com/Ciyfly/FakerMysql/sql/expression"
)
// Set represents a set statement. This can be variables, but in some instances can also refer to row values.
type Set struct {
Exprs []sql.Expression
}
// NewSet creates a new Set node.
func NewSet(vars []sql.Expression) *Set {
return &Set{Exprs: vars}
}
// Resolved implements the sql.Node interface.
func (s *Set) Resolved() bool {
for _, v := range s.Exprs {
if !v.Resolved() {
return false
}
}
return true
}
// Children implements the sql.Node interface.
func (s *Set) Children() []sql.Node { return nil }
// WithChildren implements the sql.Node interface.
func (s *Set) WithChildren(children ...sql.Node) (sql.Node, error) {
if len(children) != 0 {
return nil, sql.ErrInvalidChildrenNumber.New(s, len(children), 0)
}
return s, nil
}
// WithExpressions implements the sql.Expressioner interface.
func (s *Set) WithExpressions(exprs ...sql.Expression) (sql.Node, error) {
if len(exprs) != len(s.Exprs) {
return nil, sql.ErrInvalidChildrenNumber.New(s, len(exprs), len(s.Exprs))
}
return NewSet(exprs), nil
}
// Expressions implements the sql.Expressioner interface.
func (s *Set) Expressions() []sql.Expression {
return s.Exprs
}
// RowIter implements the sql.Node interface.
func (s *Set) RowIter(ctx *sql.Context, row sql.Row) (sql.RowIter, error) {
span, ctx := ctx.Span("plan.Set")
defer span.Finish()
var updateExprs []sql.Expression
for _, v := range s.Exprs {
setField, ok := v.(*expression.SetField)
if !ok {
return nil, fmt.Errorf("unsupported type for set: %T", v)
}
switch left := setField.Left.(type) {
case *expression.SystemVar:
err := setSystemVar(ctx, left, setField.Right, row)
if err != nil {
return nil, err
}
case *expression.UserVar:
err := setUserVar(ctx, left, setField.Right, row)
if err != nil {
return nil, err
}
case *expression.ProcedureParam:
value, err := setField.Right.Eval(ctx, row)
if err != nil {
return nil, err
}
err = left.Set(value, setField.Right.Type())
if err != nil {
return nil, err
}
case *expression.GetField:
updateExprs = append(updateExprs, setField)
default:
return nil, fmt.Errorf("unsupported type for set: %T", left)
}
}
var resultRow sql.Row
if len(updateExprs) > 0 {
newRow, err := applyUpdateExpressions(ctx, updateExprs, row)
if err != nil {
return nil, err
}
copy(resultRow, row)
resultRow = row.Append(newRow)
}
return sql.RowsToRowIter(resultRow), nil
}
func setUserVar(ctx *sql.Context, userVar *expression.UserVar, right sql.Expression, row sql.Row) error {
val, err := right.Eval(ctx, row)
if err != nil {
return err
}
err = ctx.SetUserVariable(ctx, userVar.Name, val)
if err != nil {
return err
}
return nil
}
func setSystemVar(ctx *sql.Context, sysVar *expression.SystemVar, right sql.Expression, row sql.Row) error {
val, err := right.Eval(ctx, row)
if err != nil {
return err
}
switch sysVar.Scope {
case sql.SystemVariableScope_Global:
err = sql.SystemVariables.SetGlobal(sysVar.Name, val)
if err != nil {
return err
}
case sql.SystemVariableScope_Session:
err = ctx.SetSessionVariable(ctx, sysVar.Name, val)
if err != nil {
return err
}
default: // should never be hit
return fmt.Errorf("unable to set `%s` due to unknown scope `%v`", sysVar.Name, sysVar.Scope)
}
return nil
}
// Schema implements the sql.Node interface.
func (s *Set) Schema() sql.Schema {
return nil
}
func (s *Set) String() string {
var children = make([]string, len(s.Exprs))
for i, v := range s.Exprs {
children[i] = fmt.Sprintf(v.String())
}
return strings.Join(children, ", ")
}
func (s *Set) DebugString() string {
var children = make([]string, len(s.Exprs))
for i, v := range s.Exprs {
children[i] = fmt.Sprintf(sql.DebugString(v))
}
return strings.Join(children, ", ")
}