/
auto_increment.go
168 lines (143 loc) · 4.44 KB
/
auto_increment.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 expression
import (
"fmt"
"gopkg.in/src-d/go-errors.v1"
"github.com/dolthub/go-mysql-server/sql"
)
var (
// ErrAutoIncrementUnsupported is returned when table does not support AUTO_INCREMENT.
ErrAutoIncrementUnsupported = errors.NewKind("table %s does not support AUTO_INCREMENT columns")
// ErrNoAutoIncrementCols is returned when table has no AUTO_INCREMENT columns.
ErrNoAutoIncrementCols = errors.NewKind("table %s has no AUTO_INCREMENT columns")
)
// AutoIncrement implements AUTO_INCREMENT
type AutoIncrement struct {
UnaryExpression
autoTbl sql.AutoIncrementTable
autoCol *sql.Column
}
var _ sql.Expression = (*AutoIncrement)(nil)
var _ sql.CollationCoercible = (*AutoIncrement)(nil)
// NewAutoIncrement creates a new AutoIncrement expression.
func NewAutoIncrement(ctx *sql.Context, table sql.Table, given sql.Expression) (*AutoIncrement, error) {
autoTbl, ok := table.(sql.AutoIncrementTable)
if !ok {
return nil, ErrAutoIncrementUnsupported.New(table.Name())
}
var autoCol *sql.Column
for _, c := range autoTbl.Schema() {
if c.AutoIncrement {
autoCol = c
break
}
}
if autoCol == nil {
return nil, ErrNoAutoIncrementCols.New(table.Name())
}
return &AutoIncrement{
UnaryExpression{Child: given},
autoTbl,
autoCol,
}, nil
}
// NewAutoIncrementForColumn creates a new AutoIncrement expression for the column given.
func NewAutoIncrementForColumn(ctx *sql.Context, table sql.Table, autoCol *sql.Column, given sql.Expression) (*AutoIncrement, error) {
autoTbl, ok := table.(sql.AutoIncrementTable)
if !ok {
return nil, ErrAutoIncrementUnsupported.New(table.Name())
}
return &AutoIncrement{
UnaryExpression{Child: given},
autoTbl,
autoCol,
}, nil
}
// IsNullable implements the Expression interface.
func (i *AutoIncrement) IsNullable() bool {
return false
}
// Type implements the Expression interface.
func (i *AutoIncrement) Type() sql.Type {
return i.autoCol.Type
}
// CollationCoercibility implements the interface sql.CollationCoercible.
func (i *AutoIncrement) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
return sql.GetCoercibility(ctx, i.Child)
}
// Eval implements the Expression interface.
func (i *AutoIncrement) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
// get value provided by INSERT
given, err := i.Child.Eval(ctx, row)
if err != nil {
return nil, err
}
// When a row passes in 0 as the auto_increment value it is equivalent to NULL.
cmp, err := i.Type().Compare(given, i.Type().Zero())
if err != nil {
return nil, err
}
// if given is negative, don't do any auto_increment logic
if cmp < 0 {
ret, _, err := i.Type().Convert(given)
if err != nil {
return nil, err
}
return ret, nil
}
if cmp == 0 {
if sql.LoadSqlMode(ctx).ModeEnabled(sql.NoAutoValueOnZero) {
ret, _, err := i.Type().Convert(given)
if err != nil {
return nil, err
}
return ret, nil
}
// if given is 0, it is equivalent to NULL
given = nil
}
// Update integrator AUTO_INCREMENT sequence with our value
seq, err := i.autoTbl.GetNextAutoIncrementValue(ctx, given)
if err != nil {
return nil, err
}
// Use sequence value if NULL or 0 were provided
if given == nil {
given = seq
}
ret, _, err := i.Type().Convert(given)
if err != nil {
return nil, err
}
return ret, nil
}
func (i *AutoIncrement) String() string {
return fmt.Sprintf("AutoIncrement(%s)", i.Child.String())
}
// WithChildren implements the Expression interface.
func (i *AutoIncrement) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(i, len(children), 1)
}
return &AutoIncrement{
UnaryExpression{Child: children[0]},
i.autoTbl,
i.autoCol,
}, nil
}
// Children implements the Expression interface.
func (i *AutoIncrement) Children() []sql.Expression {
return []sql.Expression{i.Child}
}