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timediff.go
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timediff.go
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// Copyright 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 function
import (
"fmt"
"math"
"strings"
"time"
"gopkg.in/src-d/go-errors.v1"
"github.com/gabereiser/go-mysql-server/sql"
"github.com/gabereiser/go-mysql-server/sql/expression"
"github.com/gabereiser/go-mysql-server/sql/types"
)
// TimeDiff subtracts the second argument from the first expressed as a time value.
type TimeDiff struct {
expression.BinaryExpression
}
var _ sql.FunctionExpression = (*TimeDiff)(nil)
// NewTimeDiff creates a new NewTimeDiff expression.
func NewTimeDiff(e1, e2 sql.Expression) sql.Expression {
return &TimeDiff{
expression.BinaryExpression{
Left: e1,
Right: e2,
},
}
}
// FunctionName implements sql.FunctionExpression
func (td *TimeDiff) FunctionName() string {
return "timediff"
}
// Description implements sql.FunctionExpression
func (td *TimeDiff) Description() string {
return "returns expr1 − expr2 expressed as a time value. expr1 and expr2 are time or date-and-time expressions, but both must be of the same type."
}
// Type implements the Expression interface.
func (td *TimeDiff) Type() sql.Type { return types.Time }
func (td *TimeDiff) String() string {
return fmt.Sprintf("%s(%s,%s)", td.FunctionName(), td.Left, td.Right)
}
// WithChildren implements the Expression interface.
func (td *TimeDiff) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 2 {
return nil, sql.ErrInvalidChildrenNumber.New(td, len(children), 2)
}
return NewTimeDiff(children[0], children[1]), nil
}
func convToDateOrTime(val interface{}) (interface{}, error) {
date, err := types.Datetime.Convert(val)
if err == nil {
return date, nil
}
tim, err := types.Time.Convert(val)
if err == nil {
return tim, err
}
return nil, err
}
// Eval implements the Expression interface.
func (td *TimeDiff) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
if td.Left == nil || td.Right == nil {
return nil, nil
}
left, err := td.Left.Eval(ctx, row)
if err != nil {
return nil, err
}
right, err := td.Right.Eval(ctx, row)
if err != nil {
return nil, err
}
if left == nil || right == nil {
return nil, nil
}
// always convert string types
if _, ok := left.(string); ok {
left, err = convToDateOrTime(left)
if err != nil {
ctx.Warn(1292, err.Error())
return nil, nil
}
}
if _, ok := right.(string); ok {
right, err = convToDateOrTime(right)
if err != nil {
ctx.Warn(1292, err.Error())
return nil, nil
}
}
// handle as date
if leftDatetime, ok := left.(time.Time); ok {
rightDatetime, ok := right.(time.Time)
if !ok {
return nil, nil
}
if leftDatetime.Location() != rightDatetime.Location() {
rightDatetime = rightDatetime.In(leftDatetime.Location())
}
return types.Time.Convert(leftDatetime.Sub(rightDatetime))
}
// handle as time
if leftTime, ok := left.(types.Timespan); ok {
rightTime, ok := right.(types.Timespan)
if !ok {
return nil, nil
}
return leftTime.Subtract(rightTime), nil
}
return nil, sql.ErrInvalidArgumentType.New("timediff")
}
// DateDiff returns expr1 − expr2 expressed as a value in days from one date to the other.
type DateDiff struct {
expression.BinaryExpression
}
var _ sql.FunctionExpression = (*DateDiff)(nil)
// NewDateDiff creates a new DATEDIFF() function.
func NewDateDiff(expr1, expr2 sql.Expression) sql.Expression {
return &DateDiff{
expression.BinaryExpression{
Left: expr1,
Right: expr2,
},
}
}
// FunctionName implements sql.FunctionExpression
func (d *DateDiff) FunctionName() string {
return "datediff"
}
// Description implements sql.FunctionExpression
func (d *DateDiff) Description() string {
return "gets difference between two dates in result of days."
}
// Type implements the sql.Expression interface.
func (d *DateDiff) Type() sql.Type { return types.Int64 }
// WithChildren implements the Expression interface.
func (d *DateDiff) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 2 {
return nil, sql.ErrInvalidChildrenNumber.New(d, len(children), 2)
}
return NewDateDiff(children[0], children[1]), nil
}
// Eval implements the sql.Expression interface.
func (d *DateDiff) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
if d.Left == nil || d.Right == nil {
return nil, nil
}
expr1, err := d.Left.Eval(ctx, row)
if err != nil {
return nil, err
}
if expr1 == nil {
return nil, nil
}
expr1, err = types.Datetime.Convert(expr1)
if err != nil {
return nil, err
}
expr1str := expr1.(time.Time).String()[:10]
expr1, _ = types.Datetime.Convert(expr1str)
expr2, err := d.Right.Eval(ctx, row)
if err != nil {
return nil, err
}
if expr2 == nil {
return nil, nil
}
expr2, err = types.Datetime.Convert(expr2)
if err != nil {
return nil, err
}
expr2str := expr2.(time.Time).String()[:10]
expr2, _ = types.Datetime.Convert(expr2str)
date1 := expr1.(time.Time)
date2 := expr2.(time.Time)
diff := int64(math.Round(date1.Sub(date2).Hours() / 24))
return diff, nil
}
func (d *DateDiff) String() string {
return fmt.Sprintf("DATEDIFF(%s, %s)", d.Left, d.Right)
}
// TimestampDiff returns expr1 − expr2 expressed as a value in unit specified.
type TimestampDiff struct {
unit sql.Expression
expr1 sql.Expression
expr2 sql.Expression
}
var _ sql.FunctionExpression = (*TimestampDiff)(nil)
// NewTimestampDiff creates a new TIMESTAMPDIFF() function.
func NewTimestampDiff(u, e1, e2 sql.Expression) sql.Expression {
return &TimestampDiff{u, e1, e2}
}
// FunctionName implements sql.FunctionExpression
func (t *TimestampDiff) FunctionName() string {
return "timestampdiff"
}
// Description implements sql.FunctionExpression
func (t *TimestampDiff) Description() string {
return "gets difference between two dates in result of units specified."
}
// Children implements the sql.Expression interface.
func (t *TimestampDiff) Children() []sql.Expression {
return []sql.Expression{t.unit, t.expr1, t.expr2}
}
// Resolved implements the sql.Expression interface.
func (t *TimestampDiff) Resolved() bool {
return t.unit.Resolved() && t.expr1.Resolved() && t.expr2.Resolved()
}
// IsNullable implements the sql.Expression interface.
func (t *TimestampDiff) IsNullable() bool {
return t.unit.IsNullable() && t.expr1.IsNullable() && t.expr2.IsNullable()
}
// Type implements the sql.Expression interface.
func (t *TimestampDiff) Type() sql.Type { return types.Int64 }
// WithChildren implements the Expression interface.
func (t *TimestampDiff) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 3 {
return nil, sql.ErrInvalidChildrenNumber.New(t, len(children), 3)
}
return NewTimestampDiff(children[0], children[1], children[2]), nil
}
// Eval implements the sql.Expression interface.
func (t *TimestampDiff) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
if t.unit == nil {
return nil, errors.NewKind("unit cannot be null").New(t.unit)
}
if t.expr1 == nil || t.expr2 == nil {
return nil, nil
}
expr1, err := t.expr1.Eval(ctx, row)
if err != nil {
return nil, err
}
if expr1 == nil {
return nil, nil
}
expr2, err := t.expr2.Eval(ctx, row)
if err != nil {
return nil, err
}
if expr2 == nil {
return nil, nil
}
expr1, err = types.Datetime.Convert(expr1)
if err != nil {
return nil, err
}
expr2, err = types.Datetime.Convert(expr2)
if err != nil {
return nil, err
}
unit, err := t.unit.Eval(ctx, row)
if err != nil {
return nil, err
}
if unit == nil {
return nil, errors.NewKind("unit cannot be null").New(unit)
}
unit = strings.TrimPrefix(strings.ToLower(unit.(string)), "sql_tsi_")
date1 := expr1.(time.Time)
date2 := expr2.(time.Time)
diff := date2.Sub(date1)
var res int64
switch unit {
case "microsecond":
res = diff.Microseconds()
case "second":
res = int64(diff.Seconds())
case "minute":
res = int64(diff.Minutes())
case "hour":
res = int64(diff.Hours())
case "day":
res = int64(diff.Hours() / 24)
case "week":
res = int64(diff.Hours() / (24 * 7))
case "month":
res = int64(diff.Hours() / (24 * 30))
if res > 0 {
if date2.Day()-date1.Day() < 0 {
res -= 1
} else if date2.Hour()-date1.Hour() < 0 {
res -= 1
} else if date2.Minute()-date1.Minute() < 0 {
res -= 1
} else if date2.Second()-date1.Second() < 0 {
res -= 1
}
}
case "quarter":
monthRes := int64(diff.Hours() / (24 * 30))
if monthRes > 0 {
if date2.Day()-date1.Day() < 0 {
monthRes -= 1
} else if date2.Hour()-date1.Hour() < 0 {
monthRes -= 1
} else if date2.Minute()-date1.Minute() < 0 {
monthRes -= 1
} else if date2.Second()-date1.Second() < 0 {
monthRes -= 1
}
}
res = monthRes / 3
case "year":
yearRes := int64(diff.Hours() / (24 * 365))
if yearRes > 0 {
monthRes := int64(diff.Hours() / (24 * 30))
if monthRes > 0 {
if date2.Day()-date1.Day() < 0 {
monthRes -= 1
} else if date2.Hour()-date1.Hour() < 0 {
monthRes -= 1
} else if date2.Minute()-date1.Minute() < 0 {
monthRes -= 1
} else if date2.Second()-date1.Second() < 0 {
monthRes -= 1
}
}
res = monthRes / 12
} else {
res = yearRes
}
default:
return nil, errors.NewKind("invalid interval unit: %s").New(unit)
}
return res, nil
}
func (t *TimestampDiff) String() string {
return fmt.Sprintf("TIMESTAMPDIFF(%s, %s, %s)", t.unit, t.expr1, t.expr2)
}