/
arraylength.go
87 lines (72 loc) · 2.25 KB
/
arraylength.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 function
import (
"fmt"
"github.com/Ciyfly/FakerMysql/sql"
"github.com/Ciyfly/FakerMysql/sql/expression"
)
// ArrayLength returns the length of an array.
type ArrayLength struct {
expression.UnaryExpression
}
var _ sql.FunctionExpression = (*ArrayLength)(nil)
// NewArrayLength creates a new ArrayLength UDF.
func NewArrayLength(array sql.Expression) sql.Expression {
return &ArrayLength{expression.UnaryExpression{Child: array}}
}
// FunctionName implements sql.FunctionExpression
func (f *ArrayLength) FunctionName() string {
return "array_length"
}
// Type implements the Expression interface.
func (*ArrayLength) Type() sql.Type {
return sql.Int32
}
func (f *ArrayLength) String() string {
return fmt.Sprintf("array_length(%s)", f.Child)
}
// WithChildren implements the Expression interface.
func (f *ArrayLength) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(f, len(children), 1)
}
return NewArrayLength(children[0]), nil
}
// Eval implements the Expression interface.
func (f *ArrayLength) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
t := f.Child.Type()
if !sql.IsArray(t) && !sql.IsJSON(t) {
return nil, nil
}
child, err := f.Child.Eval(ctx, row)
if err != nil {
return nil, err
}
if child == nil {
return nil, nil
}
if val, ok := child.(sql.JSONValue); ok {
js, err := val.Unmarshall(ctx)
if err != nil {
return nil, err
}
child = js.Val
}
array, ok := child.([]interface{})
if !ok {
return nil, nil
}
return int32(len(array)), nil
}