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factorial.go
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factorial.go
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// Copyright 2024 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 functions
import (
"fmt"
"github.com/shopspring/decimal"
"github.com/dolthub/doltgresql/server/functions/framework"
pgtypes "github.com/dolthub/doltgresql/server/types"
)
// initFactorial registers the functions to the catalog.
func initFactorial() {
framework.RegisterFunction(factorial_int64)
}
// factorial_int64 represents the PostgreSQL function of the same name, taking the same parameters.
var factorial_int64 = framework.Function1{
Name: "factorial",
Return: pgtypes.Numeric,
Parameters: []pgtypes.DoltgresType{pgtypes.Int64},
Callable: func(ctx framework.Context, val1Interface any) (any, error) {
if val1Interface == nil {
return nil, nil
}
val1 := val1Interface.(int64)
if val1 < 0 {
return nil, fmt.Errorf("factorial of a negative number is undefined")
}
total := int64(1)
for i := int64(2); i <= val1; i++ {
total *= i
}
return decimal.NewFromInt(total), nil
},
}