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float.go
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float.go
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// Copyright 2019 HouseCanary, 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 nillabletypes
import (
"bytes"
"database/sql/driver"
"strconv"
"github.com/pkg/errors"
"github.com/segmentio/encoding/json"
)
// Float represents a nil-able float
type Float struct {
v float64
present bool
initialized bool
}
// NewFloat makes a new non-nil Float
func NewFloat(v float64) Float {
return Float{v: v, present: true, initialized: true}
}
// NilFloat makes a new nil Float
func NilFloat() Float {
return Float{0, false, true}
}
// Float returns the built-in float64 value
func (v Float) Float() float64 {
return v.v
}
// Nil returns whether this scalar is nil
func (v Float) Nil() bool {
return !v.present
}
// String implements the fmt.Stringer interface
func (v Float) String() string {
return strconv.FormatFloat(v.v, 'f', -1, 64)
}
// UnmarshalJSON implements the json.Unmarshaler interface
func (v *Float) UnmarshalJSON(data []byte) error {
if bytes.Equal(data, []byte{'n', 'u', 'l', 'l'}) {
v.present = false
v.initialized = true
return nil
}
err := json.Unmarshal(data, &v.v)
if err != nil {
return errors.WithStack(err)
}
v.present = true
v.initialized = true
return nil
}
// MarshalJSON implements the json.Marshaler interface
func (v Float) MarshalJSON() ([]byte, error) {
if !v.initialized || !v.present {
return []byte{'n', 'u', 'l', 'l'}, nil
}
return json.Marshal(v.v)
}
// Value implements the driver.Valuer interface
func (v Float) Value() (driver.Value, error) {
if !v.present {
return nil, nil
}
return v.v, nil
}
// Scan implements the sql.Scanner interface
func (v *Float) Scan(src interface{}) error {
if src == nil {
*v = Float{present: false, initialized: true}
return nil
}
switch t := src.(type) {
case float64:
*v = Float{v: t, present: true, initialized: true}
return nil
case int64:
*v = Float{v: float64(t), present: true, initialized: true}
return nil
case bool:
if t {
*v = Float{v: 1, present: true, initialized: true}
} else {
*v = Float{v: 0, present: true, initialized: true}
}
return nil
case []byte:
s := string(t)
return v.scanString(s)
case string:
return v.scanString(t)
}
return errors.Errorf("cannot scan value %[1]v of type %[1]T to a float", src)
}
func (v *Float) scanString(src string) error {
f, err := strconv.ParseFloat(src, 64)
if err != nil {
return errors.Errorf("cannot scan value %[1]v of type %[1]T to a float", src)
}
*v = Float{v: f, present: true, initialized: true}
return nil
}