niljson/niljson.go

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// SPDX-FileCopyrightText: 2024 Winni Neessen <wn@neessen.dev>
//
// SPDX-License-Identifier: MIT
package niljson
import (
"encoding/json"
)
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// Variable is a generic variable type that can be null.
type Variable[T any] struct {
value T
notNil bool
}
// Value returns the value of the Variable
func (v *Variable[T]) Value() T {
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return v.value
}
// NotNil returns true when a Variable is not nil
func (v *Variable[T]) NotNil() bool {
return v.notNil
}
// IsNil returns true when a Variable is nil
func (v *Variable[T]) IsNil() bool {
return !v.notNil
}
// Reset resets the value to the Variable to a zero value and sets it to be nil
func (v *Variable[T]) Reset() {
var newVal T
v.value = newVal
v.notNil = false
}
// NewVariable returns a new Variable of generic type
func NewVariable[T any](value T) Variable[T] {
return Variable[T]{
notNil: true,
value: value,
}
}
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// NilBoolean is an boolean type that can be nil
type NilBoolean = Variable[bool]
// NilByteSlice is a []byte type that can be nil
type NilByteSlice = Variable[[]byte]
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// NilInt is an int type that can be nil
type NilInt = Variable[int]
// NilInt64 is an int64 type that can be nil
type NilInt64 = Variable[int64]
// NilUInt is an uint type that can be nil
type NilUInt = Variable[uint]
// NilUInt8 is an uint8 type that can be nil
type NilUInt8 = Variable[uint8]
// NilUInt16 is an uint16 type that can be nil
type NilUInt16 = Variable[uint16]
// NilUInt32 is an uint32 type that can be nil
type NilUInt32 = Variable[uint32]
// NilUInt64 is an uint64 type that can be nil
type NilUInt64 = Variable[uint64]
// NilFloat32 is an float32 type that can be nil
type NilFloat32 = Variable[float32]
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// NilFloat64 is an float64 type that can be nil
type NilFloat64 = Variable[float64]
// NilString is a string type that can be nil
type NilString = Variable[string]
// UnmarshalJSON satisfies the json.Unmarshaler interface for generic Variable types
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func (v *Variable[T]) UnmarshalJSON(data []byte) error {
if string(data) != "null" {
v.value = *new(T)
v.notNil = true
return json.Unmarshal(data, &v.value)
}
return nil
}
// MarshalJSON satisfies the json.Marshaler interface for generic Variable types
func (v *Variable[T]) MarshalJSON() ([]byte, error) {
if !v.notNil {
return json.Marshal(nil)
}
return json.Marshal(v.value)
}