54 lines
1.1 KiB
Go
54 lines
1.1 KiB
Go
package types
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import (
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"encoding/json"
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)
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// Null represents a value of any type T that may be null.
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type Null[T any] struct {
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value T
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valid bool
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}
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// NullWithValue creates a new, valid Null[T].
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func NullWithValue[T any](value T) Null[T] {
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return Null[T]{value: value, valid: true}
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}
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// Value returns the value of the Type[T] if set, otherwise it returns the provided default value or the zero value of T.
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func (n Null[T]) Value(defaultValue ...T) T {
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if n.valid {
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return n.value
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}
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if len(defaultValue) > 0 {
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return defaultValue[0]
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}
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var zero T
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return zero
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}
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// SetValue sets the value of the Type[T].
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func (n *Null[T]) SetValue(t T) {
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n.value = t
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n.valid = true
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}
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// MarshalJSON implements [json.Marshaler].
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func (n Null[T]) MarshalJSON() ([]byte, error) {
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if n.valid {
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return json.Marshal(n.value)
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}
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return []byte("null"), nil
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}
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// UnmarshalJSON implements [json.Unmarshaler].
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func (n *Null[T]) UnmarshalJSON(data []byte) error {
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if string(data) != "null" {
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if err := json.Unmarshal(data, &n.value); err != nil {
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return err
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}
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n.valid = true
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}
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return nil
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}
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