115 lines
2.4 KiB
Go
115 lines
2.4 KiB
Go
package lemmy
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"net/url"
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)
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// Optional represents an optional value
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type Optional[T any] struct {
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value *T
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}
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// NewOptional creates an optional with value v
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func NewOptional[T any](v T) Optional[T] {
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return Optional[T]{value: &v}
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}
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// NewOptionalNil creates a new nil optional value
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func NewOptionalNil[T any]() Optional[T] {
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return Optional[T]{}
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}
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// Set sets the value of the optional
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func (o Optional[T]) Set(v T) Optional[T] {
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o.value = &v
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return o
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}
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// SetNil sets the optional value to nil
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func (o Optional[T]) SetNil() Optional[T] {
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o.value = nil
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return o
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}
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// IsValid returns true if the value of the optional is not nil
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func (o Optional[T]) IsValid() bool {
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return o.value != nil
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}
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// MustValue returns the value in the optional. It panics if the value is nil.
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func (o Optional[T]) MustValue() T {
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if o.value == nil {
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panic("optional value is nil")
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}
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return *o.value
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}
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// Value returns the value in the optional.
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func (o Optional[T]) Value() (T, bool) {
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if o.value != nil {
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return *o.value, true
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}
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return *new(T), false
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}
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// ValueOr returns the value inside the optional if it exists, or else it returns fallback
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func (o Optional[T]) ValueOr(fallback T) T {
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if o.value != nil {
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return *o.value
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}
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return fallback
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}
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// ValueOrZero returns the value inside the optional if it exists, or else it returns the zero value of T
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func (o Optional[T]) ValueOrZero() T {
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if o.value != nil {
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return *o.value
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}
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var value T
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return value
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}
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// MarshalJSON encodes the optional value as JSON
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func (o Optional[T]) MarshalJSON() ([]byte, error) {
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return json.Marshal(o.value)
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}
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// UnmarshalJSON decodes JSON into the optional value
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func (o *Optional[T]) UnmarshalJSON(b []byte) error {
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if bytes.Equal(b, []byte("null")) {
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o.value = nil
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return nil
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}
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o.value = new(T)
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return json.Unmarshal(b, o.value)
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}
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// EncodeValues encodes the optional as a URL query parameter
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func (o Optional[T]) EncodeValues(key string, v *url.Values) error {
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s := o.String()
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if s != "<nil>" {
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v.Set(key, s)
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}
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return nil
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}
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// String returns the string representation of the optional value
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func (o Optional[T]) String() string {
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if o.value == nil {
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return "<nil>"
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}
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return fmt.Sprint(*o.value)
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}
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// GoString returns the Go representation of the optional value
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func (o Optional[T]) GoString() string {
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if o.value == nil {
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return "nil"
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}
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return fmt.Sprintf("%#v", *o.value)
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}
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