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70 lines
1.5 KiB
Go
70 lines
1.5 KiB
Go
package opt
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import "fmt"
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// String holds an optional string value.
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type String struct {
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value *string
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}
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// NullString represents an empty optional String.
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var NullString = String{nil}
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// NewString creates a new optional String with the given value.
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func NewString(value string) String {
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return String{&value}
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}
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// NewNotEmptyString creates a new optional String with the given value or
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// returns NullString if the value is an empty string.
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func NewNotEmptyString(value string) String {
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if value == "" {
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return NullString
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} else {
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return NewString(value)
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}
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}
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// IsNull returns whether the optional String has no value.
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func (s String) IsNull() bool {
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return s.value == nil
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}
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// Or returns the receiver if it is not null, otherwise the given optional
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// String.
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func (s String) Or(other String) String {
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if s.IsNull() {
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return other
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} else {
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return s
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}
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}
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// OrDefault returns the optional String value or the given default string if
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// it is null.
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func (s String) OrDefault(def string) string {
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if s.IsNull() {
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return def
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} else {
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return *s.value
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}
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}
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// Unwrap returns the optional String value or an empty String if none is set.
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func (s String) Unwrap() string {
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return s.OrDefault("")
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}
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func (s String) Equal(other String) bool {
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return s.value == other.value ||
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(s.value != nil && other.value != nil && *s.value == *other.value)
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}
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func (s String) String() string {
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return s.OrDefault("")
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}
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func (s String) MarshalJSON() ([]byte, error) {
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return []byte(fmt.Sprintf(`"%v"`, s)), nil
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}
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