Enum TriState 

pub enum TriState {
    Yes,
    No,
    Unknown,
}

A three-valued type equivalent to Option<bool>.

Variants

Yes

The tri-state value signifying definitive truth.

No

The tri-state value signifying definitive falsity.

Unknown

The tri-state value signifying an unknown truth value.

Implementations

impl TriState

pub fn yes(self) -> bool

Is self equal to Yes?

pub fn no(self) -> bool

Is self equal to No?

pub fn unknown(self) -> bool

Is self equal to Unknown?

pub fn definitely(self) -> bool

A mnemonic for yes().

pub fn definitely_not(self) -> bool

A mnemonic for no().

pub fn to_bool(self) -> Option<bool>

Converts self to an Option<bool>. Equivalent to Option::<bool>::from(self).

Trait Implementations

impl Clone for TriState

fn clone(&self) -> TriState

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TriState

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TriState

fn default() -> Self

Returns the “default value” for a type.

impl From<Option<bool>> for TriState

fn from(b: Option<bool>) -> TriState

Converts to this type from the input type.

impl From<TriState> for Option<bool>

fn from(t: TriState) -> Option<bool>

Converts to this type from the input type.

impl From<bool> for TriState

fn from(b: bool) -> TriState

Converts to this type from the input type.

impl Ord for TriState

fn cmp(&self, other: &TriState) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for TriState

fn eq(&self, other: &TriState) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for TriState

fn partial_cmp(&self, other: &TriState) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for TriState

impl Eq for TriState

impl StructuralPartialEq for TriState