Struct ItemPresent 

pub struct ItemPresent<T: Default>(pub T);

An item that only matters in terms of presence of absence.

Useful for items such as tunnelled-dir-server where the mere presence implies a truthful value.

This wrapper implements ItemValueParseable and ItemValueEncodable rejecting all arguments and objects and just expecting/emitting the keyword (or not).

Examples

The following shows an except from a hypothetical netdoc with a ItemPresent item.

use derive_deftly::Deftly;
use tor_netdoc::types::*;
use tor_netdoc::parse2::*;
use tor_netdoc::*;

#[derive(Debug, Default)]
struct Hello;

#[derive(Deftly, Debug)]
#[derive_deftly(NetdocParseable)]
struct TestDoc {
    intro: Ignored,
    hello: Option<ItemPresent<Hello>>,
}

// hello is not present.
let doc = parse_netdoc::<TestDoc>(&ParseInput::new("intro\n", "")).unwrap();
assert!(doc.hello.is_none());

// hello is present.
let doc = parse_netdoc::<TestDoc>(&ParseInput::new("intro\nhello\n", "")).unwrap();
assert!(doc.hello.is_some());

// hello has arguments which are ignored.
let doc = parse_netdoc::<TestDoc>(&ParseInput::new("intro\nhello world\n", "")).unwrap();
assert!(doc.hello.is_some());

// hello is present twice which is not allowed.
let doc = parse_netdoc::<TestDoc>(&ParseInput::new("intro\nhello\nhello\n", "")).unwrap_err();

Tuple Fields

0: T

Trait Implementations

impl<T: Default> AsMut<T> for ItemPresent<T>

fn as_mut(&mut self) -> &mut T

Converts this type into a mutable reference of the (usually inferred) input type.

impl<T: Default> AsRef<T> for ItemPresent<T>

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<T: Clone + Default> Clone for ItemPresent<T>

fn clone(&self) -> ItemPresent<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Copy + Default> Copy for ItemPresent<T>

impl<T: Debug + Default> Debug for ItemPresent<T>

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

Formats the value using the given formatter.

impl<T: Default + Default> Default for ItemPresent<T>

fn default() -> ItemPresent<T>

Returns the “default value” for a type.

impl<T: Default> Deref for ItemPresent<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T: Default> DerefMut for ItemPresent<T>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T: Eq + Default> Eq for ItemPresent<T>

impl<T: Default> From<T> for ItemPresent<T>

fn from(value: T) -> Self

Converts to this type from the input type.

impl<T: Hash + Default> Hash for ItemPresent<T>

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<T: Default> ItemValueEncodable for ItemPresent<T>

fn write_item_value_onto(&self, out: ItemEncoder<'_>) -> StdResult<(), Bug>

Write the item’s arguments, and any object, onto out

impl<T: Default> ItemValueParseable for ItemPresent<T>

fn from_unparsed(item: UnparsedItem<'_>) -> StdResult<Self, EP>

Parse the item’s value

impl<T: Ord + Default> Ord for ItemPresent<T>

fn cmp(&self, other: &ItemPresent<T>) -> 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<T: PartialEq + Default> PartialEq for ItemPresent<T>

fn eq(&self, other: &ItemPresent<T>) -> 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<T: PartialOrd + Default> PartialOrd for ItemPresent<T>

fn partial_cmp(&self, other: &ItemPresent<T>) -> 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<T: PartialEq + Default> StructuralPartialEq for ItemPresent<T>