# Needed in nom - Rust
Contains information on needed data if a parser returned `Incomplete`
Keywords: rust, rustlang, rust-lang, Needed

# Enum nom::Needed

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    pub enum Needed {
        Unknown,
        Size(NonZeroUsize),
    }

Expand description

Contains information on needed data if a parser returned `Incomplete`

## Variants

### `Unknown`

Needs more data, but we do not know how much

### `Size(NonZeroUsize)`

Contains the required data size in bytes

## Implementations

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### impl Needed

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#### pub fn new(s: usize) -> Self

Creates `Needed` instance, returns `Needed::Unknown` if the argument is zero

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#### pub fn is_known(&self) -> bool

Indicates if we know how many bytes we need

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#### pub fn map<F: Fn(NonZeroUsize) -> usize>(self, f: F) -> Needed

Maps a `Needed` to `Needed` by applying a function to a contained `Size` value.

## Trait Implementations

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### impl Clone for Needed

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#### fn clone(&self) -> Needed

Returns a copy of the value. Read more

1.0.0 · source

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

Performs copy-assignment from `source`. Read more

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### impl Debug for Needed

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

Formats the value using the given formatter. Read more

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### impl PartialEq<Needed> for Needed

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

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

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

This method tests for `!=`.

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### impl Copy for Needed

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### impl Eq for Needed

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### impl StructuralEq for Needed

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### impl StructuralPartialEq for Needed

## Auto Trait Implementations

### impl RefUnwindSafe for Needed

### impl Send for Needed

### impl Sync for Needed

### impl Unpin for Needed

### impl UnwindSafe for Needed

## Blanket Implementations

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### impl<T> Any for T where
T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more

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### impl<T> Borrow<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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### impl<T> BorrowMut<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T where
U: From<T>,

const: unstable · source

#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> ToOwned for T where
T: Clone,

#### type Owned = T

The resulting type after obtaining ownership.

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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more

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### impl<T, U> TryFrom<U> for T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

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### impl<T, U> TryInto<U> for T where
U: TryFrom<T>,

#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.