# Struct Stack

    pub struct Stack { /* private fields */ }

Expand description

Operand stack for DICTs and charstrings.

The operand stack can contain either 32-bit integers or 16.16 fixed point values. The type is known when pushing to the stack and the expected type is also known (based on the operator) when reading from the stack, so the conversion is performed on demand at read time.

Storing the entries as an enum would require 8 bytes each and since these objects are created on the stack, we reduce the required size by storing the entries in parallel arrays holding the raw 32-bit value and a flag that tracks which values are fixed point.

## Implementations§

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### impl Stack

#### pub fn new() -> Stack

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

#### pub fn len(&self) -> usize

#### pub fn verify_exact_len(&self, len: usize) -> Result<(), Error>

#### pub fn verify_at_least_len(&self, len: usize) -> Result<(), Error>

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

Returns true if the number of elements on the stack is odd.

Used for processing some charstring operators where an odd count represents the presence of the glyph advance width at the bottom of the stack.

#### pub fn clear(&mut self)

#### pub fn reverse(&mut self)

Reverse the order of all elements on the stack.

Some charstring operators are simpler to process on a reversed stack.

#### pub fn push(&mut self, number: impl Into<Number>) -> Result<(), Error>

#### pub fn get_i32(&self, index: usize) -> Result<i32, Error>

Returns the 32-bit integer at the given index on the stack.

Will return an error if the value at that index was not pushed as an integer.

#### pub fn get_fixed(&self, index: usize) -> Result<Fixed, Error>

Returns the 16.16 fixed point value at the given index on the stack.

If the value was pushed as an integer, it will be automatically converted to 16.16 fixed point.

#### pub fn pop_i32(&mut self) -> Result<i32, Error>

Pops a 32-bit integer from the top of stack.

Will return an error if the top value on the stack was not pushed as an integer.

#### pub fn pop_fixed(&mut self) -> Result<Fixed, Error>

Pops a 16.16 fixed point value from the top of the stack.

If the value was pushed as an integer, it will be automatically converted to 16.16 fixed point.

#### pub fn fixed_values(&self) -> impl Iterator<Item = Fixed>

Returns an iterator yielding all elements on the stack as 16.16 fixed point values.

Used to read array style DICT entries such as blue values, font matrix and font bounding box.

#### pub fn fixed_array<const N: usize>( &self, first_index: usize, ) -> Result<[Fixed; N], Error>

Returns an array of `N` 16.16 fixed point values starting at `first_index`.

#### pub fn number_values(&self) -> impl Iterator<Item = Number>

Returns an iterator yielding all elements on the stack as number values.

This is useful for capturing the current state of the stack.

#### pub fn apply_delta_prefix_sum(&mut self)

Apply a prefix sum to decode delta-encoded numbers.

“The second and subsequent numbers in a delta are encoded as the difference between successive values.”

Roughly equivalent to the FreeType logic at https://gitlab.freedesktop.org/freetype/freetype/-/blob/57617782464411201ce7bbc93b086c1b4d7d84a5/src/cff/cffparse.c#L1431

See https://learn.microsoft.com/en-us/typography/opentype/spec/cff2#table-6-operand-types

#### pub fn apply_blend(&mut self, blend_state: &BlendState<'_>) -> Result<(), Error>

Apply the `blend` operator.

See https://learn.microsoft.com/en-us/typography/opentype/spec/cff2charstr#syntax-for-font-variations-support-operators

## Trait Implementations§

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### impl Default for Stack

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#### fn default() -> Stack

Returns the “default value” for a type. Read more

## Auto Trait Implementations§

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### impl Freeze for Stack

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### impl RefUnwindSafe for Stack

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### impl Send for Stack

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### impl Sync for Stack

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### impl Unpin for Stack

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### impl UnwindSafe for Stack

## Blanket Implementations§

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### impl<S, D, Swp, Dwp, T> AdaptInto<D, Swp, Dwp, T> for S
where T: Real + Zero + Arithmetics + Clone, Swp: WhitePoint<T>, Dwp: WhitePoint<T>, D: AdaptFrom<S, Swp, Dwp, T>,

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#### fn adapt_into_using<M>(self, method: M) -> D
where M: TransformMatrix<T>,

Convert the source color to the destination color using the specified method.
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#### fn adapt_into(self) -> D

Convert the source color to the destination color using the bradford method by default.
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### impl<T> Also for T

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#### fn also<F>(self, block: F) -> Self
where F: FnOnce(&mut Self),

Apply a function to this value and return the (possibly) modified value.
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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, Res> Apply<Res> for T
where T: ?Sized,

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#### fn apply<F>(self, f: F) -> Res
where F: FnOnce(Self) -> Res, Self: Sized,

Apply a function which takes the parameter by value.
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#### fn apply_ref<F>(&self, f: F) -> Res
where F: FnOnce(&Self) -> Res,

Apply a function which takes the parameter by reference.
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#### fn apply_mut<F>(&mut self, f: F) -> Res
where F: FnOnce(&mut Self) -> Res,

Apply a function which takes the parameter by mutable reference.
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### impl<T, C> ArraysFrom<C> for T
where C: IntoArrays<T>,

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#### fn arrays_from(colors: C) -> T

Cast a collection of colors into a collection of arrays.
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### impl<T, C> ArraysInto<C> for T
where C: FromArrays<T>,

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#### fn arrays_into(self) -> C

Cast this collection of arrays into a collection of colors.
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### 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,

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

Mutably borrows from an owned value. Read more
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### impl<WpParam, T, U> Cam16IntoUnclamped<WpParam, T> for U
where T: FromCam16Unclamped<WpParam, U>,

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#### type Scalar = <T as FromCam16Unclamped<WpParam, U>>::Scalar

The number type that’s used in `parameters` when converting.
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#### fn cam16_into_unclamped( self, parameters: BakedParameters<WpParam, <U as Cam16IntoUnclamped<WpParam, T>>::Scalar>, ) -> T

Converts `self` into `C`, using the provided parameters.
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### impl<T, C> ComponentsFrom<C> for T
where C: IntoComponents<T>,

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#### fn components_from(colors: C) -> T

Cast a collection of colors into a collection of color components.
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### impl<T> Downcast for T
where T: Any,

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#### fn into_any(self: Box<T>) -> Box<dyn Any>

Convert `Box<dyn Trait>` (where `Trait: Downcast`) to `Box<dyn Any>`. `Box<dyn Any>` can then be further `downcast` into `Box<ConcreteType>` where `ConcreteType` implements `Trait`.
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#### fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>

Convert `Rc<Trait>` (where `Trait: Downcast`) to `Rc<Any>`. `Rc<Any>` can then be further `downcast` into `Rc<ConcreteType>` where `ConcreteType` implements `Trait`.
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#### fn as_any(&self) -> &(dyn Any + 'static)

Convert `&Trait` (where `Trait: Downcast`) to `&Any`. This is needed since Rust cannot generate `&Any`’s vtable from `&Trait`’s.
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#### fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Convert `&mut Trait` (where `Trait: Downcast`) to `&Any`. This is needed since Rust cannot generate `&mut Any`’s vtable from `&mut Trait`’s.
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### impl<T> DowncastSync for T
where T: Any + Send + Sync,

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#### fn into_any_arc(self: Arc<T>) -> Arc<dyn Any + Sync + Send>

Convert `Arc<Trait>` (where `Trait: Downcast`) to `Arc<Any>`. `Arc<Any>` can then be further `downcast` into `Arc<ConcreteType>` where `ConcreteType` implements `Trait`.
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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> FromAngle<T> for T

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#### fn from_angle(angle: T) -> T

Performs a conversion from `angle`.
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### impl<T, U> FromStimulus<U> for T
where U: IntoStimulus<T>,

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#### fn from_stimulus(other: U) -> T

Converts `other` into `Self`, while performing the appropriate scaling, rounding and clamping.
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### impl<T> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self> ⓘ

Instruments this type with the provided [`Span`], returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self> ⓘ

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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### impl<T, U> Into<U> for T
where U: From<T>,

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#### 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, U> IntoAngle<U> for T
where U: FromAngle<T>,

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

Performs a conversion into `T`.
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### impl<State, Message> IntoBoot<State, Message> for State

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#### fn into_boot(self) -> (State, Task<Message>)

Turns some type into the initial state of some `Application`.
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### impl<WpParam, T, U> IntoCam16Unclamped<WpParam, T> for U
where T: Cam16FromUnclamped<WpParam, U>,

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#### type Scalar = <T as Cam16FromUnclamped<WpParam, U>>::Scalar

The number type that’s used in `parameters` when converting.
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#### fn into_cam16_unclamped( self, parameters: BakedParameters<WpParam, <U as IntoCam16Unclamped<WpParam, T>>::Scalar>, ) -> T

Converts `self` into `C`, using the provided parameters.
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### impl<T, U> IntoColor<U> for T
where U: FromColor<T>,

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

Convert into T with values clamped to the color defined bounds Read more
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### impl<T, U> IntoColorUnclamped<U> for T
where U: FromColorUnclamped<T>,

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

Convert into T. The resulting color might be invalid in its color space Read more
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### impl<T> IntoStimulus<T> for T

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#### fn into_stimulus(self) -> T

Converts `self` into `T`, while performing the appropriate scaling, rounding and clamping.
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### impl<T> NoneValue for T
where T: Default,

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#### type NoneType = T

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#### fn null_value() -> T

The none-equivalent value.
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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<T, C> TryComponentsInto<C> for T
where C: TryFromComponents<T>,

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#### type Error = <C as TryFromComponents<T>>::Error

The error for when `try_into_colors` fails to cast.
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#### fn try_components_into(self) -> Result<C, <T as TryComponentsInto<C>>::Error>

Try to cast this collection of color components into a collection of colors. Read more
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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### 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>,

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

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<T, U> TryIntoColor<U> for T
where U: TryFromColor<T>,

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#### fn try_into_color(self) -> Result<U, OutOfBounds<U>>

Convert into T, returning ok if the color is inside of its defined range, otherwise an `OutOfBounds` error is returned which contains the unclamped color. Read more
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### impl<C, U> UintsFrom<C> for U
where C: IntoUints<U>,

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#### fn uints_from(colors: C) -> U

Cast a collection of colors into a collection of unsigned integers.
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### impl<C, U> UintsInto<C> for U
where C: FromUints<U>,

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#### fn uints_into(self) -> C

Cast this collection of unsigned integers into a collection of colors.
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### impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> ⓘ
where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a [`WithDispatch`] wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self> ⓘ

Attaches the current default `Subscriber` to this type, returning a [`WithDispatch`] wrapper. Read more
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### impl<T> MaybeClone for T

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### impl<T> MaybeDebug for T

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### impl<T> MaybeSend for T
where T: Send,

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### impl<T> MaybeSend for T
where T: Send,

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### impl<T> MaybeSync for T
where T: Sync,

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### impl<T> MaybeSync for T
where T: Sync,