Struct GenericPackedPatterns 

pub struct GenericPackedPatterns<'data, T: VarULE + ?Sized> {
    pub header: u32,
    pub elements: VarZeroVec<'data, T>,
}

📏 This item has a stack size of 32 bytes on the stable toolchain at release date.

Variants

This supports a set of “standard” patterns plus up to two “variants”. The variants are currently used by year formatting:

• Standard: Year, which could be partial precision (2-digit Gregorian)
• Variant 0: Full Year, which is always full precision
• Variant 1: Year With Era

And by time formatting:

• Standard: Hour only
• Variant 0: Hour and minute
• Variant 1: Hour, minute, and second

Variants should be used when the pattern could depend on the value being formatted. For example, with YearStyle::Auto, any of these three patterns could be selected based on the year value.

Representation

Currently, there are at most 9 patterns that need to be stored together, named according to this table:

	Standard	Variant 0	Variant 1
Long	La	Lb	Lc
Medium	Ma	Mb	Mc
Short	Sa	Sb	Sc

The header byte encodes which pattern in the patterns array corresponds to a particular cell in the table. It contains the following information:

• Bits 0-1: “LMS” value of the standard column
• Bit 2: “Q” value: 1 for directly-indexed variants; 0 for per-cell offsets
• Bits 3-20: Packed offset into patterns table for each variant cell
• Bits 21-31: unused/reserved

The LMS value determines which pattern index is used for the first column:

LMS Value	Long Index	Medium Index	Short Index
0 (L=M=S)	0	0	0
1 (L, M=S)	0	1	1
2 (L=M, S)	0	0	1
3 (L, M, S)	0	1	2

If bit 2 is 1 (Q=1), it means there is one pattern per table cell, with the index offset by the short index S from the table above. However, this requires storing multiple, possibly duplicate, patterns in the packed structure. The more common case is Q=0 and then to store per-cell offsets in chunks of 3 bits per cell:

• Chunk = 0: Inherit according to the table below
• Chunk = 1-7: Use pattern index Chunk - 1

This is summarized below:

Cell in Table	Q=1 Pattern Index	Q=0 Header Bits	Inheritance
Lb	S + 1	3-5	La
Mb	S + 2	6-8	Ma
Sb	S + 3	9-11	Sa
Lc	S + 4	12-14	La
Mc	S + 5	15-17	Ma
Sc	S + 6	18-20	Sa

As a result, if there are no variants, bits 2 and higher will be all zero, making the header int suitable for varint packing, such as that used by postcard and other size-optimized serialization formats.

Fields

header: u32

An encoding of which standard/variant cell corresponds to which entry in the patterns table. See class docs.

elements: VarZeroVec<'data, T>

The list of patterns. Length should be between 1 and 9, depending on the header.

Implementations

impl<'data> GenericPackedPatterns<'data, PluralElementsPackedULE<ZeroSlice<PatternItem>>>

pub fn to_builder(&self) -> PackedPatternsBuilder<'_>

Converts this packed data to a builder that can be mutated.

Trait Implementations

impl<'data, T: VarULE + ?Sized> Bake for GenericPackedPatterns<'data, T>

where VarZeroVec<'data, T>: Bake,

fn bake(&self, env: &CrateEnv) -> TokenStream

Returns a TokenStream that would evaluate to self.

impl<'data, T: VarULE + ?Sized> BakeSize for GenericPackedPatterns<'data, T>

where VarZeroVec<'data, T>: BakeSize,

fn borrows_size(&self) -> usize

Returns the size

impl<'data, T: VarULE + ?Sized> Clone for GenericPackedPatterns<'data, T>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'data, T: Debug + VarULE + ?Sized> Debug for GenericPackedPatterns<'data, T>

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

Formats the value using the given formatter.

impl<'de, 'data> Deserialize<'de> for GenericPackedPatterns<'data, PluralElementsPackedULE<ZeroSlice<PatternItem>>>

where 'de: 'data,

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'data, T: Eq + VarULE + ?Sized> Eq for GenericPackedPatterns<'data, T>

impl<'data, T: PartialEq + VarULE + ?Sized> PartialEq for GenericPackedPatterns<'data, T>

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for GenericPackedPatterns<'_, PluralElementsPackedULE<ZeroSlice<PatternItem>>>

Available on crate feature datagen only.

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<'data, T: PartialEq + VarULE + ?Sized> StructuralPartialEq for GenericPackedPatterns<'data, T>

impl<'yoke, T> Yokeable<'yoke> for GenericPackedPatterns<'static, T>

where T: 'static + VarULE + ?Sized,

type Output = GenericPackedPatterns<'yoke, T>

This type MUST be Self with the 'static replaced with 'a, i.e. Self<'a>

fn transform(&'yoke self) -> &'yoke Self::Output

This method must cast self between &'a Self<'static> and &'a Self<'a>.

fn transform_owned(self) -> Self::Output

This method must cast self between Self<'static> and Self<'a>.

unsafe fn make(from: Self::Output) -> Self

This method can be used to cast away Self<'a>’s lifetime.

fn transform_mut<F>(&'yoke mut self, f: F)

where F: 'static + for<'_yoke> FnOnce(&'_yoke mut Self::Output),

This method must cast self between &'a mut Self<'static> and &'a mut Self<'a>, and pass it to f.

impl<'zf, 'zf_inner, T: VarULE + ?Sized> ZeroFrom<'zf, GenericPackedPatterns<'zf_inner, T>> for GenericPackedPatterns<'zf, T>

where VarZeroVec<'zf, T>: ZeroFrom<'zf, VarZeroVec<'zf_inner, T>>,

fn zero_from(this: &'zf GenericPackedPatterns<'zf_inner, T>) -> Self

Clone the other C into a struct that may retain references into C.