Enum CompositionRule 

#[non_exhaustive]
pub enum CompositionRule {
    Partition,
    Overlay(CombineOp),
    Group,
}

The composition rule declared by a composite head (composition_rule wire field).

Models combine_op as part of the rule (rather than a sibling field) so that illegal combinations — e.g. a non-zero combine_op on a partition or group head — are unrepresentable in this type: only CompositionRule::Overlay carries a CombineOp at all.

Examples

use hurray_core::layout::{CombineOp, CompositionRule};

let partition = CompositionRule::Partition;
assert_eq!(partition.rule_byte(), 0x01);
assert_eq!(partition.combine_op_byte(), 0x00);

let overlay = CompositionRule::Overlay(CombineOp::Add);
assert_eq!(overlay.rule_byte(), 0x02);
assert_eq!(overlay.combine_op_byte(), 0x02);

assert_eq!(
    CompositionRule::from_wire(0x02, 0x01).unwrap(),
    CompositionRule::Overlay(CombineOp::Replace),
);

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Partition

Exact-cover, non-overlapping tiling of the head’s index space. Wire 0x01.

Overlay(CombineOp)

A base spanning the whole index space plus scattered corrections. Wire 0x02.

Group

Independent tensors under one head identity; no spatial semantics. Wire 0x03.

Implementations

impl CompositionRule

pub fn rule_byte(&self) -> u8

Returns the wire composition_rule byte for this rule.

Examples

use hurray_core::layout::{CombineOp, CompositionRule};

assert_eq!(CompositionRule::Group.rule_byte(), 0x03);
assert_eq!(CompositionRule::Overlay(CombineOp::Replace).rule_byte(), 0x02);

pub fn combine_op_byte(&self) -> u8

Returns the wire combine_op byte: 0x00 unless this is CompositionRule::Overlay, in which case it is the wrapped CombineOp’s wire byte.

Examples

use hurray_core::layout::CompositionRule;

assert_eq!(CompositionRule::Partition.combine_op_byte(), 0x00);

pub fn from_wire(rule: u8, combine_op: u8) -> Result<Self>

Constructs a CompositionRule from its wire composition_rule and combine_op bytes, validating both per spec § Head Layout-Specific Fields.

The private-range rejection (0xF0–0xFE) mirrors crate::layout::is_private_tag’s layout-tag convention, for consistency across the crate’s wire-byte taxonomies.

Errors

• Error::InvalidCompositionRule — rule == 0xFF (permanently invalid).
• Error::ReservedCompositionRule — rule == 0x00 or in 0x04..=0xEF.
• Error::PrivateCompositionRule — rule is in 0xF0..=0xFE.
• Error::InvalidCombineOp — combine_op is not 0x00 for partition/group, or not 0x01/0x02 for overlay.

Examples

use hurray_core::{Error, layout::{CombineOp, CompositionRule}};

assert_eq!(CompositionRule::from_wire(0x01, 0x00).unwrap(), CompositionRule::Partition);
assert_eq!(CompositionRule::from_wire(0x03, 0x00).unwrap(), CompositionRule::Group);
assert_eq!(
    CompositionRule::from_wire(0x02, 0x02).unwrap(),
    CompositionRule::Overlay(CombineOp::Add),
);

// 0x00 is reserved (not the permanently-invalid sentinel — that's 0xFF).
assert!(matches!(
    CompositionRule::from_wire(0x00, 0x00),
    Err(Error::ReservedCompositionRule(0x00))
));
assert!(matches!(
    CompositionRule::from_wire(0xFF, 0x00),
    Err(Error::InvalidCompositionRule(0xFF))
));
// A non-zero combine_op on a partition head is rejected.
assert!(CompositionRule::from_wire(0x01, 0x01).is_err());
// combine_op outside {0x01, 0x02} on an overlay head is rejected.
assert!(CompositionRule::from_wire(0x02, 0x03).is_err());

Trait Implementations

impl Clone for CompositionRule

fn clone(&self) -> CompositionRule

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CompositionRule

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

Formats the value using the given formatter.

impl Eq for CompositionRule

impl Hash for CompositionRule

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 PartialEq for CompositionRule

fn eq(&self, other: &CompositionRule) -> 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 StructuralPartialEq for CompositionRule