Struct SplitRatio 

pub struct SplitRatio(/* private fields */);

The fraction of a split’s area allotted to side a, refined so that the illegal values have no representation.

Why a newtype and not a validated f32

The field used to be a public f32, which meant 0.0, 1.0, -3.0, inf and NaN were all constructible and all deserialisable from the wire. validate() rejected them — but validate() is called by a caller who remembers to, and CBOR deserialisation writes the field directly, so the guard was one forgotten call away from useless.

NaN was the worst of them because it fails silently in the wrong direction. split_extent computes (total * ratio).round() and then clamps — and f32::clamp returns NaN for a NaN input (it only panics when the bounds are NaN), after which NaN as u16 saturates to 0. So a NaN ratio did not panic and did not error: side a silently got zero cells and the pane vanished. The old comment on split_extent claimed the clamp “pins NaN-free bounds”; it did not.

Now the only way in is SplitRatio::new, which normalises non-finite input to the balanced default and clamps the rest into [MIN_RATIO, 1 - MIN_RATIO]. The field is private, Deserialize routes through the same constructor, and Serialize is transparent — so the CBOR wire shape is byte-identical to the bare f32 it replaces.

Tier: truly-unrepresentable in-process (no constructor produces an out-of-range or non-finite value); parse-time-normalised on the wire.

Implementations

impl SplitRatio

pub const BALANCED: Self

An even split. The value every balanced constructor uses.

pub fn new(v: f32) -> Self

Refine an arbitrary f32.

Non-finite input (NaN, ±inf) becomes Self::BALANCED rather than propagating: there is no sensible clamp for a value that is not on the number line, and silently yielding a zero-width pane is the bug this type exists to remove.

pub const fn get(self) -> f32

The refined value. Always finite and always within [MIN_RATIO, 1 - MIN_RATIO].

Trait Implementations

impl Clone for SplitRatio

fn clone(&self) -> SplitRatio

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for SplitRatio

impl Debug for SplitRatio

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

Formats the value using the given formatter.

impl Default for SplitRatio

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for SplitRatio

fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error>

Routes through SplitRatio::new, so a hostile or merely stale peer cannot put an out-of-range or NaN ratio into a live tree.

impl From<f32> for SplitRatio

fn from(v: f32) -> Self

Converts to this type from the input type.

impl PartialEq for SplitRatio

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for SplitRatio

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for SplitRatio