Struct ExpressionTree 

pub struct ExpressionTree { /* private fields */ }

A decoded expression tree stored in level-order (breadth-first) layout.

The coding prefix of a chromosome decodes to this structure (see GepDecoder). Nodes are held in BFS order, so every node’s children occupy a contiguous, strictly-higher index range. That lets evaluation run as a single right-to-left sweep: when a parent is reached, its children (higher indices) have already been computed.

Implementations

impl ExpressionTree

pub fn node_count(&self) -> usize

Number of coding nodes (the open-reading-frame length).

pub fn nodes(&self) -> &[Symbol]

Symbols in level order (root first). Primarily for tests/inspection.

pub fn depth(&self) -> usize

Tree depth: edges on the longest root-to-leaf path (a single-node tree has depth 0). A bloat metric.

pub fn eval<F: FunctionSet>( &self, alphabet: &Alphabet<F>, inputs: &[f32], ) -> f32

Evaluates the tree on one input row.

Variable nodes resolve to inputs[input_index] (missing indices read as 0.0); constant nodes resolve to their stored value; function nodes call FunctionSet::apply with their children’s already-computed results, then sanitize the result via finite_or_clamp: a NaN collapses to 0.0 (it has no meaningful sign or magnitude), while ±Inf clamps to ±EVAL_CLAMP (sign preserved). Clamping — rather than zeroing — a diverged (±Inf) subtree keeps its magnitude large, so it yields a large MSE and ranks worst instead of masquerading as a perfect 0.0 predictor near zero-valued targets (GEP finding tree.rs §1.2). This differs from the CGP evaluator’s finite_or_zero rule, which zeros both.

alphabet must be the same one the tree was decoded with.

Trait Implementations

impl Clone for ExpressionTree

fn clone(&self) -> ExpressionTree

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ExpressionTree

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

Formats the value using the given formatter.