clvmr 0.19.0

Implementation of `clvm` for Chia Network's cryptocurrency
Documentation 
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//! Visit-order strategies for the 2026 serializer.
//!
//! The serializer walks the interned pair tree and emits a stream of
//! instructions. At each pair, the strategy decides which child to visit
//! first (`LeftFirst` -> opcode `1`, `RightFirst` -> opcode `-1`) and may
//! thread a per-node context forward (e.g. a remaining DP budget).

use super::ser::SerializerState;

/// Which child to visit first at a pair.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum Direction {
    LeftFirst,
    #[allow(dead_code)]
    RightFirst,
}

impl Direction {
    pub(super) fn cons_opcode(self) -> i64 {
        match self {
            Direction::LeftFirst => 1,
            Direction::RightFirst => -1,
        }
    }
}

/// Pluggable visit-order strategy for `emit_instructions`.
///
/// A strategy may carry its own precomputed tables (e.g. DP results) and
/// thread a per-node context (`NodeCtx`) through the traversal.
pub trait VisitStrategy {
    /// Per-node context propagated down the tree. Use `()` if not needed.
    type NodeCtx: Copy;

    /// Initial context for the root node.
    fn root_ctx(&self, state: &SerializerState) -> Self::NodeCtx;

    /// Decide visit direction at `pair_idx` given the inherited context.
    ///
    /// Returns `(direction, left_ctx, right_ctx)`.
    fn decide(
        &self,
        state: &SerializerState,
        pair_idx: usize,
        ctx: Self::NodeCtx,
    ) -> (Direction, Self::NodeCtx, Self::NodeCtx);
}

/// Always visit the left child first (opcode `1`).
pub struct LeftFirst;

impl VisitStrategy for LeftFirst {
    type NodeCtx = ();

    fn root_ctx(&self, _state: &SerializerState) -> Self::NodeCtx {}

    fn decide(&self, _state: &SerializerState, _pair_idx: usize, _ctx: ()) -> (Direction, (), ()) {
        (Direction::LeftFirst, (), ())
    }
}