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// Copyright (c) 2026 Austin Han <austinhan1024@gmail.com>
//
// This file is part of RocksGraph.
//
// RocksGraph is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// RocksGraph is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with RocksGraph. If not, see <https://www.gnu.org/licenses/>.
use crate::types::{PIPELINE_PRODUCE_SIZE, SMALL_VECTOR_LENGTH};
use std::rc::Rc;
use smallvec::SmallVec;
use crate::engine::volcano::steps::traits::ExplainNode;
use crate::{
engine::{
context::GraphCtx,
traverser::Traverser,
volcano::steps::traits::{CoreStep, StepRef},
},
types::{
error::StoreError,
keys::{AdjacentEdgeCursor, AdjacentEdgesOptions, Rank},
BatchScenario, Direction, GValue, LabelId, VertexKey,
},
};
/// A physical step that traverses both incoming and outgoing edges from a vertex, returning adjacent vertices or edges.
#[derive(Debug)]
pub struct BothStep {
// ── Upstream link ──
upstream: Option<StepRef>,
// ── Static/Fixed configuration ──
/// The edge labels to filter by during traversal (empty means all labels).
label_ids: SmallVec<[LabelId; SMALL_VECTOR_LENGTH]>,
/// Maximum number of results to produce per input vertex.
limit: Option<u32>,
/// Optional target vertex IDs to filter the destination vertices of the traversed edges.
end_vertex_ids: Option<SmallVec<[VertexKey; SMALL_VECTOR_LENGTH]>>,
/// Optional edge rank to filter by, folded in from a `.has("rank", N)` filter.
rank: Option<Rank>,
/// Whether to return the traversed edges themselves (true) or the adjacent vertices (false).
output_edges: bool,
/// Whether to link the parent chain on emitted traversers (`false` skips the `Rc::clone`
/// when the plan has no `as()`/`select()`/`path()` anywhere in it).
track_path: bool,
// ── Dynamic/Runtime execution state ──
/// The parent traverser currently being expanded.
current_input: Option<Rc<Traverser>>,
/// The index of the label in `label_ids` currently being processed for the active input.
current_label_idx: usize,
/// The active direction of the edge traversal (incoming or outgoing).
current_direction: Direction,
/// Suffix cursor for paginating results of the current label/direction scan.
cursor: Option<AdjacentEdgeCursor>,
}
impl BothStep {
/// Creates a new `BothStep` for traversing incident vertices or edges in both directions.
pub fn new(
label_ids: SmallVec<[LabelId; SMALL_VECTOR_LENGTH]>,
end_vertex_ids: Option<SmallVec<[VertexKey; SMALL_VECTOR_LENGTH]>>,
rank: Option<Rank>,
output_edges: bool,
track_path: bool,
) -> Self {
Self {
upstream: None,
label_ids,
limit: None,
end_vertex_ids,
rank,
current_input: None,
current_label_idx: 0,
current_direction: Direction::OUT,
cursor: None,
output_edges,
track_path,
}
}
}
impl CoreStep for BothStep {
fn add_upper(&mut self, upstream: StepRef) {
self.upstream = Some(upstream);
}
fn produce(
&mut self,
ctx: &mut dyn GraphCtx,
) -> Result<Option<SmallVec<[Rc<Traverser>; PIPELINE_PRODUCE_SIZE]>>, StoreError> {
loop {
if self.current_input.is_none() {
let Some(upstream) = self.upstream.as_ref() else { return Ok(None) };
let Some(t) = upstream.next(ctx)? else { return Ok(None) };
if matches!(&t.value, GValue::Vertex(_)) {
self.current_input = Some(t);
self.current_label_idx = 0;
self.current_direction = Direction::OUT;
self.cursor = None;
} else {
continue;
}
}
let t = Rc::clone(self.current_input.as_ref().unwrap());
if let GValue::Vertex(vk) = &t.value {
let label = if self.label_ids.is_empty() { None } else { Some(self.label_ids[self.current_label_idx]) };
let mut results = SmallVec::new();
if self.current_direction == Direction::OUT {
let opts = AdjacentEdgesOptions {
label,
dst: self.end_vertex_ids.as_deref(),
rank: self.rank.as_ref().map(std::slice::from_ref),
start_from: self.cursor,
};
let batch_size = ctx.batch_size(BatchScenario::GetAdjacentEdges);
let fetch_limit = match self.limit {
Some(l) => std::cmp::min(l, batch_size),
None => batch_size,
};
let (edges, next_cursor) =
ctx.get_adjacent_edges(*vk, self.current_direction, opts, Some(fetch_limit))?;
self.cursor = next_cursor;
for edge in edges {
let val =
if self.output_edges { GValue::Edge(edge) } else { GValue::Vertex(edge.secondary_id) };
results.push(Traverser::new_rc_conditional(val, &t, self.track_path));
}
if self.cursor.is_none() {
self.current_direction = Direction::IN;
}
if !results.is_empty() {
return Ok(Some(results));
}
}
if self.current_direction == Direction::IN {
let opts = AdjacentEdgesOptions {
label,
dst: self.end_vertex_ids.as_deref(),
rank: self.rank.as_ref().map(std::slice::from_ref),
start_from: self.cursor,
};
let batch_size = ctx.batch_size(BatchScenario::GetAdjacentEdges);
let fetch_limit = match self.limit {
Some(l) => std::cmp::min(l, batch_size),
None => batch_size,
};
let (edges, next_cursor) =
ctx.get_adjacent_edges(*vk, self.current_direction, opts, Some(fetch_limit))?;
self.cursor = next_cursor;
for edge in edges {
let val =
if self.output_edges { GValue::Edge(edge) } else { GValue::Vertex(edge.secondary_id) };
results.push(Traverser::new_rc_conditional(val, &t, self.track_path));
}
if self.cursor.is_none() {
self.current_direction = Direction::OUT;
self.current_label_idx += 1;
if self.label_ids.is_empty() || self.current_label_idx >= self.label_ids.len() {
self.current_input = None;
}
}
if !results.is_empty() {
return Ok(Some(results));
}
}
} else {
self.current_input = None;
}
}
}
fn reset(&mut self) {
if let Some(up) = &self.upstream {
up.reset();
}
self.current_input = None;
self.current_label_idx = 0;
self.current_direction = Direction::OUT;
self.cursor = None;
}
fn upper(&self) -> Option<StepRef> {
self.upstream.clone()
}
fn explain(&self) -> ExplainNode {
let params = vec![("direction", "Both".to_string()), ("labels", format!("{:?}", self.label_ids))];
ExplainNode::new("InOutStep").with_params(params)
}
}