1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
// 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;
use std::rc::Rc;
use smallvec::{smallvec, SmallVec};
use crate::engine::volcano::steps::traits::ExplainNode;
use crate::{
engine::{
context::GraphCtx,
traverser::Traverser,
volcano::{
builder::PhysicalPlan,
steps::traits::{CoreStep, StepRef},
},
},
types::error::StoreError,
};
/// A physical step that filters incoming traversers based on the results of a sub-plan.
#[derive(Debug)]
pub struct WhereStep {
// ── Upstream link ──
upstream: Option<StepRef>,
// ── Static/Fixed configuration ──
/// The physical sub-plan representing the filter traversal condition.
physical_plans: PhysicalPlan,
}
/// Creates a new `WhereStep` with the given physical sub-plan.
impl WhereStep {
pub fn new(physical_sub_plan: PhysicalPlan) -> Self {
Self { upstream: None, physical_plans: physical_sub_plan }
}
}
impl CoreStep for WhereStep {
fn add_upper(&mut self, upstream: StepRef) {
// Sets the upstream step for this filter.
self.upstream = Some(upstream);
}
fn produce(
&mut self,
ctx: &mut dyn GraphCtx,
) -> Result<Option<SmallVec<[Rc<Traverser>; PIPELINE_PRODUCE_SIZE]>>, StoreError> {
// Produces traversers from its upstream if the sub-plan yields any results for that traverser.
loop {
let Some(upstream) = self.upstream.as_ref() else { return Ok(None) };
let Some(t) = upstream.next(ctx)? else { return Ok(None) };
let physical_sub_plan = &self.physical_plans;
physical_sub_plan.reset();
physical_sub_plan.inject(smallvec![Rc::clone(&t)]);
// Sub pipeline evaluates properly — if sub-traversal yields at least one item, original goes through
if physical_sub_plan.next(ctx)?.is_some() {
return Ok(Some(smallvec![t]));
}
}
}
fn reset(&mut self) {
// Resets the state of this step, its upstream, and its sub-plan.
if let Some(up) = &self.upstream {
up.reset();
}
self.physical_plans.reset();
}
fn upper(&self) -> Option<StepRef> {
// Returns a clone of the upstream step reference.
self.upstream.clone()
}
fn explain(&self) -> ExplainNode {
let children = vec![(String::new(), self.physical_plans.explain())];
ExplainNode::new("WhereStep").with_children(children)
}
}