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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 std::rc::Rc;
use smallvec::SmallVec;
use crate::types::PIPELINE_PRODUCE_SIZE;
use crate::{
engine::{
context::GraphCtx,
traverser::Traverser,
volcano::steps::traits::{CoreStep, ExplainNode, StepRef},
},
types::{
error::StoreError,
gvalue::{GValue, Primitive},
},
};
/// Extracts the id of the current element. For vertices returns `Int64(vk)`,
/// for edges returns the Base64-encoded canonical edge key. Any other traverser value causes an `UnexpectedDataType` error
/// through unchanged.
#[derive(Debug, Default)]
pub struct IdStep {
upstream: Option<StepRef>,
track_path: bool,
}
impl IdStep {
pub fn new(track_path: bool) -> Self {
Self { upstream: None, track_path }
}
}
impl CoreStep for IdStep {
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> {
let Some(upstream) = self.upstream.as_ref() else {
return Ok(None);
};
let mut batch = SmallVec::with_capacity(PIPELINE_PRODUCE_SIZE);
while batch.len() < PIPELINE_PRODUCE_SIZE {
let Some(t) = upstream.next(ctx)? else { break };
let id_value = match &t.value {
GValue::Vertex(vk) => GValue::Scalar(Primitive::Int64(*vk)),
GValue::Edge(ek) => GValue::Scalar(Primitive::String(ek.to_id_string())),
other => {
return Err(StoreError::UnexpectedDataType(format!(
"id() expects a Vertex or Edge, got {:?}",
other
)));
}
};
batch.push(Traverser::new_rc_conditional(id_value, &t, self.track_path));
}
if batch.is_empty() {
Ok(None)
} else {
Ok(Some(batch))
}
}
fn reset(&mut self) {
if let Some(up) = &self.upstream {
up.reset();
}
}
fn upper(&self) -> Option<StepRef> {
self.upstream.clone()
}
fn explain(&self) -> ExplainNode {
ExplainNode::new("IdStep")
}
}