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use super::{Desc, ExecutionNode};
use annis::db::Match;
use annis::operator::Operator;
use std::iter::Peekable;
pub struct NestedLoop<'a> {
outer: Peekable<Box<ExecutionNode<Item = Vec<Match>> + 'a>>,
inner: Box<ExecutionNode<Item = Vec<Match>> + 'a>,
op: Box<Operator>,
inner_idx: usize,
outer_idx: usize,
inner_cache: Vec<Vec<Match>>,
pos_inner_cache: Option<usize>,
left_is_outer: bool,
desc: Desc,
}
impl<'a> NestedLoop<'a> {
pub fn new(
lhs: Box<ExecutionNode<Item = Vec<Match>> + 'a>,
rhs: Box<ExecutionNode<Item = Vec<Match>> + 'a>,
lhs_idx: usize,
rhs_idx: usize,
node_nr_lhs: usize,
node_nr_rhs: usize,
op: Box<Operator>,
) -> NestedLoop<'a> {
let mut left_is_outer = true;
if let (Some(ref desc_lhs), Some(ref desc_rhs)) = (lhs.get_desc(), rhs.get_desc()) {
if let (&Some(ref cost_lhs), &Some(ref cost_rhs)) = (&desc_lhs.cost, &desc_rhs.cost) {
if cost_lhs.output > cost_rhs.output {
left_is_outer = false;
}
}
}
let processed_func = |_, out_lhs: usize, out_rhs: usize| {
if out_lhs <= out_rhs {
out_lhs + (out_lhs * out_rhs)
} else {
out_rhs + (out_rhs * out_lhs)
}
};
if left_is_outer {
NestedLoop {
desc: Desc::join(
op.as_ref(),
lhs.get_desc(),
rhs.get_desc(),
"nestedloop L-R",
&format!("#{} {} #{}", node_nr_lhs, op, node_nr_rhs),
&processed_func,
),
outer: lhs.peekable(),
inner: rhs,
op,
outer_idx: lhs_idx,
inner_idx: rhs_idx,
inner_cache: Vec::new(),
pos_inner_cache: None,
left_is_outer,
}
} else {
NestedLoop {
desc: Desc::join(
op.as_ref(),
rhs.get_desc(),
lhs.get_desc(),
"nestedloop R-L",
&format!("#{} {} #{}", node_nr_lhs, op, node_nr_rhs),
&processed_func,
),
outer: rhs.peekable(),
inner: lhs,
op,
outer_idx: rhs_idx,
inner_idx: lhs_idx,
inner_cache: Vec::new(),
pos_inner_cache: None,
left_is_outer,
}
}
}
}
impl<'a> ExecutionNode for NestedLoop<'a> {
fn as_iter(&mut self) -> &mut Iterator<Item = Vec<Match>> {
self
}
fn get_desc(&self) -> Option<&Desc> {
Some(&self.desc)
}
}
impl<'a> Iterator for NestedLoop<'a> {
type Item = Vec<Match>;
fn next(&mut self) -> Option<Vec<Match>> {
loop {
if let Some(m_outer) = self.outer.peek() {
if self.pos_inner_cache.is_some() {
let mut cache_pos = self.pos_inner_cache.unwrap();
while cache_pos < self.inner_cache.len() {
let m_inner = &self.inner_cache[cache_pos];
cache_pos += 1;
self.pos_inner_cache = Some(cache_pos);
let filter_true = if self.left_is_outer {
self.op
.filter_match(&m_outer[self.outer_idx], &m_inner[self.inner_idx])
} else {
self.op
.filter_match(&m_inner[self.inner_idx], &m_outer[self.outer_idx])
};
if filter_true
&& (self.op.is_reflexive()
|| m_outer[self.outer_idx].node != m_inner[self.inner_idx].node
|| m_outer[self.outer_idx].anno_key
!= m_inner[self.inner_idx].anno_key)
{
let mut result = m_outer.clone();
result.append(&mut m_inner.clone());
return Some(result);
}
}
} else {
while let Some(m_inner) = self.inner.next() {
self.inner_cache.push(m_inner.clone());
let filter_true = if self.left_is_outer {
self.op
.filter_match(&m_outer[self.outer_idx], &m_inner[self.inner_idx])
} else {
self.op
.filter_match(&m_inner[self.inner_idx], &m_outer[self.outer_idx])
};
if filter_true
&& (self.op.is_reflexive()
|| m_outer[self.outer_idx].node != m_inner[self.inner_idx].node
|| m_outer[self.outer_idx].anno_key
!= m_inner[self.inner_idx].anno_key)
{
let mut result = m_outer.clone();
result.append(&mut m_inner.clone());
return Some(result);
}
}
}
self.pos_inner_cache = Some(0)
}
self.outer.next()?;
}
}
}