zenoh_keyexpr/keyexpr_tree/iters/intersection.rs
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//
// Copyright (c) 2023 ZettaScale Technology
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License 2.0 which is available at
// http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
//
// Contributors:
// ZettaScale Zenoh Team, <zenoh@zettascale.tech>
//
use alloc::vec::Vec;
use zenoh_result::unlikely;
use crate::keyexpr_tree::*;
struct StackFrame<'a, Children: IChildrenProvider<Node>, Node: UIKeyExprTreeNode<Weight>, Weight>
where
Children::Assoc: IChildren<Node> + 'a,
<Children::Assoc as IChildren<Node>>::Node: 'a,
{
iterator: <Children::Assoc as IChildren<Node>>::Iter<'a>,
start: usize,
end: usize,
_marker: core::marker::PhantomData<Weight>,
}
pub struct Intersection<
'a,
Children: IChildrenProvider<Node>,
Node: UIKeyExprTreeNode<Weight>,
Weight,
> where
Children::Assoc: IChildren<Node> + 'a,
{
key: &'a keyexpr,
ke_indices: Vec<usize>,
iterators: Vec<StackFrame<'a, Children, Node, Weight>>,
}
impl<'a, Children: IChildrenProvider<Node>, Node: UIKeyExprTreeNode<Weight>, Weight>
Intersection<'a, Children, Node, Weight>
where
Children::Assoc: IChildren<Node> + 'a,
{
pub(crate) fn new(children: &'a Children::Assoc, key: &'a keyexpr) -> Self {
let mut ke_indices = Vec::with_capacity(32);
ke_indices.push(0);
let mut iterators = Vec::with_capacity(16);
iterators.push(StackFrame {
iterator: children.children(),
start: 0,
end: 1,
_marker: Default::default(),
});
Self {
key,
ke_indices,
iterators,
}
}
}
impl<
'a,
Children: IChildrenProvider<Node>,
Node: UIKeyExprTreeNode<Weight, Children = Children::Assoc> + 'a,
Weight,
> Iterator for Intersection<'a, Children, Node, Weight>
where
Children::Assoc: IChildren<Node> + 'a,
{
type Item = &'a Node;
fn next(&mut self) -> Option<Self::Item> {
loop {
let StackFrame {
iterator,
start,
end,
_marker,
} = self.iterators.last_mut()?;
match iterator.next() {
Some(node) => {
let mut node_matches = false;
let new_start = *end;
let mut new_end = *end;
macro_rules! push {
($index: expr) => {
let index = $index;
if new_end == new_start || self.ke_indices[new_end - 1] < index {
self.ke_indices.push(index);
new_end += 1;
}
};
}
let chunk = node.chunk();
let chunk_is_verbatim = chunk.first_byte() == b'@';
if unlikely(chunk.as_bytes() == b"**") {
// If the current node is `**`, it is guaranteed to match...
node_matches = true;
// and may consume any number of chunks from the KE
push!(self.ke_indices[*start]);
if self.key.len() != self.ke_indices[*start] {
if self.key.as_bytes()[self.ke_indices[*start]] != b'@' {
for i in self.ke_indices[*start]..self.key.len() {
if self.key.as_bytes()[i] == b'/' {
push!(i + 1);
if self.key.as_bytes()[i + 1] == b'@' {
node_matches = false; // ...unless the KE contains a verbatim chunk.
break;
}
}
}
} else {
node_matches = false;
}
}
} else {
// The current node is not `**`
// For all candidate chunks of the KE
for i in *start..*end {
// construct that chunk, while checking whether or not it's the last one
let kec_start = self.ke_indices[i];
if unlikely(kec_start == self.key.len()) {
break;
}
let key = &self.key.as_bytes()[kec_start..];
match key.iter().position(|&c| c == b'/') {
Some(kec_end) => {
// If we aren't in the last chunk
let subkey =
unsafe { keyexpr::from_slice_unchecked(&key[..kec_end]) };
if unlikely(subkey.as_bytes() == b"**") {
if !chunk_is_verbatim {
// If the query chunk is `**`:
// children will have to process it again
push!(kec_start);
}
// and we need to process this chunk as if the `**` wasn't there,
// but with the knowledge that the next chunk won't be `**`.
let post_key = &key[kec_end + 1..];
match post_key.iter().position(|&c| c == b'/') {
Some(sec_end) => {
let post_key = unsafe {
keyexpr::from_slice_unchecked(
&post_key[..sec_end],
)
};
if post_key.intersects(chunk) {
push!(kec_start + kec_end + sec_end + 2);
}
}
None => {
if unsafe {
keyexpr::from_slice_unchecked(post_key)
}
.intersects(chunk)
{
push!(self.key.len());
node_matches = true;
}
}
}
} else if chunk.intersects(subkey) {
push!(kec_start + kec_end + 1);
}
}
None => {
// If it's the last chunk of the query, check whether it's `**`
let key = unsafe { keyexpr::from_slice_unchecked(key) };
if unlikely(key.as_bytes() == b"**") && !chunk_is_verbatim {
// If yes, it automatically matches, and must be reused from now on for iteration.
push!(kec_start);
node_matches = true;
} else if chunk.intersects(key) {
// else, if it intersects with the chunk, make sure the children of the node
// are searched for `**`
push!(self.key.len());
node_matches = true;
}
}
}
}
}
// If new progress points have been set
if new_end != new_start {
// Check if any of them is `**`, as this would mean a match
for &i in &self.ke_indices[new_start..new_end] {
if &self.key.as_bytes()[i..] == b"**" {
node_matches = true;
break;
}
}
// Prepare the next children
let iterator = unsafe { node.as_node().__children() }.children();
self.iterators.push(StackFrame {
iterator,
start: new_start,
end: new_end,
_marker: Default::default(),
})
}
// yield the node if a match was found
if node_matches {
return Some(node.as_node());
}
}
None => {
if let Some(StackFrame { start, .. }) = self.iterators.pop() {
self.ke_indices.truncate(start);
}
}
}
}
}
}
struct StackFrameMut<'a, Children: IChildrenProvider<Node>, Node: IKeyExprTreeNode<Weight>, Weight>
where
Children::Assoc: IChildren<Node> + 'a,
<Children::Assoc as IChildren<Node>>::Node: 'a,
{
iterator: <Children::Assoc as IChildren<Node>>::IterMut<'a>,
start: usize,
end: usize,
_marker: core::marker::PhantomData<Weight>,
}
pub struct IntersectionMut<
'a,
Children: IChildrenProvider<Node>,
Node: IKeyExprTreeNode<Weight>,
Weight,
> where
Children::Assoc: IChildren<Node> + 'a,
{
key: &'a keyexpr,
ke_indices: Vec<usize>,
iterators: Vec<StackFrameMut<'a, Children, Node, Weight>>,
}
impl<'a, Children: IChildrenProvider<Node>, Node: IKeyExprTreeNode<Weight>, Weight>
IntersectionMut<'a, Children, Node, Weight>
where
Children::Assoc: IChildren<Node> + 'a,
{
pub(crate) fn new(children: &'a mut Children::Assoc, key: &'a keyexpr) -> Self {
let mut ke_indices = Vec::with_capacity(32);
ke_indices.push(0);
let mut iterators = Vec::with_capacity(16);
iterators.push(StackFrameMut {
iterator: children.children_mut(),
start: 0,
end: 1,
_marker: Default::default(),
});
Self {
key,
ke_indices,
iterators,
}
}
}
impl<
'a,
Children: IChildrenProvider<Node>,
Node: IKeyExprTreeNodeMut<Weight, Children = Children::Assoc> + 'a,
Weight,
> Iterator for IntersectionMut<'a, Children, Node, Weight>
where
Children::Assoc: IChildren<Node> + 'a,
{
type Item = &'a mut <Children::Assoc as IChildren<Node>>::Node;
fn next(&mut self) -> Option<Self::Item> {
loop {
let StackFrameMut {
iterator,
start,
end,
_marker,
} = self.iterators.last_mut()?;
match iterator.next() {
Some(node) => {
let mut node_matches = false;
let new_start = *end;
let mut new_end = *end;
macro_rules! push {
($index: expr) => {
let index = $index;
if new_end == new_start || self.ke_indices[new_end - 1] < index {
self.ke_indices.push(index);
new_end += 1;
}
};
}
let chunk = node.chunk();
let chunk_is_verbatim = chunk.first_byte() == b'@';
if unlikely(chunk.as_bytes() == b"**") {
// If the current node is `**`, it is guaranteed to match...
node_matches = true;
// and may consume any number of chunks from the KE
push!(self.ke_indices[*start]);
if self.key.len() != self.ke_indices[*start] {
if self.key.as_bytes()[self.ke_indices[*start]] != b'@' {
for i in self.ke_indices[*start]..self.key.len() {
if self.key.as_bytes()[i] == b'/' {
push!(i + 1);
if self.key.as_bytes()[i + 1] == b'@' {
node_matches = false; // ...unless the KE contains a verbatim chunk.
break;
}
}
}
} else {
node_matches = false;
}
}
} else {
// The current node is not `**`
// For all candidate chunks of the KE
for i in *start..*end {
// construct that chunk, while checking whether or not it's the last one
let kec_start = self.ke_indices[i];
if unlikely(kec_start == self.key.len()) {
break;
}
let key = &self.key.as_bytes()[kec_start..];
match key.iter().position(|&c| c == b'/') {
Some(kec_end) => {
// If we aren't in the last chunk
let subkey =
unsafe { keyexpr::from_slice_unchecked(&key[..kec_end]) };
if unlikely(subkey.as_bytes() == b"**") {
if !chunk_is_verbatim {
// If the query chunk is `**`:
// children will have to process it again
push!(kec_start);
}
// and we need to process this chunk as if the `**` wasn't there,
// but with the knowledge that the next chunk won't be `**`.
let post_key = &key[kec_end + 1..];
match post_key.iter().position(|&c| c == b'/') {
Some(sec_end) => {
let post_key = unsafe {
keyexpr::from_slice_unchecked(
&post_key[..sec_end],
)
};
if post_key.intersects(chunk) {
push!(kec_start + kec_end + sec_end + 2);
}
}
None => {
if unsafe {
keyexpr::from_slice_unchecked(post_key)
}
.intersects(chunk)
{
push!(self.key.len());
node_matches = true;
}
}
}
} else if chunk.intersects(subkey) {
push!(kec_start + kec_end + 1);
}
}
None => {
// If it's the last chunk of the query, check whether it's `**`
let key = unsafe { keyexpr::from_slice_unchecked(key) };
if unlikely(key.as_bytes() == b"**") && !chunk_is_verbatim {
// If yes, it automatically matches, and must be reused from now on for iteration.
push!(kec_start);
node_matches = true;
} else if chunk.intersects(key) {
// else, if it intersects with the chunk, make sure the children of the node
// are searched for `**`
push!(self.key.len());
node_matches = true;
}
}
}
}
}
if new_end != new_start {
for &i in &self.ke_indices[new_start..new_end] {
if &self.key.as_bytes()[i..] == b"**" {
node_matches = true;
break;
}
}
let iterator = unsafe { &mut *(node.as_node_mut() as *mut Node) }
.children_mut()
.children_mut();
self.iterators.push(StackFrameMut {
iterator,
start: new_start,
end: new_end,
_marker: Default::default(),
})
}
if node_matches {
return Some(node);
}
}
None => {
if let Some(StackFrameMut { start, .. }) = self.iterators.pop() {
self.ke_indices.truncate(start);
}
}
}
}
}
}