From bf448ea93574ddaaf41a092c4894a6e66c950664 Mon Sep 17 00:00:00 2001
From: Denis Smirnov <sd@picodata.io>
Date: Fri, 17 Dec 2021 12:01:32 +0700
Subject: [PATCH] refactoring: move tree traversal to a separate module.
---
src/ir.rs | 106 +------------------------------------------
src/ir/traversal.rs | 108 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 109 insertions(+), 105 deletions(-)
create mode 100644 src/ir/traversal.rs
diff --git a/src/ir.rs b/src/ir.rs
index 82ed8306d4..b092c3ea6c 100644
--- a/src/ir.rs
+++ b/src/ir.rs
@@ -6,6 +6,7 @@ pub mod distribution;
pub mod expression;
pub mod operator;
pub mod relation;
+pub mod traversal;
pub mod value;
use crate::errors::QueryPlannerError;
@@ -14,7 +15,6 @@ use expression::Expression;
use operator::Relational;
use relation::Table;
use serde::{Deserialize, Serialize};
-use std::cell::RefCell;
use std::collections::{HashMap, HashSet};
/// Plan tree node.
@@ -533,109 +533,5 @@ impl Plan {
}
}
-/// Plan node iterator over its branches.
-///
-/// For example, inner join returns at first a left child, then
-/// the right one. But a relation scan doesn't have any children
-/// and stop iteration at the moment.
-///
-/// We need this iterator to traverse plan tree with `traversal` crate.
-#[derive(Debug)]
-pub struct BranchIterator<'n> {
- node: &'n Node,
- step: RefCell<usize>,
- plan: &'n Plan,
-}
-
-#[allow(dead_code)]
-impl<'n> BranchIterator<'n> {
- /// Constructor for a new branch iterator instance.
- #[must_use]
- pub fn new(node: &'n Node, plan: &'n Plan) -> Self {
- BranchIterator {
- node,
- step: RefCell::new(0),
- plan,
- }
- }
-}
-
-impl<'n> Iterator for BranchIterator<'n> {
- type Item = &'n Node;
-
- fn next(&mut self) -> Option<Self::Item> {
- let get_next_child = |children: &Vec<usize>| -> Option<&Node> {
- let current_step = *self.step.borrow();
- let child = children.get(current_step);
- child.and_then(|pos| {
- let node = self.plan.nodes.get(*pos);
- *self.step.borrow_mut() += 1;
- node
- })
- };
-
- match self.node {
- Node::Expression(expr) => match expr {
- Expression::Alias { child, .. } => {
- let current_step = *self.step.borrow();
- if current_step == 0 {
- *self.step.borrow_mut() += 1;
- return self.plan.nodes.get(*child);
- }
- None
- }
- Expression::Bool { left, right, .. } => {
- let current_step = *self.step.borrow();
- if current_step == 0 {
- *self.step.borrow_mut() += 1;
- return self.plan.nodes.get(*left);
- } else if current_step == 1 {
- *self.step.borrow_mut() += 1;
- return self.plan.nodes.get(*right);
- }
- None
- }
- Expression::Constant { .. } | Expression::Reference { .. } => None,
- Expression::Row { list, .. } => {
- let current_step = *self.step.borrow();
- if let Some(node) = list.get(current_step) {
- *self.step.borrow_mut() += 1;
- return self.plan.nodes.get(*node);
- }
- None
- }
- },
- Node::Relational(rel) => match rel {
- Relational::InnerJoin {
- children,
- condition,
- ..
- } => {
- let current_step = *self.step.borrow();
- if current_step == 0 || current_step == 1 {
- return get_next_child(children);
- } else if current_step == 2 {
- *self.step.borrow_mut() += 1;
- return self.plan.nodes.get(*condition);
- }
- None
- }
- Relational::ScanRelation { .. } => None,
- Relational::ScanSubQuery { children, .. }
- | Relational::Motion { children, .. }
- | Relational::Selection { children, .. }
- | Relational::Projection { children, .. } => get_next_child(children),
- Relational::UnionAll { children, .. } => {
- let current_step = *self.step.borrow();
- if current_step == 0 || current_step == 1 {
- return get_next_child(children);
- }
- None
- }
- },
- }
- }
-}
-
#[cfg(test)]
mod tests;
diff --git a/src/ir/traversal.rs b/src/ir/traversal.rs
new file mode 100644
index 0000000000..c201fba5ab
--- /dev/null
+++ b/src/ir/traversal.rs
@@ -0,0 +1,108 @@
+use super::expression::Expression;
+use super::operator::Relational;
+use super::{Node, Plan};
+use std::cell::RefCell;
+
+/// Plan node iterator over its branches.
+///
+/// For example, inner join returns at first a left child, then
+/// the right one. But a relation scan doesn't have any children
+/// and stop iteration at the moment.
+///
+/// We need this iterator to traverse plan tree with `traversal` crate.
+#[derive(Debug)]
+pub struct BranchIterator<'n> {
+ node: &'n Node,
+ step: RefCell<usize>,
+ plan: &'n Plan,
+}
+
+#[allow(dead_code)]
+impl<'n> BranchIterator<'n> {
+ /// Constructor for a new branch iterator instance.
+ #[must_use]
+ pub fn new(node: &'n Node, plan: &'n Plan) -> Self {
+ BranchIterator {
+ node,
+ step: RefCell::new(0),
+ plan,
+ }
+ }
+}
+
+impl<'n> Iterator for BranchIterator<'n> {
+ type Item = &'n Node;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let get_next_child = |children: &Vec<usize>| -> Option<&Node> {
+ let current_step = *self.step.borrow();
+ let child = children.get(current_step);
+ child.and_then(|pos| {
+ let node = self.plan.nodes.get(*pos);
+ *self.step.borrow_mut() += 1;
+ node
+ })
+ };
+
+ match self.node {
+ Node::Expression(expr) => match expr {
+ Expression::Alias { child, .. } => {
+ let current_step = *self.step.borrow();
+ if current_step == 0 {
+ *self.step.borrow_mut() += 1;
+ return self.plan.nodes.get(*child);
+ }
+ None
+ }
+ Expression::Bool { left, right, .. } => {
+ let current_step = *self.step.borrow();
+ if current_step == 0 {
+ *self.step.borrow_mut() += 1;
+ return self.plan.nodes.get(*left);
+ } else if current_step == 1 {
+ *self.step.borrow_mut() += 1;
+ return self.plan.nodes.get(*right);
+ }
+ None
+ }
+ Expression::Constant { .. } | Expression::Reference { .. } => None,
+ Expression::Row { list, .. } => {
+ let current_step = *self.step.borrow();
+ if let Some(node) = list.get(current_step) {
+ *self.step.borrow_mut() += 1;
+ return self.plan.nodes.get(*node);
+ }
+ None
+ }
+ },
+ Node::Relational(rel) => match rel {
+ Relational::InnerJoin {
+ children,
+ condition,
+ ..
+ } => {
+ let current_step = *self.step.borrow();
+ if current_step == 0 || current_step == 1 {
+ return get_next_child(children);
+ } else if current_step == 2 {
+ *self.step.borrow_mut() += 1;
+ return self.plan.nodes.get(*condition);
+ }
+ None
+ }
+ Relational::ScanRelation { .. } => None,
+ Relational::ScanSubQuery { children, .. }
+ | Relational::Motion { children, .. }
+ | Relational::Selection { children, .. }
+ | Relational::Projection { children, .. } => get_next_child(children),
+ Relational::UnionAll { children, .. } => {
+ let current_step = *self.step.borrow();
+ if current_step == 0 || current_step == 1 {
+ return get_next_child(children);
+ }
+ None
+ }
+ },
+ }
+ }
+}
--
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