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Introduce RBTree implementation tailored for proto2::Arena #2285

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Introduce RBTree implementation tailored for proto2::Arena #2285

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20 changes: 20 additions & 0 deletions internal/BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,26 @@ cc_test(
],
)

cc_library(
name = "arena_tree",
srcs = ["arena_tree.cc"],
hdrs = ["arena_tree.h"],
deps = [
"@com_google_absl//absl/base:nullability",
"@com_google_absl//absl/log:absl_check",
"@com_google_protobuf//:protobuf",
],
)

cc_test(
name = "arena_tree_test",
srcs = ["arena_tree_test.cc"],
deps = [
":arena_tree",
":testing",
],
)

cc_library(
name = "new",
srcs = ["new.cc"],
Expand Down
352 changes: 352 additions & 0 deletions internal/arena_tree.cc
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Original file line number Diff line number Diff line change
@@ -0,0 +1,352 @@
// Copyright 2026 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "internal/arena_tree.h"

#include "absl/base/nullability.h"

namespace cel::internal {

namespace {

void ArenaTreeRotateLeft(ArenaTreeNodeBase** head, ArenaTreeNodeBase* elem) {
ArenaTreeNodeBase* tmp = ArenaTreeNodeGetRight(elem);
if (ArenaTreeNodeSetRight(elem, ArenaTreeNodeGetLeft(tmp)) != nullptr) {
ArenaTreeNodeSetParent(ArenaTreeNodeGetLeft(tmp), elem);
}
ArenaTreeNodeBase* parent = ArenaTreeNodeGetParent(elem);
ArenaTreeNodeSetParent(tmp, parent);
if (parent != nullptr) {
if (elem == ArenaTreeNodeGetLeft(parent)) {
ArenaTreeNodeSetLeft(parent, tmp);
} else {
ArenaTreeNodeSetRight(parent, tmp);
}
} else {
*head = tmp;
}
ArenaTreeNodeSetLeft(tmp, elem);
ArenaTreeNodeSetParent(elem, tmp);
}

void ArenaTreeRotateRight(ArenaTreeNodeBase** head, ArenaTreeNodeBase* elem) {
ArenaTreeNodeBase* tmp = ArenaTreeNodeGetLeft(elem);
if (ArenaTreeNodeSetLeft(elem, ArenaTreeNodeGetRight(tmp)) != nullptr) {
ArenaTreeNodeSetParent(ArenaTreeNodeGetRight(tmp), elem);
}
ArenaTreeNodeBase* parent = ArenaTreeNodeGetParent(elem);
ArenaTreeNodeSetParent(tmp, parent);
if (parent != nullptr) {
if (elem == ArenaTreeNodeGetLeft(parent)) {
ArenaTreeNodeSetLeft(parent, tmp);
} else {
ArenaTreeNodeSetRight(parent, tmp);
}
} else {
*head = tmp;
}
ArenaTreeNodeSetRight(tmp, elem);
ArenaTreeNodeSetParent(elem, tmp);
}

void ArenaTreeRemoveColor(ArenaTreeNodeBase** head, ArenaTreeNodeBase* parent,
ArenaTreeNodeBase* elem) {
ArenaTreeNodeBase* tmp;
while ((elem == nullptr ||
ArenaTreeNodeGetColor(elem) == ArenaTreeNodeColor::kBlack) &&
elem != *head) {
if (ArenaTreeNodeGetLeft(parent) == elem) {
tmp = ArenaTreeNodeGetRight(parent);
if (ArenaTreeNodeGetColor(tmp) == ArenaTreeNodeColor::kRed) {
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeColor::kBlack);
ArenaTreeNodeSetColor(parent, ArenaTreeNodeColor::kRed);
ArenaTreeRotateLeft(head, parent);
tmp = ArenaTreeNodeGetRight(parent);
}
if ((ArenaTreeNodeGetLeft(tmp) == nullptr ||
ArenaTreeNodeGetColor(ArenaTreeNodeGetLeft(tmp)) ==
ArenaTreeNodeColor::kBlack) &&
(ArenaTreeNodeGetRight(tmp) == nullptr ||
ArenaTreeNodeGetColor(ArenaTreeNodeGetRight(tmp)) ==
ArenaTreeNodeColor::kBlack)) {
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeColor::kRed);
elem = parent;
parent = ArenaTreeNodeGetParent(elem);
} else {
if (ArenaTreeNodeGetRight(tmp) == nullptr ||
ArenaTreeNodeGetColor(ArenaTreeNodeGetRight(tmp)) ==
ArenaTreeNodeColor::kBlack) {
ArenaTreeNodeBase* left;
if ((left = ArenaTreeNodeGetLeft(tmp)) != nullptr) {
ArenaTreeNodeSetColor(left, ArenaTreeNodeColor::kBlack);
}
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeColor::kRed);
ArenaTreeRotateRight(head, tmp);
tmp = ArenaTreeNodeGetRight(parent);
}
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeGetColor(parent));
ArenaTreeNodeSetColor(parent, ArenaTreeNodeColor::kBlack);
if (ArenaTreeNodeGetRight(tmp) != nullptr) {
ArenaTreeNodeSetColor(ArenaTreeNodeGetRight(tmp),
ArenaTreeNodeColor::kBlack);
}
ArenaTreeRotateLeft(head, parent);
elem = *head;
break;
}
} else {
tmp = ArenaTreeNodeGetLeft(parent);
if (ArenaTreeNodeGetColor(tmp) == ArenaTreeNodeColor::kRed) {
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeColor::kBlack);
ArenaTreeNodeSetColor(parent, ArenaTreeNodeColor::kRed);
ArenaTreeRotateRight(head, parent);
tmp = ArenaTreeNodeGetLeft(parent);
}
if ((ArenaTreeNodeGetLeft(tmp) == nullptr ||
ArenaTreeNodeGetColor(ArenaTreeNodeGetLeft(tmp)) ==
ArenaTreeNodeColor::kBlack) &&
(ArenaTreeNodeGetRight(tmp) == nullptr ||
ArenaTreeNodeGetColor(ArenaTreeNodeGetRight(tmp)) ==
ArenaTreeNodeColor::kBlack)) {
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeColor::kRed);
elem = parent;
parent = ArenaTreeNodeGetParent(elem);
} else {
if (ArenaTreeNodeGetLeft(tmp) == nullptr ||
ArenaTreeNodeGetColor(ArenaTreeNodeGetLeft(tmp)) ==
ArenaTreeNodeColor::kBlack) {
ArenaTreeNodeBase* right;
if ((right = ArenaTreeNodeGetRight(tmp)) != nullptr) {
ArenaTreeNodeSetColor(right, ArenaTreeNodeColor::kBlack);
}
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeColor::kRed);
ArenaTreeRotateLeft(head, tmp);
tmp = ArenaTreeNodeGetLeft(parent);
}
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeGetColor(parent));
ArenaTreeNodeSetColor(parent, ArenaTreeNodeColor::kBlack);
if (ArenaTreeNodeGetLeft(tmp) != nullptr) {
ArenaTreeNodeSetColor(ArenaTreeNodeGetLeft(tmp),
ArenaTreeNodeColor::kBlack);
}
ArenaTreeRotateRight(head, parent);
elem = *head;
break;
}
}
}
if (elem != nullptr) {
ArenaTreeNodeSetColor(elem, ArenaTreeNodeColor::kBlack);
}
}

} // namespace

const ArenaTreeNodeBase* absl_nullable ArenaTreeNext(
const ArenaTreeNodeBase* absl_nullable node) {
if (node != nullptr) {
const ArenaTreeNodeBase* right = ArenaTreeNodeGetRight(node);
if (right != nullptr) {
node = right;
const ArenaTreeNodeBase* left;
while ((left = ArenaTreeNodeGetLeft(node)) != nullptr) {
node = left;
}
} else {
const ArenaTreeNodeBase* parent = ArenaTreeNodeGetParent(node);
if (parent != nullptr && node == ArenaTreeNodeGetLeft(parent)) {
node = parent;
} else {
while (parent != nullptr && ArenaTreeNodeGetRight(parent) == node) {
node = ArenaTreeNodeGetParent(node);
parent = ArenaTreeNodeGetParent(node);
}
node = parent;
}
}
}
return node;
}

const ArenaTreeNodeBase* absl_nullable ArenaTreePrev(
const ArenaTreeNodeBase* absl_nullable node) {
if (node != nullptr) {
const ArenaTreeNodeBase* left = ArenaTreeNodeGetLeft(node);
if (left != nullptr) {
node = left;
const ArenaTreeNodeBase* right;
while ((right = ArenaTreeNodeGetRight(node)) != nullptr) {
node = right;
}
} else {
const ArenaTreeNodeBase* parent = ArenaTreeNodeGetParent(node);
if (parent != nullptr && node == ArenaTreeNodeGetRight(parent)) {
node = parent;
} else {
while (parent != nullptr && ArenaTreeNodeGetLeft(parent) == node) {
node = ArenaTreeNodeGetParent(node);
parent = ArenaTreeNodeGetParent(node);
}
node = parent;
}
}
}
return node;
}

const ArenaTreeNodeBase* absl_nullable ArenaTreeMin(
const ArenaTreeNodeBase* absl_nullable node) {
const ArenaTreeNodeBase* tmp = node;
const ArenaTreeNodeBase* parent = nullptr;
while (tmp != nullptr) {
parent = tmp;
tmp = ArenaTreeNodeGetLeft(tmp);
}
return parent;
}

const ArenaTreeNodeBase* absl_nullable ArenaTreeMax(
const ArenaTreeNodeBase* absl_nullable node) {
const ArenaTreeNodeBase* tmp = node;
const ArenaTreeNodeBase* parent = nullptr;
while (tmp != nullptr) {
parent = tmp;
tmp = ArenaTreeNodeGetRight(tmp);
}
return parent;
}

void ArenaTreeRemove(ArenaTreeNodeBase* absl_nullable* absl_nonnull head,
ArenaTreeNodeBase* absl_nonnull elem) {
ArenaTreeNodeBase* child;
ArenaTreeNodeBase* parent;
ArenaTreeNodeBase* const old = elem;
ArenaTreeNodeColor color;
if (ArenaTreeNodeGetLeft(elem) == nullptr) {
child = ArenaTreeNodeGetRight(elem);
} else if (ArenaTreeNodeGetRight(elem) == nullptr) {
child = ArenaTreeNodeGetLeft(elem);
} else {
ArenaTreeNodeBase* left;
elem = ArenaTreeNodeGetRight(elem);
while ((left = ArenaTreeNodeGetLeft(elem)) != nullptr) {
elem = left;
}
child = ArenaTreeNodeGetRight(elem);
parent = ArenaTreeNodeGetParent(elem);
color = ArenaTreeNodeGetColor(elem);
if (child != nullptr) {
ArenaTreeNodeSetParent(child, parent);
}
if (parent != nullptr) {
if (ArenaTreeNodeGetLeft(parent) == elem) {
ArenaTreeNodeSetLeft(parent, child);
} else {
ArenaTreeNodeSetRight(parent, child);
}
} else {
*head = child;
}
if (ArenaTreeNodeGetParent(elem) == old) {
parent = elem;
}
ArenaTreeNodeBase* old_parent = ArenaTreeNodeGetParent(old);
if (old_parent != nullptr) {
if (ArenaTreeNodeGetLeft(old_parent) == old) {
ArenaTreeNodeSetLeft(old_parent, elem);
} else {
ArenaTreeNodeSetRight(old_parent, elem);
}
} else {
*head = elem;
}
ArenaTreeNodeSetParent(ArenaTreeNodeGetLeft(old), elem);
if (ArenaTreeNodeGetRight(old) != nullptr) {
ArenaTreeNodeSetParent(ArenaTreeNodeGetRight(old), elem);
}
goto color;
}
parent = ArenaTreeNodeGetParent(elem);
color = ArenaTreeNodeGetColor(elem);
if (child != nullptr) {
ArenaTreeNodeSetParent(child, parent);
}
if (parent != nullptr) {
if (ArenaTreeNodeGetLeft(parent) == elem) {
ArenaTreeNodeSetLeft(parent, child);
} else {
ArenaTreeNodeSetRight(parent, child);
}
} else {
*head = child;
}
color:
if (color == ArenaTreeNodeColor::kBlack) {
ArenaTreeRemoveColor(head, parent, child);
}
ArenaTreeNodeClear(old);
}

void ArenaTreeInsertColor(ArenaTreeNodeBase* absl_nullable* absl_nonnull head,
ArenaTreeNodeBase* absl_nonnull elem) {
ArenaTreeNodeBase* parent;
ArenaTreeNodeBase* grandparent;
ArenaTreeNodeBase* tmp;
while ((parent = ArenaTreeNodeGetParent(elem)) != nullptr &&
ArenaTreeNodeGetColor(parent) == ArenaTreeNodeColor::kRed) {
grandparent = ArenaTreeNodeGetParent(parent);
if (parent == ArenaTreeNodeGetLeft(grandparent)) {
tmp = ArenaTreeNodeGetRight(grandparent);
if (tmp != nullptr &&
ArenaTreeNodeGetColor(tmp) == ArenaTreeNodeColor::kRed) {
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeColor::kBlack);
ArenaTreeNodeSetColor(parent, ArenaTreeNodeColor::kBlack);
ArenaTreeNodeSetColor(grandparent, ArenaTreeNodeColor::kRed);
elem = grandparent;
continue;
}
if (ArenaTreeNodeGetRight(parent) == elem) {
ArenaTreeRotateLeft(head, parent);
tmp = parent;
parent = elem;
elem = tmp;
}
ArenaTreeNodeSetColor(parent, ArenaTreeNodeColor::kBlack);
ArenaTreeNodeSetColor(grandparent, ArenaTreeNodeColor::kRed);
ArenaTreeRotateRight(head, grandparent);
} else {
tmp = ArenaTreeNodeGetLeft(grandparent);
if (tmp != nullptr &&
ArenaTreeNodeGetColor(tmp) == ArenaTreeNodeColor::kRed) {
ArenaTreeNodeSetColor(tmp, ArenaTreeNodeColor::kBlack);
ArenaTreeNodeSetColor(parent, ArenaTreeNodeColor::kBlack);
ArenaTreeNodeSetColor(grandparent, ArenaTreeNodeColor::kRed);
elem = grandparent;
continue;
}
if (ArenaTreeNodeGetLeft(parent) == elem) {
ArenaTreeRotateRight(head, parent);
tmp = parent;
parent = elem;
elem = tmp;
}
ArenaTreeNodeSetColor(parent, ArenaTreeNodeColor::kBlack);
ArenaTreeNodeSetColor(grandparent, ArenaTreeNodeColor::kRed);
ArenaTreeRotateLeft(head, grandparent);
}
}
ArenaTreeNodeSetColor(*head, ArenaTreeNodeColor::kBlack);
}

} // namespace cel::internal
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