Introduce common helpers for handling AST navigation#1170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
copybara-service merged 1 commit into from
Aug 7, 2026
Merged

Introduce common helpers for handling AST navigation #1170

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 10 additions & 0 deletions common/navigation/BUILD.bazel
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -25,3 +25,13 @@ java_library(
name = "mutable_navigation",
exports = ["//common/src/main/java/dev/cel/common/navigation:mutable_navigation"],
)

java_library(
name = "expr_util",
exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util"],
)

cel_android_library(
name = "expr_util_android",
exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util_android"],
)
30 changes: 30 additions & 0 deletions common/src/main/java/dev/cel/common/navigation/BUILD.bazel
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -48,6 +48,36 @@ cel_android_library(
],
)

java_library(
name = "expr_util",
srcs = [
"CelNavigableExprUtil.java",
],
tags = [
],
deps = [
":common",
"//common/ast",
"@maven//:com_google_errorprone_error_prone_annotations",
"@maven//:com_google_guava_guava",
],
)

cel_android_library(
name = "expr_util_android",
srcs = [
"CelNavigableExprUtil.java",
],
tags = [
],
deps = [
":common_android",
"//common/ast:ast_android",
"@maven//:com_google_errorprone_error_prone_annotations",
"@maven_android//:com_google_guava_guava",
],
)

java_library(
name = "navigation",
srcs = [
Expand Down
9 changes: 8 additions & 1 deletion common/src/main/java/dev/cel/common/navigation/BaseNavigableExpr.java
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -16,6 +16,7 @@

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.DoNotMock;
import dev.cel.common.ast.CelExpr;
import dev.cel.common.ast.CelExpr.ExprKind;
import dev.cel.common.ast.Expression;
Expand All@@ -25,9 +26,15 @@
/**
* BaseNavigableExpr represents the base navigable expression value with methods to inspect the
* parent and child expressions.
*
* <p>This class is intentionally non-extensible outside of the {@code dev.cel.common.navigation}
* package.
*/
@DoNotMock("Use CelNavigableExpr or CelNavigableMutableExpr")
@SuppressWarnings("unchecked") // Generic types are properly bound to Expression
abstract class BaseNavigableExpr<E extends Expression> {
public abstract class BaseNavigableExpr<E extends Expression> {

BaseNavigableExpr() {}

public abstract E expr();

Expand Down
156 changes: 156 additions & 0 deletions common/src/main/java/dev/cel/common/navigation/CelNavigableExprUtil.java
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,156 @@
// 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.

package dev.cel.common.navigation;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.CheckReturnValue;
import dev.cel.common.ast.CelExpr.ExprKind.Kind;
import dev.cel.common.ast.Expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Optional;

/** Utility class for common AST navigation and scoping inspections on {@link BaseNavigableExpr}. */
@CheckReturnValue
public final class CelNavigableExprUtil {

/**
* Returns true if {@code variableName} is in scope and shadowed by an enclosing comprehension
* above {@code expr}.
*
* <p>A variable is shadowed at {@code expr} if an ancestor comprehension declares it as an
* iteration variable ({@code iterVar}, {@code iterVar2}) or accumulator variable ({@code
* accuVar}) and {@code expr} resides within a branch where that variable is active:
*
* <ul>
* <li>In {@code loopCondition} and {@code loopStep}: {@code iterVar}, {@code iterVar2}, and
* {@code accuVar} are in scope.
* <li>In {@code result}: only {@code accuVar} is in scope ({@code iterVar} and {@code iterVar2}
* have fallen out of scope).
* <li>In {@code iterRange} and {@code accuInit}: none of the comprehension variables are in
* scope.
* </ul>
*
* <p>For example, in the expression:
*
* <pre>{@code
* [1, 2].all(x, x > 0)
* }</pre>
*
* <ul>
* <li>At {@code x} in {@code x > 0}: {@code isVariableShadowed(x, "x")} is {@code true}.
* <li>At the list {@code [1, 2]}: {@code isVariableShadowed(list, "x")} is {@code false}.
* </ul>
*/
public static boolean isVariableShadowed(BaseNavigableExpr<?> expr, String variableName) {
return areVariablesShadowed(expr, Collections.singleton(variableName));
}

/**
* Returns true if any of {@code variableNames} is in scope and shadowed by an enclosing
* comprehension above {@code expr}.
*
* <p>For example, in the nested comprehension expression:
*
* <pre>{@code
* [1, 2].all(x, [3, 4].all(y, x > 0 && y > 0))
* }</pre>
*
* At {@code y > 0}, {@code areVariablesShadowed(node, ImmutableSet.of("x", "z"))} is {@code true}
* because {@code x} is in scope from the outer comprehension.
*/
@SuppressWarnings("ReferenceEquality") // Required to disambiguate child branches
public static boolean areVariablesShadowed(
BaseNavigableExpr<?> expr, Collection<String> variableNames) {
checkNotNull(expr);
checkNotNull(variableNames);
if (variableNames.isEmpty()) {
return false;
}
BaseNavigableExpr<?> curr = expr;
Optional<? extends BaseNavigableExpr<?>> maybeParent = curr.parent();
while (maybeParent.isPresent()) {
BaseNavigableExpr<?> parent = maybeParent.get();
if (parent.getKind() == Kind.COMPREHENSION) {
Expression.Comprehension<?> comp = parent.expr().comprehension();
Expression currExpr = curr.expr();

if (currExpr != comp.iterRange() && currExpr != comp.accuInit()) {
if (currExpr == comp.result()) {
if (variableNames.contains(comp.accuVar())) {
return true;
}
} else {
if (variableNames.contains(comp.iterVar())
|| variableNames.contains(comp.iterVar2())
|| variableNames.contains(comp.accuVar())) {
return true;
}
}
}
}
curr = parent;
maybeParent = parent.parent();
}
return false;
}

/**
* Returns true if {@code expr} is an {@code IDENT} node that references a variable declared by an
* enclosing comprehension.
*
* <p>For example, in the expression:
*
* <pre>{@code
* [a].all(x, x > a)
* }</pre>
*
* <ul>
* <li>At identifier {@code x}: {@code isComprehensionVariable(x)} is {@code true}.
* <li>At identifier {@code a}: {@code isComprehensionVariable(a)} is {@code false}.
* </ul>
*/
public static boolean isComprehensionVariable(BaseNavigableExpr<?> expr) {
checkNotNull(expr);
return expr.getKind() == Kind.IDENT
&& areVariablesShadowed(expr, Collections.singleton(expr.expr().ident().name()));
}

/**
* Returns true if {@code expr} or any identifier within {@code expr} references a variable
* declared by an enclosing comprehension.
*
* <p>For example, in the expression:
*
* <pre>{@code
* [a].all(x, x > a)
* }</pre>
*
* <ul>
* <li>At the subtree {@code x > a}: {@code hasComprehensionVariable(subtree)} is {@code true}
* because {@code x} is a comprehension variable.
* <li>At the subtree {@code [a]}: {@code hasComprehensionVariable(iterRange)} is {@code false}.
* </ul>
*/
public static boolean hasComprehensionVariable(BaseNavigableExpr<?> expr) {
checkNotNull(expr);
return expr.allNodes()
.filter(node -> node.getKind() == Kind.IDENT)
.anyMatch(CelNavigableExprUtil::isComprehensionVariable);
}

private CelNavigableExprUtil() {}
}
2 changes: 2 additions & 0 deletions common/src/test/java/dev/cel/common/navigation/BUILD.bazel
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -21,10 +21,12 @@ java_library(
"//common/ast:mutable_expr",
"//common/navigation",
"//common/navigation:common",
"//common/navigation:expr_util",
"//common/navigation:mutable_navigation",
"//common/types",
"//compiler",
"//compiler:compiler_builder",
"//extensions",
"//parser:macro",
"@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",
"@maven//:com_google_guava_guava",
Expand Down
Loading
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
Introduce common helpers for handling AST navigation#1170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

copybara-service
merged 1 commit into

from

Aug 7, 2026
 Merged


Introduce common helpers for handling AST navigation
#1170
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


Select commit


File filter

Filter by extension
Filter by extension
Conversations

Failed to load comments. 
Loading
Jump to

Jump to file


Failed to load files. 
Loading
 Diff view

 Diff view


10 changes: 10 additions & 0 deletions
common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -25,3 +25,13 @@ java_library(
 name = "mutable_navigation",
 exports = ["//common/src/main/java/dev/cel/common/navigation:mutable_navigation"],
)

java_library(
 name = "expr_util",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util"],
)

cel_android_library(
 name = "expr_util_android",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util_android"],
)

30 changes: 30 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -48,6 +48,36 @@ cel_android_library(
 ],
)

java_library(
 name = "expr_util",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common",
 "//common/ast",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven//:com_google_guava_guava",
 ],
)

cel_android_library(
 name = "expr_util_android",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common_android",
 "//common/ast:ast_android",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven_android//:com_google_guava_guava",
 ],
)

java_library(
 name = "navigation",
 srcs = [
Expand Down

9 changes: 8 additions & 1 deletion
common/src/main/java/dev/cel/common/navigation/BaseNavigableExpr.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -16,6 +16,7 @@

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.DoNotMock;
import dev.cel.common.ast.CelExpr;
import dev.cel.common.ast.CelExpr.ExprKind;
import dev.cel.common.ast.Expression;
Expand All@@ -25,9 +26,15 @@
/**
 * BaseNavigableExpr represents the base navigable expression value with methods to inspect the
 * parent and child expressions.
 *
 * <p>This class is intentionally non-extensible outside of the {@code dev.cel.common.navigation}
 * package.
 */
@DoNotMock("Use CelNavigableExpr or CelNavigableMutableExpr")
@SuppressWarnings("unchecked") // Generic types are properly bound to Expression
abstract class BaseNavigableExpr<E extends Expression> {
public abstract class BaseNavigableExpr<E extends Expression> {

 BaseNavigableExpr() {}

 public abstract E expr();

Expand Down

156 changes: 156 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/CelNavigableExprUtil.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,156 @@
// 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.

package dev.cel.common.navigation;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.CheckReturnValue;
import dev.cel.common.ast.CelExpr.ExprKind.Kind;
import dev.cel.common.ast.Expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Optional;

/** Utility class for common AST navigation and scoping inspections on {@link BaseNavigableExpr}. */
@CheckReturnValue
public final class CelNavigableExprUtil {

 /**
 * Returns true if {@code variableName} is in scope and shadowed by an enclosing comprehension
 * above {@code expr}.
 *
 * <p>A variable is shadowed at {@code expr} if an ancestor comprehension declares it as an
 * iteration variable ({@code iterVar}, {@code iterVar2}) or accumulator variable ({@code
 * accuVar}) and {@code expr} resides within a branch where that variable is active:
 *
 * <ul>
 * <li>In {@code loopCondition} and {@code loopStep}: {@code iterVar}, {@code iterVar2}, and
 * {@code accuVar} are in scope.
 * <li>In {@code result}: only {@code accuVar} is in scope ({@code iterVar} and {@code iterVar2}
 * have fallen out of scope).
 * <li>In {@code iterRange} and {@code accuInit}: none of the comprehension variables are in
 * scope.
 * </ul>
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [1, 2].all(x, x > 0)
 * }</pre>
 *
 * <ul>
 * <li>At {@code x} in {@code x > 0}: {@code isVariableShadowed(x, "x")} is {@code true}.
 * <li>At the list {@code [1, 2]}: {@code isVariableShadowed(list, "x")} is {@code false}.
 * </ul>
 */
 public static boolean isVariableShadowed(BaseNavigableExpr<?> expr, String variableName) {
 return areVariablesShadowed(expr, Collections.singleton(variableName));
 }

 /**
 * Returns true if any of {@code variableNames} is in scope and shadowed by an enclosing
 * comprehension above {@code expr}.
 *
 * <p>For example, in the nested comprehension expression:
 *
 * <pre>{@code
 * [1, 2].all(x, [3, 4].all(y, x > 0 && y > 0))
 * }</pre>
 *
 * At {@code y > 0}, {@code areVariablesShadowed(node, ImmutableSet.of("x", "z"))} is {@code true}
 * because {@code x} is in scope from the outer comprehension.
 */
 @SuppressWarnings("ReferenceEquality") // Required to disambiguate child branches
 public static boolean areVariablesShadowed(
 BaseNavigableExpr<?> expr, Collection<String> variableNames) {
 checkNotNull(expr);
 checkNotNull(variableNames);
 if (variableNames.isEmpty()) {
 return false;
 }
 BaseNavigableExpr<?> curr = expr;
 Optional<? extends BaseNavigableExpr<?>> maybeParent = curr.parent();
 while (maybeParent.isPresent()) {
 BaseNavigableExpr<?> parent = maybeParent.get();
 if (parent.getKind() == Kind.COMPREHENSION) {
 Expression.Comprehension<?> comp = parent.expr().comprehension();
 Expression currExpr = curr.expr();

 if (currExpr != comp.iterRange() && currExpr != comp.accuInit()) {
 if (currExpr == comp.result()) {
 if (variableNames.contains(comp.accuVar())) {
 return true;
 }
 } else {
 if (variableNames.contains(comp.iterVar())
 || variableNames.contains(comp.iterVar2())
 || variableNames.contains(comp.accuVar())) {
 return true;
 }
 }
 }
 }
 curr = parent;
 maybeParent = parent.parent();
 }
 return false;
 }

 /**
 * Returns true if {@code expr} is an {@code IDENT} node that references a variable declared by an
 * enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At identifier {@code x}: {@code isComprehensionVariable(x)} is {@code true}.
 * <li>At identifier {@code a}: {@code isComprehensionVariable(a)} is {@code false}.
 * </ul>
 */
 public static boolean isComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.getKind() == Kind.IDENT
 && areVariablesShadowed(expr, Collections.singleton(expr.expr().ident().name()));
 }

 /**
 * Returns true if {@code expr} or any identifier within {@code expr} references a variable
 * declared by an enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At the subtree {@code x > a}: {@code hasComprehensionVariable(subtree)} is {@code true}
 * because {@code x} is a comprehension variable.
 * <li>At the subtree {@code [a]}: {@code hasComprehensionVariable(iterRange)} is {@code false}.
 * </ul>
 */
 public static boolean hasComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.allNodes()
 .filter(node -> node.getKind() == Kind.IDENT)
 .anyMatch(CelNavigableExprUtil::isComprehensionVariable);
 }

 private CelNavigableExprUtil() {}
}

2 changes: 2 additions & 0 deletions
common/src/test/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -21,10 +21,12 @@ java_library(
 "//common/ast:mutable_expr",
 "//common/navigation",
 "//common/navigation:common",
 "//common/navigation:expr_util",
 "//common/navigation:mutable_navigation",
 "//common/types",
 "//compiler",
 "//compiler:compiler_builder",
 "//extensions",
 "//parser:macro",
 "@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",
 "@maven//:com_google_guava_guava",
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Introduce common helpers for handling AST navigation#1170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

copybara-service
merged 1 commit into

from

Aug 7, 2026
 Merged


Introduce common helpers for handling AST navigation
#1170
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


Select commit


File filter

Filter by extension
Filter by extension
Conversations

Failed to load comments. 
Loading
Jump to

Jump to file


Failed to load files. 
Loading
 Diff view

 Diff view


10 changes: 10 additions & 0 deletions
common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -25,3 +25,13 @@ java_library(
 name = "mutable_navigation",
 exports = ["//common/src/main/java/dev/cel/common/navigation:mutable_navigation"],
)

java_library(
 name = "expr_util",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util"],
)

cel_android_library(
 name = "expr_util_android",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util_android"],
)

30 changes: 30 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -48,6 +48,36 @@ cel_android_library(
 ],
)

java_library(
 name = "expr_util",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common",
 "//common/ast",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven//:com_google_guava_guava",
 ],
)

cel_android_library(
 name = "expr_util_android",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common_android",
 "//common/ast:ast_android",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven_android//:com_google_guava_guava",
 ],
)

java_library(
 name = "navigation",
 srcs = [
Expand Down

9 changes: 8 additions & 1 deletion
common/src/main/java/dev/cel/common/navigation/BaseNavigableExpr.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -16,6 +16,7 @@

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.DoNotMock;
import dev.cel.common.ast.CelExpr;
import dev.cel.common.ast.CelExpr.ExprKind;
import dev.cel.common.ast.Expression;
Expand All@@ -25,9 +26,15 @@
/**
 * BaseNavigableExpr represents the base navigable expression value with methods to inspect the
 * parent and child expressions.
 *
 * <p>This class is intentionally non-extensible outside of the {@code dev.cel.common.navigation}
 * package.
 */
@DoNotMock("Use CelNavigableExpr or CelNavigableMutableExpr")
@SuppressWarnings("unchecked") // Generic types are properly bound to Expression
abstract class BaseNavigableExpr<E extends Expression> {
public abstract class BaseNavigableExpr<E extends Expression> {

 BaseNavigableExpr() {}

 public abstract E expr();

Expand Down

156 changes: 156 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/CelNavigableExprUtil.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,156 @@
// 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.

package dev.cel.common.navigation;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.CheckReturnValue;
import dev.cel.common.ast.CelExpr.ExprKind.Kind;
import dev.cel.common.ast.Expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Optional;

/** Utility class for common AST navigation and scoping inspections on {@link BaseNavigableExpr}. */
@CheckReturnValue
public final class CelNavigableExprUtil {

 /**
 * Returns true if {@code variableName} is in scope and shadowed by an enclosing comprehension
 * above {@code expr}.
 *
 * <p>A variable is shadowed at {@code expr} if an ancestor comprehension declares it as an
 * iteration variable ({@code iterVar}, {@code iterVar2}) or accumulator variable ({@code
 * accuVar}) and {@code expr} resides within a branch where that variable is active:
 *
 * <ul>
 * <li>In {@code loopCondition} and {@code loopStep}: {@code iterVar}, {@code iterVar2}, and
 * {@code accuVar} are in scope.
 * <li>In {@code result}: only {@code accuVar} is in scope ({@code iterVar} and {@code iterVar2}
 * have fallen out of scope).
 * <li>In {@code iterRange} and {@code accuInit}: none of the comprehension variables are in
 * scope.
 * </ul>
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [1, 2].all(x, x > 0)
 * }</pre>
 *
 * <ul>
 * <li>At {@code x} in {@code x > 0}: {@code isVariableShadowed(x, "x")} is {@code true}.
 * <li>At the list {@code [1, 2]}: {@code isVariableShadowed(list, "x")} is {@code false}.
 * </ul>
 */
 public static boolean isVariableShadowed(BaseNavigableExpr<?> expr, String variableName) {
 return areVariablesShadowed(expr, Collections.singleton(variableName));
 }

 /**
 * Returns true if any of {@code variableNames} is in scope and shadowed by an enclosing
 * comprehension above {@code expr}.
 *
 * <p>For example, in the nested comprehension expression:
 *
 * <pre>{@code
 * [1, 2].all(x, [3, 4].all(y, x > 0 && y > 0))
 * }</pre>
 *
 * At {@code y > 0}, {@code areVariablesShadowed(node, ImmutableSet.of("x", "z"))} is {@code true}
 * because {@code x} is in scope from the outer comprehension.
 */
 @SuppressWarnings("ReferenceEquality") // Required to disambiguate child branches
 public static boolean areVariablesShadowed(
 BaseNavigableExpr<?> expr, Collection<String> variableNames) {
 checkNotNull(expr);
 checkNotNull(variableNames);
 if (variableNames.isEmpty()) {
 return false;
 }
 BaseNavigableExpr<?> curr = expr;
 Optional<? extends BaseNavigableExpr<?>> maybeParent = curr.parent();
 while (maybeParent.isPresent()) {
 BaseNavigableExpr<?> parent = maybeParent.get();
 if (parent.getKind() == Kind.COMPREHENSION) {
 Expression.Comprehension<?> comp = parent.expr().comprehension();
 Expression currExpr = curr.expr();

 if (currExpr != comp.iterRange() && currExpr != comp.accuInit()) {
 if (currExpr == comp.result()) {
 if (variableNames.contains(comp.accuVar())) {
 return true;
 }
 } else {
 if (variableNames.contains(comp.iterVar())
 || variableNames.contains(comp.iterVar2())
 || variableNames.contains(comp.accuVar())) {
 return true;
 }
 }
 }
 }
 curr = parent;
 maybeParent = parent.parent();
 }
 return false;
 }

 /**
 * Returns true if {@code expr} is an {@code IDENT} node that references a variable declared by an
 * enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At identifier {@code x}: {@code isComprehensionVariable(x)} is {@code true}.
 * <li>At identifier {@code a}: {@code isComprehensionVariable(a)} is {@code false}.
 * </ul>
 */
 public static boolean isComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.getKind() == Kind.IDENT
 && areVariablesShadowed(expr, Collections.singleton(expr.expr().ident().name()));
 }

 /**
 * Returns true if {@code expr} or any identifier within {@code expr} references a variable
 * declared by an enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At the subtree {@code x > a}: {@code hasComprehensionVariable(subtree)} is {@code true}
 * because {@code x} is a comprehension variable.
 * <li>At the subtree {@code [a]}: {@code hasComprehensionVariable(iterRange)} is {@code false}.
 * </ul>
 */
 public static boolean hasComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.allNodes()
 .filter(node -> node.getKind() == Kind.IDENT)
 .anyMatch(CelNavigableExprUtil::isComprehensionVariable);
 }

 private CelNavigableExprUtil() {}
}

2 changes: 2 additions & 0 deletions
common/src/test/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -21,10 +21,12 @@ java_library(
 "//common/ast:mutable_expr",
 "//common/navigation",
 "//common/navigation:common",
 "//common/navigation:expr_util",
 "//common/navigation:mutable_navigation",
 "//common/types",
 "//compiler",
 "//compiler:compiler_builder",
 "//extensions",
 "//parser:macro",
 "@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",
 "@maven//:com_google_guava_guava",
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Introduce common helpers for handling AST navigation#1170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

copybara-service
merged 1 commit into

from

Aug 7, 2026
 Merged


Introduce common helpers for handling AST navigation
#1170
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


Select commit


File filter

Filter by extension
Filter by extension
Conversations

Failed to load comments. 
Loading
Jump to

Jump to file


Failed to load files. 
Loading
 Diff view

 Diff view


10 changes: 10 additions & 0 deletions
common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -25,3 +25,13 @@ java_library(
 name = "mutable_navigation",
 exports = ["//common/src/main/java/dev/cel/common/navigation:mutable_navigation"],
)

java_library(
 name = "expr_util",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util"],
)

cel_android_library(
 name = "expr_util_android",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util_android"],
)

30 changes: 30 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -48,6 +48,36 @@ cel_android_library(
 ],
)

java_library(
 name = "expr_util",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common",
 "//common/ast",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven//:com_google_guava_guava",
 ],
)

cel_android_library(
 name = "expr_util_android",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common_android",
 "//common/ast:ast_android",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven_android//:com_google_guava_guava",
 ],
)

java_library(
 name = "navigation",
 srcs = [
Expand Down

9 changes: 8 additions & 1 deletion
common/src/main/java/dev/cel/common/navigation/BaseNavigableExpr.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -16,6 +16,7 @@

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.DoNotMock;
import dev.cel.common.ast.CelExpr;
import dev.cel.common.ast.CelExpr.ExprKind;
import dev.cel.common.ast.Expression;
Expand All@@ -25,9 +26,15 @@
/**
 * BaseNavigableExpr represents the base navigable expression value with methods to inspect the
 * parent and child expressions.
 *
 * <p>This class is intentionally non-extensible outside of the {@code dev.cel.common.navigation}
 * package.
 */
@DoNotMock("Use CelNavigableExpr or CelNavigableMutableExpr")
@SuppressWarnings("unchecked") // Generic types are properly bound to Expression
abstract class BaseNavigableExpr<E extends Expression> {
public abstract class BaseNavigableExpr<E extends Expression> {

 BaseNavigableExpr() {}

 public abstract E expr();

Expand Down

156 changes: 156 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/CelNavigableExprUtil.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,156 @@
// 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.

package dev.cel.common.navigation;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.CheckReturnValue;
import dev.cel.common.ast.CelExpr.ExprKind.Kind;
import dev.cel.common.ast.Expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Optional;

/** Utility class for common AST navigation and scoping inspections on {@link BaseNavigableExpr}. */
@CheckReturnValue
public final class CelNavigableExprUtil {

 /**
 * Returns true if {@code variableName} is in scope and shadowed by an enclosing comprehension
 * above {@code expr}.
 *
 * <p>A variable is shadowed at {@code expr} if an ancestor comprehension declares it as an
 * iteration variable ({@code iterVar}, {@code iterVar2}) or accumulator variable ({@code
 * accuVar}) and {@code expr} resides within a branch where that variable is active:
 *
 * <ul>
 * <li>In {@code loopCondition} and {@code loopStep}: {@code iterVar}, {@code iterVar2}, and
 * {@code accuVar} are in scope.
 * <li>In {@code result}: only {@code accuVar} is in scope ({@code iterVar} and {@code iterVar2}
 * have fallen out of scope).
 * <li>In {@code iterRange} and {@code accuInit}: none of the comprehension variables are in
 * scope.
 * </ul>
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [1, 2].all(x, x > 0)
 * }</pre>
 *
 * <ul>
 * <li>At {@code x} in {@code x > 0}: {@code isVariableShadowed(x, "x")} is {@code true}.
 * <li>At the list {@code [1, 2]}: {@code isVariableShadowed(list, "x")} is {@code false}.
 * </ul>
 */
 public static boolean isVariableShadowed(BaseNavigableExpr<?> expr, String variableName) {
 return areVariablesShadowed(expr, Collections.singleton(variableName));
 }

 /**
 * Returns true if any of {@code variableNames} is in scope and shadowed by an enclosing
 * comprehension above {@code expr}.
 *
 * <p>For example, in the nested comprehension expression:
 *
 * <pre>{@code
 * [1, 2].all(x, [3, 4].all(y, x > 0 && y > 0))
 * }</pre>
 *
 * At {@code y > 0}, {@code areVariablesShadowed(node, ImmutableSet.of("x", "z"))} is {@code true}
 * because {@code x} is in scope from the outer comprehension.
 */
 @SuppressWarnings("ReferenceEquality") // Required to disambiguate child branches
 public static boolean areVariablesShadowed(
 BaseNavigableExpr<?> expr, Collection<String> variableNames) {
 checkNotNull(expr);
 checkNotNull(variableNames);
 if (variableNames.isEmpty()) {
 return false;
 }
 BaseNavigableExpr<?> curr = expr;
 Optional<? extends BaseNavigableExpr<?>> maybeParent = curr.parent();
 while (maybeParent.isPresent()) {
 BaseNavigableExpr<?> parent = maybeParent.get();
 if (parent.getKind() == Kind.COMPREHENSION) {
 Expression.Comprehension<?> comp = parent.expr().comprehension();
 Expression currExpr = curr.expr();

 if (currExpr != comp.iterRange() && currExpr != comp.accuInit()) {
 if (currExpr == comp.result()) {
 if (variableNames.contains(comp.accuVar())) {
 return true;
 }
 } else {
 if (variableNames.contains(comp.iterVar())
 || variableNames.contains(comp.iterVar2())
 || variableNames.contains(comp.accuVar())) {
 return true;
 }
 }
 }
 }
 curr = parent;
 maybeParent = parent.parent();
 }
 return false;
 }

 /**
 * Returns true if {@code expr} is an {@code IDENT} node that references a variable declared by an
 * enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At identifier {@code x}: {@code isComprehensionVariable(x)} is {@code true}.
 * <li>At identifier {@code a}: {@code isComprehensionVariable(a)} is {@code false}.
 * </ul>
 */
 public static boolean isComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.getKind() == Kind.IDENT
 && areVariablesShadowed(expr, Collections.singleton(expr.expr().ident().name()));
 }

 /**
 * Returns true if {@code expr} or any identifier within {@code expr} references a variable
 * declared by an enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At the subtree {@code x > a}: {@code hasComprehensionVariable(subtree)} is {@code true}
 * because {@code x} is a comprehension variable.
 * <li>At the subtree {@code [a]}: {@code hasComprehensionVariable(iterRange)} is {@code false}.
 * </ul>
 */
 public static boolean hasComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.allNodes()
 .filter(node -> node.getKind() == Kind.IDENT)
 .anyMatch(CelNavigableExprUtil::isComprehensionVariable);
 }

 private CelNavigableExprUtil() {}
}

2 changes: 2 additions & 0 deletions
common/src/test/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -21,10 +21,12 @@ java_library(
 "//common/ast:mutable_expr",
 "//common/navigation",
 "//common/navigation:common",
 "//common/navigation:expr_util",
 "//common/navigation:mutable_navigation",
 "//common/types",
 "//compiler",
 "//compiler:compiler_builder",
 "//extensions",
 "//parser:macro",
 "@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",
 "@maven//:com_google_guava_guava",
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
Introduce common helpers for handling AST navigation#1170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

copybara-service
merged 1 commit into

from

Aug 7, 2026
 Merged


Introduce common helpers for handling AST navigation
#1170
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


Select commit


File filter

Filter by extension
Filter by extension
Conversations

Failed to load comments. 
Loading
Jump to

Jump to file


Failed to load files. 
Loading
 Diff view

 Diff view


10 changes: 10 additions & 0 deletions
common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -25,3 +25,13 @@ java_library(
 name = "mutable_navigation",
 exports = ["//common/src/main/java/dev/cel/common/navigation:mutable_navigation"],
)

java_library(
 name = "expr_util",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util"],
)

cel_android_library(
 name = "expr_util_android",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util_android"],
)

30 changes: 30 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -48,6 +48,36 @@ cel_android_library(
 ],
)

java_library(
 name = "expr_util",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common",
 "//common/ast",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven//:com_google_guava_guava",
 ],
)

cel_android_library(
 name = "expr_util_android",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common_android",
 "//common/ast:ast_android",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven_android//:com_google_guava_guava",
 ],
)

java_library(
 name = "navigation",
 srcs = [
Expand Down

9 changes: 8 additions & 1 deletion
common/src/main/java/dev/cel/common/navigation/BaseNavigableExpr.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -16,6 +16,7 @@

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.DoNotMock;
import dev.cel.common.ast.CelExpr;
import dev.cel.common.ast.CelExpr.ExprKind;
import dev.cel.common.ast.Expression;
Expand All@@ -25,9 +26,15 @@
/**
 * BaseNavigableExpr represents the base navigable expression value with methods to inspect the
 * parent and child expressions.
 *
 * <p>This class is intentionally non-extensible outside of the {@code dev.cel.common.navigation}
 * package.
 */
@DoNotMock("Use CelNavigableExpr or CelNavigableMutableExpr")
@SuppressWarnings("unchecked") // Generic types are properly bound to Expression
abstract class BaseNavigableExpr<E extends Expression> {
public abstract class BaseNavigableExpr<E extends Expression> {

 BaseNavigableExpr() {}

 public abstract E expr();

Expand Down

156 changes: 156 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/CelNavigableExprUtil.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,156 @@
// 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.

package dev.cel.common.navigation;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.CheckReturnValue;
import dev.cel.common.ast.CelExpr.ExprKind.Kind;
import dev.cel.common.ast.Expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Optional;

/** Utility class for common AST navigation and scoping inspections on {@link BaseNavigableExpr}. */
@CheckReturnValue
public final class CelNavigableExprUtil {

 /**
 * Returns true if {@code variableName} is in scope and shadowed by an enclosing comprehension
 * above {@code expr}.
 *
 * <p>A variable is shadowed at {@code expr} if an ancestor comprehension declares it as an
 * iteration variable ({@code iterVar}, {@code iterVar2}) or accumulator variable ({@code
 * accuVar}) and {@code expr} resides within a branch where that variable is active:
 *
 * <ul>
 * <li>In {@code loopCondition} and {@code loopStep}: {@code iterVar}, {@code iterVar2}, and
 * {@code accuVar} are in scope.
 * <li>In {@code result}: only {@code accuVar} is in scope ({@code iterVar} and {@code iterVar2}
 * have fallen out of scope).
 * <li>In {@code iterRange} and {@code accuInit}: none of the comprehension variables are in
 * scope.
 * </ul>
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [1, 2].all(x, x > 0)
 * }</pre>
 *
 * <ul>
 * <li>At {@code x} in {@code x > 0}: {@code isVariableShadowed(x, "x")} is {@code true}.
 * <li>At the list {@code [1, 2]}: {@code isVariableShadowed(list, "x")} is {@code false}.
 * </ul>
 */
 public static boolean isVariableShadowed(BaseNavigableExpr<?> expr, String variableName) {
 return areVariablesShadowed(expr, Collections.singleton(variableName));
 }

 /**
 * Returns true if any of {@code variableNames} is in scope and shadowed by an enclosing
 * comprehension above {@code expr}.
 *
 * <p>For example, in the nested comprehension expression:
 *
 * <pre>{@code
 * [1, 2].all(x, [3, 4].all(y, x > 0 && y > 0))
 * }</pre>
 *
 * At {@code y > 0}, {@code areVariablesShadowed(node, ImmutableSet.of("x", "z"))} is {@code true}
 * because {@code x} is in scope from the outer comprehension.
 */
 @SuppressWarnings("ReferenceEquality") // Required to disambiguate child branches
 public static boolean areVariablesShadowed(
 BaseNavigableExpr<?> expr, Collection<String> variableNames) {
 checkNotNull(expr);
 checkNotNull(variableNames);
 if (variableNames.isEmpty()) {
 return false;
 }
 BaseNavigableExpr<?> curr = expr;
 Optional<? extends BaseNavigableExpr<?>> maybeParent = curr.parent();
 while (maybeParent.isPresent()) {
 BaseNavigableExpr<?> parent = maybeParent.get();
 if (parent.getKind() == Kind.COMPREHENSION) {
 Expression.Comprehension<?> comp = parent.expr().comprehension();
 Expression currExpr = curr.expr();

 if (currExpr != comp.iterRange() && currExpr != comp.accuInit()) {
 if (currExpr == comp.result()) {
 if (variableNames.contains(comp.accuVar())) {
 return true;
 }
 } else {
 if (variableNames.contains(comp.iterVar())
 || variableNames.contains(comp.iterVar2())
 || variableNames.contains(comp.accuVar())) {
 return true;
 }
 }
 }
 }
 curr = parent;
 maybeParent = parent.parent();
 }
 return false;
 }

 /**
 * Returns true if {@code expr} is an {@code IDENT} node that references a variable declared by an
 * enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At identifier {@code x}: {@code isComprehensionVariable(x)} is {@code true}.
 * <li>At identifier {@code a}: {@code isComprehensionVariable(a)} is {@code false}.
 * </ul>
 */
 public static boolean isComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.getKind() == Kind.IDENT
 && areVariablesShadowed(expr, Collections.singleton(expr.expr().ident().name()));
 }

 /**
 * Returns true if {@code expr} or any identifier within {@code expr} references a variable
 * declared by an enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At the subtree {@code x > a}: {@code hasComprehensionVariable(subtree)} is {@code true}
 * because {@code x} is a comprehension variable.
 * <li>At the subtree {@code [a]}: {@code hasComprehensionVariable(iterRange)} is {@code false}.
 * </ul>
 */
 public static boolean hasComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.allNodes()
 .filter(node -> node.getKind() == Kind.IDENT)
 .anyMatch(CelNavigableExprUtil::isComprehensionVariable);
 }

 private CelNavigableExprUtil() {}
}

2 changes: 2 additions & 0 deletions
common/src/test/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -21,10 +21,12 @@ java_library(
 "//common/ast:mutable_expr",
 "//common/navigation",
 "//common/navigation:common",
 "//common/navigation:expr_util",
 "//common/navigation:mutable_navigation",
 "//common/types",
 "//compiler",
 "//compiler:compiler_builder",
 "//extensions",
 "//parser:macro",
 "@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",
 "@maven//:com_google_guava_guava",
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Introduce common helpers for handling AST navigation#1170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

copybara-service
merged 1 commit into

from

Aug 7, 2026
 Merged


Introduce common helpers for handling AST navigation
#1170
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


Select commit


File filter

Filter by extension
Filter by extension
Conversations

Failed to load comments. 
Loading
Jump to

Jump to file


Failed to load files. 
Loading
 Diff view

 Diff view


10 changes: 10 additions & 0 deletions
common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -25,3 +25,13 @@ java_library(
 name = "mutable_navigation",
 exports = ["//common/src/main/java/dev/cel/common/navigation:mutable_navigation"],
)

java_library(
 name = "expr_util",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util"],
)

cel_android_library(
 name = "expr_util_android",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util_android"],
)

30 changes: 30 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -48,6 +48,36 @@ cel_android_library(
 ],
)

java_library(
 name = "expr_util",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common",
 "//common/ast",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven//:com_google_guava_guava",
 ],
)

cel_android_library(
 name = "expr_util_android",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common_android",
 "//common/ast:ast_android",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven_android//:com_google_guava_guava",
 ],
)

java_library(
 name = "navigation",
 srcs = [
Expand Down

9 changes: 8 additions & 1 deletion
common/src/main/java/dev/cel/common/navigation/BaseNavigableExpr.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -16,6 +16,7 @@

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.DoNotMock;
import dev.cel.common.ast.CelExpr;
import dev.cel.common.ast.CelExpr.ExprKind;
import dev.cel.common.ast.Expression;
Expand All@@ -25,9 +26,15 @@
/**
 * BaseNavigableExpr represents the base navigable expression value with methods to inspect the
 * parent and child expressions.
 *
 * <p>This class is intentionally non-extensible outside of the {@code dev.cel.common.navigation}
 * package.
 */
@DoNotMock("Use CelNavigableExpr or CelNavigableMutableExpr")
@SuppressWarnings("unchecked") // Generic types are properly bound to Expression
abstract class BaseNavigableExpr<E extends Expression> {
public abstract class BaseNavigableExpr<E extends Expression> {

 BaseNavigableExpr() {}

 public abstract E expr();

Expand Down

156 changes: 156 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/CelNavigableExprUtil.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,156 @@
// 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.

package dev.cel.common.navigation;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.CheckReturnValue;
import dev.cel.common.ast.CelExpr.ExprKind.Kind;
import dev.cel.common.ast.Expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Optional;

/** Utility class for common AST navigation and scoping inspections on {@link BaseNavigableExpr}. */
@CheckReturnValue
public final class CelNavigableExprUtil {

 /**
 * Returns true if {@code variableName} is in scope and shadowed by an enclosing comprehension
 * above {@code expr}.
 *
 * <p>A variable is shadowed at {@code expr} if an ancestor comprehension declares it as an
 * iteration variable ({@code iterVar}, {@code iterVar2}) or accumulator variable ({@code
 * accuVar}) and {@code expr} resides within a branch where that variable is active:
 *
 * <ul>
 * <li>In {@code loopCondition} and {@code loopStep}: {@code iterVar}, {@code iterVar2}, and
 * {@code accuVar} are in scope.
 * <li>In {@code result}: only {@code accuVar} is in scope ({@code iterVar} and {@code iterVar2}
 * have fallen out of scope).
 * <li>In {@code iterRange} and {@code accuInit}: none of the comprehension variables are in
 * scope.
 * </ul>
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [1, 2].all(x, x > 0)
 * }</pre>
 *
 * <ul>
 * <li>At {@code x} in {@code x > 0}: {@code isVariableShadowed(x, "x")} is {@code true}.
 * <li>At the list {@code [1, 2]}: {@code isVariableShadowed(list, "x")} is {@code false}.
 * </ul>
 */
 public static boolean isVariableShadowed(BaseNavigableExpr<?> expr, String variableName) {
 return areVariablesShadowed(expr, Collections.singleton(variableName));
 }

 /**
 * Returns true if any of {@code variableNames} is in scope and shadowed by an enclosing
 * comprehension above {@code expr}.
 *
 * <p>For example, in the nested comprehension expression:
 *
 * <pre>{@code
 * [1, 2].all(x, [3, 4].all(y, x > 0 && y > 0))
 * }</pre>
 *
 * At {@code y > 0}, {@code areVariablesShadowed(node, ImmutableSet.of("x", "z"))} is {@code true}
 * because {@code x} is in scope from the outer comprehension.
 */
 @SuppressWarnings("ReferenceEquality") // Required to disambiguate child branches
 public static boolean areVariablesShadowed(
 BaseNavigableExpr<?> expr, Collection<String> variableNames) {
 checkNotNull(expr);
 checkNotNull(variableNames);
 if (variableNames.isEmpty()) {
 return false;
 }
 BaseNavigableExpr<?> curr = expr;
 Optional<? extends BaseNavigableExpr<?>> maybeParent = curr.parent();
 while (maybeParent.isPresent()) {
 BaseNavigableExpr<?> parent = maybeParent.get();
 if (parent.getKind() == Kind.COMPREHENSION) {
 Expression.Comprehension<?> comp = parent.expr().comprehension();
 Expression currExpr = curr.expr();

 if (currExpr != comp.iterRange() && currExpr != comp.accuInit()) {
 if (currExpr == comp.result()) {
 if (variableNames.contains(comp.accuVar())) {
 return true;
 }
 } else {
 if (variableNames.contains(comp.iterVar())
 || variableNames.contains(comp.iterVar2())
 || variableNames.contains(comp.accuVar())) {
 return true;
 }
 }
 }
 }
 curr = parent;
 maybeParent = parent.parent();
 }
 return false;
 }

 /**
 * Returns true if {@code expr} is an {@code IDENT} node that references a variable declared by an
 * enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At identifier {@code x}: {@code isComprehensionVariable(x)} is {@code true}.
 * <li>At identifier {@code a}: {@code isComprehensionVariable(a)} is {@code false}.
 * </ul>
 */
 public static boolean isComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.getKind() == Kind.IDENT
 && areVariablesShadowed(expr, Collections.singleton(expr.expr().ident().name()));
 }

 /**
 * Returns true if {@code expr} or any identifier within {@code expr} references a variable
 * declared by an enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At the subtree {@code x > a}: {@code hasComprehensionVariable(subtree)} is {@code true}
 * because {@code x} is a comprehension variable.
 * <li>At the subtree {@code [a]}: {@code hasComprehensionVariable(iterRange)} is {@code false}.
 * </ul>
 */
 public static boolean hasComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.allNodes()
 .filter(node -> node.getKind() == Kind.IDENT)
 .anyMatch(CelNavigableExprUtil::isComprehensionVariable);
 }

 private CelNavigableExprUtil() {}
}

2 changes: 2 additions & 0 deletions
common/src/test/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -21,10 +21,12 @@ java_library(
 "//common/ast:mutable_expr",
 "//common/navigation",
 "//common/navigation:common",
 "//common/navigation:expr_util",
 "//common/navigation:mutable_navigation",
 "//common/types",
 "//compiler",
 "//compiler:compiler_builder",
 "//extensions",
 "//parser:macro",
 "@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",
 "@maven//:com_google_guava_guava",
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Introduce common helpers for handling AST navigation#1170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

copybara-service
merged 1 commit into

from

Aug 7, 2026
 Merged


Introduce common helpers for handling AST navigation
#1170
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


Select commit


File filter

Filter by extension
Filter by extension
Conversations

Failed to load comments. 
Loading
Jump to

Jump to file


Failed to load files. 
Loading
 Diff view

 Diff view


10 changes: 10 additions & 0 deletions
common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -25,3 +25,13 @@ java_library(
 name = "mutable_navigation",
 exports = ["//common/src/main/java/dev/cel/common/navigation:mutable_navigation"],
)

java_library(
 name = "expr_util",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util"],
)

cel_android_library(
 name = "expr_util_android",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util_android"],
)

30 changes: 30 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -48,6 +48,36 @@ cel_android_library(
 ],
)

java_library(
 name = "expr_util",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common",
 "//common/ast",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven//:com_google_guava_guava",
 ],
)

cel_android_library(
 name = "expr_util_android",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common_android",
 "//common/ast:ast_android",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven_android//:com_google_guava_guava",
 ],
)

java_library(
 name = "navigation",
 srcs = [
Expand Down

9 changes: 8 additions & 1 deletion
common/src/main/java/dev/cel/common/navigation/BaseNavigableExpr.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -16,6 +16,7 @@

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.DoNotMock;
import dev.cel.common.ast.CelExpr;
import dev.cel.common.ast.CelExpr.ExprKind;
import dev.cel.common.ast.Expression;
Expand All@@ -25,9 +26,15 @@
/**
 * BaseNavigableExpr represents the base navigable expression value with methods to inspect the
 * parent and child expressions.
 *
 * <p>This class is intentionally non-extensible outside of the {@code dev.cel.common.navigation}
 * package.
 */
@DoNotMock("Use CelNavigableExpr or CelNavigableMutableExpr")
@SuppressWarnings("unchecked") // Generic types are properly bound to Expression
abstract class BaseNavigableExpr<E extends Expression> {
public abstract class BaseNavigableExpr<E extends Expression> {

 BaseNavigableExpr() {}

 public abstract E expr();

Expand Down

156 changes: 156 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/CelNavigableExprUtil.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,156 @@
// 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.

package dev.cel.common.navigation;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.CheckReturnValue;
import dev.cel.common.ast.CelExpr.ExprKind.Kind;
import dev.cel.common.ast.Expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Optional;

/** Utility class for common AST navigation and scoping inspections on {@link BaseNavigableExpr}. */
@CheckReturnValue
public final class CelNavigableExprUtil {

 /**
 * Returns true if {@code variableName} is in scope and shadowed by an enclosing comprehension
 * above {@code expr}.
 *
 * <p>A variable is shadowed at {@code expr} if an ancestor comprehension declares it as an
 * iteration variable ({@code iterVar}, {@code iterVar2}) or accumulator variable ({@code
 * accuVar}) and {@code expr} resides within a branch where that variable is active:
 *
 * <ul>
 * <li>In {@code loopCondition} and {@code loopStep}: {@code iterVar}, {@code iterVar2}, and
 * {@code accuVar} are in scope.
 * <li>In {@code result}: only {@code accuVar} is in scope ({@code iterVar} and {@code iterVar2}
 * have fallen out of scope).
 * <li>In {@code iterRange} and {@code accuInit}: none of the comprehension variables are in
 * scope.
 * </ul>
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [1, 2].all(x, x > 0)
 * }</pre>
 *
 * <ul>
 * <li>At {@code x} in {@code x > 0}: {@code isVariableShadowed(x, "x")} is {@code true}.
 * <li>At the list {@code [1, 2]}: {@code isVariableShadowed(list, "x")} is {@code false}.
 * </ul>
 */
 public static boolean isVariableShadowed(BaseNavigableExpr<?> expr, String variableName) {
 return areVariablesShadowed(expr, Collections.singleton(variableName));
 }

 /**
 * Returns true if any of {@code variableNames} is in scope and shadowed by an enclosing
 * comprehension above {@code expr}.
 *
 * <p>For example, in the nested comprehension expression:
 *
 * <pre>{@code
 * [1, 2].all(x, [3, 4].all(y, x > 0 && y > 0))
 * }</pre>
 *
 * At {@code y > 0}, {@code areVariablesShadowed(node, ImmutableSet.of("x", "z"))} is {@code true}
 * because {@code x} is in scope from the outer comprehension.
 */
 @SuppressWarnings("ReferenceEquality") // Required to disambiguate child branches
 public static boolean areVariablesShadowed(
 BaseNavigableExpr<?> expr, Collection<String> variableNames) {
 checkNotNull(expr);
 checkNotNull(variableNames);
 if (variableNames.isEmpty()) {
 return false;
 }
 BaseNavigableExpr<?> curr = expr;
 Optional<? extends BaseNavigableExpr<?>> maybeParent = curr.parent();
 while (maybeParent.isPresent()) {
 BaseNavigableExpr<?> parent = maybeParent.get();
 if (parent.getKind() == Kind.COMPREHENSION) {
 Expression.Comprehension<?> comp = parent.expr().comprehension();
 Expression currExpr = curr.expr();

 if (currExpr != comp.iterRange() && currExpr != comp.accuInit()) {
 if (currExpr == comp.result()) {
 if (variableNames.contains(comp.accuVar())) {
 return true;
 }
 } else {
 if (variableNames.contains(comp.iterVar())
 || variableNames.contains(comp.iterVar2())
 || variableNames.contains(comp.accuVar())) {
 return true;
 }
 }
 }
 }
 curr = parent;
 maybeParent = parent.parent();
 }
 return false;
 }

 /**
 * Returns true if {@code expr} is an {@code IDENT} node that references a variable declared by an
 * enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At identifier {@code x}: {@code isComprehensionVariable(x)} is {@code true}.
 * <li>At identifier {@code a}: {@code isComprehensionVariable(a)} is {@code false}.
 * </ul>
 */
 public static boolean isComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.getKind() == Kind.IDENT
 && areVariablesShadowed(expr, Collections.singleton(expr.expr().ident().name()));
 }

 /**
 * Returns true if {@code expr} or any identifier within {@code expr} references a variable
 * declared by an enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At the subtree {@code x > a}: {@code hasComprehensionVariable(subtree)} is {@code true}
 * because {@code x} is a comprehension variable.
 * <li>At the subtree {@code [a]}: {@code hasComprehensionVariable(iterRange)} is {@code false}.
 * </ul>
 */
 public static boolean hasComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.allNodes()
 .filter(node -> node.getKind() == Kind.IDENT)
 .anyMatch(CelNavigableExprUtil::isComprehensionVariable);
 }

 private CelNavigableExprUtil() {}
}

2 changes: 2 additions & 0 deletions
common/src/test/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -21,10 +21,12 @@ java_library(
 "//common/ast:mutable_expr",
 "//common/navigation",
 "//common/navigation:common",
 "//common/navigation:expr_util",
 "//common/navigation:mutable_navigation",
 "//common/types",
 "//compiler",
 "//compiler:compiler_builder",
 "//extensions",
 "//parser:macro",
 "@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",
 "@maven//:com_google_guava_guava",
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

Skip to content
Introduce common helpers for handling AST navigation#1170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and
privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

copybara-service
merged 1 commit into

from

Aug 7, 2026
 Merged


Introduce common helpers for handling AST navigation
#1170
Show file tree
Hide file tree
 Changes from all commits
Commits

Show all changes


1 commit


Select commit


File filter

Filter by extension
Filter by extension
Conversations

Failed to load comments. 
Loading
Jump to

Jump to file


Failed to load files. 
Loading
 Diff view

 Diff view


10 changes: 10 additions & 0 deletions
common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -25,3 +25,13 @@ java_library(
 name = "mutable_navigation",
 exports = ["//common/src/main/java/dev/cel/common/navigation:mutable_navigation"],
)

java_library(
 name = "expr_util",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util"],
)

cel_android_library(
 name = "expr_util_android",
 exports = ["//common/src/main/java/dev/cel/common/navigation:expr_util_android"],
)

30 changes: 30 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -48,6 +48,36 @@ cel_android_library(
 ],
)

java_library(
 name = "expr_util",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common",
 "//common/ast",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven//:com_google_guava_guava",
 ],
)

cel_android_library(
 name = "expr_util_android",
 srcs = [
 "CelNavigableExprUtil.java",
 ],
 tags = [
 ],
 deps = [
 ":common_android",
 "//common/ast:ast_android",
 "@maven//:com_google_errorprone_error_prone_annotations",
 "@maven_android//:com_google_guava_guava",
 ],
)

java_library(
 name = "navigation",
 srcs = [
Expand Down

9 changes: 8 additions & 1 deletion
common/src/main/java/dev/cel/common/navigation/BaseNavigableExpr.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -16,6 +16,7 @@

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.DoNotMock;
import dev.cel.common.ast.CelExpr;
import dev.cel.common.ast.CelExpr.ExprKind;
import dev.cel.common.ast.Expression;
Expand All@@ -25,9 +26,15 @@
/**
 * BaseNavigableExpr represents the base navigable expression value with methods to inspect the
 * parent and child expressions.
 *
 * <p>This class is intentionally non-extensible outside of the {@code dev.cel.common.navigation}
 * package.
 */
@DoNotMock("Use CelNavigableExpr or CelNavigableMutableExpr")
@SuppressWarnings("unchecked") // Generic types are properly bound to Expression
abstract class BaseNavigableExpr<E extends Expression> {
public abstract class BaseNavigableExpr<E extends Expression> {

 BaseNavigableExpr() {}

 public abstract E expr();

Expand Down

156 changes: 156 additions & 0 deletions
common/src/main/java/dev/cel/common/navigation/CelNavigableExprUtil.java

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,156 @@
// 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.

package dev.cel.common.navigation;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.errorprone.annotations.CheckReturnValue;
import dev.cel.common.ast.CelExpr.ExprKind.Kind;
import dev.cel.common.ast.Expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Optional;

/** Utility class for common AST navigation and scoping inspections on {@link BaseNavigableExpr}. */
@CheckReturnValue
public final class CelNavigableExprUtil {

 /**
 * Returns true if {@code variableName} is in scope and shadowed by an enclosing comprehension
 * above {@code expr}.
 *
 * <p>A variable is shadowed at {@code expr} if an ancestor comprehension declares it as an
 * iteration variable ({@code iterVar}, {@code iterVar2}) or accumulator variable ({@code
 * accuVar}) and {@code expr} resides within a branch where that variable is active:
 *
 * <ul>
 * <li>In {@code loopCondition} and {@code loopStep}: {@code iterVar}, {@code iterVar2}, and
 * {@code accuVar} are in scope.
 * <li>In {@code result}: only {@code accuVar} is in scope ({@code iterVar} and {@code iterVar2}
 * have fallen out of scope).
 * <li>In {@code iterRange} and {@code accuInit}: none of the comprehension variables are in
 * scope.
 * </ul>
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [1, 2].all(x, x > 0)
 * }</pre>
 *
 * <ul>
 * <li>At {@code x} in {@code x > 0}: {@code isVariableShadowed(x, "x")} is {@code true}.
 * <li>At the list {@code [1, 2]}: {@code isVariableShadowed(list, "x")} is {@code false}.
 * </ul>
 */
 public static boolean isVariableShadowed(BaseNavigableExpr<?> expr, String variableName) {
 return areVariablesShadowed(expr, Collections.singleton(variableName));
 }

 /**
 * Returns true if any of {@code variableNames} is in scope and shadowed by an enclosing
 * comprehension above {@code expr}.
 *
 * <p>For example, in the nested comprehension expression:
 *
 * <pre>{@code
 * [1, 2].all(x, [3, 4].all(y, x > 0 && y > 0))
 * }</pre>
 *
 * At {@code y > 0}, {@code areVariablesShadowed(node, ImmutableSet.of("x", "z"))} is {@code true}
 * because {@code x} is in scope from the outer comprehension.
 */
 @SuppressWarnings("ReferenceEquality") // Required to disambiguate child branches
 public static boolean areVariablesShadowed(
 BaseNavigableExpr<?> expr, Collection<String> variableNames) {
 checkNotNull(expr);
 checkNotNull(variableNames);
 if (variableNames.isEmpty()) {
 return false;
 }
 BaseNavigableExpr<?> curr = expr;
 Optional<? extends BaseNavigableExpr<?>> maybeParent = curr.parent();
 while (maybeParent.isPresent()) {
 BaseNavigableExpr<?> parent = maybeParent.get();
 if (parent.getKind() == Kind.COMPREHENSION) {
 Expression.Comprehension<?> comp = parent.expr().comprehension();
 Expression currExpr = curr.expr();

 if (currExpr != comp.iterRange() && currExpr != comp.accuInit()) {
 if (currExpr == comp.result()) {
 if (variableNames.contains(comp.accuVar())) {
 return true;
 }
 } else {
 if (variableNames.contains(comp.iterVar())
 || variableNames.contains(comp.iterVar2())
 || variableNames.contains(comp.accuVar())) {
 return true;
 }
 }
 }
 }
 curr = parent;
 maybeParent = parent.parent();
 }
 return false;
 }

 /**
 * Returns true if {@code expr} is an {@code IDENT} node that references a variable declared by an
 * enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At identifier {@code x}: {@code isComprehensionVariable(x)} is {@code true}.
 * <li>At identifier {@code a}: {@code isComprehensionVariable(a)} is {@code false}.
 * </ul>
 */
 public static boolean isComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.getKind() == Kind.IDENT
 && areVariablesShadowed(expr, Collections.singleton(expr.expr().ident().name()));
 }

 /**
 * Returns true if {@code expr} or any identifier within {@code expr} references a variable
 * declared by an enclosing comprehension.
 *
 * <p>For example, in the expression:
 *
 * <pre>{@code
 * [a].all(x, x > a)
 * }</pre>
 *
 * <ul>
 * <li>At the subtree {@code x > a}: {@code hasComprehensionVariable(subtree)} is {@code true}
 * because {@code x} is a comprehension variable.
 * <li>At the subtree {@code [a]}: {@code hasComprehensionVariable(iterRange)} is {@code false}.
 * </ul>
 */
 public static boolean hasComprehensionVariable(BaseNavigableExpr<?> expr) {
 checkNotNull(expr);
 return expr.allNodes()
 .filter(node -> node.getKind() == Kind.IDENT)
 .anyMatch(CelNavigableExprUtil::isComprehensionVariable);
 }

 private CelNavigableExprUtil() {}
}

2 changes: 2 additions & 0 deletions
common/src/test/java/dev/cel/common/navigation/BUILD.bazel

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -21,10 +21,12 @@ java_library(
 "//common/ast:mutable_expr",
 "//common/navigation",
 "//common/navigation:common",
 "//common/navigation:expr_util",
 "//common/navigation:mutable_navigation",
 "//common/types",
 "//compiler",
 "//compiler:compiler_builder",
 "//extensions",
 "//parser:macro",
 "@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",
 "@maven//:com_google_guava_guava",
Expand Down
Loading
Loading