io.codemodder.codemods.SwitchLiteralFirstComparisonsCodemod Maven / Gradle / Ivy
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Codemods for fixing common errors across many Java projects
package io.codemodder.codemods;
import com.contrastsecurity.sarif.Result;
import com.github.javaparser.Range;
import com.github.javaparser.ast.CompilationUnit;
import com.github.javaparser.ast.ImportDeclaration;
import com.github.javaparser.ast.Node;
import com.github.javaparser.ast.NodeList;
import com.github.javaparser.ast.body.FieldDeclaration;
import com.github.javaparser.ast.body.Parameter;
import com.github.javaparser.ast.body.VariableDeclarator;
import com.github.javaparser.ast.expr.AnnotationExpr;
import com.github.javaparser.ast.expr.BinaryExpr;
import com.github.javaparser.ast.expr.ConditionalExpr;
import com.github.javaparser.ast.expr.Expression;
import com.github.javaparser.ast.expr.FieldAccessExpr;
import com.github.javaparser.ast.expr.LiteralExpr;
import com.github.javaparser.ast.expr.MethodCallExpr;
import com.github.javaparser.ast.expr.Name;
import com.github.javaparser.ast.expr.NameExpr;
import com.github.javaparser.ast.expr.NullLiteralExpr;
import com.github.javaparser.ast.expr.SimpleName;
import com.github.javaparser.ast.expr.StringLiteralExpr;
import com.github.javaparser.ast.nodeTypes.NodeWithAnnotations;
import com.github.javaparser.ast.nodeTypes.NodeWithSimpleName;
import com.github.javaparser.resolution.UnsolvedSymbolException;
import com.github.javaparser.resolution.types.ResolvedType;
import io.codemodder.*;
import io.codemodder.javaparser.ChangesResult;
import io.codemodder.providers.sarif.pmd.PmdScan;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import javax.inject.Inject;
/**
* A codemod for automatically switching the order of literals and variables in comparisons so
* they're guaranteed not to throw {@link NullPointerException} when the variable is unexpectedly
* null.
*/
@Codemod(
id = "pixee:java/switch-literal-first",
importance = Importance.LOW,
reviewGuidance = ReviewGuidance.MERGE_WITHOUT_REVIEW)
public final class SwitchLiteralFirstComparisonsCodemod
extends SarifPluginJavaParserChanger {
@Inject
public SwitchLiteralFirstComparisonsCodemod(
@PmdScan(ruleId = "category/java/bestpractices.xml/LiteralsFirstInComparisons")
final RuleSarif ruleSarif) {
super(ruleSarif, MethodCallExpr.class);
}
@Override
public ChangesResult onResultFound(
final CodemodInvocationContext context,
final CompilationUnit cu,
final MethodCallExpr methodCallExpr,
final Result result) {
// some of the methods that this rule applies to are not flippable, like compareTo() would
// change the logic after
if (!flippableComparisonMethods.contains(methodCallExpr.getNameAsString())) {
return ChangesResult.noChanges;
}
final List variableDeclarators = cu.findAll(VariableDeclarator.class);
final Optional simpleNameOptional = getSimpleNameFromMethodCallExpr(methodCallExpr);
/**
* This codemod will not be executed if:
*
*
* - Variable has a previous not null assertion
*
- Variable has a {@link @NotNull} or {@link @Nonnull} annotation
*
- Variable was previously initialized to a not null value
*
*/
if (simpleNameOptional.isPresent()
&& (hasSimpleNameNotNullAnnotation(cu, simpleNameOptional.get(), variableDeclarators)
|| hasSimpleNamePreviousNullAssertion(cu, simpleNameOptional.get())
|| isSimpleNameANotNullInitializedVariableDeclarator(cu, simpleNameOptional.get()))) {
return ChangesResult.noChanges;
}
Expression leftSide = methodCallExpr.getScope().get();
Expression rightSide = methodCallExpr.getArgument(0);
try {
final ResolvedType leftType = leftSide.calculateResolvedType();
if ("Ljava/lang/String;".equals(leftType.toDescriptor())) {
methodCallExpr.setScope(rightSide);
methodCallExpr.setArgument(0, leftSide);
return ChangesResult.changesApplied;
}
} catch (final UnsolvedSymbolException e) {
// expected in cases where we can't resolve the type
}
return ChangesResult.noChanges;
}
/**
* Method used to check if variable (nameNode) has a previous node that represents:
*
*
* - A not null assertion
*
- A not null annotation
*
- An initialization to a not null value
*
*/
private boolean isPreviousNodeBefore(final Node nameNode, final Node previousNode) {
final Optional nameNodeRange = nameNode.getRange();
final Optional previousNodeRange = previousNode.getRange();
if (nameNodeRange.isEmpty() || previousNodeRange.isEmpty()) {
return false;
}
return previousNodeRange.get().begin.isBefore(nameNodeRange.get().begin);
}
/**
* Checks if the given Variable {@link SimpleName} has a previous null assertion in the {@link
* CompilationUnit}.
*/
private boolean hasSimpleNamePreviousNullAssertion(
final CompilationUnit cu, final SimpleName name) {
final List nullLiterals = cu.findAll(NullLiteralExpr.class);
if (nullLiterals != null && !nullLiterals.isEmpty()) {
return nullLiterals.stream()
.filter(
nullLiteralExpr ->
nullLiteralExpr.getParentNode().isPresent()
&& nullLiteralExpr.getParentNode().get() instanceof BinaryExpr)
.map(nullLiteralExpr -> (BinaryExpr) nullLiteralExpr.getParentNode().get())
.filter(
parentBinaryExpr -> parentBinaryExpr.getOperator() == BinaryExpr.Operator.NOT_EQUALS)
.anyMatch(
parentBinaryExpr -> {
final Node left = parentBinaryExpr.getLeft();
final Node right = parentBinaryExpr.getRight();
return isBinaryNodeChildPreviouslyCreatedAndEqualToSimpleName(left, name)
|| isBinaryNodeChildPreviouslyCreatedAndEqualToSimpleName(right, name);
});
}
return false;
}
/**
* Checks if the given {@link Node} is a binary expression child node and is equal to the provided
* {@link SimpleName}. Additionally, it verifies if the child node is located before the provided
* {@link SimpleName}.
*/
private boolean isBinaryNodeChildPreviouslyCreatedAndEqualToSimpleName(
final Node child, final SimpleName name) {
return child instanceof NameExpr nameExpr
&& nameExpr.getName().equals(name)
&& isPreviousNodeBefore(name, nameExpr.getName());
}
/**
* Checks if the given {@link SimpleName} variable has a @NotNull or @Nonnull annotation in the
* provided {@link CompilationUnit}.
*/
private boolean hasSimpleNameNotNullAnnotation(
final CompilationUnit cu,
final SimpleName simpleName,
final List variableDeclarators) {
final List fieldDeclarations = cu.findAll(FieldDeclaration.class);
final List parameters = cu.findAll(Parameter.class);
final List annotationNodesCandidates = new ArrayList<>();
annotationNodesCandidates.addAll(variableDeclarators);
annotationNodesCandidates.addAll(fieldDeclarations);
annotationNodesCandidates.addAll(parameters);
final List annotations = filterNodesWithNotNullAnnotations(annotationNodesCandidates);
return annotations.stream()
.anyMatch(
annotation ->
isSimpleNotNullAnnotationForParameterOrVariable(annotation, simpleName)
|| isSimpleNotNullAnnotationForFieldDeclaration(annotation, simpleName));
}
/**
* Checks if the given {@link Node} represents a @NotNull or @Nonnull annotation for a
* FieldDeclaration and the associated VariableDeclarator has the provided {@link SimpleName}.
*/
private boolean isSimpleNotNullAnnotationForFieldDeclaration(
final Node annotation, final SimpleName simpleName) {
if (annotation instanceof FieldDeclaration fieldDeclaration) {
final List fieldDeclarationVariables = fieldDeclaration.getVariables();
return fieldDeclarationVariables.stream()
.anyMatch(
variableDeclarator ->
variableDeclarator.getName().equals(simpleName)
&& isPreviousNodeBefore(simpleName, variableDeclarator.getName()));
}
return false;
}
/**
* Checks if the given {@link Node} represents a @NotNull or @Nonnull annotation for a Parameter
* or VariableDeclarator, and the associated SimpleName matches the provided {@link SimpleName}.
*/
private boolean isSimpleNotNullAnnotationForParameterOrVariable(
final Node annotation, final SimpleName simpleName) {
if (annotation instanceof Parameter || annotation instanceof VariableDeclarator) {
final SimpleName annotationSimpleName = ((NodeWithSimpleName) annotation).getName();
return annotationSimpleName.equals(simpleName)
&& isPreviousNodeBefore(simpleName, annotationSimpleName);
}
return false;
}
/**
* Filters the provided list of nodes to include only those with @NotNull or @Nonnull annotations.
*/
private List filterNodesWithNotNullAnnotations(final List annotationNodes) {
return annotationNodes.stream()
.filter(node -> node instanceof NodeWithAnnotations)
.filter(node -> !((NodeWithAnnotations) node).getAnnotations().isEmpty())
.filter(
node -> hasNotNullOrNonnullAnnotation(((NodeWithAnnotations) node).getAnnotations()))
.toList();
}
/** Checks if the provided list of annotations contains any @NotNull or @Nonnull annotations. */
private boolean hasNotNullOrNonnullAnnotation(final NodeList annotations) {
return annotations.stream().anyMatch(this::isNotNullOrNonnullAnnotation);
}
private boolean isNotNullOrNonnullAnnotation(final AnnotationExpr annotation) {
final Name annotationName = annotation.getName();
final String name = annotationName.getIdentifier();
return "NotNull".equals(name) || "Nonnull".equals(name);
}
/**
* Checks if the provided {@link SimpleName} variable corresponds to a {@link VariableDeclarator}
* that was previously initialized to a non-null expression.
*/
private boolean isSimpleNameANotNullInitializedVariableDeclarator(
final CompilationUnit cu, final SimpleName targetName) {
final Optional variableDeclaratorOptional =
getDeclaredVariable(cu, targetName);
if (variableDeclaratorOptional.isEmpty()
|| variableDeclaratorOptional.get().getInitializer().isEmpty()) {
return false;
}
return isNullSafeExpression(cu, variableDeclaratorOptional.get().getInitializer().get());
}
/**
* Retrieves the {@link SimpleName} from the given {@link MethodCallExpr}. This codemod assumes
* that {@link MethodCallExpr} nodes contain only one {@link SimpleName} node.
*/
private Optional getSimpleNameFromMethodCallExpr(
final MethodCallExpr methodCallExpr) {
final List simpleNames =
methodCallExpr.getChildNodes().stream()
.filter(NameExpr.class::isInstance)
.map(node -> ((NameExpr) node).getName())
.toList();
return simpleNames.isEmpty() ? Optional.empty() : Optional.of(simpleNames.get(0));
}
private boolean isNullSafeExpression(final CompilationUnit cu, final Expression expression) {
if (expression instanceof NullLiteralExpr) {
return false;
}
if (expression instanceof MethodCallExpr methodCallExpr) {
return isNullSafeMethodExpr(cu, methodCallExpr);
}
if (expression instanceof ConditionalExpr conditionalExpr) {
return isNullSafeExpression(cu, conditionalExpr.getThenExpr())
&& isNullSafeExpression(cu, conditionalExpr.getElseExpr());
}
if (expression instanceof NameExpr nameExpr) {
return isSimpleNameANotNullInitializedVariableDeclarator(cu, nameExpr.getName());
}
return expression instanceof LiteralExpr;
}
private boolean isNullSafeMethodExpr(
final CompilationUnit cu, final MethodCallExpr methodCallExpr) {
final Optional optionalScope = methodCallExpr.getScope();
final String method = methodCallExpr.getName().getIdentifier();
// Static import case for example: import static
// org.apache.commons.lang3.StringUtils.defaultString
if (optionalScope.isEmpty()) {
return isNullSafeImportLibrary(cu, methodCallExpr.getName().getIdentifier(), method);
}
final Expression scope = optionalScope.get();
// Using java.lang.String's method
if (scope instanceof StringLiteralExpr) {
return commonMethodsThatCantReturnNull.contains("java.lang.String#".concat(method));
}
// Using full import name as scope of method, for example
// String str = org.apache.commons.lang3.StringUtils.defaultString("")
if (scope instanceof FieldAccessExpr fieldAccessExpr) {
final String fullImportName = fieldAccessExpr.toString();
return commonMethodsThatCantReturnNull.contains(fullImportName.concat("#").concat(method));
}
if (scope instanceof NameExpr scopeName) {
if (!isVariable(cu, scopeName)) {
// check if scope is non-static import like: import org.apache.commons.lang3.StringUtils
return isNullSafeImportLibrary(cu, scopeName.getName().getIdentifier(), method);
}
final Optional variableDeclaratorOptional =
getDeclaredVariable(cu, scopeName.getName());
if (variableDeclaratorOptional.isEmpty()) {
return false;
}
final String type = variableDeclaratorOptional.get().getTypeAsString();
// when scope is an object variable, check class type to determine if it is an implicit or
// explicit import
return isClassObjectMethodNullSafe(cu, type, method);
}
return false;
}
/** Some basic java lang type classes */
private boolean isClassObjectMethodNullSafe(
final CompilationUnit cu, final String type, final String method) {
switch (type) {
case "String" -> {
return commonMethodsThatCantReturnNull.contains("java.lang.String#".concat(method));
}
case "Integer" -> {
return commonMethodsThatCantReturnNull.contains("java.lang.Integer#".concat(method));
}
case "Double" -> {
return commonMethodsThatCantReturnNull.contains("java.lang.Double#".concat(method));
}
case "Character" -> {
return commonMethodsThatCantReturnNull.contains("java.lang.Character#".concat(method));
}
case "Long" -> {
return commonMethodsThatCantReturnNull.contains("java.lang.Long#".concat(method));
}
default -> {
return isNullSafeImportLibrary(cu, type, method);
}
}
}
private boolean isVariable(final CompilationUnit cu, final NameExpr nameExpr) {
final SimpleName simpleName = nameExpr.getName();
final Optional variableDeclaratorOptional =
getDeclaredVariable(cu, simpleName);
return variableDeclaratorOptional.isPresent();
}
private boolean isNullSafeImportLibrary(
final CompilationUnit cu, final String identifier, final String method) {
final Optional optionalImport =
cu.getImports().stream()
.filter(importName -> importName.getName().getIdentifier().equals(identifier))
.findFirst();
if (optionalImport.isEmpty()) {
return false;
}
if (optionalImport.get().isStatic()
&& optionalImport.get().getName().getQualifier().isEmpty()) {
return false;
}
final Name importDeclaration =
optionalImport.get().isStatic()
? optionalImport.get().getName().getQualifier().get()
: optionalImport.get().getName();
return commonMethodsThatCantReturnNull.contains(
importDeclaration.asString().concat("#").concat(method));
}
private Optional getDeclaredVariable(
final CompilationUnit cu, final SimpleName simpleName) {
final List variableDeclarators = cu.findAll(VariableDeclarator.class);
return variableDeclarators.stream()
.filter(declarator -> declarator.getName().equals(simpleName))
.filter(declarator -> isPreviousNodeBefore(simpleName, declarator.getName()))
.findFirst();
}
private static final Set flippableComparisonMethods =
Set.of("equals", "equalsIgnoreCase");
private static final List commonMethodsThatCantReturnNull =
List.of(
"org.apache.commons.lang3.StringUtils#defaultString",
"java.lang.String#concat",
"java.lang.String#replace",
"java.lang.String#replaceAll",
"java.lang.String#replaceFirst",
"java.lang.String#join",
"java.lang.String#substring",
"java.lang.String#substring",
"java.lang.String#toLowerCase",
"java.lang.String#toUpperCase",
"java.lang.String#trim",
"java.lang.String#strip",
"java.lang.String#stripLeading",
"java.lang.String#stripTrailing",
"java.lang.String#toString",
"java.lang.String#valueOf",
"java.lang.String#formatted");
}