Package org.checkerframework.checker.optional

Class OptionalVisitor

java.lang.Object

com.sun.source.util.TreeScanner<R,P>

com.sun.source.util.TreePathScanner<R,P>

org.checkerframework.framework.source.SourceVisitor<Void,Void>

org.checkerframework.common.basetype.BaseTypeVisitor<BaseAnnotatedTypeFactory>

org.checkerframework.checker.optional.OptionalVisitor

All Implemented Interfaces:

TreeVisitor<Void,Void>

public class OptionalVisitor
extends BaseTypeVisitor<BaseAnnotatedTypeFactory>

The OptionalVisitor enforces the Optional Checker rules. These rules are described in the Checker Framework Manual.

See the Checker Framework Manual:

Optional Checker

Nested Class Summary

Nested classes/interfaces inherited from class org.checkerframework.common.basetype.BaseTypeVisitor

BaseTypeVisitor.OverrideChecker

Field Summary

Fields inherited from class org.checkerframework.common.basetype.BaseTypeVisitor

atypeFactory, checker, DETERMINISTIC, IMPURE, methodTree, positions, PURE, qualHierarchy, showchecks, SIDE_EFFECT_FREE, TARGET, targetValueElement, typeHierarchy, typeValidator, unusedWhenElement

Fields inherited from class org.checkerframework.framework.source.SourceVisitor

elements, root, trees, treesWithSuppressWarnings, types

Constructor Summary

Constructors

Constructor	Description
OptionalVisitor(BaseTypeChecker checker)	Create an OptionalVisitor.

Method Summary

Modifier and Type	Method	Description
protected BaseTypeValidator	createTypeValidator()
void	handleConditionalStatementIsPresentGet(IfTree tree)	Part of rule #3.
void	handleCreationElimination(MethodInvocationTree tree)	Rule #4.
void	handleTernaryIsPresentGet(ConditionalExpressionTree tree)	Part of rule #3.
static StatementTree	skipBlocks(StatementTree tree)	If the given tree is a block tree with a single element, return the enclosed non-block statement.
Void	visitConditionalExpression(ConditionalExpressionTree tree, Void p)	If the computation of the type of the ConditionalExpressionTree in org.checkerframework.framework.type.TypeFromTree.TypeFromExpression.visitConditionalExpression(ConditionalExpressionTree, AnnotatedTypeFactory) is correct, the following checks are redundant.
Void	visitIf(IfTree tree, Void p)
Void	visitMethodInvocation(MethodInvocationTree tree, Void p)	Performs a method invocation check.
Void	visitVariable(VariableTree tree, Void p)	Rule #6 (partial).

Methods inherited from class org.checkerframework.common.basetype.BaseTypeVisitor

checkAccess, checkAccessAllowed, checkArguments, checkArrayInitialization, checkConditionalPostcondition, checkConstructorInvocation, checkConstructorResult, checkContract, checkDefaultConstructor, checkExceptionParameter, checkExplicitAnnotationsOnIntersectionBounds, checkExtendsAndImplements, checkExtendsOrImplements, checkFieldInvariantDeclarations, checkForPolymorphicQualifiers, checkForPolymorphicQualifiers, checkMethodInvocability, checkMethodReferenceAsOverride, checkOverride, checkOverride, checkPostcondition, checkPreconditions, checkPurity, checkQualifierParameter, checkSuperConstructorCall, checkThisConstructorCall, checkThisOrSuperConstructorCall, checkThrownExpression, checkTypeArguments, checkTypecastRedundancy, checkTypecastSafety, checkVarargs, commonAssignmentCheck, commonAssignmentCheck, commonAssignmentCheck, commonAssignmentCheckEndDiagnostic, commonAssignmentCheckEndDiagnostic, commonAssignmentCheckStartDiagnostic, createOverrideChecker, createTypeFactory, createTypeFactoryPublic, enclosingMemberSelect, enclosingStatement, getExceptionParameterLowerBoundAnnotations, getThrowUpperBoundAnnotations, getTypeFactory, isTypeCastSafe, isValidUse, isValidUse, isValidUse, processClassTree, reportMethodInvocabilityError, reportPurityErrors, scan, setRoot, shouldPerformContractInference, shouldSkipUses, shouldWarnAboutIrrelevantJavaTypes, skipReceiverSubtypeCheck, testAnnotationInsertion, testJointJavacJavaParserVisitor, testTypevarContainment, typeCheckVectorCopyIntoArgument, validateType, validateTypeOf, visitAnnotatedType, visitAnnotatedType, visitAnnotation, visitAssignment, visitCatch, visitClass, visitCompilationUnit, visitCompoundAssignment, visitEnhancedForLoop, visitIdentifier, visitInstanceOf, visitLambdaExpression, visitMemberReference, visitMethod, visitNewArray, visitNewClass, visitReturn, visitSwitchExpression17, visitThrow, visitTypeCast, visitTypeParameter, visitUnary, warnAboutIrrelevantJavaTypes, warnRedundantAnnotations

Methods inherited from class org.checkerframework.framework.source.SourceVisitor

visit

Methods inherited from class com.sun.source.util.TreePathScanner

getCurrentPath, scan

Methods inherited from class com.sun.source.util.TreeScanner

reduce, scan, visitArrayAccess, visitArrayType, visitAssert, visitBinary, visitBindingPattern, visitBlock, visitBreak, visitCase, visitContinue, visitDefaultCaseLabel, visitDoWhileLoop, visitEmptyStatement, visitErroneous, visitExports, visitExpressionStatement, visitForLoop, visitGuardedPattern, visitImport, visitIntersectionType, visitLabeledStatement, visitLiteral, visitMemberSelect, visitModifiers, visitModule, visitOpens, visitOther, visitPackage, visitParameterizedType, visitParenthesized, visitParenthesizedPattern, visitPrimitiveType, visitProvides, visitRequires, visitSwitch, visitSwitchExpression, visitSynchronized, visitTry, visitUnionType, visitUses, visitWhileLoop, visitWildcard, visitYield

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

OptionalVisitor

public OptionalVisitor(BaseTypeChecker checker)

Create an OptionalVisitor.

Method Details

createTypeValidator

protected BaseTypeValidator createTypeValidator()

Overrides:

createTypeValidator in class BaseTypeVisitor<BaseAnnotatedTypeFactory>

visitConditionalExpression

public Void visitConditionalExpression(ConditionalExpressionTree tree,
 Void p)

Description copied from class: BaseTypeVisitor

If the computation of the type of the ConditionalExpressionTree in org.checkerframework.framework.type.TypeFromTree.TypeFromExpression.visitConditionalExpression(ConditionalExpressionTree, AnnotatedTypeFactory) is correct, the following checks are redundant. However, let's add another failsafe guard and do the checks.

Specified by:

visitConditionalExpression in interface TreeVisitor<Void,Void>

Overrides:

visitConditionalExpression in class BaseTypeVisitor<BaseAnnotatedTypeFactory>

handleTernaryIsPresentGet

public void handleTernaryIsPresentGet(ConditionalExpressionTree tree)

Part of rule #3.

Pattern match for: VAR.isPresent() ? VAR.get().METHOD() : VALUE

Prefer: VAR.map(METHOD).orElse(VALUE);

Parameters:

tree - a conditional expression that can perhaps be simplified

visitIf

public Void visitIf(IfTree tree,
 Void p)

Specified by:

visitIf in interface TreeVisitor<Void,Void>

Overrides:

visitIf in class TreeScanner<Void,Void>

handleConditionalStatementIsPresentGet

public void handleConditionalStatementIsPresentGet(IfTree tree)

Part of rule #3.

Pattern match for: if (VAR.isPresent()) { METHOD(VAR.get()); }

Prefer: VAR.ifPresent(METHOD);

Parameters:

tree - an if statement that can perhaps be simplified

visitMethodInvocation

public Void visitMethodInvocation(MethodInvocationTree tree,
 Void p)

Description copied from class: BaseTypeVisitor

Performs a method invocation check.

An invocation of a method, m, on the receiver, r is valid only if:

• passed arguments are subtypes of corresponding m parameters
• r is a subtype of m receiver type
• if m is generic, passed type arguments are subtypes of m type variables

Specified by:

visitMethodInvocation in interface TreeVisitor<Void,Void>

Overrides:

visitMethodInvocation in class BaseTypeVisitor<BaseAnnotatedTypeFactory>

handleCreationElimination

public void handleCreationElimination(MethodInvocationTree tree)

Rule #4.

Pattern match for: CREATION().ELIMINATION()

Prefer: VAR.ifPresent(METHOD);

Parameters:

tree - a method invocation that can perhaps be simplified

visitVariable

public Void visitVariable(VariableTree tree,
 Void p)

Rule #6 (partial).

Don't use Optional in fields and method parameters.

Specified by:

visitVariable in interface TreeVisitor<Void,Void>

Overrides:

visitVariable in class BaseTypeVisitor<BaseAnnotatedTypeFactory>

skipBlocks

public static StatementTree skipBlocks(StatementTree tree)

If the given tree is a block tree with a single element, return the enclosed non-block statement. Otherwise, return the same tree.

Parameters:

tree - a statement tree

Returns:

the single enclosed statement, if it exists; otherwise, the same tree