org.checkerframework.checker.nullness

Class NullnessVisitor

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<Factory>

org.checkerframework.checker.initialization.InitializationVisitor<NullnessAnnotatedTypeFactory,NullnessValue,NullnessStore>

org.checkerframework.checker.nullness.NullnessVisitor

All Implemented Interfaces:

TreeVisitor<Void,Void>

public class NullnessVisitor
extends InitializationVisitor<NullnessAnnotatedTypeFactory,NullnessValue,NullnessStore>

The visitor for the nullness type-system.

Field Summary

Fields inherited from class org.checkerframework.checker.initialization.InitializationVisitor

annoFormatter, initializedFields

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

atypeFactory, checker, contractsUtils, positions, typeValidator, visitorState

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

elements, root, trees, types

Constructor Summary

Constructors

Constructor and Description
NullnessVisitor(BaseTypeChecker checker, boolean useFbc)

Method Summary

Modifier and Type	Method and Description
protected void	checkExceptionParameter(CatchTree node) Issue error if the exception parameter is not a super type of the annotation specified by getExceptionParameterLowerBoundAnnotations(), which is top by default (Subclasses may override this method to change the behavior of this check.
protected void	checkForRedundantTests(BinaryTree node) Reports an error if a comparison of a @NonNull expression with the null literal is performed.
protected void	checkMethodInvocability(AnnotatedTypeMirror.AnnotatedExecutableType method, MethodInvocationTree node) Tests whether the method can be invoked using the receiver of the 'node' method invocation, and issues a "method.invocation.invalid" if the invocation is invalid.
protected void	checkThrownExpression(ThrowTree node) Case 4: Check for thrown exception nullness
protected void	commonAssignmentCheck(AnnotatedTypeMirror varType, ExpressionTree valueExp, @CompilerMessageKey String errorKey) Checks the validity of an assignment (or pseudo-assignment) from a value to a variable and emits an error message (through the compiler's messaging interface) if it is not valid.
protected void	commonAssignmentCheck(Tree varTree, ExpressionTree valueExp, @CompilerMessageKey String errorKey) Checks the validity of an assignment (or pseudo-assignment) from a value to a variable and emits an error message (through the compiler's messaging interface) if it is not valid.
NullnessAnnotatedTypeFactory	createTypeFactory() Constructs an instance of the appropriate type factory for the implemented type system.
boolean	isValidUse(AnnotatedTypeMirror.AnnotatedDeclaredType declarationType, AnnotatedTypeMirror.AnnotatedDeclaredType useType, Tree tree) Tests that the qualifiers present on the useType are valid qualifiers, given the qualifiers on the declaration of the type, declarationType.
boolean	isValidUse(AnnotatedTypeMirror.AnnotatedPrimitiveType type, Tree tree) Tests that the qualifiers present on the primitive type are valid.
Void	visitArrayAccess(ArrayAccessTree node, Void p) Case 3: Check for array dereferencing
Void	visitAssert(AssertTree node, Void p)
Void	visitBinary(BinaryTree node, Void p) Case 6: Check for redundant nullness tests Case 7: unboxing case: primitive operations
Void	visitCompoundAssignment(CompoundAssignmentTree node, Void p) Case 7: unboxing case: primitive operation
Void	visitConditionalExpression(ConditionalExpressionTree node, 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	visitDoWhileLoop(DoWhileLoopTree node, Void p)
Void	visitEnhancedForLoop(EnhancedForLoopTree node, Void p) Case 2: Check for implicit .iterator call
Void	visitForLoop(ForLoopTree node, Void p)
Void	visitIf(IfTree node, Void p)
Void	visitMemberSelect(MemberSelectTree node, Void p) Case 1: Check for null dereferencing
Void	visitNewArray(NewArrayTree node, Void p)
Void	visitNewClass(NewClassTree node, Void p) Performs a new class invocation check.
Void	visitSwitch(SwitchTree node, Void p)
Void	visitSynchronized(SynchronizedTree node, Void p) Case 5: Check for synchronizing locks
Void	visitTypeCast(TypeCastTree node, Void p) Case 7: unboxing case: casting to a primitive
Void	visitUnary(UnaryTree node, Void p) Case 7: unboxing case: primitive operation
Void	visitWhileLoop(WhileLoopTree node, Void p)

Methods inherited from class org.checkerframework.checker.initialization.InitializationVisitor

checkConstructorInvocation, checkContract, checkFieldsInitialized, getExplicitReturnTypeAnnotations, setRoot, visitBlock, visitClass, visitMethod, visitVariable

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

checkAccess, checkAccess, checkArguments, checkArrayInitialization, checkAssignability, checkConditionalPostconditions, checkConditionalPostconditionsConsistency, checkDefaultConstructor, checkFlowExprParameters, checkForAnnotatedJdk, checkMethodReferenceAsOverride, checkOverride, checkPostconditions, checkPostconditionsConsistency, checkPreconditions, checkPreconditions, checkPreconditionsConsistency, checkTypeArguments, checkTypecastRedundancy, checkTypecastSafety, commonAssignmentCheck, createTypeValidator, enclosingMemberSelect, enclosingStatement, getExceptionParameterLowerBoundAnnotations, getThrowUpperBoundAnnotations, getTypeFactory, isAccessAllowed, isAssignable, isValidUse, isVectorCopyInto, reportPurityErrors, scan, shouldSkipUses, skipContractCheck, skipReceiverSubtypeCheck, testTypevarContainment, typeCheckVectorCopyIntoArgument, validateType, validateTypeOf, visitAnnotation, visitAssignment, visitCatch, visitCompilationUnit, visitIdentifier, visitInstanceOf, visitLambdaExpression, visitMemberReference, visitMethodInvocation, visitParameterizedType, visitReturn, visitThrow, visitTypeParameter

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, visitAnnotatedType, visitArrayType, visitBreak, visitCase, visitContinue, visitEmptyStatement, visitErroneous, visitExpressionStatement, visitImport, visitIntersectionType, visitLabeledStatement, visitLiteral, visitModifiers, visitOther, visitParenthesized, visitPrimitiveType, visitTry, visitUnionType, visitWildcard

Methods inherited from class java.lang.Object

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

Constructor Detail

NullnessVisitor

public NullnessVisitor(BaseTypeChecker checker,
                       boolean useFbc)

Method Detail

createTypeFactory

public NullnessAnnotatedTypeFactory createTypeFactory()

Description copied from class: BaseTypeVisitor

Constructs an instance of the appropriate type factory for the implemented type system. The default implementation uses the checker naming convention to create the appropriate type factory. If no factory is found, it returns BaseAnnotatedTypeFactory. It reflectively invokes the constructor that accepts this checker and compilation unit tree (in that order) as arguments. Subclasses have to override this method to create the appropriate visitor if they do not follow the checker naming convention.

Overrides:

createTypeFactory in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

Returns:

the appropriate type factory

isValidUse

public boolean isValidUse(AnnotatedTypeMirror.AnnotatedDeclaredType declarationType,
                          AnnotatedTypeMirror.AnnotatedDeclaredType useType,
                          Tree tree)

Description copied from class: BaseTypeVisitor

Tests that the qualifiers present on the useType are valid qualifiers, given the qualifiers on the declaration of the type, declarationType.

The check is shallow, as it does not descend into generic or array types (i.e. only performing the validity check on the raw type or outermost array dimension). BaseTypeVisitor.validateTypeOf(Tree) would call this for each type argument or array dimension separately.

For instance, in the IGJ type system, a @Mutable is an invalid qualifier for String, as String is declared as @Immutable String.

In most cases, useType simply needs to be a subtype of declarationType, but there are exceptions. In IGJ, a variable may be declared @ReadOnly String, even though String is @Immutable String; ReadOnly is not a subtype of Immutable.

Overrides:

isValidUse in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

Parameters:

declarationType - the type of the class (TypeElement)

useType - the use of the class (instance type)

tree - the tree where the type is used

Returns:

true if the useType is a valid use of elemType

isValidUse

public boolean isValidUse(AnnotatedTypeMirror.AnnotatedPrimitiveType type,
                          Tree tree)

Description copied from class: BaseTypeVisitor

Tests that the qualifiers present on the primitive type are valid. The default implementation always returns true. Subclasses should override this method to limit what annotations are allowed on primitive types.

Overrides:

isValidUse in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

Parameters:

type - the use of the primitive type

tree - the tree where the type is used

Returns:

true if the type is a valid use of the primitive type

commonAssignmentCheck

protected void commonAssignmentCheck(Tree varTree,
                                     ExpressionTree valueExp,
                                     @CompilerMessageKey String errorKey)

Description copied from class: BaseTypeVisitor

Checks the validity of an assignment (or pseudo-assignment) from a value to a variable and emits an error message (through the compiler's messaging interface) if it is not valid.

Overrides:

commonAssignmentCheck in class InitializationVisitor<NullnessAnnotatedTypeFactory,NullnessValue,NullnessStore>

Parameters:

varTree - the AST node for the variable

valueExp - the AST node for the value

errorKey - the error message to use if the check fails (must be a compiler message key, see CompilerMessageKey)

commonAssignmentCheck

protected void commonAssignmentCheck(AnnotatedTypeMirror varType,
                                     ExpressionTree valueExp,
                                     @CompilerMessageKey String errorKey)

Description copied from class: BaseTypeVisitor

Checks the validity of an assignment (or pseudo-assignment) from a value to a variable and emits an error message (through the compiler's messaging interface) if it is not valid.

Overrides:

commonAssignmentCheck in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

Parameters:

varType - the annotated type of the variable

valueExp - the AST node for the value

errorKey - the error message to use if the check fails (must be a compiler message key, see CompilerMessageKey)

visitMemberSelect

public Void visitMemberSelect(MemberSelectTree node,
                              Void p)

Case 1: Check for null dereferencing

Specified by:

visitMemberSelect in interface TreeVisitor<Void,Void>

Overrides:

visitMemberSelect in class TreeScanner<Void,Void>

visitEnhancedForLoop

public Void visitEnhancedForLoop(EnhancedForLoopTree node,
                                 Void p)

Case 2: Check for implicit .iterator call

Specified by:

visitEnhancedForLoop in interface TreeVisitor<Void,Void>

Overrides:

visitEnhancedForLoop in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

visitArrayAccess

public Void visitArrayAccess(ArrayAccessTree node,
                             Void p)

Case 3: Check for array dereferencing

Specified by:

visitArrayAccess in interface TreeVisitor<Void,Void>

Overrides:

visitArrayAccess in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

visitNewArray

public Void visitNewArray(NewArrayTree node,
                          Void p)

Specified by:

visitNewArray in interface TreeVisitor<Void,Void>

Overrides:

visitNewArray in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

checkThrownExpression

protected void checkThrownExpression(ThrowTree node)

Case 4: Check for thrown exception nullness

Overrides:

checkThrownExpression in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

Parameters:

node - ThrowTree to check

visitSynchronized

public Void visitSynchronized(SynchronizedTree node,
                              Void p)

Case 5: Check for synchronizing locks

Specified by:

visitSynchronized in interface TreeVisitor<Void,Void>

Overrides:

visitSynchronized in class TreeScanner<Void,Void>

visitAssert

public Void visitAssert(AssertTree node,
                        Void p)

Specified by:

visitAssert in interface TreeVisitor<Void,Void>

Overrides:

visitAssert in class TreeScanner<Void,Void>

visitIf

public Void visitIf(IfTree node,
                    Void p)

Specified by:

visitIf in interface TreeVisitor<Void,Void>

Overrides:

visitIf in class TreeScanner<Void,Void>

checkForRedundantTests

protected void checkForRedundantTests(BinaryTree node)

Reports an error if a comparison of a @NonNull expression with the null literal is performed.

visitBinary

public Void visitBinary(BinaryTree node,
                        Void p)

Case 6: Check for redundant nullness tests Case 7: unboxing case: primitive operations

Specified by:

visitBinary in interface TreeVisitor<Void,Void>

Overrides:

visitBinary in class TreeScanner<Void,Void>

visitUnary

public Void visitUnary(UnaryTree node,
                       Void p)

Case 7: unboxing case: primitive operation

Specified by:

visitUnary in interface TreeVisitor<Void,Void>

Overrides:

visitUnary in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

visitCompoundAssignment

public Void visitCompoundAssignment(CompoundAssignmentTree node,
                                    Void p)

Case 7: unboxing case: primitive operation

Specified by:

visitCompoundAssignment in interface TreeVisitor<Void,Void>

Overrides:

visitCompoundAssignment in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

visitTypeCast

public Void visitTypeCast(TypeCastTree node,
                          Void p)

Case 7: unboxing case: casting to a primitive

Specified by:

visitTypeCast in interface TreeVisitor<Void,Void>

Overrides:

visitTypeCast in class InitializationVisitor<NullnessAnnotatedTypeFactory,NullnessValue,NullnessStore>

checkMethodInvocability

protected void checkMethodInvocability(AnnotatedTypeMirror.AnnotatedExecutableType method,
                                       MethodInvocationTree node)

Description copied from class: BaseTypeVisitor

Tests whether the method can be invoked using the receiver of the 'node' method invocation, and issues a "method.invocation.invalid" if the invocation is invalid. This implementation tests whether the receiver in the method invocation is a subtype of the method receiver type. This behavior can be specialized by overriding skipReceiverSubtypeCheck.

Overrides:

checkMethodInvocability in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

Parameters:

method - the type of the invoked method

node - the method invocation node

visitSwitch

public Void visitSwitch(SwitchTree node,
                        Void p)

Specified by:

visitSwitch in interface TreeVisitor<Void,Void>

Overrides:

visitSwitch in class TreeScanner<Void,Void>

visitForLoop

public Void visitForLoop(ForLoopTree node,
                         Void p)

Specified by:

visitForLoop in interface TreeVisitor<Void,Void>

Overrides:

visitForLoop in class TreeScanner<Void,Void>

visitNewClass

public Void visitNewClass(NewClassTree node,
                          Void p)

Description copied from class: BaseTypeVisitor

Performs a new class invocation check. An invocation of a constructor, c, is valid only if:

• passed arguments are subtypes of corresponding c parameters
• if c is generic, passed type arguments are subtypes of c type variables

Specified by:

visitNewClass in interface TreeVisitor<Void,Void>

Overrides:

visitNewClass in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

visitWhileLoop

public Void visitWhileLoop(WhileLoopTree node,
                           Void p)

Specified by:

visitWhileLoop in interface TreeVisitor<Void,Void>

Overrides:

visitWhileLoop in class TreeScanner<Void,Void>

visitDoWhileLoop

public Void visitDoWhileLoop(DoWhileLoopTree node,
                             Void p)

Specified by:

visitDoWhileLoop in interface TreeVisitor<Void,Void>

Overrides:

visitDoWhileLoop in class TreeScanner<Void,Void>

visitConditionalExpression

public Void visitConditionalExpression(ConditionalExpressionTree node,
                                       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<NullnessAnnotatedTypeFactory>

checkExceptionParameter

protected void checkExceptionParameter(CatchTree node)

Description copied from class: BaseTypeVisitor

Issue error if the exception parameter is not a super type of the annotation specified by getExceptionParameterLowerBoundAnnotations(), which is top by default (Subclasses may override this method to change the behavior of this check. Subclasses wishing to enforce that exception parameter be annotated with other annotations can just override getExceptionParameterLowerBoundAnnotations())

Overrides:

checkExceptionParameter in class BaseTypeVisitor<NullnessAnnotatedTypeFactory>

Parameters:

node - CatchTree to check