org.eclipse.jdt.internal.compiler.flow

Class FlowInfo

java.lang.Object

org.eclipse.jdt.internal.compiler.flow.FlowInfo

Direct Known Subclasses:

ConditionalFlowInfo, UnconditionalFlowInfo

public abstract class FlowInfo
extends Object

Field Summary

Fields

Modifier and Type	Field and Description
static UnconditionalFlowInfo	DEAD_END
static int	NON_NULL
static int	NULL
static int	NULL_FLAG_MASK
static int	POTENTIALLY_NON_NULL
static int	POTENTIALLY_NULL
static int	POTENTIALLY_UNKNOWN
static int	REACHABLE
int	tagBits
static int	UNKNOWN
static int	UNREACHABLE
static int	UNREACHABLE_BY_NULLANALYSIS
static int	UNREACHABLE_OR_DEAD

Constructor Summary

Constructors

Constructor and Description
FlowInfo()

Method Summary

Modifier and Type	Method and Description
abstract FlowInfo	addInitializationsFrom(FlowInfo otherInits) Add other inits to this flow info, then return this.
abstract FlowInfo	addNullInfoFrom(FlowInfo otherInits) Add all null information from otherInits to this flow info and return this.
abstract FlowInfo	addPotentialInitializationsFrom(FlowInfo otherInits) Compose other inits over this flow info, then return this.
FlowInfo	asNegatedCondition()
boolean	cannotBeDefinitelyNullOrNonNull(LocalVariableBinding local) Check whether a given local variable is known to be unable to gain a definite non null or definite null status by the use of an enclosing flow info.
boolean	cannotBeNull(LocalVariableBinding local) Check whether a given local variable is known to be non null, either because it is definitely non null, or because is has been tested against non null.
boolean	canOnlyBeNull(LocalVariableBinding local) Check whether a given local variable is known to be null, either because it is definitely null, or because is has been tested against null.
static FlowInfo	conditional(FlowInfo initsWhenTrue, FlowInfo initsWhenFalse)
abstract FlowInfo	copy() Return a deep copy of the current instance.
abstract boolean	hasNullInfoFor(LocalVariableBinding local) Check if any null info has been recorded for a given local variable.
static UnconditionalFlowInfo	initial(int maxFieldCount)
abstract FlowInfo	initsWhenFalse() Return the flow info that would result from the path associated to the value false for the condition expression that generated this flow info.
abstract FlowInfo	initsWhenTrue() Return the flow info that would result from the path associated to the value true for the condition expression that generated this flow info.
abstract boolean	isDefinitelyAssigned(FieldBinding field) Check status of definite assignment for a field.
abstract boolean	isDefinitelyAssigned(LocalVariableBinding local) Check status of definite assignment for a local.
abstract boolean	isDefinitelyNonNull(LocalVariableBinding local) Check status of definite non-null value for a given local variable.
abstract boolean	isDefinitelyNull(LocalVariableBinding local) Check status of definite null value for a given local variable.
abstract boolean	isDefinitelyUnknown(LocalVariableBinding local) Check status of definite unknown value for a given local variable.
abstract boolean	isPotentiallyAssigned(FieldBinding field) Check status of potential assignment for a field.
abstract boolean	isPotentiallyAssigned(LocalVariableBinding field) Check status of potential assignment for a local variable.
abstract boolean	isPotentiallyNonNull(LocalVariableBinding local) Check status of potential null assignment for a local.
abstract boolean	isPotentiallyNull(LocalVariableBinding local) Check status of potential null assignment for a local.
abstract boolean	isPotentiallyUnknown(LocalVariableBinding local) Return true if the given local may have been assigned to an unknown value.
abstract boolean	isProtectedNonNull(LocalVariableBinding local) Return true if the given local is protected by a test against a non null value.
abstract boolean	isProtectedNull(LocalVariableBinding local) Return true if the given local is protected by a test against null.
abstract void	markAsComparedEqualToNonNull(LocalVariableBinding local) Record that a local variable got checked to be non null.
abstract void	markAsComparedEqualToNull(LocalVariableBinding local) Record that a local variable got checked to be null.
abstract void	markAsDefinitelyAssigned(FieldBinding field) Record a field got definitely assigned.
abstract void	markAsDefinitelyAssigned(LocalVariableBinding local) Record a local got definitely assigned.
abstract void	markAsDefinitelyNonNull(LocalVariableBinding local) Record a local got definitely assigned to a non-null value.
abstract void	markAsDefinitelyNull(LocalVariableBinding local) Record a local got definitely assigned to null.
abstract void	markAsDefinitelyUnknown(LocalVariableBinding local) Record a local got definitely assigned to an unknown value.
void	markNullStatus(LocalVariableBinding local, int nullStatus) Mark the null status of the given local according to the given status
abstract void	markPotentiallyNonNullBit(LocalVariableBinding local) Record a local may have got assigned to non-null (set the bit on existing info).
abstract void	markPotentiallyNullBit(LocalVariableBinding local) Record a local may have got assigned to null (set the bit on existing info).
abstract void	markPotentiallyUnknownBit(LocalVariableBinding local) Record a local may have got assigned to unknown (set the bit on existing info).
static UnconditionalFlowInfo	mergedOptimizedBranches(FlowInfo initsWhenTrue, boolean isOptimizedTrue, FlowInfo initsWhenFalse, boolean isOptimizedFalse, boolean allowFakeDeadBranch) Merge branches using optimized boolean conditions
static UnconditionalFlowInfo	mergedOptimizedBranchesIfElse(FlowInfo initsWhenTrue, boolean isOptimizedTrue, FlowInfo initsWhenFalse, boolean isOptimizedFalse, boolean allowFakeDeadBranch, FlowInfo flowInfo, IfStatement ifStatement, boolean reportDeadCodeInKnownPattern) Merge if-else branches using optimized boolean conditions
abstract UnconditionalFlowInfo	mergedWith(UnconditionalFlowInfo otherInits) Return the intersection of this and otherInits, that is one of: the receiver updated in the following way: intersection of definitely assigned variables, union of potentially assigned variables, similar operations for null, or the receiver or otherInits if the other one is non reachable. otherInits is not affected, and is not returned either (no need to protect the result).
static int	mergeNullStatus(int nullStatus1, int nullStatus2) Merge two single bits (NULL, NON_NULL, POTENTIALLY*..) into one.
abstract UnconditionalFlowInfo	nullInfoLessUnconditionalCopy() Return a copy of this unconditional flow info, deprived from its null info.
int	nullStatus(LocalVariableBinding local) Answer the null status of the given local
int	reachMode() Find out the reachability mode of this flowInfo.
abstract void	resetAssignmentInfo(LocalVariableBinding local) Resets the definite and potential initialization info for the given local variable
abstract void	resetNullInfo(LocalVariableBinding local) Reset all null-information about a given local.
abstract FlowInfo	safeInitsWhenTrue() Return a flow info that carries the same information as the result of initsWhenTrue, but warrantied to be different from this. Caveat: side effects on the result may affect components of this.
abstract FlowInfo	setReachMode(int reachMode) Set this flow info reach mode and return this.
static int	tagBitsToNullStatus(long tagBits) Check whether 'tagBits' contains either TagBits.AnnotationNonNull or TagBits.AnnotationNullable, and answer the corresponding null status (NON_NULL etc.).
String	toString()
abstract UnconditionalFlowInfo	unconditionalCopy() Return a new flow info that holds the same information as this would after a call to unconditionalInits, but leaving this info unaffected.
abstract UnconditionalFlowInfo	unconditionalFieldLessCopy() Return a new flow info that holds the same information as this would after a call to unconditionalInits followed by the erasure of fields specific information, but leaving this flow info unaffected.
abstract UnconditionalFlowInfo	unconditionalInits() Return a flow info that merges the possible paths of execution described by this flow info.
abstract UnconditionalFlowInfo	unconditionalInitsWithoutSideEffect() Return a new flow info that holds the same information as this would after a call to unconditionalInits, but leaving this info unaffected.

Methods inherited from class java.lang.Object

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

Field Detail

tagBits

public int tagBits

REACHABLE

public static final int REACHABLE

See Also:

Constant Field Values

UNREACHABLE_OR_DEAD

public static final int UNREACHABLE_OR_DEAD

See Also:

Constant Field Values

UNREACHABLE_BY_NULLANALYSIS

public static final int UNREACHABLE_BY_NULLANALYSIS

See Also:

Constant Field Values

UNREACHABLE

public static final int UNREACHABLE

See Also:

Constant Field Values

NULL_FLAG_MASK

public static final int NULL_FLAG_MASK

See Also:

Constant Field Values

UNKNOWN

public static final int UNKNOWN

See Also:

Constant Field Values

NULL

public static final int NULL

See Also:

Constant Field Values

NON_NULL

public static final int NON_NULL

See Also:

Constant Field Values

POTENTIALLY_UNKNOWN

public static final int POTENTIALLY_UNKNOWN

See Also:

Constant Field Values

POTENTIALLY_NULL

public static final int POTENTIALLY_NULL

See Also:

Constant Field Values

POTENTIALLY_NON_NULL

public static final int POTENTIALLY_NON_NULL

See Also:

Constant Field Values

DEAD_END

public static final UnconditionalFlowInfo DEAD_END

Constructor Detail

FlowInfo

public FlowInfo()

Method Detail

addInitializationsFrom

public abstract FlowInfo addInitializationsFrom(FlowInfo otherInits)

Add other inits to this flow info, then return this. The operation semantics are to match as closely as possible the application to this flow info of all the operations that resulted into otherInits.

Parameters:

otherInits - other inits to add to this

Returns:

this, modified according to otherInits information

addNullInfoFrom

public abstract FlowInfo addNullInfoFrom(FlowInfo otherInits)

Add all null information from otherInits to this flow info and return this. The operation models the effect of an unconditional sequence of this flow info and otherInits.

addPotentialInitializationsFrom

public abstract FlowInfo addPotentialInitializationsFrom(FlowInfo otherInits)

Compose other inits over this flow info, then return this. The operation semantics are to wave into this flow info the consequences of a possible path into the operations that resulted into otherInits. The fact that this path may be left unexecuted under peculiar conditions results into less specific results than addInitializationsFrom.

Parameters:

otherInits - other inits to compose over this

Returns:

this, modified according to otherInits information

asNegatedCondition

public FlowInfo asNegatedCondition()

conditional

public static FlowInfo conditional(FlowInfo initsWhenTrue,
                                   FlowInfo initsWhenFalse)

cannotBeDefinitelyNullOrNonNull

public boolean cannotBeDefinitelyNullOrNonNull(LocalVariableBinding local)

Check whether a given local variable is known to be unable to gain a definite non null or definite null status by the use of an enclosing flow info. The semantics are that if the current flow info marks the variable as potentially unknown or else as being both potentially null and potentially non null, then it won't ever be promoted as definitely null or definitely non null. (It could still get promoted to definite unknown).

Parameters:

local - the variable to check

Returns:

true iff this flow info prevents local from being promoted to definite non null or definite null against an enclosing flow info

cannotBeNull

public boolean cannotBeNull(LocalVariableBinding local)

Check whether a given local variable is known to be non null, either because it is definitely non null, or because is has been tested against non null.

Parameters:

local - the variable to ckeck

Returns:

true iff local cannot be null for this flow info

canOnlyBeNull

public boolean canOnlyBeNull(LocalVariableBinding local)

Check whether a given local variable is known to be null, either because it is definitely null, or because is has been tested against null.

Parameters:

local - the variable to ckeck

Returns:

true iff local can only be null for this flow info

copy

public abstract FlowInfo copy()

Return a deep copy of the current instance.

Returns:

a deep copy of this flow info

initial

public static UnconditionalFlowInfo initial(int maxFieldCount)

initsWhenFalse

public abstract FlowInfo initsWhenFalse()

Return the flow info that would result from the path associated to the value false for the condition expression that generated this flow info. May be this flow info if it is not an instance of ConditionalFlowInfo. May have a side effect on subparts of this flow info (subtrees get merged).

Returns:

the flow info associated to the false branch of the condition that generated this flow info

initsWhenTrue

public abstract FlowInfo initsWhenTrue()

Return the flow info that would result from the path associated to the value true for the condition expression that generated this flow info. May be this flow info if it is not an instance of ConditionalFlowInfo. May have a side effect on subparts of this flow info (subtrees get merged).

Returns:

the flow info associated to the true branch of the condition that generated this flow info

isDefinitelyAssigned

public abstract boolean isDefinitelyAssigned(FieldBinding field)

Check status of definite assignment for a field.

isDefinitelyAssigned

public abstract boolean isDefinitelyAssigned(LocalVariableBinding local)

Check status of definite assignment for a local.

isDefinitelyNonNull

public abstract boolean isDefinitelyNonNull(LocalVariableBinding local)

Check status of definite non-null value for a given local variable.

Parameters:

local - the variable to ckeck

Returns:

true iff local is definitely non null for this flow info

isDefinitelyNull

public abstract boolean isDefinitelyNull(LocalVariableBinding local)

Check status of definite null value for a given local variable.

Parameters:

local - the variable to ckeck

Returns:

true iff local is definitely null for this flow info

isDefinitelyUnknown

public abstract boolean isDefinitelyUnknown(LocalVariableBinding local)

Check status of definite unknown value for a given local variable.

Parameters:

local - the variable to ckeck

Returns:

true iff local is definitely unknown for this flow info

hasNullInfoFor

public abstract boolean hasNullInfoFor(LocalVariableBinding local)

Check if any null info has been recorded for a given local variable. Here even recording of 'UNKNOWN' is considered as null info.

isPotentiallyAssigned

public abstract boolean isPotentiallyAssigned(FieldBinding field)

Check status of potential assignment for a field.

isPotentiallyAssigned

public abstract boolean isPotentiallyAssigned(LocalVariableBinding field)

Check status of potential assignment for a local variable.

isPotentiallyNonNull

public abstract boolean isPotentiallyNonNull(LocalVariableBinding local)

Check status of potential null assignment for a local. Return true if there is a reasonable expectation that the variable be non null at this point.

Parameters:

local - LocalVariableBinding - the binding for the checked local

Returns:

true if there is a reasonable expectation that local be non null at this point

isPotentiallyNull

public abstract boolean isPotentiallyNull(LocalVariableBinding local)

Check status of potential null assignment for a local. Return true if there is a reasonable expectation that the variable be null at this point. This includes the protected null case, so as to augment diagnostics, but does not really check that someone deliberately assigned to null on any specific path

Parameters:

local - LocalVariableBinding - the binding for the checked local

Returns:

true if there is a reasonable expectation that local be null at this point

isPotentiallyUnknown

public abstract boolean isPotentiallyUnknown(LocalVariableBinding local)

Return true if the given local may have been assigned to an unknown value.

Parameters:

local - the local to check

Returns:

true if the given local may have been assigned to an unknown value

isProtectedNonNull

public abstract boolean isProtectedNonNull(LocalVariableBinding local)

Return true if the given local is protected by a test against a non null value.

Parameters:

local - the local to check

Returns:

true if the given local is protected by a test against a non null

isProtectedNull

public abstract boolean isProtectedNull(LocalVariableBinding local)

Return true if the given local is protected by a test against null.

Parameters:

local - the local to check

Returns:

true if the given local is protected by a test against null

markAsComparedEqualToNonNull

public abstract void markAsComparedEqualToNonNull(LocalVariableBinding local)

Record that a local variable got checked to be non null.

Parameters:

local - the checked local variable

markAsComparedEqualToNull

public abstract void markAsComparedEqualToNull(LocalVariableBinding local)

Record that a local variable got checked to be null.

Parameters:

local - the checked local variable

markAsDefinitelyAssigned

public abstract void markAsDefinitelyAssigned(FieldBinding field)

Record a field got definitely assigned.

markAsDefinitelyNonNull

public abstract void markAsDefinitelyNonNull(LocalVariableBinding local)

Record a local got definitely assigned to a non-null value.

markAsDefinitelyNull

public abstract void markAsDefinitelyNull(LocalVariableBinding local)

Record a local got definitely assigned to null.

resetNullInfo

public abstract void resetNullInfo(LocalVariableBinding local)

Reset all null-information about a given local.

markPotentiallyUnknownBit

public abstract void markPotentiallyUnknownBit(LocalVariableBinding local)

Record a local may have got assigned to unknown (set the bit on existing info).

markPotentiallyNullBit

public abstract void markPotentiallyNullBit(LocalVariableBinding local)

Record a local may have got assigned to null (set the bit on existing info).

markPotentiallyNonNullBit

public abstract void markPotentiallyNonNullBit(LocalVariableBinding local)

Record a local may have got assigned to non-null (set the bit on existing info).

markAsDefinitelyAssigned

public abstract void markAsDefinitelyAssigned(LocalVariableBinding local)

Record a local got definitely assigned.

markAsDefinitelyUnknown

public abstract void markAsDefinitelyUnknown(LocalVariableBinding local)

Record a local got definitely assigned to an unknown value.

markNullStatus

public void markNullStatus(LocalVariableBinding local,
                           int nullStatus)

Mark the null status of the given local according to the given status

Parameters:

local -

nullStatus - bitset of FLowInfo.UNKNOWN ... FlowInfo.POTENTIALLY_NON_NULL

nullStatus

public int nullStatus(LocalVariableBinding local)

Answer the null status of the given local

Parameters:

local -

Returns:

bitset of FlowInfo.UNKNOWN ... FlowInfo.POTENTIALLY_NON_NULL

mergeNullStatus

public static int mergeNullStatus(int nullStatus1,
                                  int nullStatus2)

Merge two single bits (NULL, NON_NULL, POTENTIALLY*..) into one. This method implements a simpler logic than the 4-bit encoding used in FlowInfo instances.

mergedOptimizedBranches

public static UnconditionalFlowInfo mergedOptimizedBranches(FlowInfo initsWhenTrue,
                                                            boolean isOptimizedTrue,
                                                            FlowInfo initsWhenFalse,
                                                            boolean isOptimizedFalse,
                                                            boolean allowFakeDeadBranch)

Merge branches using optimized boolean conditions

mergedOptimizedBranchesIfElse

public static UnconditionalFlowInfo mergedOptimizedBranchesIfElse(FlowInfo initsWhenTrue,
                                                                  boolean isOptimizedTrue,
                                                                  FlowInfo initsWhenFalse,
                                                                  boolean isOptimizedFalse,
                                                                  boolean allowFakeDeadBranch,
                                                                  FlowInfo flowInfo,
                                                                  IfStatement ifStatement,
                                                                  boolean reportDeadCodeInKnownPattern)

Merge if-else branches using optimized boolean conditions

reachMode

public int reachMode()

Find out the reachability mode of this flowInfo.

Returns:

REACHABLE if this flow info is reachable, otherwise either UNREACHABLE_OR_DEAD or UNREACHABLE_BY_NULLANALYSIS.

safeInitsWhenTrue

public abstract FlowInfo safeInitsWhenTrue()

Return a flow info that carries the same information as the result of initsWhenTrue, but warrantied to be different from this.
Caveat: side effects on the result may affect components of this.

Returns:

the result of initsWhenTrue or a copy of it

setReachMode

public abstract FlowInfo setReachMode(int reachMode)

Set this flow info reach mode and return this.

Parameters:

reachMode - one of REACHABLE, UNREACHABLE_OR_DEAD, UNREACHABLE_BY_NULLANALYSIS or UNREACHABLE

Returns:

this, with the reach mode set to reachMode

mergedWith

public abstract UnconditionalFlowInfo mergedWith(UnconditionalFlowInfo otherInits)

Return the intersection of this and otherInits, that is one of:

• the receiver updated in the following way:
  • intersection of definitely assigned variables,
  • union of potentially assigned variables,
  • similar operations for null,
• or the receiver or otherInits if the other one is non reachable.

otherInits is not affected, and is not returned either (no need to protect the result).

Parameters:

otherInits - the flow info to merge with this

Returns:

the intersection of this and otherInits.

nullInfoLessUnconditionalCopy

public abstract UnconditionalFlowInfo nullInfoLessUnconditionalCopy()

Return a copy of this unconditional flow info, deprived from its null info. DEAD_END is returned unmodified.

Returns:

a copy of this unconditional flow info deprived from its null info

toString

public String toString()

Overrides:

toString in class Object

unconditionalCopy

public abstract UnconditionalFlowInfo unconditionalCopy()

Return a new flow info that holds the same information as this would after a call to unconditionalInits, but leaving this info unaffected. Moreover, the result can be modified without affecting this.

Returns:

a new flow info carrying this unconditional flow info

unconditionalFieldLessCopy

public abstract UnconditionalFlowInfo unconditionalFieldLessCopy()

Return a new flow info that holds the same information as this would after a call to unconditionalInits followed by the erasure of fields specific information, but leaving this flow info unaffected.

Returns:

a new flow info carrying the unconditional flow info for local variables

unconditionalInits

public abstract UnconditionalFlowInfo unconditionalInits()

Return a flow info that merges the possible paths of execution described by this flow info. In case of an unconditional flow info, return this. In case of a conditional flow info, merge branches recursively. Caveat: this may be affected, and modifying the result may affect this.

Returns:

a flow info that merges the possible paths of execution described by this

unconditionalInitsWithoutSideEffect

public abstract UnconditionalFlowInfo unconditionalInitsWithoutSideEffect()

Return a new flow info that holds the same information as this would after a call to unconditionalInits, but leaving this info unaffected. Side effects on the result might affect this though (consider it as read only).

Returns:

a flow info carrying this unconditional flow info

resetAssignmentInfo

public abstract void resetAssignmentInfo(LocalVariableBinding local)

Resets the definite and potential initialization info for the given local variable

Parameters:

local -

tagBitsToNullStatus

public static int tagBitsToNullStatus(long tagBits)

Check whether 'tagBits' contains either TagBits.AnnotationNonNull or TagBits.AnnotationNullable, and answer the corresponding null status (NON_NULL etc.).