Class ConstantExpressions

java.lang.Object

com.google.errorprone.bugpatterns.threadsafety.ConstantExpressions

public final class ConstantExpressions
extends Object

Helper for establishing whether expressions correspond to a constant expression.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	ConstantExpressions.ConstantExpression	Represents a constant expression.
static interface	ConstantExpressions.ConstantExpressionVisitor	Visitor for scanning over the components of a constant expression.
static final record	ConstantExpressions.Truthiness	Represents sets of things known to be true and false if a boolean statement evaluated true.

Method Summary

Modifier and Type	Method	Description
Optional<ConstantExpressions.ConstantExpression>	constantExpression(ExpressionTree tree, VisitorState state)
static Object	factKey(ConstantExpressions.ConstantExpression fact)	Returns the key of fact, which must be from a ConstantExpressions.Truthiness.
static @Nullable Object	factKey(ExpressionTree tree)	Returns the key that any fact truthiness(ExpressionTree, boolean, VisitorState) derives directly from tree would have, or null if tree cannot yield a fact.
static ConstantExpressions	fromFlags(ErrorProneFlags flags)
boolean	isSame(ExpressionTree aTree, ExpressionTree bTree, VisitorState state)	Returns whether aTree and bTree seem to correspond to the same expression.
static boolean	mayImply(ExpressionTree tree, boolean not, Object key)	Returns whether truthiness(ExpressionTree, boolean, VisitorState) of tree may contain a fact with the given key.
Optional<ConstantExpressions.ConstantExpression.PureMethodInvocation>	symbolizeImmutableExpression(ExpressionTree tree, VisitorState state)	Returns a list of the methods called to get to this expression, as well as a terminating variable if needed.
ConstantExpressions.Truthiness	truthiness(ExpressionTree tree, boolean not, VisitorState state)	Scans an ExpressionTree to find anything guaranteed to be false or true if this expression is true.

Methods inherited from class Object

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

Method Details

fromFlags

public static ConstantExpressions fromFlags(ErrorProneFlags flags)

truthiness

public ConstantExpressions.Truthiness truthiness(ExpressionTree tree,
 boolean not,
 VisitorState state)

Scans an ExpressionTree to find anything guaranteed to be false or true if this expression is true.

mayImply(ExpressionTree, boolean, Object) and factKey(ExpressionTree) mirror the expressions handled here, so update them when adding new kinds of facts.

mayImply

public static boolean mayImply(ExpressionTree tree,
 boolean not,
 Object key)

Returns whether truthiness(ExpressionTree, boolean, VisitorState) of tree may contain a fact with the given key.

This mirrors the traversal in truthiness(ExpressionTree, boolean, VisitorState) without calling constantExpression(ExpressionTree, VisitorState), which matches each method invocation against the known pure methods.

factKey

public static @Nullable Object factKey(ExpressionTree tree)

Returns the key that any fact truthiness(ExpressionTree, boolean, VisitorState) derives directly from tree would have, or null if tree cannot yield a fact.

Keys are opaque, and should only be compared using Object.equals(Object).

factKey

public static Object factKey(ConstantExpressions.ConstantExpression fact)

Returns the key of fact, which must be from a ConstantExpressions.Truthiness. Equal facts have equal keys, which match factKey(ExpressionTree) for the trees they're derived from.

constantExpression

public Optional<ConstantExpressions.ConstantExpression> constantExpression(ExpressionTree tree,
 VisitorState state)

isSame

public boolean isSame(ExpressionTree aTree,
 ExpressionTree bTree,
 VisitorState state)

Returns whether aTree and bTree seem to correspond to the same expression.

symbolizeImmutableExpression

public Optional<ConstantExpressions.ConstantExpression.PureMethodInvocation> symbolizeImmutableExpression(ExpressionTree tree,
 VisitorState state)

Returns a list of the methods called to get to this expression, as well as a terminating variable if needed.