com.google.gerrit.extensions.conditions

Class BooleanCondition

java.lang.Object

com.google.gerrit.extensions.conditions.BooleanCondition

Direct Known Subclasses:

PrivateInternals_BooleanCondition.SubclassOnlyInCoreServer

public abstract class BooleanCondition
extends java.lang.Object

Delayed evaluation of a boolean condition.

Field Summary

Fields

Modifier and Type	Field and Description
static BooleanCondition	FALSE
static BooleanCondition	TRUE

Method Summary

Modifier and Type	Method and Description
static BooleanCondition	and(boolean a, BooleanCondition b)
static BooleanCondition	and(BooleanCondition a, BooleanCondition b)
abstract <T> java.lang.Iterable<T>	children(java.lang.Class<T> type) Recursively collect all children of type type.
protected abstract boolean	evaluatesTrivially() Check if the condition evaluates to either true or false without providing additional information to the evaluation tree, e.g.
static BooleanCondition	not(BooleanCondition bc)
static BooleanCondition	or(boolean a, BooleanCondition b)
static BooleanCondition	or(BooleanCondition a, BooleanCondition b)
abstract BooleanCondition	reduce() Reduce evaluation tree by cutting off branches that evaluate trivially and replacing them with a leave note corresponding to the value the branch evaluated to.
abstract boolean	value()
static BooleanCondition	valueOf(boolean a)

Methods inherited from class java.lang.Object

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

Field Detail

TRUE

public static final BooleanCondition TRUE

FALSE

public static final BooleanCondition FALSE

Method Detail

valueOf

public static BooleanCondition valueOf(boolean a)

and

public static BooleanCondition and(BooleanCondition a,
                                   BooleanCondition b)

and

public static BooleanCondition and(boolean a,
                                   BooleanCondition b)

or

public static BooleanCondition or(BooleanCondition a,
                                  BooleanCondition b)

or

public static BooleanCondition or(boolean a,
                                  BooleanCondition b)

not

public static BooleanCondition not(BooleanCondition bc)

value

public abstract boolean value()

Returns:

evaluate the condition and return its value.

children

public abstract <T> java.lang.Iterable<T> children(java.lang.Class<T> type)

Recursively collect all children of type type.

Parameters:

type - implementation type of the conditions to collect and return.

Returns:

non-null, unmodifiable iteration of children of type type.

reduce

public abstract BooleanCondition reduce()

Reduce evaluation tree by cutting off branches that evaluate trivially and replacing them with a leave note corresponding to the value the branch evaluated to.

Example 1 (T=True, F=False, C=non-trivial check): OR / \ => T C T Example 2 (cuts off a not-trivial check): AND / \ => F C F Example 3: AND / \ => F T F

There is no guarantee that the resulting tree is minimal. The only guarantee made is that branches that evaluate trivially will be cut off and replaced by primitive values.

evaluatesTrivially

protected abstract boolean evaluatesTrivially()

Check if the condition evaluates to either true or false without providing additional information to the evaluation tree, e.g. through checks to a remote service such as PermissionBackend.

In this case, the tree can be reduced to skip all non-trivial checks resulting in a performance gain.