RuleElement

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net.sf.jdmf.data.output
Class RuleElement

java.lang.Object
  net.sf.jdmf.data.output.AbstractRuleElementEvaluable
      net.sf.jdmf.data.output.RuleElement

All Implemented Interfaces:: Evaluable

public class RuleElement
extends AbstractRuleElementEvaluable
extends AbstractRuleElementEvaluable

A single rule element that consists of an item, a logical operator that links this element to other elements within a rule; alternatively, a rule element may contain a list of subelements. The simplest rule element consists of a single item:

 (first_colour = 'red')

Rule elements define how items and logical operators are grouped within a rule and evaluated. Example:

 (first_colour = 'red') AND (second_colour = 'blue' OR second_colour = 'cyan')

There are two rule elements here: the first defines a single item (first_colour = 'red') and has no logical operator. The second rule element does not define an item, but has a logical operator (AND) and a list of two subelements. The first subelement defines a single item (second_colour = 'blue') and has no logical operator, while the second subelement also defines a single item (second_colour = 'cyan') and a logical operator (OR). Grouping is quite important if we are not satisfied with the default evaluation mode (from left to right; all logical operators are equally important here). Classes: Rule and RuleElement offer a few helpful methods allowing developers to define rules like sentences. As long as those methods are used to define rules, there is no need to worry about implementation details (and when it comes to the details - it is worth mentioning that the logical operator is always defined in the same element as the right operand of the operator). Subelements need to be defined separately and added to the parent rule element explicitly.

Author:: quorthon
See Also:: Rule, AbstractRuleElementEvaluable, Item

Constructor Summary
`RuleElement()`
`RuleElement(Item item)`
`RuleElement(Item item, LogicalOperator logicalOperator)`

Method Summary
`void`	`addSubElement(RuleElement subElement)`
`RuleElement`	`and(Rule parentRule)` Appends a new rule element using the AND operator.
`RuleElement`	`attribute(java.lang.String attributeName)` Defines the attribute name of an item.
`RuleElement`	`doesNotEqual(java.lang.Comparable attributeValue)` Defines the relation between the attribute name and value within an item.
`RuleElement`	`equals(java.lang.Comparable attributeValue)` Defines the relation between the attribute name and value within an item.
`boolean`	`equals(java.lang.Object obj)`
`boolean`	`evaluate(Instance instance)`
`Item`	`getItem()`
`LogicalOperator`	`getLogicalOperator()`
`RuleElement`	`isGreaterThan(java.lang.Comparable attributeValue)` Defines the relation between the attribute name and value within an item.
`RuleElement`	`isGreaterThanOrEqualTo(java.lang.Comparable attributeValue)` Defines the relation between the attribute name and value within an item.
`RuleElement`	`isLowerThan(java.lang.Comparable attributeValue)` Defines the relation between the attribute name and value within an item.
`RuleElement`	`isLowerThanOrEqualTo(java.lang.Comparable attributeValue)` Defines the relation between the attribute name and value within an item.
`RuleElement`	`or(Rule parentRule)` Appends a new rule element using the OR operator.
`void`	`setItem(Item item)`
`void`	`setLogicalOperator(LogicalOperator logicalOperator)`
`java.util.Iterator<RuleElement>`	`subElementsIterator()`
`java.lang.String`	`toString()`
`RuleElement`	`xor(Rule parentRule)` Appends a new rule element using the XOR operator.

Methods inherited from class java.lang.Object
`getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

RuleElement

public RuleElement()

RuleElement

public RuleElement(Item item)

RuleElement

public RuleElement(Item item,
                   LogicalOperator logicalOperator)

Method Detail

evaluate

public boolean evaluate(Instance instance)

See Also:: Evaluable.evaluate(net.sf.jdmf.data.input.attribute.Instance)

attribute

public RuleElement attribute(java.lang.String attributeName)

Defines the attribute name of an item.