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java.lang.Objectorg.eclipse.core.expressions.Expression
Abstract base class for all expressions provided by the common expression language.
An expression is evaluated by calling evaluate(IEvaluationContext).
This class may be subclassed to provide specific expressions.
| Field Summary | |
|---|---|
protected static String |
ATT_VALUE
Name of the value attribute of an expression (value is value). |
static Expression |
FALSE
The expression corresponding to EvaluationResult.FALSE. |
protected static int |
HASH_CODE_NOT_COMPUTED
The constant integer hash code value meaning the hash code has not yet been computed. |
protected static int |
HASH_FACTOR
A factor for computing the hash code for all expressions. |
static Expression |
TRUE
The expression corresponding to EvaluationResult.TRUE. |
| Constructor Summary | |
|---|---|
Expression()
|
|
| Method Summary | |
|---|---|
void |
collectExpressionInfo(ExpressionInfo info)
Collects information about this expression tree. |
ExpressionInfo |
computeExpressionInfo()
Computes the expression information for the given expression tree. |
protected int |
computeHashCode()
Method to compute the hash code for this object. |
protected static boolean |
equals(Object[] leftArray,
Object[] rightArray)
Tests whether two arrays of objects are equal to each other. |
protected static boolean |
equals(Object left,
Object right)
Checks whether two objects are equal using the equals(Object) method of the left object.
|
abstract EvaluationResult |
evaluate(IEvaluationContext context)
Evaluates this expression. |
int |
hashCode()
|
protected static int |
hashCode(Object object)
Returns the hash code for the given object. |
protected static int |
hashCode(Object[] array)
Returns the hash code for the given array. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
protected static final int HASH_CODE_NOT_COMPUTED
protected static final int HASH_FACTOR
protected static final String ATT_VALUE
value).
public static final Expression TRUE
EvaluationResult.TRUE.
public static final Expression FALSE
EvaluationResult.FALSE.
| Constructor Detail |
public Expression()
| Method Detail |
protected static final boolean equals(Object left,
Object right)
equals(Object) method of the left object.
This method handles null for either the left
or right object.
left - the first object to compare; may be null.right - the second object to compare; may be null.
true if the two objects are equivalent;
false otherwise.
protected static final boolean equals(Object[] leftArray,
Object[] rightArray)
null, but their elements may be
null.
leftArray - the left array to compare; may be null, and
may be empty and may contain null elements.rightArray - the right array to compare; may be null,
and may be empty and may contain null elements.
true if the arrays are equal length and the elements
at the same position are equal; false otherwise.protected static final int hashCode(Object object)
object. This method
handles null.
object - the object for which the hash code is desired; may be
null.
null.protected static final int hashCode(Object[] array)
null.
array - the array for which the hash code is desired; may be
null.
null.
public abstract EvaluationResult evaluate(IEvaluationContext context)
throws CoreException
context - an evaluation context providing information like variable,
name spaces, etc. necessary to evaluate this expression
CoreException - if the evaluation failed. The concrete reason is
defined by the subclass implementing this methodpublic final ExpressionInfo computeExpressionInfo()
This is a convenience method for collecting the expression information
using collectExpressionInfo(ExpressionInfo).
public void collectExpressionInfo(ExpressionInfo info)
info - the expression information object used
to collect the informationprotected int computeHashCode()
fHashCode
field. If the value returned from the method equals HASH_CODE_NOT_COMPUTED
(e.g. -1) then the value is incremented by one.
This default implementation calls super.hashCode()
public int hashCode()
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Guidelines for using Eclipse APIs.
Copyright (c) IBM Corp. and others 2000, 2007. All rights reserved.