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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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