com.singularsys.jep.functions
Class LazyLogical
java.lang.Object
com.singularsys.jep.functions.PostfixMathCommand
com.singularsys.jep.functions.LazyLogical
- All Implemented Interfaces:
- CallbackEvaluationI, PostfixMathCommandI, java.io.Serializable
public class LazyLogical
- extends PostfixMathCommand
- implements CallbackEvaluationI
A version of the logical operators which use lazy evaluation.
The first argument is always evaluated but the second argument is only evaluated if needed.
Hence
0 || arg2
arg2 is evaluated
1 || arg2
arg2 is not evaluated and true is returned
0 && arg2
arg2 is not evaluated and false is returned
1 && arg2
arg2 is evaluated
- Since:
- 3.1
- See Also:
- Serialized Form
Field Summary |
static int |
AND
|
static int |
OR
|
Method Summary |
java.lang.Object |
evaluate(Node node,
Evaluator pv)
Performs some special evaluation on the node. |
void |
run(java.util.Stack<java.lang.Object> inStack)
Run the function on the stack. |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
AND
public static final int AND
- See Also:
- Constant Field Values
OR
public static final int OR
- See Also:
- Constant Field Values
LazyLogical
public LazyLogical(int id_in)
run
public void run(java.util.Stack<java.lang.Object> inStack)
throws EvaluationException
- Description copied from interface:
PostfixMathCommandI
- Run the function on the stack. Pops the arguments from the stack, and
pushes the result on the top of the stack.
- Specified by:
run
in interface PostfixMathCommandI
- Throws:
EvaluationException
evaluate
public java.lang.Object evaluate(Node node,
Evaluator pv)
throws EvaluationException
- Description copied from interface:
CallbackEvaluationI
- Performs some special evaluation on the node.
This method has the responsibility for evaluating the children of the node
and it should generally call
pv.eval(node.jjtGetChild(i))
for each child.
The SymbolTable is not passed as an argument. This is because
it is better practice to get and set variable values by using
node.getVar().setValue() rather that through the SymbolTable with
requires a hashtable lookup.
- Specified by:
evaluate
in interface CallbackEvaluationI
- Parameters:
node
- The current nodepv
- The visitor, can be used evaluate the children
- Returns:
- the value after evaluation
- Throws:
EvaluationException
- See Also:
Evaluator
Copyright © 2007 Singular Systems http://www.singularsys.com/jep