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java.lang.Object com.singularsys.jep.functions.PostfixMathCommand com.singularsys.jep.functions.If
public class If
The if(condExpr, posExpr, negExpr) function. The value of trueExpr will be returned if condExpr is >0 or Boolean.TRUE and value of negExpr will be returned if condExpr is <= 0 or Boolean.TRUE. If condExpr is NaN then NaN is returned.
This function performs lazy evaluation so that only posExpr or negExpr will be evaluated. For Complex numbers only the real part is used.
An alternate form if(condExpr, posExpr, negExpr, zeroExpr) is also available. Note most computations are carried out over floating point doubles so testing for zero can be dangerous.
Note most computations are carried out over floating point doubles so testing for zero can be dangerous.
Nested Class Summary |
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Nested classes/interfaces inherited from interface com.singularsys.jep.functions.CallbackEvaluationI |
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CallbackEvaluationI.Runnable |
Field Summary | |
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protected java.lang.Object |
falseValue
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Fields inherited from class com.singularsys.jep.functions.PostfixMathCommand |
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curNumberOfParameters, name, NaN, numberOfParameters |
Constructor Summary | |
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If()
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If(java.lang.Object falseValue)
If this constructor is used then a two argument version can be used if(condExpr, posExpr)
is also available. |
Method Summary | |
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boolean |
checkNumberOfParameters(int n)
Checks the number of parameters of the call. |
java.lang.Object |
evaluate(Node node,
Evaluator pv)
Performs some special evaluation on the node. |
java.lang.Object |
getFalseValue()
The value returned for false values in the two argument version. |
void |
run(java.util.Stack<java.lang.Object> aStack)
Run the function on the stack. |
Methods inherited from class com.singularsys.jep.functions.PostfixMathCommand |
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asArray, asBool, asDouble, asInt, asLong, asStrictInt, asString, checkStack, getName, getNumberOfParameters, setCurNumberOfParameters, setName, toString |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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protected java.lang.Object falseValue
Constructor Detail |
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public If()
public If(java.lang.Object falseValue)
if(condExpr, posExpr)
is also available.
falseValue
- the value to return when condExpr is false in the two argument versionMethod Detail |
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public boolean checkNumberOfParameters(int n)
checkNumberOfParameters
in interface PostfixMathCommandI
checkNumberOfParameters
in class PostfixMathCommand
n
- number of parameters function will be called with.
public java.lang.Object evaluate(Node node, Evaluator pv) throws EvaluationException
CallbackEvaluationI
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.
evaluate
in interface CallbackEvaluationI
node
- The current nodepv
- The visitor, can be used evaluate the children
EvaluationException
Evaluator
public void run(java.util.Stack<java.lang.Object> aStack) throws EvaluationException
PostfixMathCommandI
run
in interface PostfixMathCommandI
EvaluationException
public java.lang.Object getFalseValue()
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