Package com.singularsys.jep.functions

Class Ele

java.lang.Object
com.singularsys.jep.functions.PostfixMathCommand
com.singularsys.jep.functions.NaryFunction
com.singularsys.jep.functions.Ele
All Implemented Interfaces:
LValueI, PostfixMathCommandI, Serializable
Direct Known Subclasses:
ExpandingEle, ThreadSafeEle
public class Ele extends NaryFunction implements LValueI
Function which allows array access using the a[3] notation on left and right-hand side. The first element is indexed with 1. 
a=[4,3,2,1];
a[2];   // Returns 2
a[2]=5; // Sets the 2nd element of a to 5. So a is now [4,5,2,1]
// Two dimensional matrices only work with the configurable parser
b=[[1,2,3],[4,5,6]];
b[2][3]; // returns 6
b[2][3]=7; // sets 3rd element of 2nd row to 7
Since:
Jep 4.1 can work with List<?>.
Author:
Richard Morris
See Also:

  • Field Details

    • indexShift

      protected final int indexShift

  • Constructor Details

    • Ele

      public Ele()
      Element access with mathematical convention, first element has an index of 1.

    • Ele

      public Ele(boolean javaIndex)
      Element access, either java convention (first element has an index of 0) or mathematical convention (first element has an index of 1) can be specified.
      Parameters:
      javaIndex - whether to use the java convention, if true index start at 0.

  • Method Details

    • checkNumberOfParameters

      public boolean checkNumberOfParameters(int n)
      Description copied from class: PostfixMathCommand
      Checks the number of parameters of the function. Functions which set numberOfParameter=-1 should overload this method
      Specified by:
      checkNumberOfParameters in interface PostfixMathCommandI
      Overrides:
      checkNumberOfParameters in class PostfixMathCommand
      Parameters:
      n - number of parameters function will be called with.
      Returns:
      false if an illegal number of parameters is supplied, true otherwise.

    • set

      public void set(Evaluator pv, Node node, Object value) throws EvaluationException
      Sets an element of an vector valued variable. For the expression u[2] = 5 the left hand node is ASTOpNode for the Ele pfmc the method will be called like set(pv,lhs,5); The value of the variable will be replaced by a new Vector<Object> with the appropriate element replaced.
      Specified by:
      set in interface LValueI
      Parameters:
      pv - a pointer to the evaluator. The pv.eval() method can be used to evaluate the children of the node.
      node - The top node for the LValue, root should be the ASTOpNode for the Ele pfmc.
      value - the value obtained by evaluating the right-hand side.
      Throws:
      EvaluationException - if the calculation cannot be performed

    • eval

      public Object eval(Object[] args) throws EvaluationException
      Description copied from class: NaryFunction
      Evaluate the function
      Specified by:
      eval in class NaryFunction
      Parameters:
      args - arguments to the function
      Returns:
      value returned by the function
      Throws:
      EvaluationException - if the calculation cannot be performed

    • ele

      public Object ele(Object[] args) throws EvaluationException
      Find the element of an array. Calls ele(Object, Object), ele(Object, Object, Object) or ele(Object, Object[]) depending on number of arguments.
      Parameters:
      args - First element is the vector or matrix, subsequent elements are indices
      Returns:
      the element referred to by the indices
      Throws:
      EvaluationException - if the calculation cannot be performed

    • ele

      public Object ele(Object vec, Object indexObject) throws EvaluationException
      Find the element of a vector
      Parameters:
      vec - the vector
      indexObject - the index either as a vector with a single value or as a single value.
      Returns:
      element of vec referred to by the index.
      Throws:
      EvaluationException - if the calculation cannot be performed
      Since:
      3.4.0

    • findIndex

      protected int findIndex(Object indexObject) throws EvaluationException, IllegalParameterException
      Find the index from the indexObject. If indexObject is a vector with a single value, that value is used as the index. Otherwise indexObject is converted to an integer and used as the index.
      Parameters:
      indexObject - the index either as a vector with a single value or as a single value.
      Returns:
      the index
      Throws:
      EvaluationException - if the calculation cannot be performed
      IllegalParameterException - if the parameter is not valid

    • ele

      public Object ele(Object mat, Object row, Object col) throws EvaluationException
      Find the element of a matrix
      Parameters:
      mat - the matrix represented a Vector<Vector<Object>>
      row - the index
      col - the index
      Returns:
      element of matrix referred to by row/col
      Throws:
      EvaluationException - if the calculation cannot be performed
      Since:
      3.4.0

    • ele

      public Object ele(Object mat, Object[] args) throws EvaluationException
      Find element of a multi-dimensional array
      Parameters:
      mat - the array
      args - array of indices
      Returns:
      element in mat referred to by indices
      Throws:
      EvaluationException - if the calculation cannot be performed
      Since:
      3.4.0

    • getVariable

      protected Variable getVariable(Evaluator pv, ASTVarNode node)
      Find the variable associated with a node. Overridden by subclasses which require thread-safety.
      Parameters:
      pv - the evaluator
      node - the node
      Returns:
      the variable
      Since:
      3.5