vec_math
Class ExpressionNode

java.lang.Object
  vec_math.Node<String>
      vec_math.StringNode
          vec_math.ExpressionNode

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

ExpressionFunction, ExpressionMultidimensional

public class ExpressionNode
extends StringNode

A node class for ExpressionParser. This node deals with Number instances, i.e. Double and Long, and the Boolean class. Though internally handled as objects, the final expression is always one of these types and can readily be cast.

See Also:

Serialized Form

Nested Class Summary

static class

ExpressionNode.Test Test purposes only.

Constructor Summary

ExpressionNode(String root)
Constructs a new top-level double node.

ExpressionNode(StringNode parent, String root, int level)
Constructs a daugther node.

Method Summary

String	getValue() Cast a String to the appropriate type of a Number or Boolean instance.
protected boolean	isVariable(String arg) Test if the argument is a variable or a constant double.

Methods inherited from class vec_math.StringNode

getVariables, parseOperator, parseSub, replaceVariable, replaceVariable, setValidOperator

Methods inherited from class vec_math.Node

equals, getLevel, getParent, getParseSource, getSub, getSubAt, getSubNodeNumber, getTie, isFinal, isParsed, isRoot, parse, parse, setParse, setParseSource, setSub, setTie, setValue, toString, traceVariable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ExpressionNode

public ExpressionNode(String root)

Constructs a new top-level double node. Parsing a string expression will always start with a call to this constructor, therefore the valid operators are also set here.

ExpressionNode

public ExpressionNode(StringNode parent,
                      String root,
                      int level)

Constructs a daugther node. This constructor is called repeatedly during parsing.

Method Detail

isVariable

protected boolean isVariable(String arg)

Test if the argument is a variable or a constant double. Variables must be replaced before evaluating with their numeric content.

The argument must be of type String. This string is then tested in the following ways:

• If it is equal to the string representation of the two Boolean values, Boolean.TRUE or Boolean.FALSE, this string is considered a boolean constant and this method returns false.
• If the argument is equal to PI it is considered a double constant and returns false.
• If the string is a parsable double, it is considered to be either a long or a double constant. Again false is returned.

Overrides:

isVariable in class StringNode

getValue

public String getValue()

Cast a String to the appropriate type of a Number or Boolean instance. The approach is as this:

• If the string equals Boolean.TRUE or Boolean.FALSE the appropriate Boolean type is returned.
• If the String equals PI a Double initialized to Math.PI is returned.
• If the string can be parsed into a Long, the value is returned as a Long.
• If the string can be parsed into a Double, the value is returned as a Double.

Overrides:

getValue in class Node<String>