Package com.graphbuilder.math

Class Expression

java.lang.Object

com.graphbuilder.math.Expression

Direct Known Subclasses:

OpNode, TermNode, ValNode

public abstract class Expression
extends Object

The class from which all nodes of an expression tree are descendents. Expressions can be evaluated using the eval method. Expressions that are or have FuncNodes or VarNodes as descendents must provide a VarMap or FuncMap respectively. Expressions that consist entirely of OpNodes and ValNodes do not require a VarMap or FuncMap. For Expressions that support children (OpNodes, FuncNodes), a child can only be accepted provided it currently has no parent, a cyclic reference is not formed, and it is non-null.

Field Summary

Fields

Modifier and Type	Field	Description
protected Expression	parent

Constructor Summary

Constructors

Constructor	Description
Expression()

Method Summary

Modifier and Type	Method	Description
protected void	checkBeforeAccept(Expression x)	Protected method used to verify that the specified expression can be included as a child expression of this node.
abstract double	eval(VarMap v, FuncMap f)	Returns the result of evaluating the expression tree rooted at this node.
String[]	getFunctionNames()	Returns an array of exact length of the function names contained in the expression tree rooted at this node.
Expression	getParent()	Returns the parent of this node.
private String[]	getTermNames(boolean varNames)
private static void	getTermNames(Expression x, Bag b, boolean varNames)
String[]	getVariableNames()	Returns an array of exact length of the variable names contained in the expression tree rooted at this node.
boolean	isDescendent(Expression x)	Returns true if this node is a descendent of the specified node, false otherwise.
String	toString()	Returns a string that represents the expression tree rooted at this node.
private static void	toString(Expression x, StringBuffer sb)

Methods inherited from class java.lang.Object

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

Field Details

parent

protected Expression parent

Constructor Details

Expression

public Expression()

Method Details

eval

public abstract double eval(VarMap v,
 FuncMap f)

Returns the result of evaluating the expression tree rooted at this node.

isDescendent

public boolean isDescendent(Expression x)

Returns true if this node is a descendent of the specified node, false otherwise. By this methods definition, a node is a descendent of itself.

getParent

public Expression getParent()

Returns the parent of this node. Returns null if this node is the root node of an expression-tree.

checkBeforeAccept

protected void checkBeforeAccept(Expression x)

Protected method used to verify that the specified expression can be included as a child expression of this node. An expression cannot be included as a child if it is null, it currently has a parent, or a cyclic reference would be formed.

Throws:

IllegalArgumentException - If the specified expression is not accepted.

getVariableNames

public String[] getVariableNames()

Returns an array of exact length of the variable names contained in the expression tree rooted at this node.

getFunctionNames

public String[] getFunctionNames()

Returns an array of exact length of the function names contained in the expression tree rooted at this node.

getTermNames

private String[] getTermNames(boolean varNames)

getTermNames

private static void getTermNames(Expression x,
 Bag b,
 boolean varNames)

toString

public String toString()

Returns a string that represents the expression tree rooted at this node.

Overrides:

toString in class Object

toString

private static void toString(Expression x,
 StringBuffer sb)