org.mov.parser.expression
Class AbstractExpression

java.lang.Object
  org.mov.parser.expression.AbstractExpression

All Implemented Interfaces:

java.lang.Cloneable, Expression

Direct Known Subclasses:

BinaryExpression, ClauseExpression, QuaternaryExpression, TerminalExpression, TernaryExpression, UnaryExpression

public abstract class AbstractExpression
extends java.lang.Object
implements Expression

The abstract base class for all expressions in the Gondola language. This class implements the Expression interface and provides functions for managing an expression's child nodes. E.g. the expression 4+5 would consist of three nodes. The plus being the root node, which would have two child nodes of 4 and 5.

See Also:

Expression

Field Summary

Fields inherited from interface org.mov.parser.Expression

BOOLEAN_TYPE, FALSE, FLOAT_QUOTE_TYPE, FLOAT_TYPE, INTEGER_QUOTE_TYPE, INTEGER_TYPE, STRING_TYPE, TRUE, TRUE_LEVEL

Constructor Summary

AbstractExpression()
Create a new expression.

AbstractExpression(int childCount)
Create a new expression with the given number of children.

Method Summary

abstract java.lang.Object	clone()
boolean	equals(java.lang.Object object) Returns whether this expression tree and the given expression tree are equivalent.
Expression	getChild(int index) Return the child of this node at the given index.
int	getIndex(Expression child) Return the index of the given argument in the expression.
static java.text.NumberFormat	getNumberFormat()
Expression	getParent() Get the parent of this node.
int	hashCode() If you override the equals(java.lang.Object) method then you should override this method.
boolean	isRoot() Return whether this node is the root node.
java.util.Iterator	iterator() Return an iterator over the node's children.
static double	parseDouble(java.lang.String doubleText) Parses doubleText from a string to produce a double.
static int	parseInt(java.lang.String intText) Parses intText from a string to produce an integer.
void	setChild(Expression child, int index) Set this expression's child to the given child.
void	setParent(Expression parent) Set the parent of this node.
Expression	simplify() Perform simplifications and optimisations on the expression tree.
int	size() Count the number of nodes in the tree.
int	size(int type) Count the number of nodes in the tree with the given type.
static java.lang.Double	valueOfDouble(java.lang.String doubleText) Parses doubleText from a string to produce a Double Object.
static java.lang.Integer	valueOfInt(java.lang.String intText) Parses intText from a string to produce an Integer Object.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.mov.parser.Expression

checkType, evaluate, getChildCount, getType, toString

Constructor Detail

AbstractExpression

public AbstractExpression()

Create a new expression.

AbstractExpression

public AbstractExpression(int childCount)

Create a new expression with the given number of children.

Parameters:

childCount - the number of children in the expression.

Method Detail

getParent

public Expression getParent()

Get the parent of this node.

Specified by:

getParent in interface Expression

Returns:

the parent.

setParent

public void setParent(Expression parent)

Set the parent of this node.

Specified by:

setParent in interface Expression

Parameters:

parent - the new parent.

getChild

public Expression getChild(int index)

Return the child of this node at the given index.

Specified by:

getChild in interface Expression

Parameters:

index - the argument index

Returns:

child at given index.

isRoot

public boolean isRoot()

Return whether this node is the root node. The root node has no parent.

Specified by:

isRoot in interface Expression

Returns:

TRUE iff this node is the root node.

setChild

public void setChild(Expression child,
                     int index)

Set this expression's child to the given child. The new child will be removed from its parent.

Specified by:

setChild in interface Expression

Parameters:

child - the new child.

index - the index of the new child.

simplify

public Expression simplify()

Perform simplifications and optimisations on the expression tree. For example, if the expression tree was a and true then the expression tree would be simplified to a.

Specified by:

simplify in interface Expression

getIndex

public int getIndex(Expression child)

Return the index of the given argument in the expression. This method uses reference equality rather than using the equals method.

Specified by:

getIndex in interface Expression

Parameters:

child - the child expression to locate

Returns:

index of the child expression or -1 if it could not be found

parseDouble

public static double parseDouble(java.lang.String doubleText)
                          throws java.lang.NumberFormatException

Parses doubleText from a string to produce a double.

Parameters:

doubleText - the string to be parsed

Returns:

the parsed value

Throws:

java.lang.NumberFormatException

parseInt

public static int parseInt(java.lang.String intText)
                    throws java.lang.NumberFormatException

Parses intText from a string to produce an integer.

Parameters:

intText - the string to be parsed

Returns:

the parsed value

Throws:

java.lang.NumberFormatException

valueOfDouble

public static java.lang.Double valueOfDouble(java.lang.String doubleText)
                                      throws java.lang.NumberFormatException

Parses doubleText from a string to produce a Double Object.

Parameters:

doubleText - the string to be parsed

Returns:

the parsed value as Double Object

Throws:

java.lang.NumberFormatException

valueOfInt

public static java.lang.Integer valueOfInt(java.lang.String intText)
                                    throws java.lang.NumberFormatException

Parses intText from a string to produce an Integer Object.

Parameters:

intText - the string to be parsed

Returns:

the parsed value as Integer Object

Throws:

java.lang.NumberFormatException

getNumberFormat

public static java.text.NumberFormat getNumberFormat()

equals

public boolean equals(java.lang.Object object)

Returns whether this expression tree and the given expression tree are equivalent.

Specified by:

equals in interface Expression

Overrides:

equals in class java.lang.Object

Parameters:

object - the other expression

hashCode

public int hashCode()

If you override the equals(java.lang.Object) method then you should override this method. It provides a very basic hash code function.

Specified by:

hashCode in interface Expression

Overrides:

hashCode in class java.lang.Object

Returns:

a poor hash code of the tree

size

public int size()

Count the number of nodes in the tree.

Specified by:

size in interface Expression

Returns:

number of nodes or 1 if this is a terminal node

size

public int size(int type)

Count the number of nodes in the tree with the given type.

Specified by:

size in interface Expression

Returns:

number of nodes in the tree with the given type.

iterator

public java.util.Iterator iterator()

Return an iterator over the node's children.

Specified by:

iterator in interface Expression

Returns:

iterator.

clone

public abstract java.lang.Object clone()

Specified by:

clone in interface Expression

Overrides:

clone in class java.lang.Object