nz.org.venice.parser.expression
Class AbstractExpression

java.lang.Object
  nz.org.venice.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 nz.org.venice.parser.Expression

BOOLEAN_TYPE, FALSE, FLOAT_QUOTE_TYPE, FLOAT_TYPE, INTEGER_QUOTE_TYPE, INTEGER_SHORT_TYPE, INTEGER_TYPE, NUMERIC_TYPE, STRING_TYPE, TRUE, TRUE_LEVEL, UNDEFINED_TYPE

Constructor Summary

AbstractExpression()
Create a new expression with no children.

AbstractExpression(Expression[] children)
Create a new expression with the given number of children.

AbstractExpression(java.util.List children)
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.
java.lang.String	getId()
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.
ParseMetadata	getParseMetadata()
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.
java.lang.String	printParents()
Expression	setChild(Expression child, int index) Set the argument.
void	setChildMutableVersion(Expression child, int index) Set this expression's child to the given child.
void	setParent(Expression parent) Set the parent of this node.
void	setParseMetadata(java.util.HashMap parseTree, java.util.HashMap tokenLineMap) Store the metadata about how the expressing parsing.
Expression	simplify() Perform simplifications and optimisations on the expression tree.
Expression	simplifyMutableVersion() 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.
java.lang.String	toString() Convert the given expression to a string.
boolean	validTree() Return true if none of the children of this expression are null.
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, wait, wait, wait

Methods inherited from interface nz.org.venice.parser.Expression

checkType, evaluate, getChildCount, getType

Constructor Detail

AbstractExpression

public AbstractExpression()

Create a new expression with no children.

AbstractExpression

public AbstractExpression(Expression[] children)

Create a new expression with the given number of children.

Parameters:

children - An array of the children of the expression.

AbstractExpression

public AbstractExpression(java.util.List children)

Create a new expression with the given number of children.

Parameters:

children - A List of the children of 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 Expression setChild(Expression child,
                           int index)

Description copied from interface: Expression

Set the argument.

Specified by:

setChild in interface Expression

Parameters:

child - new argument expression

index - index of the argument expression

setChildMutableVersion

public void setChildMutableVersion(Expression child,
                                   int index)

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

Parameters:

child - the new child.

index - the index of the new child.

validTree

public boolean validTree()

Return true if none of the children of this expression are null. This means the expression can be simplified safely.

Specified by:

validTree in interface Expression

Returns:

true if all children are not null

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

simplifyMutableVersion

public Expression simplifyMutableVersion()

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.

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

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

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.

toString

public java.lang.String toString()

Description copied from interface: Expression

Convert the given expression to a string.

Specified by:

toString in interface Expression

clone

public abstract java.lang.Object clone()

Specified by:

clone in interface Expression

printParents

public java.lang.String printParents()

setParseMetadata

public void setParseMetadata(java.util.HashMap parseTree,
                             java.util.HashMap tokenLineMap)

Description copied from interface: Expression

Store the metadata about how the expressing parsing.

Specified by:

setParseMetadata in interface Expression

Parameters:

parseTree - A map which relates a constructed expression with it's associated token.

tokenLineMap - A map which associates a token to which line number of the rule text it appears.

getParseMetadata

public ParseMetadata getParseMetadata()

Specified by:

getParseMetadata in interface Expression

Returns:

metadata information about the parse. (e.g. line numbers)

getId

public java.lang.String getId()

Specified by:

getId in interface Expression

Returns:

the unique id of the expression. (Not all expressions implement a proper hashcode())