org.vedantatree.expressionoasis.expressions

Class ExpressionFactory

java.lang.Object

org.vedantatree.expressionoasis.expressions.ExpressionFactory

public class ExpressionFactory
extends Object

This is the expression factory which creates the expression for given expression token. It picks the mapping of tokens and corresponding expression classes from a XML file.

Since:

3.1

Version:

1.0 Performance improvements: - Cache expression classes so they only have to be loaded once via reflection - Compile and cache the operand regular expressions so they can be reused Config enhancements: - expression configurations are retrieved from main config file, which is read via Simple XML framework rather than low-level XML APIs. - added addFunction method for function providers to register their function expressions., 1.1 Merged expression class cache in existing type <> expression cache Deprecated the addFunction method, as we are returning FunctionExpression statically for all functions Improved the logic for Operand type expression search while creating the Expression, 1.2

Author:

Mohit Gupta, Parmod Kamboj, Kris Marwood, Mohit Gupta

Field Summary

Fields

Modifier and Type	Field and Description
static String	BINARY This is the binary expression type.
static String	FUNCTION This is the function expression type.
static String	OPERAND This is the operand expression type.
static String	TRUE This is the true constant for absolute.
static String	UNARY This is the unary expression type

Method Summary

Modifier and Type	Method and Description
void	addFunction(String functionName) Deprecated. No need to add function in ExpressionFactory, as it will always return FunctionExpression for all functions
Expression	createExpression(String expressionToken, String type) Creates the expression object for given expression token and expression type
static ExpressionFactory	getInstance() Gets the shared instance of Expression Factory

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

UNARY

public static final String UNARY

This is the unary expression type

See Also:

Constant Field Values

BINARY

public static final String BINARY

This is the binary expression type.

See Also:

Constant Field Values

FUNCTION

public static final String FUNCTION

This is the function expression type.

See Also:

Constant Field Values

OPERAND

public static final String OPERAND

This is the operand expression type.

See Also:

Constant Field Values

TRUE

public static final String TRUE

This is the true constant for absolute.

See Also:

Constant Field Values

Method Detail

getInstance

public static ExpressionFactory getInstance()

Gets the shared instance of Expression Factory

Returns:

Returns the shared instance

addFunction

public void addFunction(String functionName)

Deprecated. No need to add function in ExpressionFactory, as it will always return FunctionExpression for all functions

Adds a function expression for the specified function name

Parameters:

name - name of the function to add

createExpression

public Expression createExpression(String expressionToken,
                                   String type)
                            throws ExpressionEngineException

Creates the expression object for given expression token and expression type

Parameters:

expressionToken - the token of expression

type - the type of expression i.e. operand, operator etc

Returns:

the expression object

Throws:

ExpressionEngineException - if anything goes wrong