org.forgerock.openig.el

Class Expression<T>

java.lang.Object

org.forgerock.openig.el.Expression<T>

Type Parameters:

T - expected result type

Direct Known Subclasses:

LeftValueExpression

public class Expression<T>
extends Object

An Unified Expression Language expression. Creating an expression is the equivalent to compiling it. Once created, an expression can be evaluated within a supplied scope. An expression can safely be evaluated concurrently in multiple threads.

Field Summary

Fields

Modifier and Type	Field and Description
protected javax.el.ValueExpression	valueExpression The underlying EL expression that this object represents.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Expression(String expression, Class<T> expectedType, Bindings initialBindings) Constructs an expression for later evaluation.

Method Summary

Modifier and Type	Method and Description
T	eval() Convenient method to eval an Expression that does not need a scope.
T	eval(Bindings bindings) Evaluates the expression within the specified bindings and returns the resulting object if it matches the specified type, or null if it does not resolve or match.
String	toString() Returns the original string used to create this expression, unmodified.
static <T> Expression<T>	valueOf(String expression, Class<T> expectedType) Factory method to create an Expression.
static <T> Expression<T>	valueOf(String expression, Class<T> expectedType, Bindings initialBindings) Factory method to create an Expression.

Methods inherited from class java.lang.Object

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

Field Detail

valueExpression

protected final javax.el.ValueExpression valueExpression

The underlying EL expression that this object represents.

Constructor Detail

Expression

protected Expression(String expression,
                     Class<T> expectedType,
                     Bindings initialBindings)
              throws ExpressionException

Constructs an expression for later evaluation.

Parameters:

expression - the expression to parse.

expectedType - The expected result type of the expression.

initialBindings - The initial bindings used when evaluated this expression

Throws:

ExpressionException - if the expression was not syntactically correct.

Method Detail

valueOf

public static <T> Expression<T> valueOf(String expression,
                                        Class<T> expectedType)
                                 throws ExpressionException

Factory method to create an Expression.

Type Parameters:

T - expected result type

Parameters:

expression - The expression to parse.

expectedType - The expected result type of the expression.

Returns:

An expression based on the given string.

Throws:

ExpressionException - if the expression was not syntactically correct.

valueOf

public static <T> Expression<T> valueOf(String expression,
                                        Class<T> expectedType,
                                        Bindings initialBindings)
                                 throws ExpressionException

Factory method to create an Expression.

Type Parameters:

T - expected result type

Parameters:

expression - The expression to parse.

expectedType - The expected result type of the expression.

initialBindings - The initial bindings used when evaluated this expression

Returns:

An expression based on the given string.

Throws:

ExpressionException - if the expression was not syntactically correct.

eval

public T eval(Bindings bindings)

Evaluates the expression within the specified bindings and returns the resulting object if it matches the specified type, or null if it does not resolve or match.

Parameters:

bindings - the bindings to evaluate the expression within.

Returns:

the result of the expression evaluation, or null if it does not resolve or match the type.

eval

public T eval()

Convenient method to eval an Expression that does not need a scope.

Returns:

the result of the expression evaluation, or null if it does not resolve or match the type.

toString

public String toString()

Returns the original string used to create this expression, unmodified.

Note to implementors: That returned value must be usable in Expression.valueOf() to create an equivalent Expression(somehow cloning this instance)

Overrides:

toString in class Object

Returns:

The original string used to create this expression.