Package 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
    Description
    static final String
    CLOCK_BINDING_KEY
    The key of the Clock when it is added to bindings.
    protected final de.odysseus.el.TreeValueExpression
    valueExpression
    The underlying EL expression that this object represents.

  • Constructor Summary

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

  • Method Summary

    Modifier and Type
    Method
    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.
    Promise<T,NeverThrowsException>
    evalAsync(Bindings bindings)
    Evaluates asynchronously the expression with the specified bindings and returns a promise of the resulting object if it matches the specified type, or a promise completed with 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 Details

    • CLOCK_BINDING_KEY

      public static final String CLOCK_BINDING_KEY
      The key of the Clock when it is added to bindings.
      See Also:

    • valueExpression

      protected final de.odysseus.el.TreeValueExpression valueExpression
      The underlying EL expression that this object represents.

  • Constructor Details

    • 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 Details

    • 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.

    • evalAsync

      public Promise<T,NeverThrowsException> evalAsync(Bindings bindings)
      Evaluates asynchronously the expression with the specified bindings and returns a promise of the resulting object if it matches the specified type, or a promise completed with null if it does not resolve or match.

      If this expression requires asynchronous processing (declared using "#{...}"), then the evaluation is triggered on completion of the Bindings.

      Otherwise it's evaluated immediately.

      Parameters:
      bindings - the bindings to evaluate the expression within.
      Returns:
      a promise containing the result of the expression evaluation, or containing null if it does not resolve or match the type.

    • 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.