Package org.apache.commons.jexl2

Class UnifiedJEXL.Expression

  • Enclosing class:
    UnifiedJEXL
    public abstract class UnifiedJEXL.Expression
extends java.lang.Object
    The abstract base class for all expressions, immediate '${...}' and deferred '#{...}'.

    • Method Detail

      • isImmediate

        public boolean isImmediate()
        Checks whether this expression is immediate.
        Returns:
        true if immediate, false otherwise

      • isDeferred

        public final boolean isDeferred()
        Checks whether this expression is deferred.
        Returns:
        true if deferred, false otherwise

      • toString

        public java.lang.String toString()
        Formats this expression, adding its source string representation in comments if available: 'expression /*= source *\/'' . Note: do not override; will be made final in a future release.
        Overrides:
        toString in class java.lang.Object
        Returns:
        the formatted expression string

      • asString

        public java.lang.String asString()
        Generates this expression's string representation.
        Returns:
        the string representation

      • asString

        public abstract java.lang.StringBuilder asString​(java.lang.StringBuilder strb)
        Adds this expression's string representation to a StringBuilder.
        Parameters:
        strb - the builder to fill
        Returns:
        the builder argument

      • getVariables

        public java.util.Set<java.util.List<java.lang.String>> getVariables()
        Gets the list of variables accessed by this expression.

        This method will visit all nodes of the sub-expressions and extract all variables whether they are written in 'dot' or 'bracketed' notation. (a.b is equivalent to a['b']).

        Returns:
        the set of variables, each as a list of strings (ant-ish variables use more than 1 string) or the empty set if no variables are used
        Since:
        2.1

      • getVariables

        protected void getVariables​(java.util.Set<java.util.List<java.lang.String>> refs)
        Fills up the list of variables accessed by this expression.
        Parameters:
        refs - the set of variable being filled
        Since:
        2.1

      • prepare

        public UnifiedJEXL.Expression prepare​(JexlContext context)
        Evaluates the immediate sub-expressions.

        When the expression is dependant upon immediate and deferred sub-expressions, evaluates the immediate sub-expressions with the context passed as parameter and returns this expression deferred form.

        In effect, this binds the result of the immediate sub-expressions evaluation in the context, allowing to differ evaluation of the remaining (deferred) expression within another context. This only has an effect to nested & composite expressions that contain differed & immediate sub-expressions.

        If the underlying JEXL engine is silent, errors will be logged through its logger as warning.

        Note: do not override; will be made final in a future release.
        Parameters:
        context - the context to use for immediate expression evaluations
        Returns:
        an expression or null if an error occurs and the JexlEngine is running in silent mode
        Throws:
        UnifiedJEXL.Exception - if an error occurs and the JexlEngine is not in silent mode

      • evaluate

        public java.lang.Object evaluate​(JexlContext context)
        Evaluates this expression.

        If the underlying JEXL engine is silent, errors will be logged through its logger as warning.

        Note: do not override; will be made final in a future release.
        Parameters:
        context - the variable context
        Returns:
        the result of this expression evaluation or null if an error occurs and the JexlEngine is running in silent mode
        Throws:
        UnifiedJEXL.Exception - if an error occurs and the JexlEngine is not silent

      • getSource

        public final UnifiedJEXL.Expression getSource()
        Retrieves this expression's source expression. If this expression was prepared, this allows to retrieve the original expression that lead to it. Other expressions return themselves.
        Returns:
        the source expression

      • evaluate

        protected abstract java.lang.Object evaluate​(Interpreter interpreter)
        Intreprets a sub-expression.
        Parameters:
        interpreter - a JEXL interpreter
        Returns:
        the result of interpretation
        Throws:
        JexlException - (only for nested & composite)