Package org.zkoss.xel.util

Class Evaluators

java.lang.Object
org.zkoss.xel.util.Evaluators
public class Evaluators extends Object
It maps a name with an evaluator implementation.
Since:
3.0.0
Author:
tomyeh

  • Method Details

    • getEvaluatorClass

      public static final Class<? extends ExpressionFactory> getEvaluatorClass(String name)
      Returns the implementation for the specified evaluator name.
      Parameters:
      name - the name of the evaluator, say, MVEL.
      Throws:
      SystemException - if not found or the class not found.

    • exists

      public static final boolean exists(String name)
      Tests whether the evaluator (a.k.a., the expression factory) for the specified evaluator name exists.
      Parameters:
      name - the name of the evaluator, say, MVEL.

    • add

      public static final String add(String name, String evalcls)
      Adds an evaluator (a.k.a., the expression factory, ExpressionFactory).
      Parameters:
      name - the name of the evaluator, say, MVEL. It is case insensitive.
      evalcls - the class name of the evaluator, a.k.a., the expression factory (ExpressionFactory).
      Returns:
      the previous class name, or null if not defined yet

    • add

      public static final String add(Element config)
      Adds an evaluator based on the XML declaration. The evaluator is also known as the expression factory, ExpressionFactory. 
      
<xel-config>
  <evaluator-name>SuperEL</evaluator-name><!-- case insensitive --!>
  <evaluator-class>my.MySuperEvaluator</evaluator-class>
</xel-config>
      Parameters:
      config - the XML element called zscript-config
      Returns:
      the previous class, or null if not defined yet

    • resolveVariable

      public static Object resolveVariable(XelContext ctx, VariableResolver resolver, Object base, Object name)
      Resolves the variable based on the the specified context and variable resolver.
      Since:
      5.0.0

    • resolveVariable

      public static Object resolveVariable(XelContext ctx, Object base, Object name)
      Resolves the variable based on the specified context. If the variable resolver (XelContext.getVariableResolver() is an instance of VariableResolverX, then VariableResolverX.resolveVariable(XelContext,Object,Object) will be invoked.
      Parameters:
      ctx - the context. If null, null will be returned.
      Since:
      5.0.0

    • resolveVariable

      public static Object resolveVariable(VariableResolver resolver, String name)
      Resolves the variable based on the specified resolver. If the resolver is an instance of VariableResolverX, then VariableResolverX.resolveVariable(XelContext,Object,Object) will be invoked.

      Notice that it is always better to invoke resolveVariable(XelContext,Object,Object) if XelContext is available.

      Parameters:
      resolver - the variable resolver. If null, null will be returned.
      Since:
      5.0.0