Package org.apache.commons.jexl3

Interface JexlContext

All Known Subinterfaces:

JexlContext.ThreadLocal

All Known Implementing Classes:

JexlEngine.EmptyContext, JexlScriptEngine.JexlContextWrapper, MapContext, ObjectContext

public interface JexlContext

Manages variables which can be referenced in a JEXL expression.

JEXL variable names in their simplest form are 'java-like' identifiers. JEXL also considers 'ant' inspired variables expressions as valid. For instance, the expression 'x.y.z' is an 'antish' variable and will be resolved as a whole by the context, i.e. using the key "x.y.z". This proves to be useful to solve "fully qualified class names".

The interpreter variable resolution algorithm will try the different sequences of identifiers till it finds one that exists in the context; if "x" is an object known in the context (JexlContext.has("x") returns true), "x.y" will not be looked up in the context but will most likely refer to "x.getY()".

Note that JEXL may use '$jexl' and '$ujexl' variables for internal purpose; setting or getting those variables may lead to unexpected results unless specified otherwise.

Since:

1.0

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	JexlContext.AnnotationProcessor	A marker interface of the JexlContext that processes annotations.
static interface	JexlContext.CancellationHandle	A marker interface of the JexlContext sharing a cancelling flag.
static interface	JexlContext.ClassNameResolver	A marker interface that solves a simple class name into a fully-qualified one.
static interface	JexlContext.ModuleProcessor	A marker interface of the JexlContext that processes module definitions.
static interface	JexlContext.NamespaceFunctor	A marker interface of the JexlContext, NamespaceFunctor allows creating an instance to delegate namespace methods calls to.
static interface	JexlContext.NamespaceResolver	A marker interface of the JexlContext that declares how to resolve a namespace from its name; it is used by the interpreter during evaluation.
static interface	JexlContext.OptionsHandle	A marker interface of the JexlContext that exposes runtime evaluation options.
static interface	JexlContext.PragmaProcessor	A marker interface of the JexlContext that processes pragmas.
static interface	JexlContext.ThreadLocal	A marker interface of the JexlContext that indicates the interpreter to put this context in the JexlEngine thread local context instance during evaluation.

Method Summary

Modifier and Type	Method	Description
java.lang.Object	get(java.lang.String name)	Gets the value of a variable.
boolean	has(java.lang.String name)	Checks whether a variable is defined in this context.
void	set(java.lang.String name, java.lang.Object value)	Sets the value of a variable.

Method Detail

get

java.lang.Object get(java.lang.String name)

Gets the value of a variable.

Parameters:

name - the variable's name.

Returns:

the value.

has

boolean has(java.lang.String name)

Checks whether a variable is defined in this context.

A variable may be defined with a null value; this method checks whether the value is null or if the variable is undefined.

Parameters:

name - the variable's name.

Returns:

true if it exists, false otherwise.

set

void set(java.lang.String name,
         java.lang.Object value)

Sets the value of a variable.

Parameters:

name - the variable's name.

value - the variable's value.