org.apache.commons.jexl2
Class UnifiedJEXL.Expression

java.lang.Object
  org.apache.commons.jexl2.UnifiedJEXL.Expression

Enclosing class:

UnifiedJEXL

public abstract class UnifiedJEXL.Expression
extends Object

The abstract base class for all expressions, immediate '${...}' and deferred '#{...}'.

Field Summary

protected UnifiedJEXL.Expression

source The source of this expression (see prepare(org.apache.commons.jexl2.JexlContext)).

Method Summary

String	asString() Generates this expression's string representation.
abstract StringBuilder	asString(StringBuilder strb) Adds this expression's string representation to a StringBuilder.
protected abstract Object	evaluate(Interpreter interpreter) Intreprets a sub-expression.
Object	evaluate(JexlContext context) Evaluates this expression.
UnifiedJEXL.Expression	getSource() Retrieves this expression's source expression.
Set<List<String>>	getVariables() Gets the list of variables accessed by this expression.
protected void	getVariables(Set<List<String>> refs) Fills up the list of variables accessed by this expression.
boolean	isDeferred() Checks whether this expression is deferred.
boolean	isImmediate() Checks whether this expression is immediate.
protected UnifiedJEXL.Expression	prepare(Interpreter interpreter) Prepares a sub-expression for interpretation.
UnifiedJEXL.Expression	prepare(JexlContext context) Evaluates the immediate sub-expressions.
String	toString() Formats this expression, adding its source string representation in comments if available: 'expression /*= source *\/'' .

Methods inherited from class java.lang.Object

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

Field Detail

source

protected final UnifiedJEXL.Expression source

The source of this expression (see prepare(org.apache.commons.jexl2.JexlContext)).

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 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 Object

Returns:

the formatted expression string

asString

public String asString()

Generates this expression's string representation.

Returns:

the string representation

asString

public abstract StringBuilder asString(StringBuilder strb)

Adds this expression's string representation to a StringBuilder.

Parameters:

strb - the builder to fill

Returns:

the builder argument

getVariables

public Set<List<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(Set<List<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 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

prepare

protected UnifiedJEXL.Expression prepare(Interpreter interpreter)

Prepares a sub-expression for interpretation.

Parameters:

interpreter - a JEXL interpreter

Returns:

a prepared expression

Throws:

JexlException - (only for nested & composite)

evaluate

protected abstract Object evaluate(Interpreter interpreter)

Intreprets a sub-expression.

Parameters:

interpreter - a JEXL interpreter

Returns:

the result of interpretation

Throws:

JexlException - (only for nested & composite)