org.activiti.engine.impl.juel

Interface ExpressionNode

All Superinterfaces:

Node

All Known Implementing Classes:

AstBinary, AstBoolean, AstBracket, AstChoice, AstComposite, AstDot, AstEval, AstFunction, AstIdentifier, AstLiteral, AstMethod, AstNested, AstNode, AstNull, AstNumber, AstParameters, AstProperty, AstRightValue, AstString, AstText, AstUnary

public interface ExpressionNode
extends Node

Expression node interface. This interface provides all the methods needed for value expressions and method expressions.

Author:

Christoph Beck

See Also:

Tree

Method Summary

Methods

Modifier and Type	Method and Description
MethodInfo	getMethodInfo(Bindings bindings, ELContext context, Class<?> returnType, Class<?>[] paramTypes) Get method information.
String	getStructuralId(Bindings bindings) Get the canonical expression string for this node.
Class<?>	getType(Bindings bindings, ELContext context) Get the value type accepted in setValue(Bindings, ELContext, Object).
Object	getValue(Bindings bindings, ELContext context, Class<?> expectedType) Evaluate node.
ValueReference	getValueReference(Bindings bindings, ELContext context) Get value reference.
Object	invoke(Bindings bindings, ELContext context, Class<?> returnType, Class<?>[] paramTypes, Object[] paramValues) Invoke method.
boolean	isLeftValue()
boolean	isLiteralText()
boolean	isMethodInvocation()
boolean	isReadOnly(Bindings bindings, ELContext context) Determine whether setValue(Bindings, ELContext, Object) will throw a PropertyNotWritableException.
void	setValue(Bindings bindings, ELContext context, Object value) Assign value.

Methods inherited from interface org.activiti.engine.impl.juel.Node

getCardinality, getChild

Method Detail

isLiteralText

boolean isLiteralText()

Returns:

true if this node represents literal text

isLeftValue

boolean isLeftValue()

Returns:

true if the subtree rooted at this node could be used as an lvalue expression (identifier or property sequence with non-literal prefix).

isMethodInvocation

boolean isMethodInvocation()

Returns:

true if the subtree rooted at this node is a method invocation.

getValue

Object getValue(Bindings bindings,
              ELContext context,
              Class<?> expectedType)

Evaluate node.

Parameters:

bindings - bindings containing variables and functions

context - evaluation context

expectedType - result type

Returns:

evaluated node, coerced to the expected type

getValueReference

ValueReference getValueReference(Bindings bindings,
                               ELContext context)

Get value reference.

Parameters:

bindings -

context -

Returns:

value reference

getType

Class<?> getType(Bindings bindings,
               ELContext context)

Get the value type accepted in setValue(Bindings, ELContext, Object).

Parameters:

bindings - bindings containing variables and functions

context - evaluation context

Returns:

accepted type or null for non-lvalue nodes

isReadOnly

boolean isReadOnly(Bindings bindings,
                 ELContext context)

Determine whether setValue(Bindings, ELContext, Object) will throw a PropertyNotWritableException.

Parameters:

bindings - bindings containing variables and functions

context - evaluation context

Returns:

true if this a read-only expression node

setValue

void setValue(Bindings bindings,
            ELContext context,
            Object value)

Assign value.

Parameters:

bindings - bindings containing variables and functions

context - evaluation context

value - value to set

getMethodInfo

MethodInfo getMethodInfo(Bindings bindings,
                       ELContext context,
                       Class<?> returnType,
                       Class<?>[] paramTypes)

Get method information. If this is a non-lvalue node, answer null.

Parameters:

bindings - bindings containing variables and functions

context - evaluation context

returnType - expected method return type (may be null meaning don't care)

paramTypes - expected method argument types

Returns:

method information or null

invoke

Object invoke(Bindings bindings,
            ELContext context,
            Class<?> returnType,
            Class<?>[] paramTypes,
            Object[] paramValues)

Invoke method.

Parameters:

bindings - bindings containing variables and functions

context - evaluation context

returnType - expected method return type (may be null meaning don't care)

paramTypes - expected method argument types

paramValues - parameter values

Returns:

result of the method invocation

getStructuralId

String getStructuralId(Bindings bindings)

Get the canonical expression string for this node. Variable and funtion names will be replaced in a way such that two expression nodes that have the same node structure and bindings will also answer the same value here.

For example, "${foo:bar()+2*foobar}" may lead to "${<fn>() + 2 * <var>}" if foobar is a bound variable. Otherwise, the structural id would be "${<fn>() + 2 * foobar}".

If the bindings is null, the full canonical subexpression is returned.