de.odysseus.el.tree
Interface ExpressionNode

All Superinterfaces:

Node

All Known Implementing Classes:

AstBinary, AstBoolean, AstBracket, AstChoice, AstComposite, AstDot, AstEval, AstFunction, AstIdentifier, AstLiteral, AstMethod, AstNested, AstNode, AstNull, AstNumber, 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

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

Methods inherited from interface de.odysseus.el.tree.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 proefix).

getValue

java.lang.Object getValue(Bindings bindings,
                          ELContext context,
                          java.lang.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

getType

java.lang.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,
              java.lang.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,
                         java.lang.Class<?> returnType,
                         java.lang.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

java.lang.Object invoke(Bindings bindings,
                        ELContext context,
                        java.lang.Class<?> returnType,
                        java.lang.Class<?>[] paramTypes,
                        java.lang.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

java.lang.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.