de.odysseus.el

Class TreeMethodExpression

java.lang.Object

javax.el.Expression

javax.el.MethodExpression

de.odysseus.el.TreeMethodExpression

All Implemented Interfaces:

Serializable

public final class TreeMethodExpression
extends MethodExpression

A method expression is ready to be evaluated (by calling either invoke(ELContext, Object[]) or getMethodInfo(ELContext)). Instances of this class are usually created using an ExpressionFactoryImpl.

Author:

Christoph Beck

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
TreeMethodExpression(TreeStore store, FunctionMapper functions, VariableMapper variables, TypeConverter converter, String expr, Class<?> returnType, Class<?>[] paramTypes) Create a new method expression.

Method Summary

Methods

Modifier and Type	Method and Description
void	dump(PrintWriter writer) Print the parse tree.
boolean	equals(Object obj) Expressions are compared using the concept of a structural id: variable and function names are anonymized such that two expressions with same tree structure will also have the same structural id and vice versa.
String	getExpressionString()
MethodInfo	getMethodInfo(ELContext context) Evaluates the expression and answers information about the method
int	hashCode()
Object	invoke(ELContext context, Object[] paramValues) Evaluates the expression and invokes the method.
boolean	isDeferred() Answer true if this is a deferred expression (starting with #{)
boolean	isLiteralText()
boolean	isParmetersProvided()
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

TreeMethodExpression

public TreeMethodExpression(TreeStore store,
                    FunctionMapper functions,
                    VariableMapper variables,
                    TypeConverter converter,
                    String expr,
                    Class<?> returnType,
                    Class<?>[] paramTypes)

Create a new method expression. The expression must be an lvalue expression or literal text. The expected return type may be null, meaning "don't care". If it is an lvalue expression, the parameter types must not be null. If it is literal text, the expected return type must not be void.

Parameters:

store - used to get the parse tree from.

functions - the function mapper used to bind functions

variables - the variable mapper used to bind variables

expr - the expression string

returnType - the expected return type (may be null)

paramTypes - the expected parameter types (must not be null for lvalues)

Method Detail

getMethodInfo

public MethodInfo getMethodInfo(ELContext context)
                         throws ELException

Evaluates the expression and answers information about the method

Specified by:

getMethodInfo in class MethodExpression

Parameters:

context - used to resolve properties (base.property and base[property])

Returns:

method information or null for literal expressions

Throws:

ELException - if evaluation fails (e.g. suitable method not found)

getExpressionString

public String getExpressionString()

Specified by:

getExpressionString in class Expression

invoke

public Object invoke(ELContext context,
            Object[] paramValues)
              throws ELException

Evaluates the expression and invokes the method.

Specified by:

invoke in class MethodExpression

Parameters:

context - used to resolve properties (base.property and base[property])

paramValues -

Returns:

method result or null if this is a literal text expression

Throws:

ELException - if evaluation fails (e.g. suitable method not found)

isLiteralText

public boolean isLiteralText()

Specified by:

isLiteralText in class Expression

Returns:

true if this is a literal text expression

isParmetersProvided

public boolean isParmetersProvided()

Overrides:

isParmetersProvided in class MethodExpression

Returns:

true if this is a method invocation expression

isDeferred

public boolean isDeferred()

Answer true if this is a deferred expression (starting with #{)

equals

public boolean equals(Object obj)

Expressions are compared using the concept of a structural id: variable and function names are anonymized such that two expressions with same tree structure will also have the same structural id and vice versa. Two method expressions are equal if

1. their builders are equal
2. their structural id's are equal
3. their bindings are equal
4. their expected types match
5. their parameter types are equal

Specified by:

equals in class Expression

hashCode

public int hashCode()

Specified by:

hashCode in class Expression

toString

public String toString()

Overrides:

toString in class Object

dump

public void dump(PrintWriter writer)

Print the parse tree.

Parameters:

writer -