org.apache.tapestry.services
Interface ExpressionEvaluator

All Known Implementing Classes:

ExpressionEvaluatorImpl

public interface ExpressionEvaluator

Wrapper around the OGNL library.

Since:

4.0

Author:

Howard M. Lewis Ship

Method Summary

OgnlContext	createContext(Object target) Creates a default OGNL context object that can be used against the specified object for expression evaluation.
boolean	isConstant(Object target, String expression) Returns true if the expression evaluates to a constant or other literal value.
boolean	isConstant(String expression) Returns true if the expression evaluates to a constant or other literal value.
Object	read(Object target, ognl.enhance.ExpressionAccessor expression) Reads a property of the target, defined by the (previously compiled) expression.
Object	read(Object target, String expression) Reads a property of the target, defined by the expression.
Object	readCompiled(Object target, Object expression) Reads a property of the target, defined by the (previously compiled) expression.
void	write(Object target, ognl.enhance.ExpressionAccessor expression, Object value) Updates a property of the target, defined by the (previously compiled) expression.
void	write(Object target, String expression, Object value) Updates a property of the target, defined by the expression.
void	writeCompiled(Object target, Object expression, Object value) Updates a property of the target, defined by the (previously compiled) expression.

Method Detail

read

Object read(Object target,
            String expression)

Reads a property of the target, defined by the expression.

Throws:

org.apache.hivemind.ApplicationRuntimeException - if the expression can not be parsed, or if some other error occurs during evaluation of the expression.

readCompiled

Object readCompiled(Object target,
                    Object expression)

Reads a property of the target, defined by the (previously compiled) expression.

Throws:

org.apache.hivemind.ApplicationRuntimeException - if some other error occurs during evaluation of the expression.

read

Object read(Object target,
            ognl.enhance.ExpressionAccessor expression)

Reads a property of the target, defined by the (previously compiled) expression.

Parameters:

target - The object to resolve the expression against.

expression - The compiled expression.

Returns:

The result of reading on the expression.

write

void write(Object target,
           String expression,
           Object value)

Updates a property of the target, defined by the expression.

Throws:

org.apache.hivemind.ApplicationRuntimeException - if the expression can not be parsed, or if some other error occurs during evaluation of the expression.

writeCompiled

void writeCompiled(Object target,
                   Object expression,
                   Object value)

Updates a property of the target, defined by the (previously compiled) expression.

Throws:

org.apache.hivemind.ApplicationRuntimeException - if some other error occurs during evaluation of the expression.

write

void write(Object target,
           ognl.enhance.ExpressionAccessor expression,
           Object value)

Updates a property of the target, defined by the (previously compiled) expression.

Parameters:

target - The target object to set a value on.

expression - The pre-compiled expression.

value - The value to set.

isConstant

boolean isConstant(String expression)

Returns true if the expression evaluates to a constant or other literal value.

Throws:

org.apache.hivemind.ApplicationRuntimeException - if the expression is not valid

isConstant

boolean isConstant(Object target,
                   String expression)

Returns true if the expression evaluates to a constant or other literal value.

Throws:

org.apache.hivemind.ApplicationRuntimeException - if the expression is not valid

createContext

OgnlContext createContext(Object target)

Creates a default OGNL context object that can be used against the specified object for expression evaluation.

Parameters:

target - The object to get a context for.

Returns:

An ognl context map.