org.apache.nifi.expression

Interface ExpressionLanguageCompiler

public interface ExpressionLanguageCompiler

Method Summary

Methods

Modifier and Type	Method and Description
AttributeExpression	compile(String expression) Compiles the given Attribute Expression string into an AttributeExpression that can be evaluated
AttributeExpression.ResultType	getResultType(String expression) Returns the ResultType that will be returned by the given Expression
boolean	isValidExpression(String expression) Indicates whether or not the given string is a valid Attribute Expression.
String	validateExpression(String expression, boolean allowSurroundingCharacters) Attempts to validate the given expression and returns null if the expression is syntactically valid or a String indicating why the expression is invalid otherwise.

Method Detail

compile

AttributeExpression compile(String expression)
                            throws IllegalArgumentException

Compiles the given Attribute Expression string into an AttributeExpression that can be evaluated

Parameters:

expression - the Attribute Expression to be compiled

Returns:

expression that can be evaluated

Throws:

IllegalArgumentException - if the given expression is not valid

isValidExpression

boolean isValidExpression(String expression)

Indicates whether or not the given string is a valid Attribute Expression.

Parameters:

expression - to validate

Returns:

if is value or not

validateExpression

String validateExpression(String expression,
                        boolean allowSurroundingCharacters)

Attempts to validate the given expression and returns null if the expression is syntactically valid or a String indicating why the expression is invalid otherwise.

Parameters:

expression - to validate

allowSurroundingCharacters - if true allows characters to surround the Expression, otherwise the expression must be exactly equal to a valid Expression. E.g., /${path} is valid if and only if allowSurroundingCharacters is true

Returns:

a String indicating the reason that the expression is not syntactically correct, or null if the expression is syntactically correct

getResultType

AttributeExpression.ResultType getResultType(String expression)
                                             throws IllegalArgumentException

Returns the ResultType that will be returned by the given Expression

Parameters:

expression - the Expression to evaluate

Returns:

result type for the given expression

Throws:

IllegalArgumentException - if the given Expression is not a valid Expression Language Expression; the message of this Exception will indicate the problem if the expression is not syntactically valid.