de.unkrig.commons.text.expression

Interface Expression

All Known Implementing Classes:

AbstractExpression

public interface Expression

An expression evaluates to a value each time it is evaluated. If you want to evaluate an expression only once, you better use ExpressionEvaluator.evaluate(String, Mapping).

See Also:

Parser.parse()

Field Summary

Fields

Modifier and Type	Field and Description
static Expression	FALSE An expression which always evaluates to false.
static Expression	NULL An expression which always evaluates to null.
static Expression	TRUE An expression which always evaluates to true.

Method Summary

Modifier and Type	Method and Description
Object	evaluate(Mapping<String,?> variables) Computes the value of the expression
Object	evaluate(Object... variableNamesAndValues) Computes the value of the expression.
<T> T	evaluateTo(Class<T> targetType, Object... variableNamesAndValues)
<T> T	evaluateTo(Mapping<String,?> variables, Class<T> targetType)
boolean	evaluateToBoolean(Mapping<String,?> variables)
boolean	evaluateToBoolean(Object... variableNamesAndValues)
<T> T	evaluateToPrimitive(Class<T> targetType, Object... variableNamesAndValues)
<T> T	evaluateToPrimitive(Mapping<String,?> variables, Class<T> targetType)

Field Detail

TRUE

static final Expression TRUE

An expression which always evaluates to true.

FALSE

static final Expression FALSE

An expression which always evaluates to false.

NULL

static final Expression NULL

An expression which always evaluates to null.

Method Detail

evaluate

@Nullable
Object evaluate(Mapping<String,?> variables)
                    throws EvaluationException

Computes the value of the expression

Parameters:

variables - The values of the variables that were named when the expression was parsed. Allowed values are String, Integer, Boolean, any other Object, or null.

Returns:

A String, Integer, Boolean, any other {link Object}, or null

Throws:

EvaluationException - A problem occurred during evaluation, e.g. any array element access was attempted and the index value could not be converted to int

RuntimeException - Any other runtime exception that occurred while evaluating the expression, e.g. an IllegalArgumentException when accessing an element of a non-array

evaluate

@Nullable
Object evaluate(Object... variableNamesAndValues)
                    throws EvaluationException

Computes the value of the expression. This method typically verifies that all required parameters exist in variableNamesAndValues before evaluating it.

Parameters:

variableNamesAndValues - Pairs of variable names and values; the even elements' type must be String, the odd elements' type must be String, Integer, Boolean, any other Object, or null.

Returns:

A String, Integer, Boolean, any other {link Object}, or null

Throws:

EvaluationException - A problem occurred during evaluation, e.g. any array element access was attempted and the index value could not be converted to int

RuntimeException - Any other runtime exception that occurred while evaluating the expression, e.g. an IllegalArgumentException when accessing an element of a non-array

evaluateTo

@Nullable
<T> T evaluateTo(Mapping<String,?> variables,
                            Class<T> targetType)
                     throws EvaluationException

Throws:

EvaluationException

See Also:

AbstractExpression.evaluateTo(Mapping, Class)

evaluateTo

@Nullable
<T> T evaluateTo(Class<T> targetType,
                            Object... variableNamesAndValues)
                     throws EvaluationException

Throws:

EvaluationException

See Also:

AbstractExpression.evaluateTo(Class, Object...)

evaluateToPrimitive

<T> T evaluateToPrimitive(Mapping<String,?> variables,
                          Class<T> targetType)
                   throws EvaluationException

Throws:

EvaluationException

See Also:

AbstractExpression.evaluateToPrimitive(Mapping, Class)

evaluateToPrimitive

<T> T evaluateToPrimitive(Class<T> targetType,
                          Object... variableNamesAndValues)
                   throws EvaluationException

Throws:

EvaluationException

See Also:

AbstractExpression.evaluateToPrimitive(Class, Object...)

evaluateToBoolean

boolean evaluateToBoolean(Mapping<String,?> variables)
                   throws EvaluationException

Throws:

EvaluationException

See Also:

AbstractExpression.evaluateToBoolean(Mapping)

evaluateToBoolean

boolean evaluateToBoolean(Object... variableNamesAndValues)
                   throws EvaluationException

Throws:

EvaluationException

See Also:

AbstractExpression.evaluateToBoolean(Object...)