de.unkrig.commons.text.expression

Class ExpressionUtil

java.lang.Object

de.unkrig.commons.text.expression.ExpressionUtil

public final class ExpressionUtil
extends Object

Utility class for Expression.

Method Summary

Modifier and Type	Method and Description
static Expression	constantExpression(Object value)
static <T> T	evaluateExpressionTo(String[] imports, String input, Class<T> targetType, Mapping<String,?> variables) Scans, parses and evaluates an expression, and converts the result to <T>.
static String	evaluateLeniently(Expression expression, Mapping<String,?> variables)
static String	evaluateLeniently(Expression expression, Object... variableNamesAndValues)
static <T> T	evaluateTo(Expression expression, Class<T> targetClass, Mapping<String,?> variables)
static <T> T	evaluateTo(Expression expression, Class<T> targetClass, Object... variableNamesAndValues)
static Expression	expand(String s, Predicate<? super String> isValidVariableName) Turns the given string into an expression.
static Expression	expand(String s, Set<String> variableNames) Turns the given string into an expression.
static Expression	expand(String s, String... variableNames) Turns the given string into an expression.
static Expression	fromPredicate(Predicate<? super String> predicate, String variableName)
static Expression	logicalAnd(Expression operand1, Expression operand2)
static Expression	logicalOr(Expression operand1, Expression operand2)
static <T> Predicate<T>	toPredicate(Expression expression, String parameterName)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

constantExpression

public static Expression constantExpression(@Nullable
                                            Object value)

Returns:

An Expression that evaluates to a constant value; Expression.TRUE iff the expression is constant and evaluates to true; Expression.FALSE iff the expression is constant and evaluates to false; Expression.NULL iff the expression is constant and evaluates to null

expand

public static Expression expand(String s,
                                String... variableNames)
                         throws ParseException

Turns the given string into an expression. If the string contains '#' characters, then the text between two '#' characters is parsed as an expression.

Parameters:

s - The string to expand

variableNames - All contained variable names can be used in the expression

Returns:

The expanded string

Throws:

ParseException

expand

public static Expression expand(String s,
                                Set<String> variableNames)
                         throws ParseException

Turns the given string into an expression. If the string contains '#' characters, then the text between two '#' characters is parsed as an expression.

Parameters:

s - The string to expand

variableNames - All contained variable names can be used in the expression

Returns:

The expanded string

Throws:

ParseException

expand

public static Expression expand(String s,
                                Predicate<? super String> isValidVariableName)
                         throws ParseException

Turns the given string into an expression. If the string contains '#' characters, then the text between two '#' characters is parsed as an expression.

Parameters:

s - The string to expand

isValidVariableName - Evalutaes to whether the subject is a valid variable name

Returns:

The expanded string

Throws:

ParseException

evaluateLeniently

public static String evaluateLeniently(Expression expression,
                                       Mapping<String,?> variables)

Returns:

The result of the evaluation, or a verbose HTML comment reporting the error

evaluateLeniently

public static String evaluateLeniently(Expression expression,
                                       Object... variableNamesAndValues)

Returns:

The result of the evaluation, or a verbose HTML comment reporting the error

evaluateTo

@Nullable
public static <T> T evaluateTo(Expression expression,
                                          Class<T> targetClass,
                                          Mapping<String,?> variables)
                                   throws EvaluationException

Returns:

The evaluated value

Throws:

EvaluationException - The expression evaluates to null

EvaluationException - A problem occurred during evaluation, e.g. a class could not be loaded, or a type cast could not be performed

evaluateTo

@Nullable
public static <T> T evaluateTo(Expression expression,
                                          Class<T> targetClass,
                                          Object... variableNamesAndValues)
                                   throws EvaluationException

Returns:

The evaluated value

Throws:

EvaluationException - The expression evaluates to null

EvaluationException - A problem occurred during evaluation, e.g. a class could not be loaded, or a type cast could not be performed

evaluateExpressionTo

@Nullable
public static <T> T evaluateExpressionTo(@Nullable
                                                    String[] imports,
                                                    String input,
                                                    Class<T> targetType,
                                                    Mapping<String,?> variables)
                                             throws ParseException,
                                                    EvaluationException

Scans, parses and evaluates an expression, and converts the result to <T>.

Parameters:

variables - The variables that the expression can use

Returns:

The evaluated value

Throws:

ParseException

EvaluationException

toPredicate

public static <T> Predicate<T> toPredicate(Expression expression,
                                           String parameterName)

Type Parameters:

T - The type of the predicate's subject

Parameters:

parameterName - The name under which the predicate subject is accessible for the expression

Returns:

A Predicate which evaluates to the value of the given expression; Expression.TRUE iff the expression is constant and evaluates to true; Expression.FALSE iff the expression is constant and evaluates to false

fromPredicate

public static Expression fromPredicate(Predicate<? super String> predicate,
                                       String variableName)

Returns:

An Expression which evaluates to the result of the given predicate, where the subject to the predicate is the value of the named variable of the expression

logicalAnd

public static Expression logicalAnd(Expression operand1,
                                    Expression operand2)

Returns:

An Expression which evaluates the operand1, and, if that is true the operand2

logicalOr

public static Expression logicalOr(Expression operand1,
                                   Expression operand2)

Returns:

An Expression which evaluates the operand1, and, if that is false the operand2