Examples of org.apache.commons.jexl2.JexlEngine

org.apache.commons.jexl2.JexlEngine
Creates and evaluates Expression and Script objects. Determines the behavior of Expressions & Scripts during their evaluation with respect to:
- Introspection, see {@link Uberspect}
- Arithmetic & comparison, see {@link JexlArithmetic}
- Error reporting
- Logging
The setSilent and setLenient methods allow to fine-tune an engine instance behavior according to various error control needs. The lenient/strict flag tells the engine when and if null as operand is considered an error, the silent/verbose flag tells the engine what to do with the error (log as warning or throw exception).
- When "silent" & "lenient":
  0 & null should be indicators of "default" values so that even in an case of error, something meaningfull can still be inferred; may be convenient for configurations.
- When "silent" & "strict":
  One should probably consider using null as an error case - ie, every object manipulated by JEXL should be valued; the ternary operator, especially the '?:' form can be used to workaround exceptional cases. Use case could be configuration with no implicit values or defaults.
- When "verbose" & "lenient":
  The error control grain is roughly on par with JEXL 1.0
- When "verbose" & "strict":
  The finest error control grain is obtained; it is the closest to Java code - still augmented by "script" capabilities regarding automated conversions & type matching.
Note that methods that evaluate expressions may throw unchecked exceptions; The {@link JexlException} are thrown in "non-silent" mode but since these areRuntimeException, user-code should catch them wherever most appropriate.
@since 2.0


        log.debug("Evaluating expression: {}", expression);
        
        Expression expr = engine.createExpression(expression);


        JexlContext ctx = new MapContext(vars);


        Object result = expr.evaluate(ctx);
        log.debug("Result: {}", result);


        return result;

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        }


        // Evaluate AccountLink expression
        String evalAccountLink = null;
        if (StringUtils.isNotBlank(attrUtil.getAccountLink(resource))) {
            final JexlContext jexlContext = new MapContext();
            JexlUtil.addFieldsToContext(subject, jexlContext);
            JexlUtil.addAttrsToContext(subject.getAttributes(), jexlContext);
            JexlUtil.addDerAttrsToContext(subject.getDerivedAttributes(), subject.getAttributes(), jexlContext);
            evalAccountLink = JexlUtil.evaluate(attrUtil.getAccountLink(resource), jexlContext);
        }

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     * {@link FeatureState#DISABLED} otherwise.
     */
    @Override
    public FeatureState process(final ContextManager contextManager)
    {
        final JexlEngine jexlEngine = new JexlEngine();
        Expression jexlExpression;
        if (expression != null) {
            jexlExpression = jexlEngine.createExpression(expression);
        } else {
            jexlExpression = getOldExpression(jexlEngine);
        }
        
        final Map<String, Object> contextMap = contextManager.getContext(context);

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    public JexlExpressionParser(final Map<String, Object> vars) {
        if (vars == null) {
            throw new IllegalArgumentException("vars");
        }
        
        engine = new JexlEngine();
        context = new MapContext(vars);
        variables = vars;
        
        log.trace("Using variables: {}", vars);
    }

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        Map<String, Object> sysVars = new HashMap<String, Object>();
        for (Entry<Object,Object> entry : System.getProperties().entrySet()){
            sysVars.put((String)entry.getKey(), entry.getValue());
        }
        
        engine = new JexlEngine();
        context = new MapContext(sysVars);
        variables = sysVars;
        
        log.trace("Using variables: {}", sysVars);
    }

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    public JexlConditionParser(final Map<String, Object> vars) {
        if (vars == null) {
            throw new IllegalArgumentException("vars");
        }
        this.vars = vars;
        engine = new JexlEngine();
    }

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    public JexlConditionParser() {
        // Setup the default vars
        vars = new HashMap<String, Object>();
        ParserUtils.addDefaultVariables(vars);
        
        engine = new JexlEngine();
    }

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    private static JexlEngine jexlEngine;


    private static JexlEngine getEngine() {
        synchronized (LOG) {
            if (jexlEngine == null) {
                jexlEngine = new JexlEngine(new ClassFreeUberspectImpl(null), null, null, null);
                jexlEngine.setClassLoader(new EmptyClassLoader());
                jexlEngine.setCache(512);
                jexlEngine.setLenient(true);
                jexlEngine.setSilent(false);
            }

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    private static JexlEngine jexlEngine;


    private static JexlEngine getEngine() {
        synchronized (LOG) {
            if (jexlEngine == null) {
                jexlEngine = new JexlEngine(new ClassFreeUberspectImpl(null), null, null, null);
                jexlEngine.setClassLoader(new EmptyClassLoader());
                jexlEngine.setCache(512);
                jexlEngine.setLenient(true);
                jexlEngine.setSilent(false);
            }

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    private static JexlEngine jexlEngine;


    private static JexlEngine getEngine() {
        synchronized (LOG) {
            if (jexlEngine == null) {
                jexlEngine = new JexlEngine(new ClassFreeUberspectImpl(null), null, null, null);
                jexlEngine.setClassLoader(new EmptyClassLoader());
                jexlEngine.setCache(512);
                jexlEngine.setLenient(true);
                jexlEngine.setSilent(false);
            }

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