Examples with IExpressionObjects org.thymeleaf.expression.IExpressionObjects used on opensource projects

Example 1 with IExpressionObjects

use of org.thymeleaf.expression.IExpressionObjects in project thymeleaf by thymeleaf.

the class OGNLVariableExpressionEvaluator method evaluate.

private static Object evaluate(final IExpressionContext context, final IStandardVariableExpression expression, final StandardExpressionExecutionContext expContext, final boolean applyOGNLShortcuts) {
    try {
        if (logger.isTraceEnabled()) {
            logger.trace("[THYMELEAF][{}] OGNL expression: evaluating expression \"{}\" on target", TemplateEngine.threadIndex(), expression.getExpression());
        }
        final IEngineConfiguration configuration = context.getConfiguration();
        final String exp = expression.getExpression();
        final boolean useSelectionAsRoot = expression.getUseSelectionAsRoot();
        if (exp == null) {
            throw new TemplateProcessingException("Expression content is null, which is not allowed");
        }
        final ComputedOGNLExpression parsedExpression = obtainComputedOGNLExpression(configuration, expression, exp, applyOGNLShortcuts);
        final Map<String, Object> contextVariablesMap;
        if (parsedExpression.mightNeedExpressionObjects) {
            // The IExpressionObjects implementation returned by processing contexts that include the Standard
            // Dialects will be lazy in the creation of expression objects (i.e. they won't be created until really
            // needed). And in order for this behaviour to be accepted by OGNL, we will be wrapping this object
            // inside an implementation of Map<String,Object>, which will afterwards be fed to the constructor
            // of an OgnlContext object.
            // Note this will never happen with shortcut expressions, as the '#' character with which all
            // expression object names start is not allowed by the OGNLShortcutExpression parser.
            final IExpressionObjects expressionObjects = context.getExpressionObjects();
            contextVariablesMap = new OGNLExpressionObjectsWrapper(expressionObjects, expContext.getRestrictVariableAccess());
            // can later lookup during evaluation.
            if (expContext.getRestrictVariableAccess()) {
                contextVariablesMap.put(OGNLContextPropertyAccessor.RESTRICT_REQUEST_PARAMETERS, OGNLContextPropertyAccessor.RESTRICT_REQUEST_PARAMETERS);
            } else {
                contextVariablesMap.remove(OGNLContextPropertyAccessor.RESTRICT_REQUEST_PARAMETERS);
            }
        } else {
            if (expContext.getRestrictVariableAccess()) {
                contextVariablesMap = CONTEXT_VARIABLES_MAP_NOEXPOBJECTS_RESTRICTIONS;
            } else {
                contextVariablesMap = Collections.EMPTY_MAP;
            }
        }
        // The root object on which we will evaluate expressions will depend on whether a selection target is
        // active or not...
        final ITemplateContext templateContext = (context instanceof ITemplateContext ? (ITemplateContext) context : null);
        final Object evaluationRoot = (useSelectionAsRoot && templateContext != null && templateContext.hasSelectionTarget() ? templateContext.getSelectionTarget() : templateContext);
        // Execute the expression!
        final Object result;
        try {
            result = executeExpression(configuration, parsedExpression.expression, contextVariablesMap, evaluationRoot);
        } catch (final OGNLShortcutExpression.OGNLShortcutExpressionNotApplicableException notApplicable) {
            // We tried to apply shortcuts, but it is not possible for this expression even if it parsed OK,
            // so we need to empty the cache and try again disabling shortcuts. Once processed for the first time,
            // an OGNL (non-shortcut) parsed expression will already be cached and this exception will not be
            // thrown again
            invalidateComputedOGNLExpression(configuration, expression, exp);
            return evaluate(context, expression, expContext, false);
        }
        if (!expContext.getPerformTypeConversion()) {
            return result;
        }
        final IStandardConversionService conversionService = StandardExpressions.getConversionService(configuration);
        return conversionService.convert(context, result, String.class);
    } catch (final Exception e) {
        throw new TemplateProcessingException("Exception evaluating OGNL expression: \"" + expression.getExpression() + "\"", e);
    }
}