ro4 / vanilla

import io.github.ro4.ExpressionException;

import io.github.ro4.constant.MagicMark;

import io.github.ro4.Context;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.context.expression.BeanFactoryResolver;

import org.springframework.expression.spel.standard.SpelExpressionParser;

import org.springframework.expression.spel.support.StandardEvaluationContext;

public class SpELChecker implements Checker {

    private static final SpelExpressionParser PARSER = new SpelExpressionParser();

    private BeanFactory beanFactory = null;

    }

    public SpELChecker(BeanFactory beanFactory) {

        this.beanFactory = beanFactory;

    }

    @Override

    public boolean pass(Context ctx) {

        if (!ctx.hasAttribute(MagicMark.EXPRESSION)) {

            throw new ExpressionException("expression not found");

        }

        StandardEvaluationContext spELCtx = new StandardEvaluationContext();

        // ugly design, temporary work

        if (null != beanFactory) {

            spELCtx.setBeanResolver(new BeanFactoryResolver(beanFactory));

        }

        for (String s : ctx.attributeNames()) {

            spELCtx.setVariable(s, ctx.getAttribute(s));

        }

        String expression = (String) ctx.getAttribute(MagicMark.EXPRESSION);

        assert expression != null;

        return Boolean.TRUE.equals(PARSER.parseExpression(expression).getValue(spELCtx, Boolean.TYPE));

    }

}