io.zeebe.spring.util.ZeebeExpressionResolver Maven / Gradle / Ivy

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package io.zeebe.spring.util;

import java.util.function.UnaryOperator;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.BeanExpressionContext;
import org.springframework.beans.factory.config.BeanExpressionResolver;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.context.expression.StandardBeanExpressionResolver;

public class ZeebeExpressionResolver implements BeanFactoryAware {

  private BeanExpressionResolver resolver = new StandardBeanExpressionResolver();
  private BeanFactory beanFactory;
  private BeanExpressionContext expressionContext;

  /**
   * Resolve the specified value if possible.
   *
   * @see ConfigurableBeanFactory#resolveEmbeddedValue
   */
  private final UnaryOperator resolve =
    value ->
      (this.beanFactory instanceof ConfigurableBeanFactory)
        ? ((ConfigurableBeanFactory) this.beanFactory).resolveEmbeddedValue(value)
        : value;

  @Override
  public void setBeanFactory(final BeanFactory beanFactory) throws BeansException {
    this.beanFactory = beanFactory;
    if (beanFactory instanceof ConfigurableListableBeanFactory) {
      this.resolver = ((ConfigurableListableBeanFactory) beanFactory).getBeanExpressionResolver();
      this.expressionContext =
        new BeanExpressionContext((ConfigurableListableBeanFactory) beanFactory, null);
    }
  }

  @SuppressWarnings("unchecked")
  public  T resolve(final String value) {
    final String resolvedValue = resolve.apply(value);

    if (!(resolvedValue.startsWith("#{") && value.endsWith("}"))) {
      return (T) resolvedValue;
    }

    return (T) this.resolver.evaluate(resolvedValue, this.expressionContext);
  }
}