ebean/src/main/java/io/ebeaninternal/server/expression/IsEmptyExpression.java

package io.ebeaninternal.server.expression;

import io.ebeaninternal.api.ManyWhereJoins;
import io.ebeaninternal.api.SpiExpression;
import io.ebeaninternal.api.SpiExpressionRequest;
import io.ebeaninternal.server.deploy.BeanDescriptor;
import io.ebeaninternal.server.el.ElPropertyValue;
import io.ebean.util.SplitName;

import java.io.IOException;

class IsEmptyExpression extends AbstractExpression {

  private final boolean empty;

  private final String propertyPath;

  private String nestedPath;

  IsEmptyExpression(String propertyName, boolean empty) {
    super(propertyName);
    this.empty = empty;
    this.propertyPath = SplitName.split(propertyName)[0];
  }

  @Override
  public String nestedPath(BeanDescriptor<?> desc) {
    if (empty) {
      // capture the nestedPath as we want to put wrap
      // a NOT around the outer of the nested path  exists
      this.nestedPath = propertyNestedPath(propName, desc);
      return null;
    } else {
      return super.nestedPath(desc);
    }
  }

  @Override
  public void writeDocQuery(DocQueryContext context) throws IOException {
    if (nestedPath == null) {
      context.writeExists(!empty, propName);
    } else {
      // wrap bool must not around the outside of nested path exists expression
      context.startBoolMustNot();
      context.startNested(nestedPath);
      context.writeExists(empty, propName);
      context.endNested();
      context.endBool();
    }
  }

  public final String getPropName() {
    return propName;
  }

  @Override
  public void addBindValues(SpiExpressionRequest request) {
    // no bind values
  }

  @Override
  public void containsMany(BeanDescriptor<?> desc, ManyWhereJoins manyWhereJoin) {
    // we don't want the extra join
    propertyContainsMany(propertyPath, desc, manyWhereJoin);
  }

  @Override
  public void addSql(SpiExpressionRequest request) {

    ElPropertyValue prop = getElProp(request);
    if (prop == null) {
      throw new IllegalStateException("Property [" + propName + "] not found");
    }

    isEmptySql(request, prop, empty, propertyPath);
  }

  /**
   * Append an exists subQuery for the property.
   */
  static void isEmptySql(SpiExpressionRequest request, ElPropertyValue prop, boolean empty, String propertyPath) {

    if (empty) {
      request.append("not ");
    }
    request
      .append("exists (select 1 from ")
      .append(prop.getAssocIsEmpty(request, propertyPath))
      .append(")");
  }

  /**
   * Based on the type and propertyName.
   */
  @Override
  public void queryPlanHash(StringBuilder builder) {
    if (empty) {
      builder.append("IsEmpty[");
    } else {
      builder.append("IsNotEmpty[");
    }
    builder.append(propName).append("]");
  }

  @Override
  public int queryBindHash() {
    return 1;
  }

  @Override
  public boolean isSameByBind(SpiExpression other) {
    return (other instanceof IsEmptyExpression);
  }
}