fe/src/main/java/org/apache/impala/analysis/ValuesStmt.java

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package org.apache.impala.analysis;

import java.util.List;

import com.google.common.base.Preconditions;

import static org.apache.impala.analysis.ToSqlOptions.DEFAULT;

/**
 * Representation of a values() statement with a list of constant-expression lists.
 * ValuesStmt is a special case of a UnionStmt with the following restrictions:
 * - Operands are only constant selects
 * - Operands are connected by UNION ALL
 * - No nesting of ValuesStmts
 */
public class ValuesStmt extends UnionStmt {

  public ValuesStmt(List<UnionOperand> operands,
      List<OrderByElement> orderByElements, LimitElement limitElement) {
    super(operands, orderByElements, limitElement);
  }

  /**
   * C'tor for cloning.
   */
  private ValuesStmt(ValuesStmt other) { super(other); }

  @Override
  protected String queryStmtToSql(QueryStmt queryStmt) {
    StringBuilder strBuilder = new StringBuilder();
    strBuilder.append("(");
    appendSelectList((SelectStmt) queryStmt, strBuilder, DEFAULT);
    strBuilder.append(")");
    return strBuilder.toString();
  }

  @Override
  public String toSql(ToSqlOptions options) {
    if (options.showRewritten()) return super.toSql(options);
    StringBuilder strBuilder = new StringBuilder();
    if (withClause_ != null) {
      strBuilder.append(withClause_.toSql(options));
      strBuilder.append(" ");
    }
    Preconditions.checkState(operands_.size() > 0);
    strBuilder.append("VALUES(");
    for (int i = 0; i < operands_.size(); ++i) {
      if (operands_.size() != 1) strBuilder.append("(");
      appendSelectList((SelectStmt) operands_.get(i).getQueryStmt(), strBuilder, options);
      if (operands_.size() != 1) strBuilder.append(")");
      strBuilder.append((i+1 != operands_.size()) ? ", " : "");
    }
    strBuilder.append(")");
    return strBuilder.toString();
  }

  private void appendSelectList(
      SelectStmt select, StringBuilder strBuilder, ToSqlOptions options) {
    SelectList selectList = select.getSelectList();
    for (int j = 0; j < selectList.getItems().size(); ++j) {
      strBuilder.append(selectList.getItems().get(j).toSql(options));
      strBuilder.append((j+1 != selectList.getItems().size()) ? ", " : "");
    }
  }

  @Override
  public ValuesStmt clone() { return new ValuesStmt(this); }
}