flink table select sqlnode的生成过程

javacc parsejj 这个需要去calcite去找

/**
 * Parses a leaf SELECT expression without ORDER BY.
 */
SqlSelect SqlSelect() :
{
    final List<SqlLiteral> keywords = new ArrayList<SqlLiteral>();
    final SqlNodeList keywordList;
    List<SqlNode> selectList;
    final SqlNode fromClause;
    final SqlNode where;
    final SqlNodeList groupBy;
    final SqlNode having;
    final SqlNodeList windowDecls;
    final Span s;
}
{
    <SELECT>
    {
        s = span();
    }
    SqlSelectKeywords(keywords)
    (
        <STREAM> {
            keywords.add(SqlSelectKeyword.STREAM.symbol(getPos()));
        }
    )?
    (
        <DISTINCT> {
            keywords.add(SqlSelectKeyword.DISTINCT.symbol(getPos()));
        }
    |   <ALL> {
            keywords.add(SqlSelectKeyword.ALL.symbol(getPos()));
        }
    )?
    {
        keywordList = new SqlNodeList(keywords, s.addAll(keywords).pos());
    }
    selectList = SelectList()
    (
        <FROM> fromClause = FromClause()
        where = WhereOpt()
        groupBy = GroupByOpt()
        having = HavingOpt()
        windowDecls = WindowOpt()
    |
        E() {
            fromClause = null;
            where = null;
            groupBy = null;
            having = null;
            windowDecls = null;
        }
    )
    {
        return new SqlSelect(s.end(this), keywordList,
            new SqlNodeList(selectList, Span.of(selectList).pos()),
            fromClause, where, groupBy, having, windowDecls, null, null, null);
    }
}

经过javacc生成的代码，这个位置

/**
 * Parses a leaf SELECT expression without ORDER BY.
 */
  final public SqlSelect SqlSelect() throws ParseException {
    final List<SqlLiteral> keywords = new ArrayList<SqlLiteral>();
    final SqlNodeList keywordList;
    List<SqlNode> selectList;
    final SqlNode fromClause;
    final SqlNode where;
    final SqlNodeList groupBy;
    final SqlNode having;
    final SqlNodeList windowDecls;
    final Span s;
    jj_consume_token(SELECT);
        s = span();
    SqlSelectKeywords(keywords);
    switch ((jj_ntk==-1)?jj_ntk():jj_ntk) {
    case STREAM:
      jj_consume_token(STREAM);
            keywords.add(SqlSelectKeyword.STREAM.symbol(getPos()));
      break;
    default:
      jj_la1[73] = jj_gen;
      ;
    }
    switch ((jj_ntk==-1)?jj_ntk():jj_ntk) {
    case ALL:
    case DISTINCT:
      switch ((jj_ntk==-1)?jj_ntk():jj_ntk) {
      case DISTINCT:
        jj_consume_token(DISTINCT);
            keywords.add(SqlSelectKeyword.DISTINCT.symbol(getPos()));
        break;
      case ALL:
        jj_consume_token(ALL);
            keywords.add(SqlSelectKeyword.ALL.symbol(getPos()));
        break;
      default:
        jj_la1[74] = jj_gen;
        jj_consume_token(-1);
        throw new ParseException();
      }
      break;
    default:
      jj_la1[75] = jj_gen;
      ;
    }
        keywordList = new SqlNodeList(keywords, s.addAll(keywords).pos());
    selectList = SelectList();
    switch ((jj_ntk==-1)?jj_ntk():jj_ntk) {
    case FROM:
      jj_consume_token(FROM);
      fromClause = FromClause();
      where = WhereOpt();
      groupBy = GroupByOpt();
      having = HavingOpt();
      windowDecls = WindowOpt();
      break;
    default:
      jj_la1[76] = jj_gen;
      E();
            fromClause = null;
            where = null;
            groupBy = null;
            having = null;
            windowDecls = null;
    }
        {if (true) return new SqlSelect(s.end(this), keywordList,
            new SqlNodeList(selectList, Span.of(selectList).pos()),
            fromClause, where, groupBy, having, windowDecls, null, null, null);}
    throw new Error("Missing return statement in function");
  }

解析后的sql node。 

使用的sql为 

Table table = tEnv.sqlQuery("SELECT * FROM test");

主要是为了弄清楚sql node中的pos到底是什么，以及parseimpl.flt文件中的

pos = getPos() 这个方法有什么用。

pos就是在描述sql 在整个text中的位置，防止sql中的 换行  空格 对最终解析造成影响。

以上面的sql为例，sql就一行  18个字符，所以pos 最后就是  1 1 1 18