AbstractSqlParser¶

AbstractSqlParser is an extension of the ParserInterface abstraction for SQL parsers that delegate parsing to an AstBuilder.

AstBuilder¶

astBuilder: AstBuilder

AstBuilder for parsing SQL statements

Used when:

AbstractSqlParser is requested to parseDataType, parseExpression, parseTableIdentifier, parseFunctionIdentifier, parseMultipartIdentifier, parseTableSchema, parsePlan

Implementations¶

Setting Up SqlBaseLexer and SqlBaseParser for Parsing¶

parse[T](
  command: String)(
  toResult: SqlBaseParser => T): T

parse sets up ANTLR parsing infrastructure with SqlBaseLexer and SqlBaseParser (which are the ANTLR-specific classes of Spark SQL that are auto-generated at build time from the SqlBaseParser.g4 grammar).

Internally, parse first prints out the following INFO message to the logs:

Parsing command: [command]

Tip

Enable INFO logging level for the custom AbstractSqlParsers to see the above and other INFO messages.

parse then creates and sets up a SqlBaseLexer and SqlBaseParser that in turn passes the latter on to the input toResult function where the parsing finally happens.

parse uses SLL prediction mode for parsing first before falling back to LL mode.

In case of parsing errors, parse reports a ParseException.

parse is used in all the parse methods.

parsePlan¶

parsePlan(
  sqlText: String): LogicalPlan

parsePlan parses the given SQL text (that requests the AstBuilder to visitSingleStatement to produce a LogicalPlan).

parsePlan is part of the ParserInterface abstraction.