Method Convert

server/plpgsql/json.go:598–641

Convert converts the JSON statement into its output form.

()

// Convert converts the JSON statement into its output form.
func (stmt *plpgSQL_stmt_fors) Convert() (block Block, err error) {
	block.Label = stmt.Label
	block.IsLoop = true

	if stmt.Query == nil {
		return Block{}, errors.New("FOR..IN..SELECT loop must have a query")
	}

	var varName string
	switch {
	case stmt.Var.Record != nil:
		varName = stmt.Var.Record.RefName
	case stmt.Var.Variable != nil:
		varName = stmt.Var.Variable.RefName
	case stmt.Var.Row != nil:
		varName = stmt.Var.Row.RefName
	default:
		return Block{}, errors.New("FOR..IN..SELECT loop variable must be a record, row, or variable")
	}

	// Use the line number to keep cursor names unique across multiple ForS loops
	// that might use the same variable name.
	cursorName := fmt.Sprintf("__cursor_%s_%d__", varName, stmt.LineNumber)
	query := stmt.Query.Expression.Query

	convertedBody, err := jsonConvertStatements(stmt.Body)
	if err != nil {
		return Block{}, err
	}
	bodySize := OperationSizeForStatements(convertedBody)

	// Layout inside the block (ScopeBegin/ScopeEnd are added by Block.AppendOperations):
	//   [0] ForQueryInit  – execute query, store rows in cursor
	//   [1] ForQueryNext  – fetch next row into varName, or jump forward by (bodySize+2) to ScopeEnd
	//   [2..2+bodySize-1] body statements
	//   [2+bodySize]      Goto back to ForQueryNext: offset = -(1 + bodySize)
	block.Body = []Statement{
		ForQueryInit{CursorName: cursorName, Query: query},
		ForQueryNext{CursorName: cursorName, RecordVar: varName, GotoOffset: bodySize + 2},
	}
	block.Body = append(block.Body, convertedBody...)
	block.Body = append(block.Body, Goto{Offset: -(1 + bodySize)})
	return block, nil
}

// Convert converts the JSON statement into its output form.
func (stmt *plpgSQL_stmt_if) Convert() (Block, error) {