Single stage

Single is the operation that returns single object from the sequence or throws an exception if the sequence contains more or less elements.

SingleStage syntax

First
  : 'single' '(' LambdaExpression? ')'  
  ;

Related tokens
LambdaExpression

Single examples

1. Find a table cell with the text 'Alex'. Throws when not found or more than one record returns.

   select(tableCells) // PdfTableCell[]
       ->single((item) => item.Text() == 'Alex') // PdfTableCell