Predicate Make :: isStartLoops

Holds if pivot and pumpEnd are a pair of loops that could be the beginning of a quadratic blowup.

There is a slight implementation difference compared to the paper: this predicate requires that pivot != pumpEnd. The case where pivot = pumpEnd causes exponential backtracking and is handled by the js/redos query.

Import path


                                import codeql.regex.nfa.SuperlinearBackTracking


                            
                                
                                    predicate
                                
                                 
                            
                            
                                isStartLoops
                            
                            
                                (
                                
                                    
                                        State
                                    
                                     
                                    pivot
                                
                                , 
                                
                                    
                                        State
                                    
                                     
                                    pumpEnd
                                
                                )