/*
 * bench_parser.prg — Parser performance benchmark
 * Compares TSqlParser (original) vs TSqlParser2 (Pratt)
 *
 * Copyright (c) 2025-2026 Charles KWON (Charles KWON OhJun)
 * All rights reserved.
 */

#include "FiveSqlDef.ch"
#include "hbclass.ch"

#define ITERS  10000

PROCEDURE Main()

   LOCAL aSQL, i, j, t0, t1, oLex, aTokens, oP, h
   LOCAL nT1, nT2, aAllTokens

   aSQL := { ;
      "SELECT name, salary FROM employees WHERE salary > 5000", ;
      "SELECT e.name, o.product FROM employees e JOIN orders o ON e.id = o.emp_id WHERE o.amount > 100", ;
      "SELECT dept, COUNT(*) AS cnt, AVG(salary) AS avg_sal FROM employees GROUP BY dept HAVING AVG(salary) > 5000 ORDER BY avg_sal DESC", ;
      "SELECT name FROM employees WHERE id IN (SELECT emp_id FROM orders WHERE amount > 500)", ;
      "SELECT name, salary, ROW_NUMBER() OVER (PARTITION BY dept ORDER BY salary DESC) AS rn FROM employees", ;
      "SELECT name, CASE WHEN salary > 7000 THEN 'High' WHEN salary > 5000 THEN 'Mid' ELSE 'Low' END AS tier FROM employees WHERE dept = 'Engineering' OR (salary > 6000 AND mgr_id IS NOT NULL)", ;
      "INSERT INTO employees (id, name, dept, salary) VALUES (99, 'Test', 'QA', 5000)", ;
      "UPDATE employees SET salary = salary * 1.1 + 500 WHERE dept = 'Sales' AND salary BETWEEN 4000 AND 6000" ;
   }

   ? "================================================================"
   ? "  Parser Benchmark: TSqlParser vs TSqlParser2 (Pratt)"
   ? "  Queries: " + hb_ntos( Len( aSQL ) ) + "   Iterations: " + hb_ntos( ITERS )
   ? "================================================================"
   ?

   /* Pre-tokenize all queries */
   aAllTokens := {}
   FOR i := 1 TO Len( aSQL )
      oLex := TSqlLexer():New( aSQL[ i ] )
      oLex:Tokenize()
      AAdd( aAllTokens, oLex:GetTokens() )
   NEXT

   /* Benchmark TSqlParser (original) */
   t0 := hb_MilliSeconds()
   FOR j := 1 TO ITERS
      FOR i := 1 TO Len( aSQL )
         oP := TSqlParser():New( aAllTokens[ i ], {} )
         h := oP:Parse()
      NEXT
   NEXT
   t1 := hb_MilliSeconds()
   nT1 := t1 - t0
   ? "  TSqlParser  (original) : " + Str( nT1, 8 ) + " ms  (" + ;
     Str( nT1 * 1000 / ( ITERS * Len( aSQL ) ), 6, 1 ) + " us/parse)"

   /* Benchmark TSqlParser2 (Pratt) */
   t0 := hb_MilliSeconds()
   FOR j := 1 TO ITERS
      FOR i := 1 TO Len( aSQL )
         oP := TSqlParser2():New( aAllTokens[ i ], {} )
         h := oP:Parse()
      NEXT
   NEXT
   t1 := hb_MilliSeconds()
   nT2 := t1 - t0
   ? "  TSqlParser2 (Pratt)    : " + Str( nT2, 8 ) + " ms  (" + ;
     Str( nT2 * 1000 / ( ITERS * Len( aSQL ) ), 6, 1 ) + " us/parse)"

   ?
   IF nT2 > 0 .AND. nT1 > 0
      IF nT1 > nT2
         ? "  Pratt is " + Str( nT1 / nT2, 5, 2 ) + "x faster"
      ELSEIF nT2 > nT1
         ? "  Original is " + Str( nT2 / nT1, 5, 2 ) + "x faster"
      ELSE
         ? "  Same speed"
      ENDIF
   ENDIF
   ? "================================================================"

RETURN