UP Lecture 12

Compilers
Parser III
(202403)

Transcript

1. jgs Compilers Lecture 12: Parser III Dr. Javier Gonzalez-Sanchez jgonzalezs@up.edu.mx
2. jgs Previously …
3. Dr. Javier Gonzalez-Sanchez | Compilers | 3 jgs Rules PROGRAM BODY ASSIGNMENT VARIABLE WHILE IF RETURN PRINT C EXPRESSION X Y R E A B
4. Dr. Javier Gonzalez-Sanchez | Compilers | 4 jgs PREDICTIVE DESCENDENT RECURSIVE PARSER
5. Dr. Javier Gonzalez-Sanchez | Compilers | 5 jgs Concepts { int a; a = 0xFF + 0b111; while (a != 05) { if (true) { a = 2.5e-1 / 7; } else { a = 'A’; while(true) { } } } print ("hello"); } PREDICTIVE DESCENDENT RECURSIVE PARSER
6. jgs Test Yourselves
7. Dr. Javier Gonzalez-Sanchez | Compilers | 7 jgs What about a parser for this § {student: 4} § { student: 4 grade:100 } § { student: 4 grade: { hw1: 100 hw2: 90 } }
8. Dr. Javier Gonzalez-Sanchez | Compilers | 8 jgs Assignment 2 | Input Are there syntactical errors? { int x; float x; string x; char x; void x; boolean x; }
9. Dr. Javier Gonzalez-Sanchez | Compilers | 9 jgs Assignment 2 | Input Are there syntactical errors? { int x; x = 5; x = 05; x = 0x5ff; x = 5.55; x = "five"; x = ’5'; x = false; }
10. Dr. Javier Gonzalez-Sanchez | Compilers | 10 jgs Assignment 2 | Input Are there syntactical errors? { x = "hello" + "world" – 'w' * 5 / 3.4; x = y – hello & 0xffff | 05; x = -7; x = !y; x = (cse340 + cse310) / cse101 ; }
11. Dr. Javier Gonzalez-Sanchez | Compilers | 11 jgs Assignment 2 | Input Are there syntactical errors? { float a; x = 0; int x; y = 1 + 1; x = (0b11) +(05 – 0xFF34); while (2 == "hi") { a = 2 > (4 + Y); if (true) { if( 2 + 2 ) {} else {} } } print ("hello" + "world"); }
12. Dr. Javier Gonzalez-Sanchez | Compilers | 12 jgs Assignment 2 | Input Are there syntactical errors? { if ( if ( if (x – 3) {} ) ) { print ("hello" + "world"); } if (); if (x > 5); ; :) }
13. jgs Next
14. Dr. Javier Gonzalez-Sanchez | Compilers | 14 jgs Review * Parser.java is the only file that you are allowed to modify
15. Dr. Javier Gonzalez-Sanchez | Compilers | 15 jgs Homework public void error () { System.out.println(”error”); System.exit(); }
16. Dr. Javier Gonzalez-Sanchez | Compilers | 16 jgs Homework
17. Dr. Javier Gonzalez-Sanchez | Compilers | 17 jgs Questions
18. jgs Compilers Javier Gonzalez-Sanchez, Ph.D. jgonzalezs@up.edu.mx Spring 2024 Copyright. These slides can only be used as study material for the Compilers course at Universidad Panamericana. They cannot be distributed or used for another purpose.