Compiler Engineering Lab#3
- 1. University of Dammam Girls’ College of Science Department of Computer Science Compiler Engineering Lab COMPILER ENGINEERING LAB # 3 : TRANSLATION FOR SIMPLE EXPRESSION
- 2. TRANSLATION FOR SIMPLE EXPRESSION Department of Computer Science - 3-7/3/12 2 Compiler Engineering Lab
- 3. FIRST.., DISCOVER MISTAKES USING THE LEXICAL ANALYZER Department of Computer Science - 3-7/3/12 3 Compiler Engineering Lab
- 4. ERROR DISCOVERY • Example(s): • When the lexeme > BSIZE • When the lexeme doesn’t match any regular definition • Dealing with Errors: • Unget character when the lexeme • Print Error Message and exit(0) Department of Computer Science - 3-7/3/12 4 Compiler Engineering Lab
- 5. A SYNTAX-DIRECTED TRANSLATOR • We shall construct a compiler that translates infix expression into postfix form. • A notation in which the operators appear after there operands Department of Computer Science - 3-7/3/12 5 Compiler Engineering Lab
- 6. A SYNTAX-DIRECTED TRANSLATOR 9–5+2 This will be translated from infix to postfix form as: 95–2+ Department of Computer Science - 3-7/3/12 6 Compiler Engineering Lab
- 7. ABSTRACT SYNTAX TREE FOR 9-5+2 + - 2 9 5 Department of Computer Science - 3-7/3/12 7 Compiler Engineering Lab
- 8. A SYNTAX-DIRECTED TRANSLATOR • Now, we construct a syntax-directed translator that translates arithmetic expressions into postfix form. • To keep the initial program manageably small, we start off with expressions consisting of digits separated by ( + , - ) signs . Department of Computer Science - 3-7/3/12 8 Compiler Engineering Lab
- 9. A SYNTAX-DIRECTED TRANSLATOR design C program to translate an infix expression into postfix form Write the program inside the main function starting with reading one character then call the functions you need . Department of Computer Science - 3-7/3/12 9 Compiler Engineering Lab
- 10. A SYNTAX-DIRECTED TRANSLATOR • Read a character from the user call it lookahead . • Declare lookahead as a global variable to be used by all functions you need. Department of Computer Science - 3-7/3/12 10 Compiler Engineering Lab
- 11. A SYNTAX-DIRECTED TRANSLATOR • You will need three functions each will perform certain operations for the translation . • All these function will be void (no return) • No variables will be passed through these function • Only the global variable lookahead Department of Computer Science - 3-7/3/12 11 Compiler Engineering Lab
- 12. ERROR ( ) • Use this function for syntax errors • It will print this sentence : ( SYNTAX ERROR ! ) when errors appears on program. Department of Computer Science - 3-7/3/12 12 Compiler Engineering Lab
- 13. TERM ( ) • Check if lookahead character is a digit • If it is a digit put the character on the screen and read another character. • If lookahead is not digit it will be a syntax error . Department of Computer Science - 3-7/3/12 13 Compiler Engineering Lab
- 14. EXPR ( ) • Use Expr function to check for operators.. • Before start checking operators inside expr( ) check if that character is digit use term ( ) function Department of Computer Science - 3-7/3/12 14 Compiler Engineering Lab
- 15. BACK TO EXPR( ) FUNCTION • After reading one character after digit check if that character is + • If true : read another character and check if that is digit, using term ( ) function that will perform previous steps of putting digit character on screen and read another , put ( + ) on screen • If the character is not (+) : check if it is (-) , do the same as previous. Department of Computer Science - 3-7/3/12 15 Compiler Engineering Lab
- 16. A SYNTAX-DIRECTED TRANSLATOR • Find way to let program to handle sequence of operations using while statement . • If the operator was not matched ( + , - ) call error() then break. Department of Computer Science - 3-7/3/12 16 Compiler Engineering Lab
- 17. QUESTIONS? Thank you for listening Department of Computer Science - 3-7/3/12 17 Compiler Engineering Lab
Editor's Notes
- #14: 8345555