Tema 300119

Page 1

Formal Languages and Compilers Proff. Breveglieri, Crespi Reghizzi, Morzenti Written exam1: laboratory question 30/01/2019 SURNAME: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NAME: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Student ID:. . . . . . . . . . . . . . . . Course: ◦ Laurea Specialistica ◦ V. O. ◦ Laurea Triennale ◦ Other: . . . Instructor: ◦ Prof. Breveglieri ◦ Prof Morzenti The laboratory question must be answered taking into account the implementation of the Acse compiler given with the exam text. Modify the specification of the lexical analyser ( flex input) and the syntactic analyser (bison input) and any other source file required to extend the Lance language with the if-then-elif-else conditional statement. The construct includes a non empty list of cases that consist of a condition (an expression) and a code block that is executed only when the condition evaluates to true. After entering a case, and executing its associated code block, the execution flow continues from the first instruction following the current if-then-elif-else block. int a; read(a); read(b); if (a==0) write(0); elif (a==1) write(1); elif (a==2){ if (b==10) write(10); else write(11);} else write(3); 1Time 60’. Textbooks and notes can be used. Pencil writing is allowed. Write your name on any additional sheet. 1 1. Define the tokens (and the related declarations in Acse.lex and Acse.y). (2 points) 2. Define the syntactic rules or the modifications required to the existing ones. (4 points) 3. Define the semantic actions needed to implement the required functionality. (18 points) The solution is in the attached patch. 2 3 4 4. Given the…