Tema 080715

Pagina 1

Formal Languages and Compilers Proff. Breveglieri, Crespi Reghizzi, Morzenti Written exam1: laboratory question 08/07/2015 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 theLance language with permutate construct for arrays. An example is provided in the following. int arr[10]; // arr = [ 10, 11, 12, 13, 14, 15 ] permutate( arr, q[ 4, 2, 0 ]p ); // arr = [ 12, 11, 14, 13, 10, 15 ] The permutation is expressed as constant vector of indices, i.e. integer constants, that must be interpred as source-destination indices pairs. For example the chain q[4, 2, 0]p: • element in position 4 of the input array goes into position 2 of the output array • element in position 2 of the input array goes into position 0 of the output array • element in position 0 of the input array goes into position 4 of the output array A graphical representation of the semantic is the following: 10 11 12 13 14 15 12 11 14 13 10 15 The permutation must be inplace, meaning that the input array is modified to obtain the output array without the need of a temporary array. Note that the vector of indices can be shorter or longer than the length of the array. Indeed…