2016/7/9Page 1 Lecture 11: Semester Review COMP3100 Dept. Computer Science and Technology United International College

2016/7/92 Introduction  Compilation vs. Interpretation  Compilation stages

2016/7/93 DFA and its equivalents  DFA&NFA Definition Accepted string  Regular expression Notation Accepted string Convert to NFA and DFA  Regular grammar Definition  DFA=NFA=Regular expression=Regular grammar

2016/7/94 Regular expression->DFA Start with a regular expression. Construct an NFA from it. Use a set of subsets construction to obtain an equivalent DFA. Construct the minimal equivalent DFA.

2016/7/95 Convert the following regular expression to a DFA  1(0|1)*101

2016/7/96 Construct an NFA from it.

2016/7/97 Obtain an equivalent DFA

2016/7/98

9 Minimization

2016/7/910 PDA and its relevant  Context free languages Definition  PDA Definition Difference between PDA and DFA How does it work?  A language is context-free iff a pushdown automata recognizes it  Non-deterministic PDA are more powerful than deterministic ones

2016/7/911 Parser-Top down parsing  Predicts a derivation Matches non-terminal against token observed in input  How to parse given a parse table?  First set, follow set  Parse table construction  LL(1) grammar  Convert non-LL(1) grammar to LL(1) grammar

2016/7/912 Exercise  Given the following grammar S->a|^|(T) T->T,S|S (1) Eliminate the left-recursion in the grammar. (2) Build the LL(1) parsing table

2016/7/913 Left-recursion Elimination

2016/7/914 Parsing table construction

2016/7/915 Parser-Bottom up parsing  Right-most derivation – Backward Start with the tokens End with the start symbol Match substring on RHS of production, replace by LHS  Parsing given parsing table for LR(0)  Parsing table construction for LR(0)  Right-associative is not LR(0)

2016/7/916 Parser-Bottom up parsing (2)  SLR Apply reduction only if C is in FOLLOW(X)  LR(1) LR(1) parsing table construction  LALR Constructs LR(1) DFA and then merge any 2 LR(1) states whose items are identical except lookahead  Classification of grammar

2016/7/917  Given the following grammar S->AS|b A->SA|a (1) Build the full LR(0) DFA (2) Is it an SLR(1) grammar?

2016/7/918

2016/7/919  For state I1, note that Follow(S ’ )={$}. Hence, the shift-reduce conflict in state I1 can be solved in SLR(1).  For state I6, note that Follow(A)={a,b}. Hence, there is a shift-reduce conflict in state I6 which cannot solved in SLR(1).  For state I7, note that Follow(S)={a,b,$}. Hence, there is a shift-reduce conflict in state I7 which cannot solved in SLR(1).

2016/7/920 Semantic Analysis  Syntax-directed definition Semantic actions Synthesized attribute Inherited attribute  lexical, syntax, semantic errors  Symbol table construction  Type derivation

2016/7/921 Intermediate Code Generation  Translate high-level to low-level sentences  4 Distinct Regions of Memory  Execution Stack  Activation record/frame

2016/7/922 Running time organization  Parameter passing modes Value Reference Value/result Name

2016/7/923 Parameter Passing Modes  int i;  int A[3];  void Q(int B) {  A[1] = 3;  i = 2;  write(B);  B = 5;  }  int main() {  i = 1;  A[1] = 2;  A[2] = 4;  Q(A[i]);  }

2016/7/924 Mark Distribution DFA, Regular language and Scanner24 CFG and Parser40 Semantic Analysis19 Intermediate Code Generation5 Runtime Organization12

2016/7/925 Good Luck!