QUESTIONS

LAST TIME:
 - SiteRiter turn-in details, Hash tables, Collision handling

TODAY:
 - On-time quiz: Memory and pointer diagrams
 - Design discussion: SiteRiter
 - More hashing; amortized O(1)

                  
PROJECT 1 ALL DONE!  PROJECT BREAK THIS WEEK!  DO EVERYTHING ELSE!




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ON-TIME QUIZ POST-MORTEM
          
1. (2 points) Draw a 'memory and pointers' diagram as of the point
   marked '/* HERE */' in the following program.  Omit 'args'.

   public class Test {
      public static void main(String[] args) {
         int x1 = 3;                                x1
         Integer x2 = x1;                          +-----+
         Integer x3 = x2;                          |     |
         /* HERE */                                |  3  |
         System.out.println(x1+x2+x3);             +-----+
      }                                              
   }                                          x2     
                                             +-------+      Integer  
                                             |       |     +---------+
                             x3              |   --------->|         |
                            +---------+      +-------+     |   3     |
                            |         |                    |         |
                            |      ----------------------->+---------+
                            |         |                                       
                            +---------+

                 
ON-TIME QUIZ POST-MORTEM
          
2. (3 points) Draw a 'memory and pointers' diagram as of the point
   marked '/* HERE */' in the following program.  Omit 'args'.

   public class Test {                                 t1        
      int num = 6;                                    +------+   
      Test(int n) { num = n; }                        |   -----\ 
      public static void main(String[] args) {        |      | | 
         Test t1 = new Test(4);                       +------+ | 
         Test t2 = new Test(1);                       t2       |   Test    
         t1 = t2;                                    +------+  |  +--------+
         /* HERE */                                  |    -----\->|        |
         System.out.println(t1.num+t2.num);          |      |     |   1    |
      }                                              +------+     |        |
   }                                                              +--------+




                                                                              


                 
ON-TIME QUIZ POST-MORTEM
          
3. (4 points) Draw a 'memory and pointers' diagram as of the point
   marked '/* HERE */' in the following program.  Omit 'args'.

   public class Test {
      int a;
      Test b, c;
      Test(int d, Test e, Test f) { a = d; b = e; c = f; }
      public static void main(String[] args) {
         Test t1 = new Test(7,null,null);            t1             Test   
         Test t2 = new Test(3,null,t1);             +--------+      +------+
         t1.b = t2;                                 |        |      |   7  |
         t1 = t2.c.b;                               |     |  |      |------|
         /* HERE */                                 +-----|--+   /-----    |
         System.out.println(t1.a+" "+t2.a);               |      |  |------|
      }                                      t2      Test v      |  |null  |
   }                                         +----+  +------+<---/  |      |
                                             |  ---->|  3   |       +------+
                                             +----+  |------|         ^    
                                                     |null  |         |
                                                     |------|         |
                                                     |    ------------/       
                                                     +------+
SITERITER DISCUSSION

 - What was harder/slower than you expected?
                                     
 - What was easier/faster than you expected?
                                     
 - What was the first bit of code you wrote?   
                                               
 - What was the last bit of code you threw out?
                                     

                                     












SITERITER DISCUSSION

 - What was harder/slower than you expected?
                                     
 - What was easier/faster than you expected?
                                     
 - What was the first bit of code you wrote?   
                                               
 - What was the last bit of code you threw out?
                                     
 - Design issues:                    
                                     
   = Lexing, reading, marking, tokens
   = Parsing strategy
   = Symbol table design









SITERITER DISCUSSION

 - What was harder/slower than you expected?
                                     
 - What was easier/faster than you expected?
                                     
 - What was the first bit of code you wrote?   
                                               
 - What was the last bit of code you threw out?
                                     
 - Design issues:                    
                                     
   = Lexing, reading, marking, tokens
   = Parsing strategy
   = Symbol table design

   Dave's choices:
   = Lexing: YES, reading: BY CHAR, marking: YES, tokens: String
   = Parsing strategy: Top down parser
   = Symbol table design: Map<String,Symbol>
      Symbol has ArrayList<Sequence>
      Sequence has ArrayList<String> for tokens


SITERITER DISCUSSION

 - What was harder/slower than you expected?
                                     
 - What was easier/faster than you expected?
                                     
 - What was the first bit of code you wrote?   
                                               
 - What was the last bit of code you threw out?
                                     
 - Design issues:                            
                                     
   = Lexing, reading, marking, tokens
   = Parsing strategy                  
   = Symbol table design

   Dave's choices:
   = Lexing: YES, reading: BY CHAR, marking: YES, tokens: String
   = Parsing strategy: Top down parser
   = Symbol table design: Map<String,Symbol>
      Symbol has ArrayList<Sequence>
      Sequence has ArrayList<String> for tokens

              [ Eclipse code peeks ]