ASSIGNMENT 07 - MOVING MARK AND SWEEP

jandalf
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ASSIGNMENT 07 - MOVING MARK AND SWEEP

Beitrag von jandalf »

Currently, I get 17/19 on the hidden tests and 6/6 on the public ones. I really thought hard about what I possibly do wrong, but I have no idea, based on the sparse task description and logic reasoning what else it could be. Anyone has suggestions or the same passing percentage?

Kind regards

lkbaerenfaenger
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Re: ASSIGNMENT 07 - MOVING MARK AND SWEEP

Beitrag von lkbaerenfaenger »

A friend of mine and me have exactly the same passing percentage, no idea why... Any help would be appreciated. :)

Talaron
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Re: ASSIGNMENT 07 - MOVING MARK AND SWEEP

Beitrag von Talaron »

Some tests are a bit strict when it comes to reordering of values.

For example:

Code: Alles auswählen

Before GC:
  Env = ('x -> 1, 'y -> 2) 
  Store = (0 -> NumV(12), 1 -> NumV(34), 2 -> NumV(56))

After GC:
  Env = ('x -> 1, 'y -> 0) 
  Store = (0 -> NumV(56), 1 -> NumV(34))
This behaviour is not really an error but causes some of the tests to fail. In general, please make sure that the following rules apply for your GC:
1. If GC doesn't sweep any values, it should also not move anything around in the store.
2. If GC sweeps values, the order of the remaining values should stay the same.

jandalf
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Re: ASSIGNMENT 07 - MOVING MARK AND SWEEP

Beitrag von jandalf »

When I test your example with my 17/19, then I get the following:

Code: Alles auswählen

STARTING GC
STACK = List(Map('y -> 2, 'x -> 1))
STORE = ArraySeq(NumV(12), NumV(34), NumV(56))
GC COMPLETE
STACK = List(Map('y -> 1, 'x -> 0))
STORE = ArraySeq(NumV(34), NumV(56), null)
NUMBER OF FREE SLOTS = 1
From what I can think of, reordering should not happen because you sweep from left to right, therefore never taking a value which is to the right before any to the left. Or am I wrong?

Talaron
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Re: ASSIGNMENT 07 - MOVING MARK AND SWEEP

Beitrag von Talaron »

Please write a discussion ticket in Weblab. I can check if your code has another issue that makes it fail some tests. The re-ordering is just one of the most common issues.

You should also test that code which contains boxes isn't reordered as well.

Talaron
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Re: ASSIGNMENT 07 - MOVING MARK AND SWEEP

Beitrag von Talaron »

One of the test cases that most of you have problems with looks like this:

Code: Alles auswählen

Store = (NumV(23), Box(0), NumV(42))
Stack = ('b -> 1, 'n -> 2)
GC should do nothing here, but it either rearranges the store or, even worse, cleans up the whole store!

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