Circular Buffer in Delphi Pascal
A data structure that uses a single, fixed-size buffer as if it were connected end-to-end.
exercism fetch delphi circular-buffer
A circular buffer, cyclic buffer or ring buffer is a data structure that uses a single, fixed-size buffer as if it were connected end-to-end.
A circular buffer first starts empty and of some predefined length. For example, this is a 7-element buffer:
[ ][ ][ ][ ][ ][ ][ ]
Assume that a 1 is written into the middle of the buffer (exact starting location does not matter in a circular buffer):
[ ][ ][ ][ ][ ][ ]
Then assume that two more elements are added — 2 & 3 — which get appended after the 1:
[ ][ ][ ][ ]
If two elements are then removed from the buffer, the oldest values inside the buffer are removed. The two elements removed, in this case, are 1 & 2, leaving the buffer with just a 3:
[ ][ ][ ][ ][ ][ ]
If the buffer has 7 elements then it is completely full:
When the buffer is full an error will be raised, alerting the client that further writes are blocked until a slot becomes free.
When the buffer is full, the client can opt to overwrite the oldest data with a forced write. In this case, two more elements — A & B — are added and they overwrite the 3 & 4:
3 & 4 have been replaced by A & B making 5 now the oldest data in the buffer. Finally, if two elements are removed then what would be returned is 5 & 6 yielding the buffer:
[ ][A][B][ ]
Because there is space available, if the client again uses overwrite to store C & D then the space where 5 & 6 were stored previously will be used not the location of 7 & 8. 7 is still the oldest element and the buffer is once again full.
In order to run the tests for this track, you will need to install DUnitX. Please see the installation instructions for more information.
Loading Exercises into Delphi
If Delphi is properly installed, and
*.dpr file types have been associated with Delphi, then double clicking the supplied
*.dpr file will start Delphi and load the exercise/project.
control + F9 is the keyboard shortcut to compile the project or pressing
F9 will compile and run the project.
Alternatively you may opt to start Delphi and load your project via. the
File drop down menu.
When Questions Come Up
Note that, when trying to submit an exercise, make sure the exercise file you're submitting is in the
For example, if you're submitting
ubob.pas for the Bob exercise, the submit command would be something like
exercism submit <path_to_exercism_dir>/delphi/bob/ubob.pas.
Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.