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Updated tests, metadata, docs for circular buffer exercise
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Bajger committed Sep 8, 2023
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# Instructions append

For error cases during operations, see Error class hiearchy (class side) to find out how to signal exception with given message.
42 changes: 42 additions & 0 deletions exercises/practice/circular-buffer/.docs/instructions.md
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# Instructions

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:
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[ ][ ][ ][ ][ ][ ][ ]

Assume that a 1 is written into the middle of the buffer (exact starting location does not matter in a circular buffer):
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[ ][ ][ ][1][ ][ ][ ]

Then assume that two more elements are added — 2 & 3 — which get appended after the 1:
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[ ][ ][ ][1][2][3][ ]

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:
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[ ][ ][ ][ ][ ][3][ ]

If the buffer has 7 elements then it is completely full:
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[5][6][7][8][9][3][4]

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:
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[5][6][7][8][9][A][B]

3 & 4 have been replaced by A & B making 5 now the oldest data in the buffer.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:
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[ ][ ][7][8][9][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.
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[C][D][7][8][9][A][B]
19 changes: 19 additions & 0 deletions exercises/practice/circular-buffer/.meta/config.json
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{
"authors": [
"Bajger"
],
"files": {
"solution": [
"CircularBuffer.class.st"
],
"test": [
"CircularBufferTest.class.st"
],
"example": [
".meta/solution/CircularBuffer.class.st"
]
},
"blurb": "A data structure that uses a single, fixed-size buffer as if it were connected end-to-end.",
"source": "Wikipedia",
"source_url": "https://en.wikipedia.org/wiki/Circular_buffer"
}
52 changes: 52 additions & 0 deletions exercises/practice/circular-buffer/.meta/tests.toml
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# This is an auto-generated file.
#
# Regenerating this file via `configlet sync` will:
# - Recreate every `description` key/value pair
# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
# - Preserve any other key/value pair
#
# As user-added comments (using the # character) will be removed when this file
# is regenerated, comments can be added via a `comment` key.

[28268ed4-4ff3-45f3-820e-895b44d53dfa]
description = "reading empty buffer should fail"

[2e6db04a-58a1-425d-ade8-ac30b5f318f3]
description = "can read an item just written"

[90741fe8-a448-45ce-be2b-de009a24c144]
description = "each item may only be read once"

[be0e62d5-da9c-47a8-b037-5db21827baa7]
description = "items are read in the order they are written"

[2af22046-3e44-4235-bfe6-05ba60439d38]
description = "full buffer can't be written to"

[547d192c-bbf0-4369-b8fa-fc37e71f2393]
description = "a read frees up capacity for another write"

[04a56659-3a81-4113-816b-6ecb659b4471]
description = "read position is maintained even across multiple writes"

[60c3a19a-81a7-43d7-bb0a-f07242b1111f]
description = "items cleared out of buffer can't be read"

[45f3ae89-3470-49f3-b50e-362e4b330a59]
description = "clear frees up capacity for another write"

[e1ac5170-a026-4725-bfbe-0cf332eddecd]
description = "clear does nothing on empty buffer"

[9c2d4f26-3ec7-453f-a895-7e7ff8ae7b5b]
description = "overwrite acts like write on non-full buffer"

[880f916b-5039-475c-bd5c-83463c36a147]
description = "overwrite replaces the oldest item on full buffer"

[bfecab5b-aca1-4fab-a2b0-cd4af2b053c3]
description = "overwrite replaces the oldest item remaining in buffer following a read"

[9cebe63a-c405-437b-8b62-e3fdc1ecec5a]
description = "initial clear does not affect wrapping around"
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