Add circular-buffer exercise (#193)
This commit is contained in:
Erik Schierboom
@@ -532,6 +532,14 @@
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"practices": [],
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"prerequisites": [],
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"difficulty": 5
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},
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{
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"slug": "circular-buffer",
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"name": "Circular Buffer",
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"uuid": "2442f2fe-3304-4d28-9539-b23a31e24c22",
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"practices": [],
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"prerequisites": [],
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"difficulty": 7
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}
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]
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},
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@@ -0,0 +1,29 @@
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# Instructions append
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This exercise introduces a couple of concepts you might not have seen before:
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## User-defined namespace
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Words in 8th all belong to a namespace, e.g. `a:new` refers to the `new` word in the `a` namespace.
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One can also define custom namespaces, which is what we do at the top of the `circular-buffer.8th` file:
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```8th
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ns: cb
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```
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This means that all words within that file can be accessed via `cb:<word>`, which is a great way to group related functionality.
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For more information, check out the [namespaces][namespaces] documentation.
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## Exceptions
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The `read` and `write` words are both expected to throw an exception when they're called on a circular buffer with an invalid state.
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For more information, check the [exceptions and error handling][exceptions-and-error-handling] documentation.
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## Objects
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While you're free to implement the circular buffer as you like, you could consider using 8th's [object support][objects].
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[namespaces]: https://8th-dev.com/manual.html#namespaces
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[exceptions-and-error-handling]: https://8th-dev.com/manual.html#exceptions-and-error-handling
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[objects]: https://8th-dev.com/manual.html#objects
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58
exercises/practice/circular-buffer/.docs/instructions.md
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58
exercises/practice/circular-buffer/.docs/instructions.md
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@@ -0,0 +1,58 @@
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# Instructions
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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.
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A circular buffer first starts empty and of some predefined length.
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For example, this is a 7-element buffer:
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```text
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[ ][ ][ ][ ][ ][ ][ ]
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```
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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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```text
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[ ][ ][ ][1][ ][ ][ ]
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```
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Then assume that two more elements are added — 2 & 3 — which get appended after the 1:
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```text
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[ ][ ][ ][1][2][3][ ]
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```
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If two elements are then removed from the buffer, the oldest values inside the buffer are removed.
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The two elements removed, in this case, are 1 & 2, leaving the buffer with just a 3:
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```text
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[ ][ ][ ][ ][ ][3][ ]
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```
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If the buffer has 7 elements then it is completely full:
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```text
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[5][6][7][8][9][3][4]
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```
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When the buffer is full an error will be raised, alerting the client that further writes are blocked until a slot becomes free.
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When the buffer is full, the client can opt to overwrite the oldest data with a forced write.
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In this case, two more elements — A & B — are added and they overwrite the 3 & 4:
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```text
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[5][6][7][8][9][A][B]
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```
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3 & 4 have been replaced by A & B making 5 now the oldest data in the buffer.
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Finally, if two elements are removed then what would be returned is 5 & 6 yielding the buffer:
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```text
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[ ][ ][7][8][9][A][B]
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```
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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.
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7 is still the oldest element and the buffer is once again full.
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```text
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[C][D][7][8][9][A][B]
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```
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19
exercises/practice/circular-buffer/.meta/config.json
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19
exercises/practice/circular-buffer/.meta/config.json
Normal file
@@ -0,0 +1,19 @@
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{
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"authors": [
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"erikschierboom"
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],
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"files": {
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"solution": [
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"circular-buffer.8th"
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],
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"test": [
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"test.8th"
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],
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"example": [
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".meta/example.8th"
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]
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},
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"blurb": "A data structure that uses a single, fixed-size buffer as if it were connected end-to-end.",
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"source": "Wikipedia",
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"source_url": "https://en.wikipedia.org/wiki/Circular_buffer"
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}
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68
exercises/practice/circular-buffer/.meta/example.8th
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68
exercises/practice/circular-buffer/.meta/example.8th
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@@ -0,0 +1,68 @@
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ns: cb
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: count \ o -- n
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"count" o:@ nip
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;
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: capacity \ o -- n
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"capacity" o:@ nip
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;
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: items \ o -- a
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"items" o:@ nip
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;
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: head \ o -- n
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"head" o:@ nip
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;
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: tail \ o -- n
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"tail" o:@ nip
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;
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: read \ o -- o x
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>r
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r@ count 0 n:= if r> "circular buffer empty" throw ;then
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r@ items r@ tail a:_@
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r@ tail n:1+ r@ capacity n:/mod drop r@ "tail" rot o:! drop
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r@ count n:1- r@ "count" rot o:!
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swap
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;
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: overwrite \ o x -- o
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swap >r
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r@ items r@ head rot a:! r@ "items" rot o:!
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r@ head n:1+ r@ capacity n:/mod drop "head" swap o:!
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r@ count r@ capacity n:=
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if
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r@ head "tail" swap o:!
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else
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r@ count n:1+ "count" swap o:!
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then
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;
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: write \ o x -- o
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swap >r
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r@ capacity r@ count n:= if drop r> "circular buffer full" throw ;then
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r> swap cb:overwrite
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;
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: clear \ o
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"head" 0 o:!
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"tail" 0 o:!
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"count" 0 o:!
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;
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: new \ n -- o
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{
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class: "circular-buffer",
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methods: {
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read: ' read,
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write: ' write,
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overwrite: ' overwrite
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}
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} o:new swap
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2dup "capacity" swap o:! drop
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n:1- ' noop 0 rot a:generate "items" swap o:!
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cb:clear
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;
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52
exercises/practice/circular-buffer/.meta/tests.toml
Normal file
52
exercises/practice/circular-buffer/.meta/tests.toml
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@@ -0,0 +1,52 @@
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# This is an auto-generated file.
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#
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# Regenerating this file via `configlet sync` will:
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# - Recreate every `description` key/value pair
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# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
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# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
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# - Preserve any other key/value pair
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#
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# As user-added comments (using the # character) will be removed when this file
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# is regenerated, comments can be added via a `comment` key.
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[28268ed4-4ff3-45f3-820e-895b44d53dfa]
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description = "reading empty buffer should fail"
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[2e6db04a-58a1-425d-ade8-ac30b5f318f3]
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description = "can read an item just written"
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[90741fe8-a448-45ce-be2b-de009a24c144]
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description = "each item may only be read once"
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[be0e62d5-da9c-47a8-b037-5db21827baa7]
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description = "items are read in the order they are written"
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[2af22046-3e44-4235-bfe6-05ba60439d38]
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description = "full buffer can't be written to"
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[547d192c-bbf0-4369-b8fa-fc37e71f2393]
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description = "a read frees up capacity for another write"
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[04a56659-3a81-4113-816b-6ecb659b4471]
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description = "read position is maintained even across multiple writes"
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[60c3a19a-81a7-43d7-bb0a-f07242b1111f]
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description = "items cleared out of buffer can't be read"
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[45f3ae89-3470-49f3-b50e-362e4b330a59]
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description = "clear frees up capacity for another write"
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[e1ac5170-a026-4725-bfbe-0cf332eddecd]
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description = "clear does nothing on empty buffer"
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[9c2d4f26-3ec7-453f-a895-7e7ff8ae7b5b]
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description = "overwrite acts like write on non-full buffer"
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[880f916b-5039-475c-bd5c-83463c36a147]
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description = "overwrite replaces the oldest item on full buffer"
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[bfecab5b-aca1-4fab-a2b0-cd4af2b053c3]
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description = "overwrite replaces the oldest item remaining in buffer following a read"
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[9cebe63a-c405-437b-8b62-e3fdc1ecec5a]
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description = "initial clear does not affect wrapping around"
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17
exercises/practice/circular-buffer/circular-buffer.8th
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17
exercises/practice/circular-buffer/circular-buffer.8th
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@@ -0,0 +1,17 @@
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ns: cb
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: read \ x -- x x'
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;
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: write \ x x' -- x
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;
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: overwrite \ x x' -- x
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;
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: new \ n -- x
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;
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173
exercises/practice/circular-buffer/libs/exercism/test
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173
exercises/practice/circular-buffer/libs/exercism/test
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@@ -0,0 +1,173 @@
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needs console/loaded
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\ -----------------------------------------------------------------
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ns: test
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-1 var, test-count
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var tests-passed
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var tests-failed
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var tests-skipped
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true var, run-test
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\ Some utility words
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: test-passed \ s x x -- \\ test name, expected value, actual value
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2drop
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1 tests-passed n:+!
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con:green con:onBlack . space " ... OK" . con:white con:onBlack cr
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;
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: test-skipped \ s --
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1 tests-skipped n:+!
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con:cyan con:onBlack . space " ... SKIPPED" . con:white con:onBlack cr
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;
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: test-failed \ s x x -- \\ test name, expected value, actual value
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1 tests-failed n:+!
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rot
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con:red con:onBlack . space " ... FAIL" . con:white con:onBlack cr
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" Actual: «" . . "»" . cr
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" Expected: «" . . "»" . cr cr
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;
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: isword? \ x -- x f
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dup >kind ns:w n:=
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;
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: run-test? \ -- T
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run-test @ if true else "RUN_ALL_TESTS" getenv n:>bool then
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;
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\ Num passed + num skipped + num failed should == num tests
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: all-tests-run? \ -- T
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tests-passed @ tests-skipped @ tests-failed @ n:+ n:+
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test-count @ n:=
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;
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\ returns true if x is a date, false otherwise
|
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: date? \ x -- x T
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dup >kind ns:d n:=
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;
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\ adapted from 8th forum -- https://8th-dev.com/forum/index.php/topic,2745.0.html
|
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: eq? \ x x -- T
|
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\ are the items the same kind?
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2dup >kind swap >kind n:=
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!if 2drop false ;then
|
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\ same kind: try different comparators
|
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number? if n:= ;then
|
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string? if s:= ;then
|
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array? if ' eq? a:= 2nip ;then
|
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map? if ' eq? m:= 2nip ;then
|
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date? if d:= ;then
|
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|
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\ otherwise fall back to 'lazy evaluation'
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l: =
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;
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: eps_eq? \ n x x -- T
|
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\ are the items the same kind?
|
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2dup >kind swap >kind n:=
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!if 2drop false ;then
|
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number? !if 2drop false ;then
|
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rot n:~=
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;
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|
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: check-depth \ ... n -- ...
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dup>r
|
||||
n:1+ depth n:=
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!if
|
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con:red con:onBlack
|
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"PANIC: expected stack depth to be " . r> . cr
|
||||
"Stack is:" . cr
|
||||
.s cr
|
||||
255 die
|
||||
then
|
||||
rdrop
|
||||
;
|
||||
|
||||
\ -----------------------------------------------------------------
|
||||
|
||||
\ status report at end of run
|
||||
( all-tests-run?
|
||||
!if con:red con:onBlack "... FAIL - not all tests completed" . con:white con:onBlack cr then
|
||||
) onexit
|
||||
|
||||
\ Print a summary of the tests run
|
||||
( con:white con:onBlack
|
||||
test-count @ . space "tests planned - " .
|
||||
tests-passed @ . space "passed - " .
|
||||
tests-skipped @ . space "skipped - " .
|
||||
tests-failed @ . space "failed" . cr
|
||||
) onexit
|
||||
|
||||
\ -----------------------------------------------------------------
|
||||
\ The public-facing words
|
||||
\ -----------------------------------------------------------------
|
||||
|
||||
: equal? \ s x w -- | s w x --
|
||||
run-test? !if 2drop test-skipped ;; then
|
||||
isword? !if swap then
|
||||
w:exec
|
||||
3 check-depth
|
||||
2dup \ so test-failed can show actual and expected
|
||||
eq? if test-passed else test-failed then
|
||||
;
|
||||
|
||||
: approx_equal? \ s x w n -- | s w x n --
|
||||
run-test? !if 3drop test-skipped ;; then
|
||||
-rot isword? !if swap then
|
||||
w:exec
|
||||
4 check-depth
|
||||
3dup \ so test-failed can show actual and expected
|
||||
eps_eq?
|
||||
if rot drop test-passed else rot drop test-failed then
|
||||
;
|
||||
|
||||
: true? \ s w --
|
||||
run-test? !if drop test-skipped ;; then
|
||||
w:exec
|
||||
2 check-depth
|
||||
true swap dup \ so test-failed can show actual and expected
|
||||
if test-passed else test-failed then
|
||||
;
|
||||
|
||||
: false? \ s w --
|
||||
run-test? !if drop test-skipped ;; then
|
||||
w:exec
|
||||
2 check-depth
|
||||
false swap dup \ so test-failed can show actual and expected
|
||||
!if test-passed else test-failed then
|
||||
;
|
||||
|
||||
: null? \ s w --
|
||||
run-test? !if drop test-skipped ;; then
|
||||
w:exec
|
||||
2 check-depth
|
||||
null swap dup \ so test-failed can show actual and expected
|
||||
G:null? nip if test-passed else test-failed then
|
||||
;
|
||||
|
||||
: SKIP-REST-OF-TESTS false run-test ! ;
|
||||
|
||||
: tests \ n --
|
||||
test-count !
|
||||
;
|
||||
|
||||
\ Set the exit status:
|
||||
\ 0 = all OK
|
||||
\ 1 = not all tests were run (some error occurred)
|
||||
\ 2 = some tests failed
|
||||
: end-of-tests \ --
|
||||
all-tests-run?
|
||||
if
|
||||
tests-failed @ 0 n:= if 0 else 2 then
|
||||
else
|
||||
1
|
||||
then
|
||||
die
|
||||
;
|
||||
|
||||
78
exercises/practice/circular-buffer/test.8th
Normal file
78
exercises/practice/circular-buffer/test.8th
Normal file
@@ -0,0 +1,78 @@
|
||||
"circular-buffer.8th" f:include
|
||||
needs exercism/test
|
||||
with: test
|
||||
14 tests
|
||||
|
||||
: throws? \ w -- T
|
||||
catch dup if nip then nip
|
||||
;
|
||||
|
||||
"reading empty buffer should fail"
|
||||
( 1 cb:new ' cb:read throws? )
|
||||
true?
|
||||
|
||||
SKIP-REST-OF-TESTS
|
||||
|
||||
"can read an item just written"
|
||||
( 1 cb:new 1 cb:write cb:read nip )
|
||||
1
|
||||
equal?
|
||||
|
||||
"each item may only be read once"
|
||||
( 1 cb:new 1 cb:write cb:read drop ' cb:read throws? )
|
||||
true?
|
||||
|
||||
"items are read in the order they are written"
|
||||
( 2 cb:new 1 cb:write 2 cb:write cb:read swap cb:read nip 2 a:close )
|
||||
[1, 2]
|
||||
equal?
|
||||
|
||||
"full buffer can't be written to"
|
||||
( 1 cb:new 1 cb:write 2 ' cb:write throws? )
|
||||
true?
|
||||
|
||||
"a read frees up capacity for another write"
|
||||
( 1 cb:new 1 cb:write cb:read swap 2 cb:write cb:read nip 2 a:close )
|
||||
[1, 2]
|
||||
equal?
|
||||
|
||||
"read position is maintained even across multiple writes"
|
||||
( 3 cb:new 1 cb:write 2 cb:write cb:read swap 3 cb:write cb:read swap cb:read nip 3 a:close )
|
||||
[1, 2, 3]
|
||||
equal?
|
||||
|
||||
"items cleared out of buffer can't be read"
|
||||
( 1 cb:new 1 cb:write cb:clear ' cb:read throws? )
|
||||
true?
|
||||
|
||||
"clear frees up capacity for another write"
|
||||
( 1 cb:new 1 cb:write cb:clear 2 cb:write cb:read nip )
|
||||
2
|
||||
equal?
|
||||
|
||||
"clear does nothing on empty buffer"
|
||||
( 1 cb:new cb:clear 1 cb:write cb:read nip )
|
||||
1
|
||||
equal?
|
||||
|
||||
"overwrite acts like write on non-full buffer"
|
||||
( 2 cb:new 1 cb:write 2 cb:overwrite cb:read swap cb:read nip 2 a:close )
|
||||
[1, 2]
|
||||
equal?
|
||||
|
||||
"overwrite replaces the oldest item on full buffer"
|
||||
( 2 cb:new 1 cb:write 2 cb:write 3 cb:overwrite cb:read swap cb:read nip 2 a:close )
|
||||
[2, 3]
|
||||
equal?
|
||||
|
||||
"overwrite replaces the oldest item remaining in buffer following a read"
|
||||
( 3 cb:new 1 cb:write 2 cb:write 3 cb:write cb:read swap 4 cb:write 5 cb:overwrite cb:read swap cb:read swap cb:read nip 4 a:close )
|
||||
[1, 3, 4, 5]
|
||||
equal?
|
||||
|
||||
"initial clear does not affect wrapping around"
|
||||
( 2 cb:new cb:clear 1 cb:write 2 cb:write 3 cb:overwrite 4 cb:overwrite cb:read drop cb:read drop ' cb:read throws? )
|
||||
true?
|
||||
|
||||
end-of-tests
|
||||
;with
|
||||
Reference in New Issue
Block a user