Merge pull request #5317 from Feoramund/fixup-container-queue

Tidy up `core:container/queue`

core/container/queue/queue.odin

@@ -4,7 +4,13 @@ import "base:builtin"
 import "base:runtime"
 _ :: runtime
 
-// Dynamically resizable double-ended queue/ring-buffer
+/*
+`Queue` is a dynamically resizable double-ended queue/ring-buffer.
+
+Being double-ended means that either end may be pushed onto or popped from
+across the same block of memory, in any order, thus providing both stack and
+queue-like behaviors in the same data structure.
+*/
 Queue :: struct($T: typeid) {
 	data:   [dynamic]T,
 	len:    uint,
@@ -13,18 +19,31 @@ Queue :: struct($T: typeid) {
 
 DEFAULT_CAPACITY :: 16
 
-// Procedure to initialize a queue
+/*
+Initialize a `Queue` with a starting `capacity` and an `allocator`.
+*/
 init :: proc(q: ^$Q/Queue($T), capacity := DEFAULT_CAPACITY, allocator := context.allocator) -> runtime.Allocator_Error {
-	if q.data.allocator.procedure == nil {
-		q.data.allocator = allocator
-	}
 	clear(q)
+	q.data = transmute([dynamic]T)runtime.Raw_Dynamic_Array{
+		data = nil,
+		len = 0,
+		cap = 0,
+		allocator = allocator,
+	}
 	return reserve(q, capacity)
 }
 
-// Procedure to initialize a queue from a fixed backing slice.
-// The contents of the `backing` will be overwritten as items are pushed onto the `Queue`.
-// Any previous contents are not available.
+/*
+Initialize a `Queue` from a fixed `backing` slice into which modifications are
+made directly.
+
+The contents of the `backing` will be overwritten as items are pushed onto the
+`Queue`. Any previous contents will not be available through the API but are
+not explicitly zeroed either.
+
+Note that procedures which need space to work (`push_back`, ...) will fail if
+the backing slice runs out of space.
+*/
 init_from_slice :: proc(q: ^$Q/Queue($T), backing: []T) -> bool {
 	clear(q)
 	q.data = transmute([dynamic]T)runtime.Raw_Dynamic_Array{
@@ -36,8 +55,14 @@ init_from_slice :: proc(q: ^$Q/Queue($T), backing: []T) -> bool {
 	return true
 }
 
-// Procedure to initialize a queue from a fixed backing slice.
-// Existing contents are preserved and available on the queue.
+/*
+Initialize a `Queue` from a fixed `backing` slice into which modifications are
+made directly.
+
+The contents of the queue will start out with all of the elements in `backing`,
+effectively creating a full queue from the slice. As such, no procedures will
+be able to add more elements to the queue until some are taken off.
+*/
 init_with_contents :: proc(q: ^$Q/Queue($T), backing: []T) -> bool {
 	clear(q)
 	q.data = transmute([dynamic]T)runtime.Raw_Dynamic_Array{
@@ -50,84 +75,200 @@ init_with_contents :: proc(q: ^$Q/Queue($T), backing: []T) -> bool {
 	return true
 }
 
-// Procedure to destroy a queue
+/*
+Delete memory that has been dynamically allocated from a `Queue` that was setup with `init`.
+
+Note that this procedure should not be used on queues setup with
+`init_from_slice` or `init_with_contents`, as neither of those procedures keep
+track of the allocator state of the underlying `backing` slice.
+*/
 destroy :: proc(q: ^$Q/Queue($T)) {
 	delete(q.data)
 }
 
-// The length of the queue
+/*
+Return the length of the queue.
+*/
 len :: proc(q: $Q/Queue($T)) -> int {
 	return int(q.len)
 }
 
-// The current capacity of the queue
+/*
+Return the capacity of the queue.
+*/
 cap :: proc(q: $Q/Queue($T)) -> int {
 	return builtin.len(q.data)
 }
 
-// Remaining space in the queue (cap-len)
+/*
+Return the remaining space in the queue.
+
+This will be `cap() - len()`.
+*/
 space :: proc(q: $Q/Queue($T)) -> int {
 	return builtin.len(q.data) - int(q.len)
 }
 
-// Reserve enough space for at least the specified capacity
+/*
+Reserve enough space in the queue for at least the specified capacity.
+
+This may return an error if allocation failed.
+*/
 reserve :: proc(q: ^$Q/Queue($T), capacity: int) -> runtime.Allocator_Error {
 	if capacity > space(q^) {
-		return _grow(q, uint(capacity)) 
+		return _grow(q, uint(capacity))
 	}
 	return nil
 }
 
+/*
+Shrink a queue's dynamically allocated array.
+
+This has no effect if the queue was initialized with a backing slice.
+*/
+shrink :: proc(q: ^$Q/Queue($T), temp_allocator := context.temp_allocator, loc := #caller_location) {
+	if q.data.allocator.procedure == runtime.nil_allocator_proc {
+		return
+	}
+
+	if q.len > 0 && q.offset > 0 {
+		// Make the array contiguous again.
+		buffer := make([]T, q.len, temp_allocator)
+		defer delete(buffer, temp_allocator)
+
+		right := uint(builtin.len(q.data)) - q.offset
+		copy(buffer[:],      q.data[q.offset:])
+		copy(buffer[right:], q.data[:q.offset])
+
+		copy(q.data[:], buffer[:])
+
+		q.offset = 0
+	}
+
+	builtin.shrink(&q.data, q.len, loc)
+}
+
+/*
+Get the element at index `i`.
 
+This will raise a bounds checking error if `i` is an invalid index.
+*/
 get :: proc(q: ^$Q/Queue($T), #any_int i: int, loc := #caller_location) -> T {
-	runtime.bounds_check_error_loc(loc, i, builtin.len(q.data))
+	runtime.bounds_check_error_loc(loc, i, int(q.len))
 
 	idx := (uint(i)+q.offset)%builtin.len(q.data)
 	return q.data[idx]
 }
 
-front :: proc(q: ^$Q/Queue($T)) -> T {
+/*
+Get a pointer to the element at index `i`.
+
+This will raise a bounds checking error if `i` is an invalid index.
+*/
+get_ptr :: proc(q: ^$Q/Queue($T), #any_int i: int, loc := #caller_location) -> ^T {
+	runtime.bounds_check_error_loc(loc, i, int(q.len))
+
+	idx := (uint(i)+q.offset)%builtin.len(q.data)
+	return &q.data[idx]
+}
+
+/*
+Set the element at index `i` to `val`.
+
+This will raise a bounds checking error if `i` is an invalid index.
+*/
+set :: proc(q: ^$Q/Queue($T), #any_int i: int, val: T, loc := #caller_location) {
+	runtime.bounds_check_error_loc(loc, i, int(q.len))
+
+	idx := (uint(i)+q.offset)%builtin.len(q.data)
+	q.data[idx] = val
+}
+
+/*
+Get the element at the front of the queue.
+
+This will raise a bounds checking error if the queue is empty.
+*/
+front :: proc(q: ^$Q/Queue($T), loc := #caller_location) -> T {
+	when !ODIN_NO_BOUNDS_CHECK {
+		ensure(q.len > 0, "Queue is empty.", loc)
+	}
 	return q.data[q.offset]
 }
-front_ptr :: proc(q: ^$Q/Queue($T)) -> ^T {
+
+/*
+Get a pointer to the element at the front of the queue.
+
+This will raise a bounds checking error if the queue is empty.
+*/
+front_ptr :: proc(q: ^$Q/Queue($T), loc := #caller_location) -> ^T {
+	when !ODIN_NO_BOUNDS_CHECK {
+		ensure(q.len > 0, "Queue is empty.", loc)
+	}
 	return &q.data[q.offset]
 }
 
-back :: proc(q: ^$Q/Queue($T)) -> T {
+/*
+Get the element at the back of the queue.
+
+This will raise a bounds checking error if the queue is empty.
+*/
+back :: proc(q: ^$Q/Queue($T), loc := #caller_location) -> T {
+	when !ODIN_NO_BOUNDS_CHECK {
+		ensure(q.len > 0, "Queue is empty.", loc)
+	}
 	idx := (q.offset+uint(q.len - 1))%builtin.len(q.data)
 	return q.data[idx]
 }
-back_ptr :: proc(q: ^$Q/Queue($T)) -> ^T {
+
+/*
+Get a pointer to the element at the back of the queue.
+
+This will raise a bounds checking error if the queue is empty.
+*/
+back_ptr :: proc(q: ^$Q/Queue($T), loc := #caller_location) -> ^T {
+	when !ODIN_NO_BOUNDS_CHECK {
+		ensure(q.len > 0, "Queue is empty.", loc)
+	}
 	idx := (q.offset+uint(q.len - 1))%builtin.len(q.data)
 	return &q.data[idx]
 }
 
-set :: proc(q: ^$Q/Queue($T), #any_int i: int, val: T, loc := #caller_location) {
-	runtime.bounds_check_error_loc(loc, i, builtin.len(q.data))
-	
-	idx := (uint(i)+q.offset)%builtin.len(q.data)
-	q.data[idx] = val
-}
-get_ptr :: proc(q: ^$Q/Queue($T), #any_int i: int, loc := #caller_location) -> ^T {
-	runtime.bounds_check_error_loc(loc, i, builtin.len(q.data))
-	
-	idx := (uint(i)+q.offset)%builtin.len(q.data)
-	return &q.data[idx]
-}
 
+@(deprecated="Use `front_ptr` instead")
 peek_front :: proc(q: ^$Q/Queue($T), loc := #caller_location) -> ^T {
-	runtime.bounds_check_error_loc(loc, 0, builtin.len(q.data))
-	idx := q.offset%builtin.len(q.data)
-	return &q.data[idx]
+	return front_ptr(q, loc)
 }
 
+@(deprecated="Use `back_ptr` instead")
 peek_back :: proc(q: ^$Q/Queue($T), loc := #caller_location) -> ^T {
-	runtime.bounds_check_error_loc(loc, int(q.len - 1), builtin.len(q.data))
-	idx := (uint(q.len - 1)+q.offset)%builtin.len(q.data)
-	return &q.data[idx]
+	return back_ptr(q, loc)
 }
 
-// Push an element to the back of the queue
+/*
+Push an element to the back of the queue.
+
+If there is no more space left and allocation fails to get more, this will
+return false with an `Allocator_Error`.
+
+Example:
+
+	import "base:runtime"
+	import "core:container/queue"
+
+	// This demonstrates typical queue behavior (First-In First-Out).
+	main :: proc() {
+		q: queue.Queue(int)
+		queue.init(&q)
+		queue.push_back(&q, 1)
+		queue.push_back(&q, 2)
+		queue.push_back(&q, 3)
+		// q.data is now [1, 2, 3, ...]
+		assert(queue.pop_front(&q) == 1)
+		assert(queue.pop_front(&q) == 2)
+		assert(queue.pop_front(&q) == 3)
+	}
+*/
 push_back :: proc(q: ^$Q/Queue($T), elem: T) -> (ok: bool, err: runtime.Allocator_Error) {
 	if space(q^) == 0 {
 		_grow(q) or_return
@@ -138,27 +279,78 @@ push_back :: proc(q: ^$Q/Queue($T), elem: T) -> (ok: bool, err: runtime.Allocato
 	return true, nil
 }
 
-// Push an element to the front of the queue
+/*
+Push an element to the front of the queue.
+
+If there is no more space left and allocation fails to get more, this will
+return false with an `Allocator_Error`.
+
+Example:
+
+	import "base:runtime"
+	import "core:container/queue"
+
+	// This demonstrates stack behavior (First-In Last-Out).
+	main :: proc() {
+		q: queue.Queue(int)
+		queue.init(&q)
+		queue.push_back(&q, 1)
+		queue.push_back(&q, 2)
+		queue.push_back(&q, 3)
+		// q.data is now [1, 2, 3, ...]
+		assert(queue.pop_back(&q) == 3)
+		assert(queue.pop_back(&q) == 2)
+		assert(queue.pop_back(&q) == 1)
+	}
+*/
 push_front :: proc(q: ^$Q/Queue($T), elem: T) -> (ok: bool, err: runtime.Allocator_Error)  {
 	if space(q^) == 0 {
 		_grow(q) or_return
-	}	
+	}
 	q.offset = uint(q.offset - 1 + builtin.len(q.data)) % builtin.len(q.data)
 	q.len += 1
 	q.data[q.offset] = elem
 	return true, nil
 }
 
+/*
+Pop an element from the back of the queue.
 
-// Pop an element from the back of the queue
+This will raise a bounds checking error if the queue is empty.
+
+Example:
+
+	import "base:runtime"
+	import "core:container/queue"
+
+	// This demonstrates stack behavior (First-In Last-Out) at the far end of the data array.
+	main :: proc() {
+		q: queue.Queue(int)
+		queue.init(&q)
+		queue.push_front(&q, 1)
+		queue.push_front(&q, 2)
+		queue.push_front(&q, 3)
+		// q.data is now [..., 3, 2, 1]
+		log.infof("%#v", q)
+		assert(queue.pop_front(&q) == 3)
+		assert(queue.pop_front(&q) == 2)
+		assert(queue.pop_front(&q) == 1)
+	}
+*/
 pop_back :: proc(q: ^$Q/Queue($T), loc := #caller_location) -> (elem: T) {
-	assert(condition=q.len > 0, loc=loc)
+	when !ODIN_NO_BOUNDS_CHECK {
+		ensure(q.len > 0, "Queue is empty.", loc)
+	}
 	q.len -= 1
 	idx := (q.offset+uint(q.len))%builtin.len(q.data)
 	elem = q.data[idx]
 	return
 }
-// Safely pop an element from the back of the queue
+
+/*
+Pop an element from the back of the queue if one exists and return true.
+Otherwise, return a nil element and false.
+*/
 pop_back_safe :: proc(q: ^$Q/Queue($T)) -> (elem: T, ok: bool) {
 	if q.len > 0 {
 		q.len -= 1
@@ -169,15 +361,25 @@ pop_back_safe :: proc(q: ^$Q/Queue($T)) -> (elem: T, ok: bool) {
 	return
 }
 
-// Pop an element from the front of the queue
+/*
+Pop an element from the front of the queue
+
+This will raise a bounds checking error if the queue is empty.
+*/
 pop_front :: proc(q: ^$Q/Queue($T), loc := #caller_location) -> (elem: T) {
-	assert(condition=q.len > 0, loc=loc)
+	when !ODIN_NO_BOUNDS_CHECK {
+		ensure(q.len > 0, "Queue is empty.", loc)
+	}
 	elem = q.data[q.offset]
 	q.offset = (q.offset+1)%builtin.len(q.data)
 	q.len -= 1
 	return
 }
-// Safely pop an element from the front of the queue
+
+/*
+Pop an element from the front of the queue if one exists and return true.
+Otherwise, return a nil element and false.
+*/
 pop_front_safe :: proc(q: ^$Q/Queue($T)) -> (elem: T, ok: bool) {
 	if q.len > 0 {
 		elem = q.data[q.offset]
@@ -188,13 +390,18 @@ pop_front_safe :: proc(q: ^$Q/Queue($T)) -> (elem: T, ok: bool) {
 	return
 }
 
-// Push multiple elements to the back of the queue
+/*
+Push many elements at once to the back of the queue.
+
+If there is not enough space left and allocation fails to get more, this will
+return false with an `Allocator_Error`.
+*/
 push_back_elems :: proc(q: ^$Q/Queue($T), elems: ..T) -> (ok: bool, err: runtime.Allocator_Error)  {
 	n := uint(builtin.len(elems))
 	if space(q^) < int(n) {
 		_grow(q, q.len + n) or_return
 	}
-	
+
 	sz := uint(builtin.len(q.data))
 	insert_from := (q.offset + q.len) % sz
 	insert_to := n
@@ -207,19 +414,31 @@ push_back_elems :: proc(q: ^$Q/Queue($T), elems: ..T) -> (ok: bool, err: runtime
 	return true, nil
 }
 
-// Consume `n` elements from the front of the queue
+/*
+Consume `n` elements from the back of the queue.
+
+This will raise a bounds checking error if the queue does not have enough elements.
+*/
 consume_front :: proc(q: ^$Q/Queue($T), n: int, loc := #caller_location) {
-	assert(condition=int(q.len) >= n, loc=loc)
+	when !ODIN_NO_BOUNDS_CHECK {
+		ensure(q.len >= uint(n), "Queue does not have enough elements to consume.", loc)
+	}
 	if n > 0 {
 		nu := uint(n)
 		q.offset = (q.offset + nu) % builtin.len(q.data)
-		q.len -= nu	
+		q.len -= nu
 	}
 }
 
-// Consume `n` elements from the back of the queue
+/*
+Consume `n` elements from the back of the queue.
+
+This will raise a bounds checking error if the queue does not have enough elements.
+*/
 consume_back :: proc(q: ^$Q/Queue($T), n: int, loc := #caller_location) {
-	assert(condition=int(q.len) >= n, loc=loc)
+	when !ODIN_NO_BOUNDS_CHECK {
+		ensure(q.len >= uint(n), "Queue does not have enough elements to consume.", loc)
+	}
 	if n > 0 {
 		q.len -= uint(n)
 	}
@@ -231,9 +450,14 @@ append_elem  :: push_back
 append_elems :: push_back_elems
 push   :: proc{push_back, push_back_elems}
 append :: proc{push_back, push_back_elems}
+enqueue :: push_back
+dequeue :: pop_front
 
 
-// Clear the contents of the queue
+/*
+Reset the queue's length and offset to zero, letting it write new elements over
+old memory, in effect clearing the accessible contents.
+*/
 clear :: proc(q: ^$Q/Queue($T)) {
 	q.len = 0
 	q.offset = 0

tests/core/container/queue.odin

@@ -0,0 +1,157 @@
+package test_core_container
+
+import "base:runtime"
+import "core:container/queue"
+import "core:testing"
+
+@test
+test_queue :: proc(t: ^testing.T) {
+	buf := [?]int{99, 99, 99, 99, 99}
+	q: queue.Queue(int)
+
+	testing.expect(t, queue.init_from_slice(&q, buf[:]))
+	testing.expect_value(t, queue.reserve(&q, len(buf)), nil)
+
+	queue.push_back(&q, 1)
+	queue.push_back_elems(&q, 2, 3)
+	queue.push_front(&q, 0)
+
+	// {
+	// data = [1, 2, 3, 99, 0],
+	// len = 4,
+	// offset = 4,
+	// }
+
+	testing.expect_value(t, queue.back(&q), 3)
+	testing.expect_value(t, queue.back_ptr(&q), &buf[2])
+	testing.expect_value(t, queue.front(&q), 0)
+	testing.expect_value(t, queue.front_ptr(&q), &buf[4])
+
+	queue.get(&q, 3)
+
+	for i in 0..<4 {
+		testing.expect_value(t, queue.get(&q, i), i)
+		queue.set(&q, i, i)
+	}
+	testing.expect_value(t, queue.get_ptr(&q, 3), &buf[2])
+
+	queue.consume_back(&q, 1)
+	queue.consume_front(&q, 1)
+	testing.expect_value(t, queue.pop_back(&q), 2)
+	v, ok := queue.pop_back_safe(&q)
+	testing.expect_value(t, v, 1)
+	testing.expect_value(t, ok, true)
+
+
+	// Test `init_with_contents`.
+	buf2 := [?]int{99, 3, 5}
+
+	queue.init_with_contents(&q, buf2[:])
+	push_ok, push_err := queue.push_back(&q, 1)
+	testing.expect(t, !push_ok)
+	testing.expect_value(t, push_err, runtime.Allocator_Error.Out_Of_Memory)
+	push_ok, push_err = queue.push_front(&q, 2)
+	testing.expect(t, !push_ok)
+	testing.expect_value(t, push_err, runtime.Allocator_Error.Out_Of_Memory)
+
+	pop_front_v, pop_front_ok := queue.pop_front_safe(&q)
+	testing.expect(t, pop_front_ok)
+	testing.expect_value(t, pop_front_v, 99)
+
+	// Re-initialization.
+	queue.init(&q, 0)
+	defer queue.destroy(&q)
+
+	queue.push_back_elems(&q, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
+	testing.expect_value(t, queue.len(q), 18)
+	queue.push_back_elems(&q, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
+	testing.expect_value(t, queue.len(q), 36)
+
+	for i in 1..=18 {
+		testing.expect_value(t, queue.pop_front(&q), i)
+	}
+	for i in 1..=18 {
+		testing.expect_value(t, queue.pop_front(&q), i)
+	}
+}
+
+@test
+test_queue_grow_edge_case :: proc(t: ^testing.T) {
+	// Create a situation in which we trigger `q.offset + q.len > n` inside
+	// `_grow` to evaluate the `copy` behavior.
+	qq: queue.Queue(int)
+	queue.init(&qq, 0)
+	defer queue.destroy(&qq)
+
+	queue.push_back_elems(&qq, 1, 2, 3, 4, 5, 6, 7)
+	testing.expect_value(t, queue.pop_front(&qq), 1)
+	testing.expect_value(t, queue.pop_front(&qq), 2)
+	testing.expect_value(t, queue.pop_front(&qq), 3)
+	queue.push_back(&qq, 8)
+	queue.push_back(&qq, 9)
+
+	testing.expect_value(t, qq.len, 6)
+	testing.expect_value(t, qq.offset, 3)
+	testing.expect_value(t, len(qq.data), 8) // value contingent on smallest dynamic array capacity on first allocation
+
+	queue.reserve(&qq, 16)
+
+	testing.expect_value(t, queue.len(qq), 6)
+	for i in 4..=9 {
+		testing.expect_value(t, queue.pop_front(&qq), i)
+	}
+	testing.expect_value(t, queue.len(qq), 0)
+
+	// If we made it to this point without failure, the queue should have
+	// copied the data into the right place after resizing the backing array.
+}
+
+@test
+test_queue_grow_edge_case_2 :: proc(t: ^testing.T) {
+	// Create a situation in which we trigger `insert_from + insert_to > sz` inside `push_back_elems`
+	// to evaluate the modified `insert_to` behavior.
+	qq: queue.Queue(int)
+	queue.init(&qq, 8)
+	defer queue.destroy(&qq)
+
+	queue.push_back_elems(&qq, -1, -2, -3, -4, -5, -6, -7)
+	queue.consume_front(&qq, 3)
+	queue.push_back_elems(&qq, -8, -9, -10)
+
+	queue.push_back_elems(&qq, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
+
+	testing.expect_value(t, queue.len(qq), 17)
+	for i in 4..=10 {
+		testing.expect_value(t, queue.pop_front(&qq), -i)
+	}
+	for i in 1..=10 {
+		testing.expect_value(t, queue.pop_front(&qq), i)
+	}
+	testing.expect_value(t, queue.len(qq), 0)
+}
+
+@test
+test_queue_shrink :: proc(t: ^testing.T) {
+	qq: queue.Queue(int)
+	queue.init(&qq, 8)
+	defer queue.destroy(&qq)
+
+	queue.push_back_elems(&qq, -1, -2, -3, -4, -5, -6, -7)
+	queue.consume_front(&qq, 3)
+	queue.push_back_elems(&qq, -8, -9, -10)
+
+	queue.push_back_elems(&qq, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
+
+	queue.shrink(&qq)
+	queue.consume_front(&qq, 7)
+	queue.shrink(&qq)
+
+	for i in 1..=10 {
+		testing.expect_value(t, queue.pop_front(&qq), i)
+	}
+
+	buf: [1]int
+	qq_backed: queue.Queue(int)
+	queue.init_from_slice(&qq_backed, buf[:])
+	queue.shrink(&qq_backed)
+}