ReusableBlock

A reusable memory block for placing objects on.

The elements are added only at the back either by copying or by moving. They are removed only from the front. The elements are never moved to a different memory location inside the buffer.

struct ReusableBlock (

Flag!"dtors" dtors = Yes.dtors

) {

this(ubyte[] buffer);

inout(T)* ptr();

size_t capacity();

size_t freeCapacity();

size_t length();

bool empty();

void opOpAssign(SourceT element);

void copyBack(const(SourceT) element);

void moveEmplace(SourceT element);

void emplaceBack(Args args);

inout(T) opIndex(size_t index);

void removeFrontN(size_t n);

void clear();

size_t opDollar();

inout(T)[] opSlice(size_t from, size_t to);

inout(T)[] opSlice();

void toString(void delegate(in char[]) sink);

}

Constructors

this this(ubyte[] buffer): Construct an object that will use the provided memory

Members

Functions

capacity size_t capacity(): Total capacity of the block
clear void clear(): The same as calling this.removeFrontN(this.length)
copyBack void copyBack(const(SourceT) element): Calls ~= to copy the specified _element
emplaceBack void emplaceBack(Args args): Construct a new element after the existing elements
empty bool empty(): Whether the block has no elements at all
freeCapacity size_t freeCapacity(): Number of elements the block currently has room for
length size_t length(): Current number of elements in the block
moveEmplace void moveEmplace(SourceT element): Move the specified _element to the back of existing elements
opDollar size_t opDollar(): Number of elements in the block
opIndex inout(T) opIndex(size_t index): Return a reference to an element
opOpAssign void opOpAssign(SourceT element): Add an _element after the existing elements; lvalues are copied, rvalues are moved.
opSlice inout(T)[] opSlice(size_t from, size_t to): A slice providing access _to the specified elements
opSlice inout(T)[] opSlice(): A slice to all elements; the same as [0..$]
ptr inout(T)* ptr(): Pointer to the beginning of the block
removeFrontN void removeFrontN(size_t n): Remove elements from the head of the block. If n == length, freeCapacity will be equal to capacity after this call. Whether the destructors are called on the removed elements is determined by the dtors template parameter.
toString void toString(void delegate(in char[]) sink): String representation of this object mostly for debugging

Parameters

T: the type of the elements that will be stored on the block
dtors: whether to execute destructors of elements upon removing them

Examples

// Constructing a block on a piece of memory
ubyte[100] buffer;
auto b = ReusableBlock!int(buffer);

// Depending on the alignment of the elements, the capacity may be less than
// then requested amount
assert(b.capacity <= buffer.length / int.sizeof);

// Add 2 elements
b ~= 0;
b ~= 1;

b.length.shouldBe(2);
b[0].shouldBe(0);
b[1].shouldBe(1);
b.freeCapacity.shouldBe(b.capacity - 2);

// Remove the first one
b.removeFrontN(1);
b.length.shouldBe(1);
b[0].shouldBe(1);
// Note that free capacity does not increase:
b.freeCapacity.shouldBe(b.capacity - 2);

// Remove all elements and reset the block
b.clear();
b.length.shouldBe(0);
// This time all capacity is free
b.freeCapacity.shouldBe(b.capacity);