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version 2.108.0

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std.range.Chunks/chunks - multiple declarations

Function chunks

This range iterates over fixed-sized chunks of size chunkSize of a source range. Source must be an input range. chunkSize must be greater than zero.

Chunks!Source chunks(Source) (
  Source source,
  size_t chunkSize
)
if (isInputRange!Source);

If !isInfinite!Source and source.walkLength is not evenly divisible by chunkSize, the back element of this range will contain fewer than chunkSize elements.

If Source is a forward range, the resulting range will be forward ranges as well. Otherwise, the resulting chunks will be input ranges consuming the same

input

iterating over front will shrink the chunk such that subsequent invocations of front will no longer return the full chunk, and calling popFront on the outer range will invalidate any lingering references to previous values of front.

Parameters

NameDescription
source Range from which the chunks will be selected
chunkSize Chunk size

See Also

slide

Returns

Range of chunks.

Example

import std.algorithm.comparison : equal;
auto source = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
auto chunks = chunks(source, 4);
writeln(chunks[0]); // [1, 2, 3, 4]
writeln(chunks[1]); // [5, 6, 7, 8]
writeln(chunks[2]); // [9, 10]
writeln(chunks.back); // chunks[2]
writeln(chunks.front); // chunks[0]
writeln(chunks.length); // 3
assert(equal(retro(array(chunks)), array(retro(chunks))));

Example

Non-forward input ranges are supported, but with limited semantics. 

import std.algorithm.comparison : equal;

int i;

// The generator doesn't save state, so it cannot be a forward range.
auto inputRange = generate!(() => ++i).take(10);

// We can still process it in chunks, but it will be single-pass only.
auto chunked = inputRange.chunks(2);

assert(chunked.front.equal([1, 2]));
assert(chunked.front.empty); // Iterating the chunk has consumed it
chunked.popFront;
assert(chunked.front.equal([3, 4]));

Struct Chunks

This range iterates over fixed-sized chunks of size chunkSize of a source range. Source must be an input range. chunkSize must be greater than zero.

struct Chunks(Source)
  
if (isInputRange!Source);

If !isInfinite!Source and source.walkLength is not evenly divisible by chunkSize, the back element of this range will contain fewer than chunkSize elements.

If Source is a forward range, the resulting range will be forward ranges as well. Otherwise, the resulting chunks will be input ranges consuming the same

Constructors

NameDescription
this (source, chunkSize) Standard constructor

Properties

NameTypeDescription
back[get] autoBidirectional range primitives. Provided only if both hasSlicing!Source and hasLength!Source are true.
empty[get] boolInput range primitives. Always present.
front[get] autoInput range primitives. Always present.
length[get] size_tLength. Only if hasLength!Source is true
save[get] typeof(this)Forward range primitives. Only present if Source is a forward range.

Methods

NameDescription
opIndex (index) Indexing and slicing operations. Provided only if hasSlicing!Source is true.
opSlice (lower, upper) Indexing and slicing operations. Provided only if hasSlicing!Source is true.
popBack () Bidirectional range primitives. Provided only if both hasSlicing!Source and hasLength!Source are true.
popFront () Input range primitives. Always present.

input

iterating over front will shrink the chunk such that subsequent invocations of front will no longer return the full chunk, and calling popFront on the outer range will invalidate any lingering references to previous values of front.

Parameters

NameDescription
source Range from which the chunks will be selected
chunkSize Chunk size

See Also

slide

Returns

Range of chunks.

Example

import std.algorithm.comparison : equal;
auto source = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
auto chunks = chunks(source, 4);
writeln(chunks[0]); // [1, 2, 3, 4]
writeln(chunks[1]); // [5, 6, 7, 8]
writeln(chunks[2]); // [9, 10]
writeln(chunks.back); // chunks[2]
writeln(chunks.front); // chunks[0]
writeln(chunks.length); // 3
assert(equal(retro(array(chunks)), array(retro(chunks))));

Example

Non-forward input ranges are supported, but with limited semantics. 

import std.algorithm.comparison : equal;

int i;

// The generator doesn't save state, so it cannot be a forward range.
auto inputRange = generate!(() => ++i).take(10);

// We can still process it in chunks, but it will be single-pass only.
auto chunked = inputRange.chunks(2);

assert(chunked.front.equal([1, 2]));
assert(chunked.front.empty); // Iterating the chunk has consumed it
chunked.popFront;
assert(chunked.front.equal([3, 4]));

Authors

Andrei Alexandrescu, David Simcha, Jonathan M Davis, and Jack Stouffer. Credit for some of the ideas in building this module goes to Leonardo Maffi.

License

Boost License 1.0.