std.range.ref_range - multiple declarations

If the given range is a class type (and thus is already a reference type), then the original range is returned rather than a RefRange.

Prototypes

auto refRange(R)(
  R* range
)
if (isInputRange!R && !is(R == class));

auto refRange(R)(
  R* range
)
if (isInputRange!R && is(R == class));

Example

import std.algorithm : map, joiner, group, until;
// fix for std.algorithm
auto r = map!(x => 0)([1]);
chain(r, r);
zip(r, r);
roundRobin(r, r);

struct NRAR {
    typeof(r) input;
    @property empty() { return input.empty; }
    @property front() { return input.front; }
    void popFront()   { input.popFront(); }
    @property save()  { return NRAR(input.save); }
}
auto n1 = NRAR(r);
cycle(n1);  // non random access range version

assumeSorted(r);

// fix for std.range
joiner([r], [9]);

struct NRAR2 {
    NRAR input;
    @property empty() { return true; }
    @property front() { return input; }
    void popFront() { }
    @property save()  { return NRAR2(input.save); }
}
auto n2 = NRAR2(n1);
joiner(n2);

group(r);

until(r, 7);
static void foo(R)(R r) { until!(x => x > 7)(r); }
foo(r);

Note that save works as normal and operates on a new range, so if save is ever called on the RefRange, then no operations on the saved range will affect the original.

Constructors

Properties

Methods

Example

Basic Example

import std.algorithm;
ubyte[] buffer = [1, 9, 45, 12, 22];
auto found1 = find(buffer, 45);
assert(found1 == [45, 12, 22]);
assert(buffer == [1, 9, 45, 12, 22]);

auto wrapped1 = refRange(&buffer);
auto found2 = find(wrapped1, 45);
assert(*found2.ptr == [45, 12, 22]);
assert(buffer == [45, 12, 22]);

auto found3 = find(wrapped1.save, 22);
assert(*found3.ptr == [22]);
assert(buffer == [45, 12, 22]);

string str = "hello world";
auto wrappedStr = refRange(&str);
assert(str.front == 'h');
str.popFrontN(5);
assert(str == " world");
assert(wrappedStr.front == ' ');
assert(*wrappedStr.ptr == " world");

Example

opAssign Example.

ubyte[] buffer1 = [1, 2, 3, 4, 5];
ubyte[] buffer2 = [6, 7, 8, 9, 10];
auto wrapped1 = refRange(&buffer1);
auto wrapped2 = refRange(&buffer2);
assert(wrapped1.ptr is &buffer1);
assert(wrapped2.ptr is &buffer2);
assert(wrapped1.ptr !is wrapped2.ptr);
assert(buffer1 != buffer2);

wrapped1 = wrapped2;

//Everything points to the same stuff as before.
assert(wrapped1.ptr is &buffer1);
assert(wrapped2.ptr is &buffer2);
assert(wrapped1.ptr !is wrapped2.ptr);

//But buffer1 has changed due to the assignment.
assert(buffer1 == [6, 7, 8, 9, 10]);
assert(buffer2 == [6, 7, 8, 9, 10]);

buffer2 = [11, 12, 13, 14, 15];

//Everything points to the same stuff as before.
assert(wrapped1.ptr is &buffer1);
assert(wrapped2.ptr is &buffer2);
assert(wrapped1.ptr !is wrapped2.ptr);

//But buffer2 has changed due to the assignment.
assert(buffer1 == [6, 7, 8, 9, 10]);
assert(buffer2 == [11, 12, 13, 14, 15]);

wrapped2 = null;

//The pointer changed for wrapped2 but not wrapped1.
assert(wrapped1.ptr is &buffer1);
assert(wrapped2.ptr is null);
assert(wrapped1.ptr !is wrapped2.ptr);

//buffer2 is not affected by the assignment.
assert(buffer1 == [6, 7, 8, 9, 10]);
assert(buffer2 == [11, 12, 13, 14, 15]);