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`std.range.RefRange/refRange` - multiple declarations

Function refRange

Wrapper which effectively makes it possible to pass a range by reference. Both the original range and the RefRange will always have the exact same elements. Any operation done on one will affect the other. So, for instance, if it's passed to a function which would implicitly copy the original range if it were passed to it, the original range is not copied but is consumed as if it were a reference type.


						
				auto auto refRange(R)
				(
				

				  R* range
				

				)
				

				if (isInputRange!R);

Note

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.

Parameters

Name	Description
range	the range to construct the `RefRange` from

Returns

A RefRange. 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.

Example

Basic Example

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

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

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

string str = "hello world";
auto wrappedStr = refRange(&str);
writeln(str.front); // 'h'
str.popFrontN(5);
writeln(str); // " world"
writeln(wrappedStr.front); // ' '
writeln(*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.
writeln(buffer1); // [6, 7, 8, 9, 10]
writeln(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.
writeln(buffer1); // [6, 7, 8, 9, 10]
writeln(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.
writeln(buffer1); // [6, 7, 8, 9, 10]
writeln(buffer2); // [11, 12, 13, 14, 15]

Example

import std.algorithm.iteration : map, joiner, group;
import std.algorithm.searching : 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);

Struct RefRange


						
				struct RefRange(R)
				

				  
				

				if (isInputRange!R);

Constructors

Name	Description
`this`

Properties

Name	Type	Description
`back`[get, set]	`auto`	Only defined if `isBidirectionalRange!R` is `true`.
`empty`[get]	`bool`
`front`[get, set]	`auto`
`length`[get]	`auto`	Only defined if `hasLength!R` is `true`.
`ptr`[get]	`inout(R*)`	A pointer to the wrapped range.
`save`[get]	`auto`	Only defined if `isForwardRange!R` is `true`.

Methods

Name	Description
`moveAt`	Only defined if `hasMobileElements!R` and `isRandomAccessRange!R` are `true`.
`moveBack`	Only defined if `hasMobileElements!R` and `isBidirectionalRange!R` are `true`.
`moveFront`	Only defined if `hasMobileElements!R` and `isForwardRange!R` are `true`.
`opAssign`	This does not assign the pointer of `rhs` to this `RefRange`. Rather it assigns the range pointed to by `rhs` to the range pointed to by this `RefRange`. This is because any operation on a `RefRange` is the same is if it occurred to the original range. The one exception is when a `RefRange` is assigned `null` either directly or because `rhs` is `null`. In that case, `RefRange` no longer refers to the original range but is `null`.
`opAssign`
`opIndex`	Only defined if `isRandomAccesRange!R` is `true`.
`opSlice`	Only defined if `isForwardRange!R` is `true`.
`opSlice`	Only defined if `hasSlicing!R` is `true`.
`popBack`	Only defined if `isBidirectionalRange!R` is `true`.
`popFront`

Aliases

Name	Description
`opDollar`	Only defined if `hasLength!R` is `true`.

Note

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.

Parameters

Name	Description
range	the range to construct the `RefRange` from

Returns

A RefRange. 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.

Example

Basic Example

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

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

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

string str = "hello world";
auto wrappedStr = refRange(&str);
writeln(str.front); // 'h'
str.popFrontN(5);
writeln(str); // " world"
writeln(wrappedStr.front); // ' '
writeln(*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.
writeln(buffer1); // [6, 7, 8, 9, 10]
writeln(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.
writeln(buffer1); // [6, 7, 8, 9, 10]
writeln(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.
writeln(buffer1); // [6, 7, 8, 9, 10]
writeln(buffer2); // [11, 12, 13, 14, 15]

Example

import std.algorithm.iteration : map, joiner, group;
import std.algorithm.searching : 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);

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.

API Documentation

std.range.RefRange/refRange - multiple declarations

Function refRange

Note

Parameters

Returns

Example

Example

Example

Struct RefRange

Constructors

Properties

Methods

Aliases

Note

Parameters

Returns

Example

Example

Example

Authors

License

`std.range.RefRange/refRange` - multiple declarations