A library for C++20 that introduced std::ranges namespace, which consists of rangified algorithms from
Questions tagged [std-ranges]
379 questions
0
votes
0 answers
std::ranges::view as mutable class member
I have a huge data structure and it's content is updated regularly.
I need to apply a filter to it each time I get a change request.
So to avoid duplicating/copying it, I use an std::view + std::views::filter. (as lightweight container)
Having this…
Peter
- 109
- 7
0
votes
1 answer
C++20 range get value by index
I want to access the first value from a range:
#include
#include
#include
using namespace std;
int main()
{
auto rg = views::split("hello there!", ' ') | views::transform([](auto word)->char{return word[0];}) ;
…
Ludovic Aubert
- 9,534
- 4
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- 28
0
votes
1 answer
converting a flat table to a tree structure using ranges-v3
I have a flat representation of a tree shown in the table below.
The unsorted data, std::vector is:
unsorted vector
(id) (path) (fn) (line) (extra)
1 /abc/file3.c foo0 10 1
2 /abc/file3.c foo0 15 2
3…
johnco3
- 2,401
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- 67
0
votes
0 answers
Handling lifetime and iterator validity when returning filtered ranges in C++20
I'm working with filter adaptors in C++20. However, I'm facing a problem when I try to return a filtered range from a function. The issue arises because the filter adaptor caches the iterator of the underlying range. When i return from the function,…
Abdullah Mohammed
- 39
- 2
0
votes
1 answer
Return range from different sources
I'm wondering how to make same type for return value? Consider an example:
auto get_securities_by_mic(const std::string& mic)
{
auto it = some_map.find(mic);
// I want to write like this:
if (it == some_map.end()) return…
Alexey Subbota
- 938
- 6
- 23
0
votes
3 answers
Why does the C++20 range concept specify apparently misleading requirements?
I'm struggling to satisfy a C++20 concept for my class.
struct C1
{
int* begin();
int* end();
};
static_assert(std::ranges::range); // Compiles fine
struct C2 {};
namespace std::ranges // (A)
{
auto begin(C2&);
auto…
Frank Heimes
- 100
- 6
0
votes
1 answer
Right associativity for `std::views`
Left associativity is already guaranteed by C++ core semantics:
R|V1|V2 is parsed as (R|V1)|V2). What if the coder wants to explicitly change the order of operations to R|(V1|V2)?
Is this possible under C++23?
The reason behind the question is that…
Red.Wave
- 2,790
- 11
- 17
0
votes
1 answer
Are there any versions of clang that have complete implementations of std::ranges?
I'm just trying to figure out how I can use clang++ to compile this:
for (int i : std::ranges::iota_view{1, 10})
std::cout << i << ' ';
The latest Apple Clang failed to recognize iota_view, and so I downloaded LLVM 15.0.7 using Homebrew.…
Oreese17
- 7
- 1
0
votes
1 answer
Transpose vector of vectors with views::zip
Duplicate: https://stackoverflow.com/a/61819663/11998382
This should be possible if we know the size of the outer vector at compile time.
You just have to write the c++ variadic-template equivalent of the following python code:
def…
Tom Huntington
- 2,260
- 10
- 20
0
votes
2 answers
Pass initializer lists and ranges seamlessly to a function parameter
I am trying to create a function that will initialize an internal std::set, and I want to expose an API that allows any type of ranges as input, including initializer lists. So what I'm aiming for is :
// API definition
class…
Timothée Chabat
- 27
- 1
- 8
0
votes
1 answer
Workaround to decrement iterator from views::transform?
Consider the following example:
int main()
{
std::string_view foo = "This is a test";
auto split_foo = foo |
std::views::split(' ') |
std::ranges::views::transform(
…
Constantinos Glynos
- 2,952
- 2
- 14
- 32
0
votes
1 answer
Correct syntax for views::istream or ranges::istream_view?
I am trying to get into ranges::views.
The following demo program does not compile:
#include
#include
#include
#include
#include
#include
namespace rng = std::ranges;
struct…
A M
- 14,694
- 5
- 19
- 44
0
votes
1 answer
Binary search over function results in C++
I am looking for a way to do a binary search over function results with a signature close to the following:
template
Георгий Гуминов
- 117
- 1
- 2
- 15
0
votes
1 answer
How to create a view that will split the data in half
I want to create a view that will have views of both halves of the string. I added some code examples of what I would like to achieve. How could I do it?
#include
#include
#include
#include
#include…
Dessus
- 301
- 2
- 10
0
votes
1 answer
pipe istream_view and views::transform. How?
Sorry, I was searching a lot, but I still do not understand.
Let's assume that I want to read line by line with an istream_view using a line proxy and convert the result to lowercase.
It would be nice, if I could write
#include
#include…
A M
- 14,694
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- 44