Implementing Range Pipelines with Temporary Containers

To create a range pipeline that processes values within temporary containers, it is essential to incorporate the views::cache1 operator. This operator caches the results of a transformation, ensuring that it is available for subsequent operations.

Consider the following scenario where a third-party function f takes a parameter of type T and returns a vector of T. To create a range pipeline that applies f to all elements of an infinite range src and flattens the results into a single range, we can utilize the following approach:

auto rng = src | views::transform(f) | views::cache1 | views::join;

Components of the Pipeline:

1. views::transform(f): Applies the f function to each element of src, resulting in a range of vector containers.
2. views::cache1: Caches the output of the previous transformation, making it available for further processing.
3. views::join: Flattens the range of vector containers into a single range, effectively combining all elements.

By incorporating views::cache1, we ensure that the temporary vector containers created by f are available for views::join to concatenate into a single range. This is essential for creating range pipelines that work correctly with temporary containers.