10BC0 Adds thin C++ wrapper by daniel-j-h · Pull Request #65 · tinygraph/tinygraph · GitHub
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Adds thin C++ wrapper #65

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@daniel-j-h daniel-j-h commented Mar 23, 2025

This changeset adds a thin C++ header-only wrapper on top of our ABI and API stable C library.

Usage

std::vector<std::uint32_t> sources = {0, 1, 2};
std::vector<std::uint32_t> targets = {1, 2, 3};

auto graph = tg::graph{sources, targets, tg::edges_are_sorted};

There's potential to make the ergonomics still a bit nicer e.g. with iterators or similar.

The stability guarantees will not apply to this header-only wrapper - instead it's just convenience for users.

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daniel-j-h commented Mar 29, 2025
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daniel-j-h commented Apr 2, 2025

I've added a graph builder for convenience, usage is as follows

auto graph = tg::builder()
  .reserve(3)
  .add_edge(0,1)
  .add_edge(1,2)
  .add_edge(2,3)
  .build()

once the graph is built it clears and shrinks the builder vectors so that the user does not accidentally have 2x memory around for the edges.

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daniel-j-h commented Apr 10, 2025 •
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I have added support for the dijkstra shortest path interface; usage is as follows for now

#include <cstdint>
#include <cstdio>

#include <tinygraph/tinygraph.hpp>


int main() {
  const std::vector<std::uint32_t> sources = {0, 1, 2};
  const std::vector<std::uint32_t> targets = {1, 2, 3};
  const std::vector<std::uint16_t> weights = {1, 1, 1};

  const auto graph = tg::graph{sources, targets, tg::edges_are_sorted};

  auto dijkstra = tg::dijkstra{graph, weights};

  if (dijkstra.shortest_path(0, 3)) {
    printf("distance=%ju\n", (uintmax_t)dijkstra.get_distance());

    std::vector<std::uint32_t> path;

    if (dijkstra.get_path(path)) {
      printf("path=");

      for (const auto n : path) {
        printf("%ju ", (uintmax_t)n);
      }

      printf("\n");
    }
  }
}

I thought about adding a graph.shortest_path(s, t) function but that hides the fact that the dijkstra context allocates graph and weight dependant data structures such as heap, bitset, etc. Having it separate makes the API a bit more low level but exposes more control over what you need and when you need it.

We need to think about this before we merge.

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