WIP: Rust wrapper

.github/workflows/linux-ci.yml

@@ -111,6 +111,14 @@ jobs:
           cmake -B build -GNinja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=RelWithDebInfo -DMLN_WITH_CLANG_TIDY=ON -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DMLN_WITH_COVERAGE=ON ${{ env.renderer_flag_cmake }}
           cmake --build build --target mbgl-core mbgl-test-runner mbgl-render-test-runner mbgl-expression-test mbgl-render mbgl-benchmark-runner
 
+      # test rust platform
+      - if: matrix.renderer == 'drawable-rust'
+        uses: taiki-e/install-action@v2
+        with: { tool: just }
+      - if: matrix.renderer == 'drawable-rust'
+        run: just -v ci-test
+        working-directory: platform/rust
+
       # mbgl-render (used for size test) & mbgl-benchmark-runner
 
       - name: Upload mbgl-render as artifact

.github/workflows/rust-ci.yaml

@@ -9,13 +9,20 @@ on:
 
 defaults:
   run:
-    shell: bash
     working-directory: rustutils/
 
 jobs:
   test:
     name: Rust tests
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: true
+      matrix:
+        include:
+          - os: macos-latest  # M-series CPU
+          - os: macos-13  # x64 CPU
+          - os: windows-latest
+          - os: ubuntu-latest
     steps:
       - uses: taiki-e/install-action@v2
         with: { tool: just }

.gitignore

@@ -61,3 +61,8 @@ cache.sqlite-journal
 out.png
 /test/android/app/.cxx
 /test/android/app/build
+
+# Rust
+**/target/
+**/*.rs.bk
+**/*.profraw

.pre-commit-config.yaml

@@ -27,12 +27,16 @@ repos:
       args: [--swiftversion, "5.8"]
 -   repo: local
     hooks:
-    -   id: rustfmt
-        name: rustfmt
+    -   id: rustfmt_utils
+        name: rustfmt rustutils
         entry: bash -c 'cd rustutils && cargo fmt' --
         language: rust
         types: [rust]
+    -   id: rustfmt_platform
+        name: rustfmt rust platform
+        entry: bash -c 'cd platform/rust && cargo fmt' --
+        language: rust
+        types: [rust]
 ci:
   # sometimes fails https://github.com/keith/pre-commit-buildifier/issues/13
   skip: [buildifier]
-

CMakeLists.txt

@@ -1585,3 +1585,5 @@ endif()
 add_subdirectory(${PROJECT_SOURCE_DIR}/test)
 add_subdirectory(${PROJECT_SOURCE_DIR}/benchmark)
 add_subdirectory(${PROJECT_SOURCE_DIR}/render-test)
+
+include(cmake/mbgl-core-deps.cmake)

cmake/mbgl-core-deps.cmake

@@ -0,0 +1,33 @@
+# this file defines a target that will generate a mbgl-core-deps.txt which includes the linker
+# flags that would need to be passed to an executable or library that links with
+# the static mbgl-core library
+
+set(DUMMY_FILE "${CMAKE_BINARY_DIR}/dummy.cpp")
+add_custom_command(
+    OUTPUT ${DUMMY_FILE}
+    COMMAND ${CMAKE_COMMAND} -E echo "int main() {}" > ${DUMMY_FILE}
+    COMMENT "Generating dummy.cpp"
+    VERBATIM
+)
+
+# https://stackoverflow.com/questions/34165365/retrieve-all-link-flags-in-cmake
+set(CMAKE_ECHO_STANDARD_LIBRARIES ${CMAKE_CXX_STANDARD_LIBRARIES})
+set(CMAKE_ECHO_FLAGS ${CMAKE_CXX_FLAGS})
+set(CMAKE_ECHO_LINK_FLAGS ${CMAKE_CXX_LINK_FLAGS})
+set(CMAKE_ECHO_IMPLICIT_LINK_DIRECTORIES ${CMAKE_CXX_IMPLICIT_LINK_DIRECTORIES})
+set(
+    CMAKE_ECHO_LINK_EXECUTABLE 
+    "<CMAKE_COMMAND> -E echo \"<FLAGS> <LINK_FLAGS> <LINK_LIBRARIES>\" > <TARGET>"
+)
+
+add_executable(mbgl-core-deps EXCLUDE_FROM_ALL "${DUMMY_FILE}")
+target_link_libraries(mbgl-core-deps mbgl-core)
+add_custom_target(generate_dummy DEPENDS ${DUMMY_FILE})
+add_dependencies(mbgl-core-deps generate_dummy)
+
+set_target_properties(
+    mbgl-core-deps
+        PROPERTIES
+            LINKER_LANGUAGE ECHO
+            SUFFIX          ".txt"
+)

include/mbgl/util/tile_server_options.hpp

@@ -265,7 +265,7 @@ class TileServerOptions final {
     TileServerOptions& withDefaultStyles(std::vector<mbgl::util::DefaultStyle> styles);
 
     /**
-     * @brief Sets the default style by name. The style name must exists in
+     * @brief Sets the default style by name. The style name must exist in
      * defaultStyles collection
      *
      * @param defaultStyle The style name

platform/rust/.gitignore

@@ -0,0 +1,16 @@
+# Generated by Cargo
+# will have compiled files and executables
+**/target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# These are temp files generated by trybuild
+wip
+
+# coverage reports
+**/*.profraw

platform/rust/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+name = "maplibre-native"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+cxx = "1.0.138"
+clap = { version = "4.5.27", features = ["derive", "env"] }
+
+[dev-dependencies]
+insta = { version = "1.42.1" }
+
+[build-dependencies]
+cmake = "0.1"
+cxx-build = "1.0.138"
+rustversion = "1.0.19"
+walkdir = "2.5.0"
+build_support = { path = "./build_support" }
+
+[features]
+metal = [] # default on Apple platforms, do not add to default features
+opengl = []
+vulkan = []  # default on other platforms
+
+[workspace]
+members = [
+    "build_support",
+    "."
+]

platform/rust/build.rs

@@ -0,0 +1,122 @@
+use std::collections::HashSet;
+use std::env;
+use std::fs;
+use std::path::{Path, PathBuf};
+use walkdir::WalkDir;
+
+use build_support::parse_deps;
+
+/// Helper that returns a new cmake::Config with common settings.
+/// It selects the renderer based on Cargo features: the user must enable exactly one of:
+/// "metal", "opengl", or "vulkan". If none are explicitly enabled, on iOS/macOS the default is metal,
+/// and on all other platforms the default is vulkan.
+fn create_cmake_config(project_root: &Path) -> cmake::Config {
+    let mut cfg = cmake::Config::new(project_root);
+    cfg.generator("Ninja");
+    cfg.define("CMAKE_C_COMPILER_LAUNCHER", "ccache");
+    cfg.define("CMAKE_CXX_COMPILER_LAUNCHER", "ccache");
+    cfg.define("MLN_DRAWABLE_RENDERER", "ON");
+    cfg.define("MLN_WITH_OPENGL", "OFF");
+
+    let (metal_enabled, opengl_enabled, vulkan_enabled) = {
+        let metal = env::var("CARGO_FEATURE_METAL").is_ok();
+        let opengl = env::var("CARGO_FEATURE_OPENGL").is_ok();
+        let vulkan = env::var("CARGO_FEATURE_VULKAN").is_ok();
+        if !metal && !opengl && !vulkan {
+            if cfg!(target_os = "ios") || cfg!(target_os = "macos") {
+                (true, false, false)
+            } else {
+                (false, false, true)
+            }
+        } else {
+            (metal, opengl, vulkan)
+        }
+    };
+
+    let num_enabled = (metal_enabled as u8) + (opengl_enabled as u8) + (vulkan_enabled as u8);
+    if num_enabled > 1 {
+        panic!("Features 'metal', 'opengl', and 'vulkan' are mutually exclusive. Please enable only one.");
+    }
+
+    if opengl_enabled {
+        cfg.define("MLN_WITH_OPENGL", "ON");
+        cfg.define("MLN_WITH_METAL", "OFF");
+        cfg.define("MLN_WITH_VULKAN", "OFF");
+    } else if metal_enabled {
+        cfg.define("MLN_WITH_OPENGL", "OFF");
+        cfg.define("MLN_WITH_METAL", "ON");
+        cfg.define("MLN_WITH_VULKAN", "OFF");
+    } else if vulkan_enabled {
+        cfg.define("MLN_WITH_OPENGL", "OFF");
+        cfg.define("MLN_WITH_METAL", "OFF");
+        cfg.define("MLN_WITH_VULKAN", "ON");
+    }
+
+    cfg.define("MLN_WITH_WERROR", "OFF");
+    cfg
+}
+
+fn main() {
+    // Determine the project root (use the parent of CARGO_MANIFEST_DIR's parent to allow in‐source Windows builds).
+    let project_root = {
+        let manifest = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+        manifest.parent().unwrap().parent().unwrap().to_path_buf()
+    };
+
+    // ------------------------------------------------------------------------
+    // 1. Build the "mbgl-core-deps" target first so that mbgl-core-deps.txt is generated.
+    // Since CMake installs targets into a "build" subdirectory, we look for the file there.
+    // ------------------------------------------------------------------------
+    let deps_build_dir = create_cmake_config(&project_root)
+        .build_target("mbgl-core-deps")
+        .build();
+    let deps_file = deps_build_dir.join("build").join("mbgl-core-deps.txt");
+    let deps_contents = fs::read_to_string(&deps_file)
+        .unwrap_or_else(|_| panic!("Failed to read {}", deps_file.display()));
+
+    // Parse the deps file into a list of Cargo instructions.
+    let instructions = parse_deps(&deps_contents, &deps_build_dir.join("build"));
+    for instr in instructions {
+        println!("{}", instr);
+    }
+
+    // ------------------------------------------------------------------------
+    // 2. Build the actual "mbgl-core" target.
+    // ------------------------------------------------------------------------
+    let core_build_dir = create_cmake_config(&project_root)
+        .build_target("mbgl-core")
+        .build();
+    let static_lib_base = core_build_dir.join("build");
+    println!(
+        "cargo:rustc-link-search=native={}",
+        static_lib_base.display()
+    );
+
+    // ------------------------------------------------------------------------
+    // 3. Gather include directories and build the C++ bridge using cxx_build.
+    // ------------------------------------------------------------------------
+    let mut include_dirs = vec![
+        project_root.join("include"),
+        project_root.join("platform/default/include"),
+    ];
+    for entry in WalkDir::new(project_root.join("vendor")) {
+        let entry = entry.expect("Failed reading vendor directory");
+        if entry.file_type().is_dir() && !entry.path_is_symlink() && entry.file_name() == "include"
+        {
+            include_dirs.push(entry.path().to_path_buf());
+        }
+    }
+
+    cxx_build::bridge("src/lib.rs")
+        .includes(include_dirs)
+        .file("src/wrapper.cpp")
+        .flag_if_supported("-std=c++20")
+        .compile("maplibre_rust_bindings");
+
+    // ------------------------------------------------------------------------
+    // 4. Instruct Cargo when to re-run the build script.
+    // ------------------------------------------------------------------------
+    println!("cargo:rerun-if-changed=src/lib.rs");
+    println!("cargo:rerun-if-changed=src/wrapper.cpp");
+    println!("cargo:rerun-if-changed=include/tile_server_options.h");
+}

platform/rust/build_support/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "build_support"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]

platform/rust/build_support/src/lib.rs

@@ -0,0 +1,76 @@
+use std::collections::HashSet;
+use std::path::{Path, PathBuf};
+
+/// Parses the contents of mbgl-core-deps.txt and returns Cargo linker instructions.
+///
+/// # Arguments
+///
+/// * `deps_contents` - The contents of the dependency file as a string.
+/// * `static_lib_base` - The base directory where the static libraries reside.
+pub fn parse_deps(deps_contents: &str, static_lib_base: &Path) -> Vec<String> {
+    let mut instructions = Vec::new();
+    let mut added_search_paths = HashSet::new();
+    let tokens: Vec<&str> = deps_contents.split_whitespace().collect();
+    let mut token_iter = tokens.iter().peekable();
+
+    while let Some(&token) = token_iter.next() {
+        if token == "-framework" {
+            if let Some(&framework) = token_iter.next() {
+                instructions.push(format!("cargo:rustc-link-lib=framework={}", framework));
+            } else {
+                panic!("Expected a framework name after '-framework'");
+            }
+        } else if token.starts_with("-l") {
+            let libname = &token[2..];
+            instructions.push(format!("cargo:rustc-link-lib={}", libname));
+        } else if token.ends_with(".a") {
+            let lib_path = Path::new(token);
+            let file_stem = lib_path.file_stem().expect("Library file has no stem");
+            let file_stem = file_stem
+                .to_str()
+                .expect("Library file stem is not valid UTF-8");
+            let lib_name = file_stem.strip_prefix("lib").unwrap_or(file_stem);
+
+            let search_dir = match lib_path.parent() {
+                Some(parent) if !parent.as_os_str().is_empty() => static_lib_base.join(parent),
+                _ => static_lib_base.to_path_buf(),
+            };
+            if added_search_paths.insert(search_dir.clone()) {
+                instructions.push(format!(
+                    "cargo:rustc-link-search=native={}",
+                    search_dir.display()
+                ));
+            }
+            instructions.push(format!("cargo:rustc-link-lib=static={}", lib_name));
+        } else {
+            instructions.push(format!("cargo:rustc-link-arg={}", token));
+        }
+    }
+    instructions
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::path::PathBuf;
+
+    #[test]
+    fn test_parse_deps() {
+        // Simulate a deps file with:
+        //   - "-lsqlite3" (link sqlite3)
+        //   - "libmbgl-core.a" (a static library with no parent directory)
+        //   - "-framework AppKit"
+        //   - "some_arg" (an extra linker argument)
+        let deps_content = "-lsqlite3 libmbgl-core.a -framework AppKit some_arg";
+        let base_dir = PathBuf::from("/build_dir/build");
+        let instructions = parse_deps(deps_content, &base_dir);
+        let expected = vec![
+            "cargo:rustc-link-lib=sqlite3".to_string(),
+            format!("cargo:rustc-link-search=native={}", base_dir.display()),
+            "cargo:rustc-link-lib=static=mbgl-core".to_string(),
+            "cargo:rustc-link-lib=framework=AppKit".to_string(),
+            "cargo:rustc-link-arg=some_arg".to_string(),
+        ];
+        assert_eq!(instructions, expected);
+    }
+}