Add a CMake example

.github/workflows/build_and_test.yml

@@ -108,3 +108,16 @@ jobs:
         run: |
           cd examples/bazel
           bazelisk build --lockfile_mode=off //...
+
+  cmake_example:
+    name: Build CMake example
+    runs-on: "ubuntu-22.04"
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build
+        run: |
+          cd examples/cmake
+          BUILD_DIR="$(mktemp -d)"
+          cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -S . -B "${BUILD_DIR}" && \
+            cmake --build "${BUILD_DIR}" -- -v && \
+            ${BUILD_DIR}/jsonnet_cmake_example

examples/cmake/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.15...4.1)
+
+project(jsonnet_cmake_example VERSION 1.0 LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# Can use add_subdirectory to point to the jsonnet source.
+# Disable tests (force BUILD_TEST OFF) so that jsonnet doesn't pull in GoogleTest.
+# Use EXCLUDE_FROM_ALL so that targets won't be built if nothing depends on them.
+set(BUILD_TESTS OFF CACHE BOOL "" FORCE)
+add_subdirectory(
+    ${CMAKE_CURRENT_SOURCE_DIR}/../..
+    ${CMAKE_CURRENT_BINARY_DIR}/jsonnet
+    EXCLUDE_FROM_ALL
+)
+
+add_executable(jsonnet_cmake_example main.cpp)
+target_link_libraries(jsonnet_cmake_example PRIVATE jsonnet_cpp_static)

examples/cmake/main.cpp

@@ -0,0 +1,18 @@
+#include <iostream>
+#include <string>
+#include <libjsonnet++.h>
+
+int main(int argc, char **argv) {
+    jsonnet::Jsonnet vm;
+    vm.init();
+    std::string code = "local c=3;{a:1,b:2,c:c}";
+    std::string output;
+    std::cout << "evaluating " << code << std::endl;
+    if (vm.evaluateSnippet("-", code, &output)) {
+        std::cout << "result:\n" << output << std::endl;
+        return 0;
+    } else {
+        std::cout << "FAILURE:\n" << vm.lastError() << std::endl;
+        return 1;
+    }
+}