feat: Add C API for host functions + support for C++, Python, Go, Node, OCaml

Makefile

@@ -18,15 +18,12 @@ else
 	FEATURE_FLAGS=--features $(FEATURES)
 endif
 
-
-.PHONY: build
+build:
+	cargo build --release $(FEATURE_FLAGS) --manifest-path libextism/Cargo.toml
 
 lint:
 	cargo clippy --release --no-deps --manifest-path runtime/Cargo.toml
 
-build:
-	cargo build --release $(FEATURE_FLAGS) --manifest-path libextism/Cargo.toml
-
 debug:
 	RUSTFLAGS=-g $(MAKE) build
 

c/main.c

@@ -9,6 +9,21 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
+void hello_world(ExtismCurrentPlugin *plugin, const struct ExtismVal *inputs,
+                 uint64_t n_inputs, struct ExtismVal *outputs,
+                 uint64_t n_outputs, void *data) {
+  puts("Hello from C!");
+  puts(data);
+
+  ExtismSize ptr_offs = inputs[0].v.i64;
+
+  uint8_t *buf = extism_current_plugin_memory(plugin) + ptr_offs;
+  uint64_t length = extism_current_plugin_memory_length(plugin, ptr_offs);
+  fwrite(buf, length, 1, stdout);
+  fputc('\n', stdout);
+  outputs[0].v.i64 = inputs[0].v.i64;
+}
+
 uint8_t *read_file(const char *filename, size_t *len) {
 
   FILE *fp = fopen(filename, "rb");
@@ -41,13 +56,17 @@ int main(int argc, char *argv[]) {
   ExtismContext *ctx = extism_context_new();
 
   size_t len = 0;
-  uint8_t *data = read_file("../wasm/code.wasm", &len);
-  ExtismPlugin plugin = extism_plugin_new(ctx, data, len, false);
+  uint8_t *data = read_file("../wasm/code-functions.wasm", &len);
+  ExtismValType inputs[] = {I64};
+  ExtismValType outputs[] = {I64};
+  ExtismFunction *f = extism_function_new("hello_world", inputs, 1, outputs, 1,
+                                          hello_world, "Hello, again!", NULL);
+  ExtismPlugin plugin = extism_plugin_new(ctx, data, len, &f, 1, true);
   free(data);
   if (plugin < 0) {
+    puts(extism_error(ctx, -1));
     exit(1);
   }
-
   assert(extism_plugin_call(ctx, plugin, "count_vowels", (uint8_t *)argv[1],
                             strlen(argv[1])) == 0);
   ExtismSize out_len = extism_plugin_output_length(ctx, plugin);
@@ -56,6 +75,7 @@ int main(int argc, char *argv[]) {
   write(STDOUT_FILENO, "\n", 1);
 
   extism_plugin_free(ctx, plugin);
+  extism_function_free(f);
   extism_context_free(ctx);
   return 0;
 }

cpp/Makefile

@@ -1,14 +1,14 @@
 FLAGS=`pkg-config --cflags --libs jsoncpp gtest` -lextism -lpthread
 
 build-example:
-	$(CXX) -std=c++11 -o example -I. example.cpp $(FLAGS)
+	$(CXX) -std=c++14 -o example -I. example.cpp $(FLAGS)
 
 .PHONY: example
 example: build-example
 	./example
 
 build-test:
-	$(CXX) -std=c++11 -o test/test -I. test/test.cpp $(FLAGS)
+	$(CXX) -std=c++14 -o test/test -I. test/test.cpp $(FLAGS)
 
 .PHONY: test
 test: build-test

cpp/example.cpp

@@ -14,10 +14,27 @@ std::vector<uint8_t> read(const char *filename) {
 }
 
 int main(int argc, char *argv[]) {
-  auto wasm = read("../wasm/code.wasm");
+  auto wasm = read("../wasm/code-functions.wasm");
   Context context = Context();
+  std::string tmp = "Testing";
 
-  Plugin plugin = context.plugin(wasm);
+  // A lambda can be used as a host function
+  auto hello_world = [&tmp](CurrentPlugin plugin,
+                            const std::vector<Val> &inputs,
+                            std::vector<Val> &outputs, void *user_data) {
+    std::cout << "Hello from C++" << std::endl;
+    std::cout << (const char *)user_data << std::endl;
+    std::cout << tmp << std::endl;
+    outputs[0].v = inputs[0].v;
+  };
+
+  std::vector<Function> functions = {
+      Function("hello_world", {ValType::I64}, {ValType::I64}, hello_world,
+               (void *)"Hello again!",
+               [](void *x) { std::cout << "Free user data" << std::endl; }),
+  };
+
+  Plugin plugin = context.plugin(wasm, true, functions);
 
   const char *input = argc > 1 ? argv[1] : "this is a test";
   ExtismSize length = strlen(input);