examples: implement imports-exports

Author: Afirium

examples/imports-exports.zig

@@ -0,0 +1,75 @@
+const std = @import("std");
+const wasmer = @import("wasmer");
+const assert = std.debug.assert;
+
+var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+const allocator = gpa.allocator();
+
+const wat =
+    \\(module
+    \\   (func $host_function (import "" "host_function"))
+    \\   ;; (global $host_global (import "env" "host_global") i32)
+    \\   (func $function (export "guest_function") (result i32) (global.get $global))
+    \\   (global $global (export "guest_global") i32 (i32.const 42))
+    \\   (table $table (export "guest_table") 1 1 funcref)
+    \\   (memory $memory (export "guest_memory") 1)
+    \\)
+;
+
+fn host_func_callback() void {
+    std.log.info("Calling back...\n> ", .{});
+}
+
+pub fn main() !void {
+    run() catch |err| {
+        const err_msg = try wasmer.lastError(std.heap.c_allocator);
+        defer std.heap.c_allocator.free(err_msg);
+
+        std.log.err("{s}", .{err_msg});
+
+        return err;
+    };
+}
+
+pub fn run() !void {
+    var wasm_bytes = try wasmer.watToWasm(wat);
+    defer wasm_bytes.deinit();
+
+    std.log.info("creating the store...", .{});
+
+    const engine = try wasmer.Engine.init();
+    defer engine.deinit();
+    const store = try wasmer.Store.init(engine);
+    defer store.deinit();
+
+    std.log.info("compiling module...", .{});
+
+    const module = try wasmer.Module.init(store, wasm_bytes.toSlice());
+    defer module.deinit();
+
+    std.log.info("creating the imported function...", .{});
+
+    const host_func = try wasmer.Func.init(store, host_func_callback);
+    // defer host_func.deinit();
+
+    // std.log.info("Creating the imported global...", .{});
+
+    std.log.info("instantiating module...", .{});
+
+    const instance = try wasmer.Instance.init(store, module, &.{host_func});
+    defer instance.deinit();
+
+    std.log.info("retrieving exports...", .{});
+
+    const guest_function = instance.getExportFunc(module, "guest_function") orelse {
+        std.log.err("failed to retrieve \"guest_function\" export from instance", .{});
+        return error.ExportNotFound;
+    };
+    defer guest_function.deinit();
+
+    const memory = instance.getExportMem(module, "guest_memory") orelse {
+        std.log.err("failed to retrieve \"guest_memory\" export from instance", .{});
+        return error.ExportNotFound;
+    };
+    defer memory.deinit();
+}