add an example to use toywasm as a library

examples/app/CMakeLists.txt

@@ -0,0 +1,17 @@
+cmake_minimum_required(VERSION 3.16)
+
+project(app LANGUAGES C)
+
+find_package(toywasm REQUIRED)
+
+set(app_sources
+	"app.c"
+)
+
+add_executable(app ${app_sources})
+target_link_libraries(app toywasm-lib)
+
+# XXX the library is built with short enum.
+# maybe we can use INTERFACE_COMPILE_OPTIONS.
+# but i feel a bit uncomfortable with it.
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fshort-enums")

examples/app/app.c

@@ -0,0 +1,46 @@
+#include <inttypes.h>
+#include <stdlib.h>
+
+#include <toywasm/fileio.h>
+#include <toywasm/load_context.h>
+#include <toywasm/module.h>
+#include <toywasm/type.h>
+#include <toywasm/xlog.h>
+
+int
+main(int argc, char **argv)
+{
+        xlog_printf("hello\n");
+        if (argc != 2) {
+                xlog_error("unexpected number of args");
+                exit(2);
+        }
+        const char *filename = argv[1];
+
+        struct module *m;
+        int ret;
+        uint8_t *p;
+        size_t sz;
+        ret = map_file(filename, (void **)&p, &sz);
+        if (ret != 0) {
+                xlog_error("map_file failed with %d", ret);
+                exit(1);
+        }
+        ret = module_create(&m);
+        if (ret != 0) {
+                xlog_error("module_create failed with %d", ret);
+                exit(1);
+        }
+        struct load_context ctx;
+        load_context_init(&ctx);
+        ret = module_load(m, p, p + sz, &ctx);
+        if (ret != 0) {
+                xlog_error("module_load failed with %d", ret);
+                exit(1);
+        }
+        xlog_printf("module %s imports %" PRIu32 " functions\n", filename,
+                    m->nimportedfuncs);
+        xlog_printf("module %s contains %" PRIu32 " functions\n", filename,
+                    m->nfuncs);
+        exit(0);
+}