From 5e11202e3b381f8f19b55e96ef19d79709fdf4d5 Mon Sep 17 00:00:00 2001
From: Ivan Enderlin <ivan@mnt.io>
Date: Fri, 18 Sep 2020 14:49:39 +0200
Subject: [PATCH] feat: Ability to give WAT to `NewModule`.

---
 wasmer/module.go | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/wasmer/module.go b/wasmer/module.go
index 97eafbbe..f190f882 100644
--- a/wasmer/module.go
+++ b/wasmer/module.go
@@ -1,16 +1,17 @@
 package wasmer
 
 // #include <wasmer_wasm.h>
+// #include <stdio.h>
 //
 // // We can't create a `wasm_byte_vec_t` directly in Go otherwise cgo
 // // complains with “Go pointer to Go pointer”. The hack consists at
 // // creating the `wasm_byte_vec_t` directly in C.
-// own wasm_module_t* go_wasm_module_new(wasm_store_t *store, uint8_t *bytes, size_t bytes_length) {
+// own wasm_module_t* to_wasm_module_new(wasm_store_t *store, uint8_t *bytes, size_t bytes_length) {
 //     wasm_byte_vec_t wasm_bytes;
 //     wasm_bytes.size = bytes_length;
 //     wasm_bytes.data = (wasm_byte_t*) bytes;
 //
-//    return wasm_module_new(store, &wasm_bytes);
+//     return wasm_module_new(store, &wasm_bytes);
 // }
 import "C"
 import (
@@ -18,8 +19,8 @@ import (
 	"unsafe"
 )
 
-// A WebAssembly module contains stateless WebAssembly code that has
-// already been compiled and can be instantiated multiple times.
+// Module contains stateless WebAssembly code that has already been
+// compiled and can be instantiated multiple times.
 //
 // Creates a new WebAssembly Module given the configuration
 // in the store.
@@ -37,25 +38,36 @@ type Module struct {
 }
 
 func NewModule(store *Store, bytes []byte) (*Module, error) {
-	var bytesPtr *C.uint8_t
+	// If `bytes` contains a Wasm module with the WAT format,
+	// compile it to Wasm bytes.
+	// If it does not, it will return the same bytes.
+	wasmBytes, err := Wat2Wasm(string(bytes))
 
-	if len(bytes) > 0 {
-		bytesPtr = (*C.uint8_t)(unsafe.Pointer(&bytes[0]))
+	if err != nil {
+		return nil, err
+	}
+
+	var wasmBytesPtr *C.uint8_t
+	wasmBytesLength := len(wasmBytes)
+
+	if wasmBytesLength > 0 {
+		wasmBytesPtr = (*C.uint8_t)(unsafe.Pointer(&wasmBytes[0]))
 	}
 
 	module := &Module{
-		_inner: C.go_wasm_module_new(store.inner(), bytesPtr, C.size_t(len(bytes))),
+		_inner: C.to_wasm_module_new(store.inner(), wasmBytesPtr, C.size_t(wasmBytesLength)),
+	}
+
+	if module._inner == nil {
+		return nil, newErrorFromWasmer()
 	}
 
 	runtime.KeepAlive(bytes)
+	runtime.KeepAlive(wasmBytes)
 	runtime.SetFinalizer(module, func(module *Module) {
 		C.wasm_module_delete(module.inner())
 	})
 
-	if module == nil {
-		return nil, newError()
-	}
-
 	return module, nil
 }