[GDNative] added API struct wrapper generator

Previously functions of the GDNative API were accessed by letting
the loader at load-time resolve the symbols. This causes troubles on
Windows (...sigh...), so now the GDNative API isn't exported anymore.

This means, that a library that wants to call a GDNative function
needs to access it via a struct of pointers that's passed to it at
right after the library was loaded. To make the usage easier, those
function pointers in the struct can be wrapped in actual function in
the global scope. This commit adds a generator for that wrapper code.

4 files changed, 71 insertions, 54 deletions

diff --git a/modules/gdnative/SCsub b/modules/gdnative/SCsub
index 31178be973..4e5f155f45 100644
--- a/modules/gdnative/SCsub
+++ b/modules/gdnative/SCsub
@@ -10,7 +10,6 @@ gdn_env.add_source_files(env.modules_sources, "register_types.cpp")
 gdn_env.add_source_files(env.modules_sources, "gdnative/*.cpp")
 gdn_env.add_source_files(env.modules_sources, "nativescript/*.cpp")
 
-gdn_env.Append(CPPFLAGS=['-DGDAPI_BUILT_IN'])
 gdn_env.Append(CPPPATH=['#modules/gdnative/include/'])
 
 def _spaced(e):
@@ -25,6 +24,8 @@ def _build_gdnative_api_struct_header(api):
         '#include <gdnative/gdnative.h>',
         '#include <nativescript/godot_nativescript.h>',
         '',
+        '#define GDNATIVE_API_INIT(options) do { extern const godot_gdnative_api_struct *_gdnative_wrapper_api_struct; _gdnative_wrapper_api_struct = options->api_struct; } while (0)',
+        '',
         '#ifdef __cplusplus',
         'extern "C" {',
         '#endif',
@@ -81,7 +82,68 @@ _, gensource = gdn_env.Command(['include/gdnative_api_struct.gen.h', 'gdnative_a
                                'gdnative_api.json', build_gdnative_api_struct)
 gdn_env.add_source_files(env.modules_sources, [gensource])
 
-if "platform" in env and env["platform"] in ["x11", "iphone"]:
-    env.Append(LINKFLAGS=["-rdynamic"])
-
 env.use_ptrcall = True
+
+
+def _build_gdnative_wrapper_code(api):
+    out = [
+        '/* THIS FILE IS GENERATED DO NOT EDIT */',
+        '',
+        '#include <gdnative/gdnative.h>',
+        '#include <nativescript/godot_nativescript.h>',
+        '',
+        '#include <gdnative_api_struct.gen.h>',
+        '',
+        'godot_gdnative_api_struct *_gdnative_wrapper_api_struct = 0;',
+        '',
+        '#ifdef __cplusplus',
+        'extern "C" {',
+        '#endif',
+        ''
+    ]
+
+    for funcname, funcdef in api['api'].items():
+        args = ', '.join(['%s%s' % (_spaced(t), n) for t, n in funcdef['arguments']])
+        out.append('%s %s(%s) {' % (_spaced(funcdef['return_type']), funcname, args))
+
+        args = ', '.join(['%s' % n for t, n in funcdef['arguments']])
+
+        return_line = '\treturn ' if funcdef['return_type'] != 'void' else '\t'
+        return_line += '_gdnative_wrapper_api_struct->' + funcname + '(' + args + ');'
+
+        out.append(return_line)
+        out.append('}')
+        out.append('')
+
+    out += [
+        '#ifdef __cplusplus',
+        '}',
+        '#endif'
+    ]
+
+    return '\n'.join(out)
+
+
+def build_gdnative_wrapper_code(target, source, env):
+    import json
+    with open(source[0].path, 'r') as fd:
+#Keep the json ordered
+        api = json.load(fd)
+
+    wrapper_file = target[0]
+    with open(wrapper_file.path, 'w') as fd:
+        fd.write(_build_gdnative_wrapper_code(api))
+
+
+
+if ARGUMENTS.get('gdnative_wrapper', False):
+    #build wrapper code
+    gdn_env.Command('gdnative_wrapper_code.gen.cpp', 'gdnative_api.json', build_gdnative_wrapper_code)
+
+    gd_wrapper_env = env.Clone()
+    gd_wrapper_env.Append(CPPPATH=['#modules/gdnative/include/'])
+
+    # I think this doesn't work on MSVC yet...
+    gd_wrapper_env.Append(CCFLAGS=['-fPIC'])
+
+    gd_wrapper_env.Library("#bin/gdnative_wrapper_code", ["#modules/gdnative/gdnative_wrapper_code.gen.cpp"])
diff --git a/modules/gdnative/gdnative_api.json b/modules/gdnative/gdnative_api.json
index 9e66f6952b..8b6593c9c3 100644
--- a/modules/gdnative/gdnative_api.json
+++ b/modules/gdnative/gdnative_api.json
@@ -3334,7 +3334,7 @@
       "arguments": [
         ["godot_variant *", "p_self"],
         ["const godot_string *", "p_method"],
-        ["const godot_variant *", "*p_args"],
+        ["const godot_variant **", "p_args"],
         ["const godot_int", "p_argcount"],
         ["godot_variant_call_error *", "r_error"]
       ]
@@ -3889,7 +3889,7 @@
       "return_type": "double",
       "arguments": [
         ["const wchar_t *", "p_str"],
-        ["const wchar_t *", "*r_end"]
+        ["const wchar_t **", "r_end"]
       ]
     },
     "godot_string_get_slice_count": {
@@ -4390,7 +4390,7 @@
       "arguments": [
         ["godot_method_bind *", "p_method_bind"],
         ["godot_object *", "p_instance"],
-        ["const void *", "*p_args"],
+        ["const void **", "p_args"],
         ["void *", "p_ret"]
       ]
     },
@@ -4399,7 +4399,7 @@
       "arguments": [
         ["godot_method_bind *", "p_method_bind"],
         ["godot_object *", "p_instance"],
-        ["const godot_variant *", "*p_args"],
+        ["const godot_variant **", "p_args"],
         ["const int", "p_arg_count"],
         ["godot_variant_call_error *", "p_call_error"]
       ]
diff --git a/modules/gdnative/include/gdnative/gdnative.h b/modules/gdnative/include/gdnative/gdnative.h
index 9134f1c581..008968a5e5 100644
--- a/modules/gdnative/include/gdnative/gdnative.h
+++ b/modules/gdnative/include/gdnative/gdnative.h
@@ -34,18 +34,9 @@
 extern "C" {
 #endif
 
-#ifdef GDAPI_BUILT_IN
-#define GDAPI_EXPORT
-#endif
-
 #ifdef _WIN32
-#if defined(GDAPI_EXPORT)
-#define GDCALLINGCONV
-#define GDAPI __declspec(dllexport) GDCALLINGCONV
-#else
 #define GDCALLINGCONV
-#define GDAPI __declspec(dllimport) GDCALLINGCONV
-#endif
+#define GDAPI GDCALLINGCONV
 #elif defined(__APPLE__)
 #include "TargetConditionals.h"
 #if TARGET_OS_IPHONE
diff --git a/modules/gdnative/include/nativescript/godot_nativescript.h b/modules/gdnative/include/nativescript/godot_nativescript.h
index 5095b7a83e..8baff0fff9 100644
--- a/modules/gdnative/include/nativescript/godot_nativescript.h
+++ b/modules/gdnative/include/nativescript/godot_nativescript.h
@@ -36,42 +36,6 @@
 extern "C" {
 #endif
 
-#ifdef GDAPI_BUILT_IN
-#define GDAPI_EXPORT
-#endif
-
-#ifdef _WIN32
-#if defined(GDAPI_EXPORT)
-#define GDCALLINGCONV
-#define GDAPI __declspec(dllexport) GDCALLINGCONV
-#else
-#define GDCALLINGCONV
-#define GDAPI __declspec(dllimport) GDCALLINGCONV
-#endif
-#elif defined(__APPLE__)
-#include "TargetConditionals.h"
-#if TARGET_OS_IPHONE
-#define GDCALLINGCONV __attribute__((visibility("default")))
-#define GDAPI GDCALLINGCONV
-#elif TARGET_OS_MAC
-#define GDCALLINGCONV __attribute__((sysv_abi))
-#define GDAPI GDCALLINGCONV
-#endif
-#else
-#define GDCALLINGCONV __attribute__((sysv_abi, visibility("default")))
-#define GDAPI GDCALLINGCONV
-#endif
-
-// This is for libraries *using* the header, NOT GODOT EXPOSING STUFF!!
-#ifdef _WIN32
-#define GDN_EXPORT __declspec(dllexport)
-#else
-#define GDN_EXPORT
-#endif
-
-#include <stdbool.h>
-#include <stdint.h>
-
 typedef enum {
 	GODOT_METHOD_RPC_MODE_DISABLED,
 	GODOT_METHOD_RPC_MODE_REMOTE,