n-api: add support for abi stable module API

Add support for abi stable module API (N-API) as "Experimental feature".
The goal of this API is to provide a stable Node API for native
module developers. N-API aims to provide ABI compatibility guarantees
across different Node versions and also across different
Node VMs - allowing N-API enabled native modules to just work
across different versions and flavors of Node.js without recompilation.

A more detailed introduction is provided in:
https://github.com/nodejs/node-eps/blob/master/005-ABI-Stable-Module-API.md
and https://github.com/nodejs/abi-stable-node/blob/doc/VM%20Summit.pdf.

The feature, during its experimental state, will be guarded by a runtime
flag "--napi-modules". Only when this flag is added to the command line
will N-API modules along with regular non N-API modules be supported.

The API is defined by the methods in "src/node_api.h" and
"src/node_api_types.h". This is the best
starting point to review the API surface. More documentation will follow.

In addition to the implementation of the API using V8, which is included
in this PR, the API has also been validated against chakracore and that
port is available in
https://github.com/nodejs/abi-stable-node/tree/api-prototype-chakracore-8.x.

The current plan is to provide N-API support in versions 8.X and 6.X
directly. For older versions, such as 4.X or pre N-API versions of 6.X,
we plan to create an external npm module to provide a migration path
that will allow modules targeting older Node.js versions to use the API,
albeit without getting the advantage of not having to recompile.

In addition, we also plan an external npm package with C++ sugar to
simplify the use of the API. The sugar will be in-line only and will
only use the exported N-API methods but is not part of the N-API
itself. The current version is in:
https://github.com/nodejs/node-api.

This PR is a result of work in the abi-stable-node repo:
https://github.com/nodejs/abi-stable-node/tree/doc,
with this PR being the cumulative work on the api-prototype-8.x
branch with the following contributors in alphabetical order:

Author: Arunesh Chandra <arunesh.chandra@microsoft.com>
Author: Gabriel Schulhof <gabriel.schulhof@intel.com>
Author: Hitesh Kanwathirtha <hiteshk@microsoft.com>
Author: Ian Halliday <ianhall@microsoft.com>
Author: Jason Ginchereau <jasongin@microsoft.com>
Author: Michael Dawson <michael_dawson@ca.ibm.com>
Author: Sampson Gao <sampsong@ca.ibm.com>
Author: Taylor Woll <taylor.woll@microsoft.com>
PR-URL: https://github.com/nodejs/node/pull/11975
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 95 insertions, 0 deletions

diff --git a/src/node_api_types.h b/src/node_api_types.h
new file mode 100644
index 0000000000..7cb242368a
--- /dev/null
+++ b/src/node_api_types.h
@@ -0,0 +1,95 @@
+#ifndef SRC_NODE_API_TYPES_H_
+#define SRC_NODE_API_TYPES_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#if !defined __cplusplus || (defined(_MSC_VER) && _MSC_VER < 1900)
+    typedef uint16_t char16_t;
+#endif
+
+// JSVM API types are all opaque pointers for ABI stability
+// typedef undefined structs instead of void* for compile time type safety
+typedef struct napi_env__ *napi_env;
+typedef struct napi_value__ *napi_value;
+typedef struct napi_ref__ *napi_ref;
+typedef struct napi_handle_scope__ *napi_handle_scope;
+typedef struct napi_escapable_handle_scope__ *napi_escapable_handle_scope;
+typedef struct napi_callback_info__ *napi_callback_info;
+
+typedef void (*napi_callback)(napi_env env,
+                              napi_callback_info info);
+typedef void (*napi_finalize)(napi_env env,
+                              void* finalize_data,
+                              void* finalize_hint);
+
+typedef enum {
+  napi_default = 0,
+  napi_read_only = 1 << 0,
+  napi_dont_enum = 1 << 1,
+  napi_dont_delete = 1 << 2,
+
+  // Used with napi_define_class to distinguish static properties
+  // from instance properties. Ignored by napi_define_properties.
+  napi_static_property = 1 << 10,
+} napi_property_attributes;
+
+typedef struct {
+  const char* utf8name;
+
+  napi_callback method;
+  napi_callback getter;
+  napi_callback setter;
+  napi_value value;
+
+  napi_property_attributes attributes;
+  void* data;
+} napi_property_descriptor;
+
+typedef enum {
+  // ES6 types (corresponds to typeof)
+  napi_undefined,
+  napi_null,
+  napi_boolean,
+  napi_number,
+  napi_string,
+  napi_symbol,
+  napi_object,
+  napi_function,
+  napi_external,
+} napi_valuetype;
+
+typedef enum {
+  napi_int8_array,
+  napi_uint8_array,
+  napi_uint8_clamped_array,
+  napi_int16_array,
+  napi_uint16_array,
+  napi_int32_array,
+  napi_uint32_array,
+  napi_float32_array,
+  napi_float64_array,
+} napi_typedarray_type;
+
+typedef enum {
+  napi_ok,
+  napi_invalid_arg,
+  napi_object_expected,
+  napi_string_expected,
+  napi_function_expected,
+  napi_number_expected,
+  napi_boolean_expected,
+  napi_array_expected,
+  napi_generic_failure,
+  napi_pending_exception,
+  napi_status_last
+} napi_status;
+
+typedef struct {
+  const char* error_message;
+  void* engine_reserved;
+  uint32_t engine_error_code;
+  napi_status error_code;
+} napi_extended_error_info;
+
+#endif  // SRC_NODE_API_TYPES_H_