6.6 KiB
napi-macros
Set of utility macros to make writing N-API modules a little easier.
npm install napi-macros
Then add the following to your target in your binding.gyp file
"include_dirs": [
"<!(node -e \"require('napi-macros')\")"
],
These patterns mostly reflect how I use N-API so far. Feel free to PR more.
Usage
#include <node_api.h>
#include <napi-macros.h>
NAPI_METHOD(times_two) {
NAPI_ARGV(1)
NAPI_ARGV_INT32(number, 0)
number *= 2;
NAPI_RETURN_INT32(number)
}
NAPI_INIT() {
NAPI_EXPORT_FUNCTION(times_two)
}
Full working example can be found in the example/ folder.
API
NAPI_INIT()
Setup init boilerplate. Pass the function body after.
static char *my_string = "hello";
NAPI_INIT() {
EXPORT_STRING(my_string)
}
NAPI_METHOD(name)
Setup method boilerplate. Pass the function body after.
NAPI_METHOD(add) {
NAPI_ARGV(2)
NAPI_ARGV_INT32(a, 0)
NAPI_ARGV_INT32(b, 1)
a = a + b
NAPI_RETURN_INT32(a)
}
NAPI_ARGV(n)
Setup up argv boilerplate. n is how many arguments you are expecting.
Expects the napi_env to be in scope as env and the napi_callback_info to be in scope as info.
NAPI_ARGV_BUFFER(name, index)
Get a buffer out of the arguments at the corresponding index.
Sets char *name and size_t name_len with the buffer and buffer length.
NAPI_ARGV_BUFFER_CAST(type, name, index)
Get a buffer out and cast the pointer to the specified type. Note that the type should include the pointer star, i.e.
NAPI_ARGV_BUFFER_CAST(uv_udp_t *, handle, 0)
Will cast the 1st argument as uv_udp_t pointer.
NAPI_ARGV_UINT32(name, index)
Get an argument as a uint32. Will throw if argument is not the right type.
NAPI_ARGV_INT32(name, index)
Get an argument as an int32. Will throw if argument is not the right type.
NAPI_ARGV_UTF8(name, length, index)
Get an argument as a utf8 string.
name will be a char[length] array.
Will throw if argument is not the right type.
NAPI_ARGV_UTF8_MALLOC(name, index)
Get an argument as a utf8 string.
name will be a char*.
Like NAPI_ARGV_UTF8() but allocates name on the heap using malloc(), which should be free()'d after usage.
NAPI_BUFFER_CAST(type, name, var)
Same as NAPI_ARGV_BUFFER_CAST but takes a generic napi_value variable instead of an argv index.
NAPI_BUFFER(name, var)
Same as NAPI_ARGV_BUFFER but takes a generic napi_value variable instead of an argv index.
NAPI_UTF8(name, size, var)
Same as NAPI_ARGV_UTF8 but takes a generic napi_value variable instead of an argv index.
NAPI_UTF8_MALLOC(name, var)
Same as NAPI_ARGV_UTF8_MALLOC but takes a generic napi_value variable instead of an argv index.
NAPI_UINT32(name, var)
Same as NAPI_ARGV_UINT32 but takes a generic napi_value variable instead of an argv index.
NAPI_INT32(name, var)
Same as NAPI_ARGV_INT32 but takes a generic napi_value variable instead of an argv index.
NAPI_EXPORT_FUNCTION(fn)
Will export a function in the Init method. Expects the env and exports to be in scope.
The name of the exported function is the same name as the c function.
NAPI_EXPORT_SIZEOF(struct)
Export the size of a strict. The exported name is sizeof_{struct-name}.
NAPI_EXPORT_UINT32(name)
Export a uint32. The name of the exported number is the same name as the c variable.
NAPI_EXPORT_INT32(name)
Export an int32. The name of the exported number is the same name as the c variable.
NAPI_EXPORT_UTF8(name, len)
Export a utf8 string. len should be the length of the string.
The name of the exported string is the same name as the c variable.
NAPI_EXPORT_STRING(name)
Export a null terminated string. The name of the exported string is the same name as the c variable.
NAPI_EXPORT_SIZEOF(type)
Exports sizeof(type).
The name of the exported number is the same name as the c variable.
NAPI_EXPORT_SIZEOF_STRUCT(structName)
Exports sizeof(struct structName).
The name of the exported number is the same name as the c variable.
NAPI_EXPORT_ALIGNMENTOF(type)
Exports the byte alignment of type.
The name of the exported number is the same name as the c variable.
NAPI_EXPORT_ALIGNMENTOF_STRUCT(structName)
Exports the byte alignment of struct structName.
The name of the exported number is the same name as the c variable.
NAPI_EXPORT_OFFSETOF(type, name)
Exports the byte offset of name within type.
The name of the exported number is the same name as the c variables.
NAPI_EXPORT_OFFSETOF_STRUCT(structName, name)
Exports the byte offset of name within struct structName.
The name of the exported number is the same name as the c variables.
NAPI_FOR_EACH(array, element)
Iterate over an array. array should be a napi_value containing a javascript array
and element is the variable name an element will be exposed as. Expects the loop body
to be passed after.
napi_value buffers = argv[0] // first argument is a js array
NAPI_FOR_EACH(buffers, buffer) {
NAPI_BUFFER(cbuf, buffer)
printf("cbuf is now a char * pointer: %s\n", cbuf);
}
NAPI_RETURN_UINT32(name)
Returns a uint32.
NAPI_RETURN_INT32(name)
Returns an int32.
NAPI_RETURN_UTF8(name, len)
Return a utf8 string. len should be the length of the string.
NAPI_RETURN_STRING(name)
Return a null terminated string.
NAPI_STATUS_THROWS(call)
Checks the return status of any napi_* function returning a napi_status type. This simplifies using a napi_status variable and comparing the result with napi_ok. It's used internally but can be used stand alone as well.
NAPI_STATUS_THROWS(
napi_create_threadsafe_function(
NULL,
callback,
0,
async_resource_name,
0,
3,
0,
my_finalize,
NULL,
my_callback,
&threadsafe_function
)
);
Above example will fail because the first env parameter is NULL and throw the following error:
Error: napi_create_threadsafe_function(NULL, callback, 0, async_resource_name, 0, 3, 0, my_finalize, \
NULL, my_callback, &threadsafe_function) failed!
NAPI_UV_THROWS(err, fn)
Checks if a libuv call fails and if so, throws an error.
int err;
NAPI_UV_THROWS(err, uv_ip4_addr((char *) &ip, port, &addr))
NAPI_MAKE_CALLBACK(env, async_ctx, ctx, func, argc, argv, result)
Same as napi_make_callback except it checks if the JS function throw an exception
and triggers a process.on('uncaughtException') if so.
License
MIT