For users of emcc, who compile C or C++ to Wasm, this package enables automated creation of an EXPORTED_FUNCTIONS list. You manually mark the desired exports with /*f*/. They become available in the automatically run script.

'-s EXPORTED_FUNCTIONS=...' is required in many cases where you want to call C or C++ from JS.

Originally forked from https://github.com/mvila/on-save. Thanks, for making it easily hackable, mvila.

Installation

For now, at least, install using this git repo.

apm install [email protected]:rdroe/on-save-emcc.git

Usage

Create an .on-save.json file at the root of your project (or anywhere in the path of the files you want to watch). Since this fork is focused on emscripten, I presume you will be configuring a CLI call to the emcc / em++ compiler.

As regular users of Emscripten to generate wasm know, any C++ function that you want to be callable from JS must be added (with a prefixed underscore) to the "EXPORTED_FUNCTIONS" flag argument.

With emcc, you can use the -s EXPORT_ALL=1 flag, but you may want more precision.

For example, if you want to export the main function from C++ (which is in fact required if you want that function to run), in your source code you would place the marker after its name in its definition, e.g.

int main /*f*/ () {
  // code
}

After so marking exportable functions, you can use ${exportedFunctions} like other template properties in the command property of the configs:

[
  {
    "srcFile": "main.cpp",
    "destDir": "build",
    "outFile": "app.html",
    "showOutput": true,
    "files": ["**/*.cpp", "**/*.html", "**/*.hpp"],
    "command": "emcc tests/hello_function.cpp -o function.html -s EXPORTED_FUNCTIONS='[${exportedFunctions}]'"
  }
]

The /*f*/ marked functions will show up in a comma-separated list in the ${exportedFunctions} template area. They will be preceded by an underscore.

Configuration file

The content of the .on-save.json file must be an array of objects with the following properties:

• srcDir (default to .on-save.json's directory): The source directory.
• destDir (default to srcDir): The destination directory.
• files: The files you want to track. You can use a glob (see minimatch), or an array of globs.
• command: The command to execute. You can use these variables:
  • ${srcFile}: The input file.
  • ${destFile}: The output file.
  • ${destFileWithoutExtension}: The output file without the extension.
  • ${exportedFunctions}: Emcc's "-s EXPORTED_FUNCTIONS" value; see the example documented above.
• showOutput (default to false): A boolean indicating whether the output stream (stdout) should be displayed or not.
• showError (default to true): A boolean indicating whether the error stream (stderr) should be displayed or not.

License

MIT