Add node resolution for transformer

[willemneal]

Try relative path first and then with normal node resolution.

[MaxGraey]

How about use require.resolve and check returned string instead try / catch wrapper over require?

[jtenner]

@MaxGraey is require.resolve() something that AssemblyScript is going to support at some point?

[MaxGraey]

This actually node (commonjs) mechanics. Don't think we need this in current time until we load everything ahead of time

[willemneal]

@MaxGraey To use resolve we would still have to check for an error:

> require.resolve("a")
Thrown:
Error: Cannot find module 'a'
Require stack:
- <repl>
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:625:15)
    at Function.resolve (internal/modules/cjs/helpers.js:21:19) {
  code: 'MODULE_NOT_FOUND',
  requireStack: [ '<repl>' ]
}

[MaxGraey]

@willemneal Yes, but you got only MODULE_NOT_FOUND error and don't need _require. With wrapping whole module you should check error type because failing could be in different reasons

[MaxGraey]

function tryResolvePath(path) {
  try { return require.resolve(path) }
  catch (e) { return null }
}

[willemneal]

So something like this:

function resolve(m) {
  try {
    return require.resolve(m);
  } catch (e) {
    return null;
  }
}

and

const classOrModule = (resolve(filename) == null) ? require(transformArgs[i]) : require(filename);

[willemneal]

Just tested it with my transformer and it works.

[MaxGraey]

great

[dcodeIO]

Here, transfromArgs[i] is not trimmed, which filename is guaranteed to be, and trying to require that is unnecessary if the path is absolute anyway. Also, require(transformArgs[i]) is relative to node_modules/assemblyscript/cli/asc.js which appears problematic. A cleaner variant might be

• if absolute, require as-is
• if relative, use node-resolve relative to cwd? (not sure about --baseDir)

[willemneal]

resolve can take an array of paths to use instead of the default, so we could use cwd and baseDir there.

Also why is the filename not guaranteed to be trimmed? Shouldn't all cli arguments be trimmed?

[willemneal]

Now we have

function _require(m, paths) {
  const _path = require.resolve(m, {paths});
  return require(_path)
}
//and

let filename = transformArgs[i].trim();
if (/\.ts$/.test(filename)) require("ts-node").register({ transpileOnly: true, skipProject: true });
try {
   const classOrModule = _require(filename, [baseDir, process.cwd()]);

If the path is absolute that it doesn't matter for the resolution paths, otherwise you try to look starting in both baseDir and process.cwd().

[willemneal]

Okay testing shows that this resolves currently in both situations where asc is locally in "node_modules" or from a different location, e.g. globally. However, when asc is non-local I get the following:

ERROR: TypeError: Cannot redefine property: signbit
    at Function.defineProperties (<anonymous>)
    at Object.<anonymous> (/Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/webpack:/assemblyscript/std/portable/index.js:280:8)
    at Object.call (/Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/assemblyscript.js:1:592833)
    at t (/Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/webpack:/assemblyscript/webpack/bootstrap:19:22)
    at Object.call (/Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/glue/js/index.ts:10:1)
    at t (/Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/webpack:/assemblyscript/webpack/bootstrap:19:22)
    at Object.call (/Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/assemblyscript.js:1:586627)
    at __webpack_require__ (/Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/webpack:/assemblyscript/webpack/bootstrap:19:22)
    at /Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/webpack:/assemblyscript/webpack/bootstrap:83:10
    at /Users/willem/near/near-assemblyscript/near-bindgen-as/tests/node_modules/assemblyscript/dist/assemblyscript.js:1:124

This is because my transformer requires "assemblyscript" and asc requires "../dist/assemblyscript". So when when everything is local this ends up being the same file and assemblyscript is not loaded the second time.

One solution could be to pass the compiler and then the transformer adds the types file to its config. Alternatively we can just keep the requirement that you must keep them together.

[willemneal]

I've tested this and it works for my transformer, but again only if they are both local.

[willemneal]

@dcodeIO @MaxGraey Any more thoughts about this? I think it is a fair assumption that if you are using the transformer, to install the transformer class along side the compiler.

[dcodeIO]

Looks good, thanks!