node-elm-compiler/dist/worker.js

A Node.js interface to the Elm compiler binaries.

var temp = require("temp").track();
var path = require("path");
var jsEmitterFilename = "emitter.js";
var KNOWN_MODULES = [
    "fullscreen",
    "embed",
    "worker",
    "Basics",
    "Maybe",
    "List",
    "Array",
    "Char",
    "Color",
    "Transform2D",
    "Text",
    "Graphics",
    "Debug",
    "Result",
    "Task",
    "Signal",
    "String",
    "Dict",
    "Json",
    "Regex",
    "VirtualDom",
    "Html",
    "Css"
];
// elmModuleName is optional, and is by default inferred based on the filename.
module.exports = function (compile) {
    return function (projectRootDir, modulePath, moduleName, workerArgs) {
        var originalWorkingDir = process.cwd();
        process.chdir(projectRootDir);
        return createTmpDir()
            .then(function (tmpDirPath) {
            var dest = path.join(tmpDirPath, jsEmitterFilename);
            return compileEmitter(compile, modulePath, { output: dest })
                .then(function () { return runWorker(dest, moduleName, workerArgs); });
        })
            .then(function (worker) {
            process.chdir(originalWorkingDir);
            return worker;
        })
            .catch(function (err) {
            process.chdir(originalWorkingDir);
            throw Error(err);
        });
    };
};
function createTmpDir() {
    return new Promise(function (resolve, reject) {
        temp.mkdir("node-elm-compiler", function (err, tmpDirPath) {
            if (err) {
                reject(err);
            }
            else {
                resolve(tmpDirPath);
            }
        });
    });
}
function suggestModulesNames(Elm) {
    return Object.keys(Elm).filter(function (key) {
        return KNOWN_MODULES.indexOf(key) === -1;
    });
}
function missingEntryModuleMessage(moduleName, Elm) {
    var errorMessage = "I couldn't find the entry module " + moduleName + ".\n";
    var suggestions = suggestModulesNames(Elm);
    if (suggestions.length > 1) {
        errorMessage += "\nMaybe you meant one of these: " + suggestions.join(",");
    }
    else if (suggestions.length === 1) {
        errorMessage += "\nMaybe you meant: " + suggestions;
    }
    errorMessage += "\nYou can pass me a different module to use with --module=<moduleName>";
    return errorMessage;
}
function noPortsMessage(moduleName) {
    var errorMessage = "The module " + moduleName + " doesn't expose any ports!\n";
    errorMessage += "\n\nTry adding something like";
    errorMessage += "port foo : Value\nport foo =\n    someValue\n\nto " + moduleName + "!";
    return errorMessage.trim();
}
function runWorker(jsFilename, moduleName, workerArgs) {
    return new Promise(function (resolve, reject) {
        var Elm = require(jsFilename).Elm;
        if (!(moduleName in Elm)) {
            return reject(missingEntryModuleMessage(moduleName, Elm));
        }
        var worker = Elm[moduleName].init(workerArgs);
        if (Object.keys(worker.ports).length === 0) {
            return reject(noPortsMessage(moduleName));
        }
        return resolve(worker);
    });
}
function compileEmitter(compile, src, options) {
    return new Promise(function (resolve, reject) {
        compile(src, options)
            .on("close", function (exitCode) {
            if (exitCode === 0) {
                resolve(exitCode);
            }
            else {
                reject("Errored with exit code " + exitCode);
            }
        });
    });
}