buffer-apg-js/dev/jsonToCLASS_.js

JavaScript APG, an ABNF Parser Generator

// Reads a JSON file defining the apglib.css colors and class names
// Produces a JavaScript file which defines the class names
// for use in utilities.js and other HTML output functions.
module.exports = function (inFile, outFile) {
    "use strict";

    function capFirst(str) {
        return str.charAt(0).toUpperCase() + str.slice(1);
    }

    function getFileExtension(filename) {
        return filename.slice(((filename.lastIndexOf(".") - 1) >>> 0) + 2);
    }

    let fs = require("fs");
    try {
        /* validate arguments */
        if (!inFile) {
            throw new Error("missing input JSON file (name.json)");
        }
        if (getFileExtension(inFile) !== "json") {
            throw new Error("input JSON file (" + inFile + ") must have .json extension");
        }
        if (!outFile) {
            throw new Error("missing output JavaScript file (name.js)");
        }
        if (getFileExtension(outFile) !== "js") {
            throw new Error("output JavaScript file (" + outFile + ") must have .js extension");
        }
        let json = fs.readFileSync(inFile, "utf8");
        let obj = JSON.parse(json);

        let js = "module.exports = {\n";
        js += "\n  // Generated by apglib/style.js \n";
        for (let key in obj.classes) {
            js += "  CLASS_" + key.toUpperCase() + ": '" + obj.classes[key] + "',\n";
        }
        js += "}\n";
        fs.writeFileSync(outFile, js);
    } catch (e) {
        console.log("jsonToCLASS_.js: EXCEPTION: \n");
        console.log(e.message);
    }
};