mimicry/dependency.js

(function privateDependencyClosure () {
    /**
     * This primitive class represents Dependency,
     * just to make the work a bit more structured
     * */
    class Dependency {
        constructor (name, contentType) {
            this.name = name;
            this.contentType = contentType;
        }

        /**
         * This function goes through an array of strings and number to make sense of it
         *
         * @param {Array} deps - an array of strings and numbers
         *
         * @returns Array<Dependency>
         * */
        static refineDependencies (deps) {
            const result = [];
            const collection = Object.create(null);
            for (let i = 0; i < deps.length; ++i) {
                let element = deps[i];
                const elementType = typeof element
                if (!collection[element] && elementType === "string") {
                    result.push(new Dependency(element));
                    collection[element] = true;
                } else if (result.length > 0 && elementType === "number" && ReverseType[element] !== undefined) {
                    let prevResult = result[result.length - 1];
                    if (deps[i - 1] === prevResult.name)
                        prevResult.contentType = element;
                }
            }
            return result
        }
        /**
         * Checks one type against another and writes a warning if they don't match
         *
         * @param {Type} original
         * @param {Type} current
         * @param {String} path
         * */
        static checkContentType (original, current, path) {
            if (original !== current) {
                const originalType = ReverseType[original];
                const currentType = ReverseType[current];
                console.warn("Mimicry error: file " + path +
                    " was originally requested as " + originalType +
                    " but next time it was requested as " + currentType +
                    " ignoring second request type and treating file as " + originalType
                );
            }
        }

        /**
         * Refines path turning all meta information into a path to query
         *
         * @typedef Mimicry.Type Type
         *
         * @param {String}              path - a source path
         * @param {Type}                type - type of the content
         * @param {String}           baseUrl - path to all project files
         * @param {Map<Type, String>}  types - collection of paths to specific content types
         * @param {Map<String, String>} libs - collection of paths to libraries
         *
         * @returns {String}
         * */
        static refinePath (path, type, baseUrl, types, libs) {
            const suffix = suffixes[type];
            const typePath = types.get(type) || "";
            if (!path.endsWith(suffix))
                path += suffix;

            switch (type) {
                case Type.js:
                    if (path[0] === "@") {
                        const hops = path.split("/");
                        const libName = hops[0].slice(1);
                        let libPath = libs.get(libName);
                        if (libPath === undefined)
                            libPath = libName;

                        path = baseUrl + libPath + path.slice(libName.length + 1);
                    } else {
                        path = baseUrl + typePath + path;
                    }
                    break;
                default:
                    path = baseUrl + typePath + path;
                    break;
            }

            return path;
        }

        /**
         * @param {Array<String>} dependencies - list of module names that this module depends on
         * @param {Function}        [callback] - module body that will be executed as soon all dependencies are resolved
         * */
        static refineModuleArguments (dependencies, callback) {
            let deps, body;
            if (dependencies instanceof Function) {
                body = dependencies;
                deps = [];
            } else {
                deps = dependencies;
                body = callback;
            }

            deps = this.refineDependencies(deps);

            return {deps, body};
        }

        /**
         * @param {String}                href - script DOM element that launched this function
         * @param {String}             baseUrl - path to all project files
         * @param {Map<Type, String>}    types - collection of paths to specific content types
         * @param {Map<String, String>}   libs - collection of paths to libraries
         * */
        static nameFromHref (href, baseUrl, types, libs) {
            const suffix = suffixes[Type.js];
            const typePath = types.get(Type.js) || "";

            if (href.endsWith(suffix))
                href = href.slice(0, -suffix.length);

            if (baseUrl.length) {
                const baseIndex = href.indexOf(baseUrl);
                if (baseIndex !== 0)
                    console.warn("Module path " + href +
                        " doesn't start with baseUrl " + baseUrl +
                        ", this is probably an error");
                else
                    href = href.slice(baseUrl.length);
            }

            let foundAmongLibs = false;
            for (const [libName, libPath] of libs) {
                const index = href.indexOf(libPath);
                if (index === 0) {
                    href = "@" + libName + href.slice(libPath.length);
                    foundAmongLibs = true;
                    break;
                }
            }

            if (!foundAmongLibs && typePath.length) {
                const typeIndex = href.indexOf(typePath);
                if (typeIndex !== 0)
                    console.warn("Module path " + href +
                        " doesn't start with a proper type path " + typePath +
                        ", this is probably an error");
                else
                    href = href.slice(typePath.length + 1);
            }

            return href;
        }

        static get Type () {return Type;}
        static getTypeTitle (/*Type*/type) {return ReverseType[type];}
    }

    const Type = {
        none: 0,        //just to prevent implicit situations, DON'T USE IT!
        js: 1,
        css: 2,
        json: 3,
        binary: 4,
        text: 5
    };

    const suffixes = ["", ".js", ".css", ".json", "", ""];
    const ReverseType = ["None", "JavaScript", "CSS", "JSON", "Binary", "Text"];

    Object.freeze(Type);
    Object.freeze(suffixes);
    Object.freeze(ReverseType);

    if (typeof module === 'object' && module.exports)
        module.exports = Dependency;
    else
        window.__MimicryDependency__ = Dependency;
})();