node-gtk/lib/index.js

GNOME Gtk+ bindings for NodeJS

/*
 * index.js
 */

const fs = require('fs')
const util = require('util')
const readdir = util.promisify(fs.readdir)
const camelCase = require('lodash.camelcase')

const internal = require('./native.js')

// The bootstrap from C here contains functions and methods for each object,
// namespaced with underscores. See gi.cc for more information.
const GI = internal.Bootstrap();

// The GIRepository API is fairly poor, and contains methods on classes,
// methods on objects, and what should be methods interpreted as functions,
// because the scanner does not interpret methods on typedefs correctly.

// We extend this bootstrap'd repo to define all flags / enums, which
// are all we need to start declaring objects.
bootstrapGIRepository(GI)

function bootstrapGIRepository(GI) {
    const repo = GI.Repository_get_default()
    const ns = 'GIRepository'

    // First, grab InfoType so we can find enums / flags.
    const InfoType = makeEnum(GI.Repository_find_by_name.call(repo, ns, 'InfoType'))

    // Now, define all enums / flags.
    const nInfos = GI.Repository_get_n_infos.call(repo, ns)
    for (let i = 0; i < nInfos; i++) {
        const info = GI.Repository_get_info.call(repo, ns, i)
        const name = GI.BaseInfo_get_name.call(info)
        const type = GI.BaseInfo_get_type.call(info)

        if (type === InfoType.ENUM || type === InfoType.FLAGS)
            GI[name] = makeEnum(info)
    }
}

// We also define GObject#on and friends, to keep NodeJS EventEmitter
// semantics. They are implemented in terms of the native .connect()
// and .disconnect() methods.
const GObject = internal.GetBaseClass()
extendGObject(GObject)

function extendGObject(GObject) {
    GObject.prototype.on = function on(event, callback, after) {
        defineListeners(this)

        if (!this._listeners.has(event))
            this._listeners.set(event, new WeakMap())

        const fnMap = this._listeners.get(event)
        const handlerID = this.connect(event, callback, after)
        if (handlerID === 0) {
            throw new Error(`Could not connect to signal ${event}`)
        }
        fnMap.set(callback, handlerID)
        return this
    }

    GObject.prototype.off = function off(event, callback) {
        defineListeners(this)

        if (!this._listeners.has(event))
            return

        const fnMap = this._listeners.get(event)
        if (!fnMap.has(callback))
            return

        const handlerID = fnMap.get(callback)
        this.disconnect(handlerID)
        fnMap.delete(callback)
        return this
    }

    GObject.prototype.once = function once(event, callback, after) {
        const newCallback = (...args) => {
            callback(...args)
            this.off(event, newCallback)
        }
        this.on(event, newCallback, after)
        return this
    }

    function defineListeners(object) {
        if (object._listeners !== undefined)
            return
        Object.defineProperty(object, '_listeners', {
            value: new Map(),
            enumerable: false,
        })
    }
}




/**
 * Module cache
 */
const moduleCache = internal.GetModuleCache();



function define(object, description) {
    const target = (description.isMethod || description.isProperty) ?
        object.prototype : object
    Object.defineProperty(target, description.name, description.property)
}

function getFunctionDescription(info) {
    const fn = internal.MakeFunction(info);
    const name = getInfoName(info);
    const flags = GI.function_info_get_flags(info);
    const isMethod = ((flags & GI.FunctionInfoFlags.IS_METHOD) != 0 &&
                      (flags & GI.FunctionInfoFlags.IS_CONSTRUCTOR) == 0);
    return {
        name,
        isMethod,
        property: {
            configurable: true,
            writable: true,
            value: fn
        }
    }
}

function getPropertyDescription(info) {
    const propertyName = getName(info)
    const name = getInfoName(info)
    const property = {
        configurable: true,
        enumerable: true,
        get: propertyGetter(propertyName),
        set: propertySetter(propertyName),
    }
    return { name, property, isProperty: true }
}

function getConstantDescription(info) {
    const name = getInfoName(info)
    const property = {
        configurable: false,
        writable: false,
        enumerable: true,
        value: makeConstant(info)
    }
    return { name, property }
}

function addFunction(object, info) {
    define(object, getFunctionDescription(info))
}

function addVirtualFunction(object, info, implementor) {
    const fn = internal.MakeVirtualFunction(info, implementor);
    const name = getInfoName(info);
    const flags = GI.function_info_get_flags(info);
    const isMethod = ((flags & GI.FunctionInfoFlags.IS_METHOD) != 0 &&
                      (flags & GI.FunctionInfoFlags.IS_CONSTRUCTOR) == 0);
    const target = (isMethod) ? object.prototype : object;
    Object.defineProperty(target, name, {
        configurable: true,
        writable: true,
        value: fn
    })
}

function fieldGetter(fieldInfo) {
    return function() {
        return internal.StructFieldGetter(this, fieldInfo);
    };
}

function fieldSetter(fieldInfo) {
    return function(value) {
        return internal.StructFieldSetter(this, fieldInfo, value);
    };
}

function addField(object, fieldInfo) {
    const flags = GI.field_info_get_flags(fieldInfo)
    const writable = (flags & GI.FieldInfoFlags.WRITABLE) !== 0
    const readable = (flags & GI.FieldInfoFlags.READABLE) !== 0

    const name = getInfoName(fieldInfo)

    Object.defineProperty(object, name, {
        configurable: true,
        enumerable: readable,
        get: readable ? fieldGetter(fieldInfo) : undefined,
        set: writable ? fieldSetter(fieldInfo) : undefined
    })
}

function propertyGetter(propertyName) {
    return function() {
        return internal.ObjectPropertyGetter(this, propertyName);
    };
}

function propertySetter(propertyName) {
    return function(value) {
        return internal.ObjectPropertySetter(this, propertyName, value);
    };
}

function addProperty(object, info) {
    define(object, getPropertyDescription(info))
}

function addConstant(object, info) {
    define(object, getConstantDescription(info))
}



function makeConstant(info) {
    return internal.GetConstantValue(info)
}

function makeFunction(info) {
    return internal.MakeFunction(info)
}

function makeVirtualFunction(info, implementor) {
    return internal.MakeVirtualFunction(info, implementor)
}

function makeEnum(info) {
    const object = {}

    const nValues = GI.enum_info_get_n_values(info);
    for (let i = 0; i < nValues; i++) {
        const valueInfo = GI.enum_info_get_value(info, i);
        const valueName = getName(valueInfo).toUpperCase()
        const value = GI.value_info_get_value(valueInfo)
        Object.defineProperty(object, valueName, {
            configurable: true,
            enumerable: true,
            value: value,
        })
        Object.defineProperty(object, value, {
            configurable: true,
            enumerable: false,
            value: valueName,
        })
    }

    const nMethods = GI.enum_info_get_n_methods(info)
    for (let i = 0; i < nMethods; i++) {
        const methodInfo = GI.enum_info_get_method(info, i)
        const methodName = camelCase(getName(methodInfo))
        const method = internal.MakeFunction(methodInfo)
        Object.defineProperty(object, methodName, {
            configurable: true,
            writable: true,
            value: method
        })
    }

    return object;
}

function makeObject(info) {
    const constructor = tryCall(internal.MakeObjectClass, info);

    if (constructor instanceof Error) {
        console.warn(constructor.message)
        return null
    }

    loop(info, GI.object_info_get_n_properties, GI.object_info_get_property, (propertyInfo) => {
        addProperty(constructor, propertyInfo)
    })

    loop(info, GI.object_info_get_n_methods, GI.object_info_get_method, (methodInfo) => {
        addFunction(constructor, methodInfo);
    })

    loop(info, GI.object_info_get_n_constants, GI.object_info_get_constant, (constantInfo) => {
        addConstant(constructor, constantInfo)
    })


    /*
     * Define interface-implemented things
     */

    loop(info, GI.object_info_get_n_interfaces, GI.object_info_get_interface, (interfaceInfo) => {
        const interface_ = getInterface(interfaceInfo)

        interface_.properties.forEach(description => {
            define(constructor, description)
        })
        interface_.methods.forEach(description => {
            define(constructor, description)
        })
        interface_.constants.forEach(description => {
            define(constructor, description)
        })
    })


    return constructor;
}

function makeBoxed(info) {
    if (getType(info) == GI.InfoType.UNION) {
        return makeUnion(info)
    } else {
        return makeStruct(info)
    }
}

function makeUnion(info) {
    const constructor = internal.MakeBoxedClass(info);

    const nMethods = GI.union_info_get_n_methods(info);
    for (let i = 0; i < nMethods; i++) {
        const methodInfo = GI.union_info_get_method(info, i);
        addFunction(constructor, methodInfo);
    }

    const nFields = GI.union_info_get_n_fields(info);
    for (let i = 0; i < nFields; i++) {
        const fieldInfo = GI.union_info_get_field(info, i);
        addField(constructor.prototype, fieldInfo);
    }

    return constructor
}

function makeStruct(info) {
    const constructor = internal.MakeBoxedClass(info);

    const nMethods = GI.struct_info_get_n_methods(info);
    for (let i = 0; i < nMethods; i++) {
        var methodInfo = GI.struct_info_get_method(info, i);
        addFunction(constructor, methodInfo);
    }

    const nFields = GI.struct_info_get_n_fields(info);
    for (let i = 0; i < nFields; i++) {
        const fieldInfo = GI.struct_info_get_field(info, i);
        addField(constructor.prototype, fieldInfo);
    }

    return constructor
}

function makeInterface(info) {
    const id = getNamespace(info) + '.' + getName(info)

    const constructor = Object.values({
        [getInfoName(info)]: function() {
            throw new Error('Cannot instantiate Interface (abstract type)')
        }
    })[0]

    constructor.properties = []
    loop(info, GI.interface_info_get_n_properties, GI.interface_info_get_property, (propInfo) => {
        constructor.properties.push(getPropertyDescription(propInfo))
    })

    /* loop(info, GI.interface_info_get_n_vfuncs, GI.interface_info_get_vfunc, (methodInfo) => {
     *     addVirtualFunction(constructor, methodInfo, constructor.gtype);
     * }) */

    constructor.methods = []
    loop(info, GI.interface_info_get_n_methods, GI.interface_info_get_method, (methodInfo) => {
        constructor.methods.push(getFunctionDescription(methodInfo))
    })

    constructor.constants = []
    loop(info, GI.interface_info_get_n_constants, GI.interface_info_get_constant, (constantInfo) => {
        constructor.constants.push(getConstantDescription(constantInfo))
    })

    return constructor;
}

function makeInfo(info) {
    const type = getType(info);
    switch (type) {
        case GI.InfoType.FUNCTION:
            return makeFunction(info);

        // case GI.InfoType.VFUNC:
            // return makeVirtualFunction(info, ...args);

        case GI.InfoType.STRUCT:
            if (GI.struct_info_is_gtype_struct(info))
                return null; // Not needed
            // else fallthrough
        case GI.InfoType.BOXED:
        case GI.InfoType.UNION:
            return makeBoxed(info);

        case GI.InfoType.ENUM:
        case GI.InfoType.FLAGS:
            return makeEnum(info);

        case GI.InfoType.OBJECT:
            return makeObject(info);

        case GI.InfoType.INTERFACE: // FIXME
            return makeInterface(info);

        case GI.InfoType.CONSTANT:
            return makeConstant(info);

        // INVALID_0
        // SIGNAL
        // VFUNC
        // PROPERTY
        // FIELD
        // ARG
        // TYPE
        // UNRESOLVED
        // INVALID
        // CALLBACK
    }
}

function getInfoName(info) {
    const type = getType(info)
    const name = getName(info)

    switch (type) {
        case GI.InfoType.FUNCTION:
        case GI.InfoType.VFUNC:
            return camelCase(name) // lowerCamelCase (snake_case by default)

        case GI.InfoType.FIELD:
            return camelCase(name) // lowerCamelCase (snake_case by default)

        case GI.InfoType.PROPERTY:
            return camelCase(name) // lowerCamelCase (dash-case by default)

        case GI.InfoType.STRUCT:
        case GI.InfoType.BOXED:
        case GI.InfoType.UNION:
            return name // UpperCamelCase

        case GI.InfoType.ENUM:
        case GI.InfoType.FLAGS:
            return name // UpperCamelCase

        case GI.InfoType.OBJECT:
            return name // UpperCamelCase

        case GI.InfoType.INTERFACE:
            return name // UpperCamelCase

        case GI.InfoType.CONSTANT:
            return name // ALL_CAPS by default

        case GI.InfoType.VALUE: // enum's value
            return name.toUpperCase() // ALL_CAPS

        // INVALID_0
        // SIGNAL
        // ARG
        // TYPE
        // UNRESOLVED
        // INVALID
        // CALLBACK
    }
}

function getInterface(info) {
    const name = getInfoName(info)
    const namespace = getNamespace(info)

    if (moduleCache[namespace][name])
        return moduleCache[namespace][name]

    moduleCache[namespace][name] = makeInterface(info)
    return moduleCache[namespace][name]
}


// Namespace loading

/**
 * Requires a module. Automatically loads dependencies.
 * @param {string} ns - namespace to load
 * @param {string} [version=null] - version to load (null for latest)
 * @returns {Object} the loaded module
 */
function giRequire(ns, version) {
    if (moduleCache[ns])
        return moduleCache[ns]

    const module = moduleCache[ns] = Object.create(null)

    const repo = GI.Repository_get_default()
    GI.Repository_require.call(repo, ns, version || null, 0)
    version = version || GI.Repository_get_version.call(repo, ns)

    loadDependencies(ns, version)

    const nInfos = GI.Repository_get_n_infos.call(repo, ns);
    for (let i = 0; i < nInfos; i++) {
        const info = GI.Repository_get_info.call(repo, ns, i);
        const item = makeInfo(info);

        if (item)
            module[getInfoName(info)] = item
    }

    try {
        const override = require(`./overrides/${[ns, version].join('-')}.js`)
        override.apply(module)
    } catch(e) {
        try {
            const override = require(`./overrides/${ns}.js`)
            override.apply(module)
        } catch(e) { /* No override */ }
    }

    return module
}

/**
 * Loads dependencies of a library
 */
function loadDependencies(ns, version) {
    const repo = GI.Repository_get_default()
    const dependencies = GI.Repository_get_dependencies.call(repo, ns, version)

    dependencies.forEach(dependency => {
        const [name, version] = dependency.split('-')
        giRequire(name, version)
    })
}

/**
 * Check if module version is loaded
 */
function _isLoaded(ns, version) {
    var namespace = moduleCache[ns] || (moduleCache[ns] = Object.create(null));
    version = version || null;

    if (namespace[version])
        return true;

    if (version == null && namespace.length > 0) {
        console.log(Object.keys(namespace)[0]);
        return true;
    }

    return false;
}

/**
 * Prepends a path to GObject-Introspection search path (for typelibs)
 * @param {string} path
 */
function prependSearchPath(path) {
    GI.Repository_prepend_search_path(path)
}

/**
 * Prepends a path to GObject-Introspection library path (for shared libraries)
 * @param {string} path
 */
function prependLibraryPath(path) {
    GI.Repository_prepend_library_path(path)
}

/**
 * @typedef ModuleDescription
 * @type {object}
 * @property {string} name
 * @property {string} version
 */

/**
 * Returns a list of available modules
 * @returns {Promise<ModuleDescription[]>}
 */
function listAvailableModules() {
    const paths = GI.Repository_get_search_path()

    return Promise.all(paths.map(path =>
        readdir(path).catch(err => Promise.resolve([]))
    ))
    .then(results => results.reduce((acc, cur) => acc.concat(cur)))
    .then(filenames => filenames.filter(filename => filename.endsWith('.typelib')))
    .then(filenames => filenames.map(parseModuleFilename))
}


/*
 * Exports
 */

// Public API
exports.require = giRequire
exports.startLoop = internal.StartLoop
exports.prependSearchPath = prependSearchPath
exports.prependLibraryPath = prependLibraryPath
exports.listAvailableModules = listAvailableModules
exports.System = internal.System

// Private API
exports._isLoaded = _isLoaded
exports._cache = moduleCache
exports._c = internal
exports._GIRepository = GI
exports._InfoType = GI.InfoType


/*
 * Helpers
 */

function getName(info) {
    return GI.BaseInfo_get_name.call(info);
}

function getNamespace(info) {
    return GI.BaseInfo_get_namespace.call(info);
}

function getType (info) {
    return GI.BaseInfo_get_type.call(info);
}

function isDeprecated(info) {
    return GI.BaseInfo_is_deprecated.call(info)
}

function deprecationWrapper(info, fn) {
    const wrapper = Object.values({
        [fn.name]: function() {
            console.log(`[node-gtk]: ${getInfoName(info)} is deprecated`)
            return fn.apply(this, arguments)
        }
    })[0]

    return wrapper
}

function loop(info, lengthFn, itemFn, fn) {
    const length = lengthFn(info)
    for (let i = 0; i < length; i++) {
        const item = itemFn(info, i)
        fn(item, i)
    }
}

function tryCall(fn, ...args) {
    try {
        return fn.apply(null, args)
    } catch (e) {
        return e
    }
}

function parseModuleFilename(filename) {
    const [name, version] = filename.replace('.typelib', '').split('-')
    return { name, version }
}