[gjs/wip/package: 5/8] Add a package/application convenience layer

[Giovanni Campagna <gcampagna src gnome org>]

commit 74eeac5abd6b094cf1490912ea09bf013cedce23
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Fri Feb 22 02:06:12 2013 +0100

    Add a package/application convenience layer
    
    Introduce a new module, called package, which includes convenience
    API and a set of simple conventions for packaged applications.
    The module takes care of setting up private search paths for JS
    modules and private typelibs, and it optionally does gettext too.

 Makefile-modules.am       |    3 +-
 libgjs-private/gjs-util.c |   11 ++
 libgjs-private/gjs-util.h |    3 +
 modules/package.js        |  277 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 293 insertions(+), 1 deletions(-)
---
diff --git a/Makefile-modules.am b/Makefile-modules.am
index edde4f1..e2ada18 100644
--- a/Makefile-modules.am
+++ b/Makefile-modules.am
@@ -15,7 +15,8 @@ dist_gjsjs_DATA +=            \
        modules/jsUnit.js       \
        modules/signals.js      \
        modules/promise.js      \
-       modules/format.js
+       modules/format.js       \
+       modules/package.js
 
 NATIVE_MODULES = libconsole.la libsystem.la
 if ENABLE_CAIRO
diff --git a/libgjs-private/gjs-util.c b/libgjs-private/gjs-util.c
index 0fb0f2e..f3f10a1 100644
--- a/libgjs-private/gjs-util.c
+++ b/libgjs-private/gjs-util.c
@@ -48,3 +48,14 @@ gjs_bindtextdomain(const char *domain,
     /* Always use UTF-8; we assume it internally here */
     bind_textdomain_codeset(domain, "UTF-8");
 }
+
+char *
+gjs_get_libdir(const char *prefix)
+{
+    /* Debian: patch for your favorite style of multi-arch */
+
+    if (sizeof (long) == 8)
+        return g_build_filename (prefix, "lib64", NULL);
+    else
+        return g_build_filename (prefix, "lib", NULL);
+}
diff --git a/libgjs-private/gjs-util.h b/libgjs-private/gjs-util.h
index 0eb55f6..a6c5845 100644
--- a/libgjs-private/gjs-util.h
+++ b/libgjs-private/gjs-util.h
@@ -35,6 +35,9 @@ void gjs_textdomain     (const char *domain);
 void gjs_bindtextdomain (const char *domain,
                          const char *location);
 
+/* For imports.package */
+char * gjs_get_libdir  (const char *prefix);
+
 G_END_DECLS
 
 #endif
diff --git a/modules/package.js b/modules/package.js
new file mode 100644
index 0000000..fb647fe
--- /dev/null
+++ b/modules/package.js
@@ -0,0 +1,277 @@
+// Copyright 2012 Giovanni Campagna
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+/**
+ * This module provides a set of convenience APIs for building packaged
+ * applications.
+ */
+
+const GLib = imports.gi.GLib;
+const GjsPrivate = imports.gi.GjsPrivate;
+const GIRepository = imports.gi.GIRepository;
+const System = imports.system;
+
+const Gettext = imports.gettext;
+
+/*< public >*/
+var name;
+var version;
+var prefix;
+var datadir;
+var libdir;
+var pkgdatadir;
+var pkglibdir;
+var moduledir;
+var localedir;
+
+/*< private >*/
+let _base;
+let _requires;
+
+/**
+ * init:
+ * @params: package parameters
+ *
+ * Initialize directories and global variables. Must be called
+ * before any of other API in Package is used.
+ * @params must be an object with at least the following keys:
+ *  - name: the package name ($(PACKAGE_NAME) in autotools)
+ *  - version: the package version
+ *  - prefix: the installation prefix
+ *
+ * init() will take care to check if the program is running from
+ * the source directory or not, by looking for a 'src' directory.
+ *
+ * At the end, the global variable 'pkg' will contain the
+ * Package module (imports.package). Additionally, the following
+ * module variables will be available:
+ *  - name, version: same as in @params
+ *  - prefix: the installation prefix (as passed in @params)
+ *  - datadir, libdir: the final datadir and libdir when installed;
+ *                     usually, these would be prefix + '/share' and
+ *                     and prefix + '/lib' (or '/lib64')
+ *  - pkgdatadir: the directory to look for private data files, such as
+ *                images, stylesheets and UI definitions;
+ *                this will be datadir + name when installed and
+ *                './data' when running from the source tree
+ *  - pkglibdir: the directory to look for private typelibs and C
+ *               libraries;
+ *               this will be libdir + name when installed and
+ *               './lib' when running from the source tree
+ *  - moduledir: the directory to look for JS modules;
+ *               this will be pkglibdir when installed and
+ *               './src' when running from the source tree
+ *  - localedir: the directory containing gettext translation files;
+ *               this will be datadir + '/locale' when installed
+ *               and './po' in the source tree
+ *
+ * All paths are absolute and will not end with '/'.
+ *
+ * As a side effect, init() calls GLib.set_prgname().
+ */
+function init(params) {
+    window.pkg = imports.package;
+    name = params.name;
+    version = params.version;
+
+    // Must call it first, because it can only be called
+    // once, and other library calls might have it as a
+    // side effect
+    GLib.set_prgname(name);
+
+    prefix = params.prefix;
+    libdir = GjsPrivate.get_libdir(prefix);
+    datadir = GLib.build_filenamev([prefix, 'share']);
+    let libpath, girpath;
+
+    if (GLib.file_test('./src',
+                       GLib.FileTest.IS_DIR)) {
+        log('Running from source tree, using local files');
+        // Running from source directory
+        _base = GLib.get_current_dir();
+        pkglibdir = GLib.build_filenamev([_base, 'lib']);
+        libpath = GLib.build_filenamev([pkglibdir, '.libs']);
+        girpath = pkglibdir;
+        pkgdatadir = GLib.build_filenamev([_base, 'data']);
+        localedir = GLib.build_filenamev([_base, 'po']);
+        moduledir = GLib.build_filenamev([_base, 'src']);
+    } else {
+        _base = prefix;
+        pkglibdir = GLib.build_filenamev([libdir, name]);
+        libpath = pkglibdir;
+        girpath = GLib.build_filenamev([pkglibdir, 'girepository-1.0']);
+        pkgdatadir = GLib.build_filenamev([datadir, name]);
+        localedir = GLib.build_filenamev([datadir, 'locale']);
+        moduledir = pkgdatadir;
+    }
+
+    imports.searchPath.push(moduledir);
+    GIRepository.Repository.prepend_search_path(girpath);
+    GIRepository.Repository.prepend_library_path(libpath);
+}
+
+/**
+ * start:
+ * @params: see init()
+ *
+ * This is a convenience function if your package has a
+ * single entry point.
+ * You must define a main(ARGV) function inside a main.js
+ * module in moduledir.
+ */
+function start(params) {
+    init(params);
+
+    return imports.main.main(ARGV);
+}
+
+function _checkVersion(required, current) {
+    // Major version must match, it's used for API
+    // incompatible changes.
+    // The rest just needs to be less or equal to
+    // current. The code is generic, but gjs modules
+    // should use only [major, minor]
+    if (required[0] != current[0])
+        return false;
+
+    for (let i = 1; i < Math.min(current.length, required.length); i++) {
+        if (required[i] > current[i])
+            return false;
+        if (required[i] < current[i])
+            return true;
+
+        // else they're equal, go on
+    }
+
+    return true;
+}
+
+function _isGjsModule(name, version) {
+    // This is a subset of the JS modules we offer,
+    // it includes only those that makes sense to use
+    // standalone and in a general app.
+    //
+    // You will not find Gettext or Format here, use
+    // the package functions instead. And Package, obviously,
+    // because it's available as window.package.
+    //
+    // cairo is also a JS module, but the version checking
+    // differs, see _isForeignModule()
+    //
+    // FIXME: Mainloop might be better as a GLib override?
+    // FIXME: Signals should be an extension to Lang
+    const RECOGNIZED_MODULE_NAMES = ['Lang',
+                                     'Mainloop',
+                                     'Signals',
+                                     'System'];
+    for (let i = 0; i < RECOGNIZED_MODULE_NAMES.length; i++) {
+        let module = RECOGNIZED_MODULE_NAMES[i];
+
+        if (module == name) {
+            let actualModule = imports[module.toLowerCase()];
+            let required = version.split('.');
+
+            if (!_checkVersion(required, actualModule.$API_VERSION)) {
+                printerr('Unsatisfied dependency: requested GJS module at version '
+                         + version + ', but only ' + (actualModule.$API_VERSION.join('.'))
+                         + ' is available');
+                System.exit(1);
+            } else {
+                window[module] = actualModule;
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+/**
+ * require:
+ * @libs: the external dependencies to import
+ *
+ * Mark a dependency on a specific version of one or more
+ * external GI typelibs.
+ * @libs must be an object whose keys are a typelib name,
+ * and values are the respective version. The empty string
+ * indicates any version.
+ *
+ * If dependencies are statisfied, require() will make
+ * the module objects available as global names.
+ */
+function require(libs) {
+    _requires = libs;
+
+    for (let l in libs) {
+        let version = libs[l];
+
+        if (_isGjsModule(l, version))
+            continue;
+
+        if (version != '')
+            imports.gi.versions[l] = version;
+
+        try {
+            if (name == 'cairo') {
+                // Import the GI package to check the version,
+                // but then load the JS one
+                imports.gi.cairo;
+                window.cairo = imports.cairo;
+            } else {
+                window[l] = imports.gi[l];
+            }
+        } catch(e) {
+            printerr('Unsatisfied dependency: ' + e.message);
+            System.exit(1);
+        }
+    }
+}
+
+function dumpRequires() {
+    print(JSON.stringify(_requires));
+}
+
+function initGettext() {
+    Gettext.bindtextdomain(name, localedir);
+    Gettext.textdomain(name);
+
+    let gettext = imports.gettext;
+    window._ = gettext.gettext;
+    window.C_ = gettext.pgettext;
+    window.N_ = function(x) { return x; }
+}
+
+function initFormat() {
+    let format = imports.format;
+    String.prototype.format = format.format;
+}
+
+function initSubmodule(name) {
+    if (moduledir != pkgdatadir) {
+        // Running from source tree, add './name' to search paths
+
+        let submoduledir = GLib.build_filenamev([_base, name]);
+        let libpath = GLib.build_filenamev([submoduledir, '.libs']);
+        GIRepository.Repository.prepend_search_path(submoduledir);
+        GIRepository.Repository.prepend_library_path(libpath);
+    } else {
+        // Running installed, submodule is in $(pkglibdir), nothing to do
+    }
+}