gnome: add mkenums_simple()

99% of all mkenums uses in C libraries use the same basic template,
so add a mkenums_simple() function that takes care of everything for
us based on that template.

Features:
 - optional function declaration decorator such as GLIB_AVAILABLE
 - optional extra header prefix (e.g. for include needed for decorator)
 - optional extra body prefix (e.g. for additional includes)
 - optional function name prefix (e.g. to add leading underscores)

Fixes issue #1384

7 files changed, 240 insertions, 2 deletions

diff --git a/docs/markdown/Gnome-module.md b/docs/markdown/Gnome-module.md
index 038f1ea..0e24bb0 100644
--- a/docs/markdown/Gnome-module.md
+++ b/docs/markdown/Gnome-module.md
@@ -72,6 +72,12 @@ Returns an array of two elements which are: `[c_source, header_file]`
 
 Generates enum files for GObject using the `glib-mkenums` tool. The first argument is the base name of the output files.
 
+This method is essentially a wrapper around the `glib-mkenums` tool's command line API. It is the most featureful method for enum creation.
+
+Typically you either provide template files or you specify the various template sections manually as strings.
+
+Most libraries and applications will be using the same standard template with only minor tweaks, in which case the `gnome.mkenums_simple()` convenience method can be used instead.
+
 Note that if you `#include` the generated header in any of the sources for a build target, you must add the generated header to the build target's list of sources to codify the dependency. This is true for all generated sources, not just `mkenums`.
 
 * `sources`: the list of sources to make enums with
@@ -93,6 +99,49 @@ Note that if you `#include` the generated header in any of the sources for a bui
 
 Returns an array of two elements which are: `[c_source, header_file]`
 
+### gnome.mkenums_simple()
+
+Generates enum `.c` and `.h` files for GObject using the `glib-mkenums` tool
+with the standard template used by most GObject-based C libraries. The first
+argument is the base name of the output files.
+
+Note that if you `#include` the generated header in any of the sources for a
+build target, you must add the generated header to the build target's list of
+sources to codify the dependency. This is true for all generated sources, not
+just `mkenums_simple`.
+
+* `sources`: the list of sources to make enums with
+* `install_header`: if true, install the generated header
+* `install_dir`: directory to install the header
+* `identifier_prefix`: prefix to use for the identifiers
+* `symbol_prefix`: prefix to use for the symbols
+* `header_prefix`: additional prefix at the top of the header file, e.g. for extra includes (which may be needed if you specify a decorator for the function declarations)
+* `decorator`: optional decorator for the function declarations, e.g. `GTK_AVAILABLE` or `GST_EXPORT`
+* `function_prefix`: additional prefix for function names, e.g. in case you want to add a leading underscore to functions used only internally
+* `body_prefix`: additional prefix at the top of the body file, e.g. for extra includes
+
+Example:
+
+```meson
+gnome = import('gnome')
+
+my_headers = ['myheader1.h', 'myheader2.h']
+my_sources = ['mysource1.c', 'mysource2.c']
+
+# will generate myenums.c and myenums.h based on enums in myheader1.h and myheader2.h
+enums = gnome.mkenums_simple('myenums', sources : my_headers)
+
+mylib = library('my', my_sources, enums,
+                include_directories: my_incs,
+                dependencies: my_deps,
+                c_args: my_cargs,
+                install: true)
+```
+
+*Added 0.42.0*
+
+Returns an array of two elements which are: `[c_source, header_file]`
+
 ### gnome.compile_schemas()
 
 When called, this method will compile the gschemas in the current directory. Note that this is not
diff --git a/docs/markdown/Release-notes-for-0.42.0.md b/docs/markdown/Release-notes-for-0.42.0.md
index 1ed74dc..3ba84eb 100644
--- a/docs/markdown/Release-notes-for-0.42.0.md
+++ b/docs/markdown/Release-notes-for-0.42.0.md
@@ -140,3 +140,10 @@ using the `pcap-config` tool. It is used like any other dependency:
 ```meson
 pcap_dep = dependency('pcap', version : '>=1.0')
 ```
+
+## GNOME module mkenums_simple() addition
+
+Most libraries and applications use the same standard templates for
+glib-mkenums. There is now a new `mkenums_simple()` convenience method
+that passes those default templates to glib-mkenums and allows some tweaks
+such as optional function decorators or leading underscores.
diff --git a/mesonbuild/modules/gnome.py b/mesonbuild/modules/gnome.py
index dc6c25f..5f9847e 100644
--- a/mesonbuild/modules/gnome.py
+++ b/mesonbuild/modules/gnome.py
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 '''This module provides helper functions for Gnome/GLib related
-functionality such as gobject-introspection and gresources.'''
+functionality such as gobject-introspection, gresources and gtk-doc'''
 
 from .. import build
 import os
@@ -32,7 +32,6 @@ from . import find_program, get_include_args
 from . import ExtensionModule
 from . import noKwargs, permittedKwargs
 
-
 # gresource compilation is broken due to the way
 # the resource compiler and Ninja clash about it
 #
@@ -955,6 +954,108 @@ class GnomeModule(ExtensionModule):
         else:
             return ModuleReturnValue(targets, targets)
 
+    def mkenums_simple(self, state, args, kwargs):
+        hdr_filename = args[0] + '.h'
+        body_filename = args[0] + '.c'
+
+        # not really needed, just for sanity checking
+        forbidden_kwargs = ['c_template', 'h_template', 'eprod', 'fhead',
+                            'fprod', 'ftail', 'vhead', 'vtail', 'comments']
+        for arg in forbidden_kwargs:
+            if arg in kwargs:
+                raise MesonException('mkenums_simple() does not take a %s keyword argument' % (arg, ))
+
+        # kwargs to pass as-is from mkenums_simple() to mkenums()
+        shared_kwargs = ['sources', 'install_header', 'install_dir',
+                         'identifier_prefix', 'symbol_prefix']
+        mkenums_kwargs = {}
+        for arg in shared_kwargs:
+            if arg in kwargs:
+                mkenums_kwargs[arg] = kwargs[arg]
+
+        # .c file generation
+        c_file_kwargs = copy.deepcopy(mkenums_kwargs)
+        if 'sources' not in kwargs:
+            raise MesonException('Missing keyword argument "sources".')
+        sources = kwargs['sources']
+        if isinstance(sources, str):
+            sources = [sources]
+        elif not isinstance(sources, list):
+            raise MesonException(
+                'Sources keyword argument must be a string or array.')
+
+        header_prefix = kwargs.get('header_prefix', '')
+        decl_decorator = kwargs.get('decorator', '')
+        func_prefix = kwargs.get('function_prefix', '')
+        body_prefix = kwargs.get('body_prefix', '')
+
+        # Maybe we should write our own template files into the build dir
+        # instead, but that seems like much more work, nice as it would be.
+        fhead = ''
+        if body_prefix != '':
+            fhead += '%s\n' % body_prefix
+        fhead += '#include "%s"\n' % hdr_filename
+        for hdr in sources:
+            fhead += '#include "%s"\n' % hdr
+        fhead += '''
+#define C_ENUM(v) ((gint) v)
+#define C_FLAGS(v) ((guint) v)
+'''
+        c_file_kwargs['fhead'] = fhead
+
+        c_file_kwargs['fprod'] = '''
+/* enumerations from "@basename@" */
+'''
+
+        c_file_kwargs['vhead'] = '''
+GType
+%s@enum_name@_get_type (void)
+{
+  static volatile gsize gtype_id = 0;
+  static const G@Type@Value values[] = {''' % func_prefix
+
+        c_file_kwargs['vprod'] = '    { C_@TYPE@(@VALUENAME@), "@VALUENAME@", "@valuenick@" },'
+
+        c_file_kwargs['vtail'] = '''    { 0, NULL, NULL }
+  };
+  if (g_once_init_enter (&gtype_id)) {
+    GType new_type = g_@type@_register_static ("@EnumName@", values);
+    g_once_init_leave (&gtype_id, new_type);
+  }
+  return (GType) gtype_id;
+}'''
+
+        rv = self.mkenums(state, [body_filename], c_file_kwargs)
+        c_file = rv.return_value
+
+        # .h file generation
+        h_file_kwargs = copy.deepcopy(mkenums_kwargs)
+
+        h_file_kwargs['fhead'] = '''#pragma once
+
+#include <glib-object.h>
+{}
+
+G_BEGIN_DECLS
+'''.format(header_prefix)
+
+        h_file_kwargs['fprod'] = '''
+/* enumerations from "@basename@" */
+'''
+
+        h_file_kwargs['vhead'] = '''
+{}
+GType {}@enum_name@_get_type (void);
+#define @ENUMPREFIX@_TYPE_@ENUMSHORT@ ({}@enum_name@_get_type())'''.format(decl_decorator, func_prefix, func_prefix)
+
+        h_file_kwargs['ftail'] = '''
+G_END_DECLS'''
+
+        rv = self.mkenums(state, [hdr_filename], h_file_kwargs)
+        h_file = rv.return_value
+
+        return ModuleReturnValue([c_file, h_file], [c_file, h_file])
+
     @staticmethod
     def _make_mkenum_custom_target(state, sources, output, cmd, kwargs):
         custom_kwargs = {
diff --git a/test cases/frameworks/7 gnome/mkenums/main4.c b/test cases/frameworks/7 gnome/mkenums/main4.c
new file mode 100644
index 0000000..3df4dd8
--- /dev/null
+++ b/test cases/frameworks/7 gnome/mkenums/main4.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <string.h>
+#include <glib-object.h>
+#include "enums4.h"
+#include "meson-sample.h"
+
+int main(int argc, char **argv) {
+    GEnumClass *xenum = g_type_class_ref(MESON_TYPE_THE_XENUM);
+    GFlagsClass *flags_enum = g_type_class_ref(MESON_TYPE_THE_FLAGS_ENUM);
+    if (g_enum_get_value_by_name(xenum, "MESON_THE_XVALUE")->value != MESON_THE_XVALUE) {
+        fprintf(stderr, "Get MESON_THE_XVALUE by name failed.\n");
+        return 1;
+    }
+    if (g_enum_get_value_by_nick(xenum, "the-xvalue")->value != MESON_THE_XVALUE) {
+        fprintf(stderr, "Get MESON_THE_XVALUE by nick failed.\n");
+        return 2;
+    }
+    if (g_flags_get_value_by_name(flags_enum, "MESON_THE_FIRST_VALUE")->value != MESON_THE_FIRST_VALUE) {
+        fprintf(stderr, "Get MESON_THE_FIRST_VALUE by name failed.\n");
+        return 3;
+    }
+    if (g_flags_get_value_by_nick(flags_enum, "the-first-value")->value != MESON_THE_FIRST_VALUE) {
+        fprintf(stderr, "Get MESON_THE_FIRST_VALUE by nick failed.\n");
+        return 4;
+    }
+
+    /* Make sure that funcs are generated with leading underscore as requested */
+    if (!_meson_the_xenum_get_type())
+      g_error ("Bad!");
+
+    g_type_class_unref(xenum);
+    g_type_class_unref(flags_enum);
+    fprintf(stderr, "All ok.\n");
+    return 0;
+}
diff --git a/test cases/frameworks/7 gnome/mkenums/main5.c b/test cases/frameworks/7 gnome/mkenums/main5.c
new file mode 100644
index 0000000..ed1ccfd
--- /dev/null
+++ b/test cases/frameworks/7 gnome/mkenums/main5.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <string.h>
+#include <glib-object.h>
+#include "enums5.h"
+#include "meson-sample.h"
+
+int main(int argc, char **argv) {
+    GEnumClass *xenum = g_type_class_ref(MESON_TYPE_THE_XENUM);
+    GFlagsClass *flags_enum = g_type_class_ref(MESON_TYPE_THE_FLAGS_ENUM);
+    if (g_enum_get_value_by_name(xenum, "MESON_THE_XVALUE")->value != MESON_THE_XVALUE) {
+        fprintf(stderr, "Get MESON_THE_XVALUE by name failed.\n");
+        return 1;
+    }
+    if (g_enum_get_value_by_nick(xenum, "the-xvalue")->value != MESON_THE_XVALUE) {
+        fprintf(stderr, "Get MESON_THE_XVALUE by nick failed.\n");
+        return 2;
+    }
+    if (g_flags_get_value_by_name(flags_enum, "MESON_THE_FIRST_VALUE")->value != MESON_THE_FIRST_VALUE) {
+        fprintf(stderr, "Get MESON_THE_FIRST_VALUE by name failed.\n");
+        return 3;
+    }
+    if (g_flags_get_value_by_nick(flags_enum, "the-first-value")->value != MESON_THE_FIRST_VALUE) {
+        fprintf(stderr, "Get MESON_THE_FIRST_VALUE by nick failed.\n");
+        return 4;
+    }
+
+    /* Make sure that funcs do not have any extra prefix */
+    if (!meson_the_xenum_get_type())
+      g_error ("Bad!");
+
+    g_type_class_unref(xenum);
+    g_type_class_unref(flags_enum);
+    fprintf(stderr, "All ok.\n");
+    return 0;
+}
diff --git a/test cases/frameworks/7 gnome/mkenums/meson-decls.h b/test cases/frameworks/7 gnome/mkenums/meson-decls.h
new file mode 100644
index 0000000..ba94eb9
--- /dev/null
+++ b/test cases/frameworks/7 gnome/mkenums/meson-decls.h
@@ -0,0 +1,2 @@
+#pragma once
+#define MESON_EXPORT extern
diff --git a/test cases/frameworks/7 gnome/mkenums/meson.build b/test cases/frameworks/7 gnome/mkenums/meson.build
index e01e9eb..9963455 100644
--- a/test cases/frameworks/7 gnome/mkenums/meson.build
+++ b/test cases/frameworks/7 gnome/mkenums/meson.build
@@ -117,3 +117,12 @@ main = configure_file(
 enumexe3 = executable('enumprog3', main, enums_c3, enums_h3,
 dependencies : gobj)
 test('enum test 3', enumexe3)
+
+enums4 = gnome.mkenums_simple('enums4', sources : 'meson-sample.h',
+                              function_prefix : '_')
+enumexe4 = executable('enumprog4', 'main4.c', enums4, dependencies : gobj)
+
+enums5 = gnome.mkenums_simple('enums5', sources : 'meson-sample.h',
+                              decorator : 'MESON_EXPORT',
+                              header_prefix : '#include "meson-decls.h"')
+enumexe5 = executable('enumprog5', main, enums5, dependencies : gobj)