i18n: Add merge_file function

This is a repeated task that we can simplify

Closes #1120

mesonbuild/modules/i18n.py

@@ -14,10 +14,26 @@
 
 from os import path
 from .. import coredata, mesonlib, build
+from ..mesonlib import MesonException
 import sys
 
 class I18nModule:
 
+    def merge_file(self, state, args, kwargs):
+        podir = kwargs.pop('po_dir', None)
+        if not podir:
+            raise MesonException('i18n: po_dir is a required kwarg')
+        podir = path.join(state.build_to_src, state.subdir, podir)
+
+        file_type = kwargs.pop('type', 'xml')
+        VALID_TYPES = ('xml', 'desktop')
+        if not file_type in VALID_TYPES:
+            raise MesonException('i18n: "{}" is not a valid type {}'.format(file_type, VALID_TYPES))
+
+        kwargs['command'] = ['msgfmt', '--' + file_type,
+                             '--template', '@INPUT@', '-d', podir, '-o', '@OUTPUT@']
+        return build.CustomTarget(kwargs['output'] + '_merge', state.subdir, kwargs)
+
     @staticmethod
     def _read_linguas(state):
         linguas = path.join(state.environment.get_source_dir(), state.subdir, 'LINGUAS')

test cases/frameworks/6 gettext/data/meson.build

@@ -0,0 +1,8 @@
+i18n.merge_file(
+  input: 'test.desktop.in',
+  output: 'test.desktop',
+  type: 'desktop',
+  po_dir: '../po',
+  install: true,
+  install_dir: join_paths(get_option('datadir'), 'applications')
+)

test cases/frameworks/6 gettext/data/test.desktop.in

@@ -0,0 +1,6 @@
+[Desktop Entry]
+Name=Test
+GenericName=Application
+Comment=Test Application
+Type=Application
+

test cases/frameworks/6 gettext/installed_files.txt

@@ -1,3 +1,4 @@
 usr/bin/intlprog
 usr/share/locale/de/LC_MESSAGES/intltest.mo
 usr/share/locale/fi/LC_MESSAGES/intltest.mo
+usr/share/applications/test.desktop

test cases/frameworks/6 gettext/meson.build

@@ -4,3 +4,4 @@ i18n = import('i18n')
 
 subdir('po')
 subdir('src')
+subdir('data')

test cases/frameworks/6 gettext/po/LINGUAS

@@ -0,0 +1,2 @@
+de
+fi

test cases/frameworks/6 gettext/po/POTFILES

@@ -1 +1,2 @@
 src/intlmain.c
+data/test.desktop