Makefile: add support for compiling and installing localizations

This means that the new `po/files.generate` target can be used to build the
`.pot` files without doing anything else; we can stop requiring translators
to install ruby-ronn.  It also means that we can put the `.pot` files in
the source tarball, to make it even easier for translators.

Unfortunately, it does add the extra step of having to create another
symlink when adding a new locale.

6 files changed, 44 insertions, 11 deletions

diff --git a/Makefile b/Makefile
index 444a669..f6b78e9 100644
--- a/Makefile
+++ b/Makefile
@@ -54,6 +54,6 @@ libretools.out.confs =
 libretools.out  = $(foreach pkg,$(pkgs),po/$(pkg).pot)
 
 files.src.gen += .srcversion-libretools.mk .srcversion-devtools.mk
-nested.subdirs = $(foreach pkg,$(pkgs),$(pkg.$(pkg)))
+nested.subdirs = $(foreach pkg,$(pkgs),$(pkg.$(pkg))) po
 
 include $(topsrcdir)/build-aux/Makefile.tail.mk
diff --git a/po/.gitignore b/po/.gitignore
index e3a8c5d..514b3d0 100644
--- a/po/.gitignore
+++ b/po/.gitignore
@@ -1 +1,2 @@
 *.pot
+*/*.mo
diff --git a/po/HACKING b/po/HACKING
index 9ab35a7..5dd207c 100644
--- a/po/HACKING
+++ b/po/HACKING
@@ -2,23 +2,24 @@ Translations for programs are provided in files with the `.po` suffix.
 These are created by copying PO-template (`.pot`) files, and filling
 in the missing "msgstr" values.
 
-To add a translation, you'll first (1) need to create the `.pot`
-files, and then (2) copy them and (3) fill them in.
+To add a translation, you'll first (1) need to create the `.pot` files
+if you don't already have them, and then (2) copy them and (3) fill
+them in.
 
 # 1. Create `.pot` files
 
+  If you are working from a release source tarball, you can skip this
+  step (the `.pot` files are included in the tarball); if you are
+  working from git, read on.
+
   libretools' .pot files are not tracked in git; they are created by
-  running `make` (you'll need a checkout of both devtools-par and
-  libretools to run `make` if building from git).  In addition to the
-  usual (`base-devel`) depenencies when running `make`, you'll need
-  the `ruby-ronn` package as well.
+  running `make`.  You'll need a checkout of both "devtools-par" and
+  "libretools" to run `make` if building from git.
 
-      $ sudo pacman -S --needed base-devel ruby-ronn
-      ...
       $ git clone https://git.parabola.nu/packages/devtools-par.git/
       $ git clone https://git.parabola.nu/packages/libretools.git/
       $ cd libretools
-      $ make
+      $ make po/files.generate
       ...
       $ cd po/
       $ ls
@@ -33,10 +34,12 @@ files, and then (2) copy them and (3) fill them in.
 
   Create a folder under `po/` with the two-letter language code[^1]
   you want to add.  Then, copy the `.pot` files to that folder,
-  changing the file extension to `.po`; for example:
+  changing the file extension to `.po`.  Finally, link the `subdir.mk`
+  file to be the Makefile for that directory.  For example:
 
       $ mkdir es
       $ for file in *.pot; do cp $file es/${file%t}; done
+      $ ln -s ../subdir.mk es/Makefile
 
   [^1]: See the langauge code table
         here: <http://www.lingoes.net/en/translator/langcode.htm>
diff --git a/po/Makefile b/po/Makefile
new file mode 100644
index 0000000..1e56edd
--- /dev/null
+++ b/po/Makefile
@@ -0,0 +1,11 @@
+include $(dir $(lastword $(MAKEFILE_LIST)))/../config.mk
+include $(topsrcdir)/build-aux/Makefile.head.mk
+
+domains = libretools librelib gitget xbs
+locales := $(filter-out .,$(sort $(patsubst %/,%,$(dir $(files.src.src)))))
+
+files.src.gen += $(addsuffix .pot,$(domains))
+nested.subdirs += $(locales)
+at.subdirs += ..
+
+include $(topsrcdir)/build-aux/Makefile.tail.mk
diff --git a/po/es/Makefile b/po/es/Makefile
new file mode 120000
index 0000000..71a1159
--- /dev/null
+++ b/po/es/Makefile
@@ -0,0 +1 @@
+../subdir.mk
\ No newline at end of file
diff --git a/po/subdir.mk b/po/subdir.mk
new file mode 100644
index 0000000..6c4120b
--- /dev/null
+++ b/po/subdir.mk
@@ -0,0 +1,17 @@
+include $(dir $(lastword $(MAKEFILE_LIST)))/../../config.mk
+include $(topsrcdir)/build-aux/Makefile.head.mk
+
+locale = $(notdir $(srcdir))
+domains = $(patsubst %.po,%,$(filter %.po,$(files.src.src)))
+
+$(outdir)/%.mo: $(srcdir)/%.po $(call at.path,../%.po)
+	msgfmt -o $@ $<
+
+$(DESTDIR)$(localedir)/$(locale)/LC_MESSAGES/%.mo: $(outdir)/%.mo
+	install -T -Dm644 '$<' '$@'
+
+files.out.all += $(addsuffix .mo,$(domains))
+files.sys.all += $(foreach domain,$(domains),$(localedir)/$(locale)/LC_MESSAGES/$(domain).mo)
+at.subdirs += ..
+
+include $(topsrcdir)/build-aux/Makefile.tail.mk