maint: Factorize po xref translation.

This ensures we use the same method in "make" as in "guix/self.scm".

* Makefile.am: Build guix/build/po.scm.
* build-aux/convert-xref.scm: New file.
* doc/local.mk (xref_command): Use it.
* guix/self.scm (translate-cross-references): Move it...
* guix/build/po.scm: Parse comments and flags separately to find fuzzy
flags.
(translate-cross-references): ...here.
(parse-tree->assoc): Ignore fuzzy entries.

5 files changed, 165 insertions, 101 deletions

diff --git a/Makefile.am b/Makefile.am
index 635147efc1..41ec19eb89 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -640,6 +640,7 @@ EXTRA_DIST +=						\
   build-aux/check-final-inputs-self-contained.scm	\
   build-aux/check-channel-news.scm			\
   build-aux/compile-as-derivation.scm			\
+  build-aux/convert-xref.scm			\
   build-aux/generate-authors.scm			\
   build-aux/test-driver.scm				\
   build-aux/update-guix-package.scm			\
@@ -699,8 +700,6 @@ $(1): $(2)
 	  --completed $(3)					\
 	  $$(filter %.scm,$$^)
 
-.PHONY: $(1)
-
 endef
 
 # Split compilation in several steps, each of which building a subset of
@@ -712,22 +711,31 @@ MODULES_CORE     = guix.scm $(filter-out guix/scripts/%,$(filter guix/%,$(MODULE
 MODULES_PACKAGES = $(filter gnu/packages/%,$(MODULES))
 MODULES_SYSTEM   = gnu.scm $(filter-out gnu/packages/%,$(filter gnu/%,$(MODULES)))
 MODULES_CLI      = $(filter guix/scripts/%,$(MODULES))
+MODULES_PO       = guix/build/po.scm
 
 $(eval $(call guile-compilation-rule,make-core-go,	\
   $(MODULES_CORE) guix/config.scm $(dist_noinst_DATA),	\
   0))
+.PHONY: make-core-go
 
 $(eval $(call guile-compilation-rule,make-packages-go,	\
   $(MODULES_PACKAGES) make-core-go,			\
   $(words $(MODULES_CORE))))
+.PHONY: make-packages-go
 
 $(eval $(call guile-compilation-rule,make-system-go,	\
   $(MODULES_SYSTEM) make-packages-go make-core-go,	\
   $(words $(MODULES_CORE) $(MODULES_PACKAGES))))
+.PHONY: make-system-go
 
 $(eval $(call guile-compilation-rule,make-cli-go,			\
   $(MODULES_CLI) make-system-go make-packages-go make-core-go,		\
   $(words $(MODULES_CORE) $(MODULES_PACKAGES) $(MODULES_SYSTEM))))
+.PHONY: make-cli-go
+
+$(eval $(call guile-compilation-rule,guix/build/po.go,			\
+  $(MODULES_PO),							\
+  0))
 
 SUFFIXES = .go
 
diff --git a/build-aux/convert-xref.scm b/build-aux/convert-xref.scm
new file mode 100644
index 0000000000..47c8828857
--- /dev/null
+++ b/build-aux/convert-xref.scm
@@ -0,0 +1,26 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2021 Julien Lepiller <julien@lepiller.eu>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+;; Translate cross-references in a translated .texi manual.
+
+(use-modules (guix build po)
+             (ice-9 match))
+
+(match (command-line)
+  ((program texi pofile)
+   (translate-cross-references texi pofile)))
diff --git a/doc/local.mk b/doc/local.mk
index 8340b75a87..fff11f8183 100644
--- a/doc/local.mk
+++ b/doc/local.mk
@@ -97,44 +97,29 @@ PO4A_PARAMS += -k 0 # produce an output even if the translation is not complete
 PO4A_PARAMS += -f texinfo # texinfo format
 
 # When a change to guix.texi occurs, it is not translated immediately.
-# Because @pxref and @xref commands are reference to a section by name, they
+# Because @pxref and @xref commands are references to sections by name, they
 # should be translated. If a modification adds a reference to a section, this
 # reference is not translated, which means it references a section that does not
 # exist.
-# This command loops through the translated files looking for references. For
-# each of these references, it tries to find the translation and replaces the
-# reference name, even in untranslated strings.
-# The last sed is a multiline sed because some references span multiple lines.
 define xref_command
-cat "$@.tmp" | egrep '@p?x?ref' -A1 | sed 'N;s|--\n||g;P;D' | sed 's|^| |g' | \
-        tr -d '\012' | sed 's|\(@p\?x\?ref\)|\n\1|g' | egrep '@p?x?ref' | \
-        sed 's|^.*@p\?x\?ref{\([^,}]*\).*$$|\1|g' | sort | uniq | while read e; do \
-    if [ -n "$$e" ]; then \
-      line=$$(grep -n "^msgid \"$$e\"" "$<" | cut -f1 --delimiter=":") ;\
-      ((line++)) ;\
-      if [ "$$line" != "1" ]; then \
-	translation=$$(head -n "$$line" "$<" | tail -1 | grep msgstr | sed 's|msgstr "\([^"]*\)"|\1|') ;\
-	if [ "$$translation" != "" ]; then \
-	      sed "N;s@\(p\?x\?ref\){$$(echo $$e | sed 's| |[\\n ]|g')\(,\|}\)@\1{$$translation\2@g;P;D" -i "$@.tmp" ;\
-	fi ;\
-      fi ;\
-   fi ;\
-done
+$(top_srcdir)/pre-inst-env $(GUILE) --no-auto-compile	\
+  "$(top_srcdir)/build-aux/convert-xref.scm"		\
+  $@.tmp $<
 endef
 
-$(srcdir)/%D%/guix.%.texi: po/doc/guix-manual.%.po $(srcdir)/%D%/contributing.%.texi
+$(srcdir)/%D%/guix.%.texi: po/doc/guix-manual.%.po $(srcdir)/%D%/contributing.%.texi guix/build/po.go
 	-$(AM_V_PO4A)$(PO4A_TRANSLATE) $(PO4A_PARAMS) -m "%D%/guix.texi" -p "$<" -l "$@.tmp"
 	-sed -i "s|guix\.info|$$(basename "$@" | sed 's|texi$$|info|')|" "$@.tmp"
 	-$(AM_V_POXREF)$(xref_command)
 	-mv "$@.tmp" "$@"
 
-$(srcdir)/%D%/guix-cookbook.%.texi: po/doc/guix-cookbook.%.po
+$(srcdir)/%D%/guix-cookbook.%.texi: po/doc/guix-cookbook.%.po guix/build/po.go
 	-$(AM_V_PO4A)$(PO4A_TRANSLATE) $(PO4A_PARAMS) -m "%D%/guix-cookbook.texi" -p "$<" -l "$@.tmp"
 	-sed -i "s|guix-cookbook\.info|$$(basename "$@" | sed 's|texi$$|info|')|" "$@.tmp"
 	-$(AM_V_POXREF)$(xref_command)
 	-mv "$@.tmp" "$@"
 
-$(srcdir)/%D%/contributing.%.texi: po/doc/guix-manual.%.po
+$(srcdir)/%D%/contributing.%.texi: po/doc/guix-manual.%.po guix/build/po.go
 	-$(AM_V_PO4A)$(PO4A_TRANSLATE) $(PO4A_PARAMS) -m "%D%/contributing.texi" -p "$<" -l "$@.tmp"
 	-$(AM_V_POXREF)$(xref_command)
 	-mv "$@.tmp" "$@"
diff --git a/guix/build/po.scm b/guix/build/po.scm
index eb9690ad1a..7f88164cd8 100644
--- a/guix/build/po.scm
+++ b/guix/build/po.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2019 Julien Lepiller <julien@lepiller.eu>
+;;; Copyright © 2019, 2021 Julien Lepiller <julien@lepiller.eu>
 ;;; Copyright © 2020 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -20,17 +20,23 @@
 (define-module (guix build po)
   #:use-module (ice-9 match)
   #:use-module (ice-9 peg)
+  #:use-module (ice-9 regex)
   #:use-module (ice-9 textual-ports)
-  #:export (read-po-file))
+  #:use-module (ice-9 vlist)
+  #:use-module (srfi srfi-1)
+  #:export (read-po-file
+            translate-cross-references))
 
 ;; A small parser for po files
-(define-peg-pattern po-file body (* (or comment entry whitespace)))
+(define-peg-pattern po-file body (* (or entry whitespace)))
 (define-peg-pattern whitespace body (or " " "\t" "\n"))
 (define-peg-pattern comment-chr body (range #\space #\頋))
 (define-peg-pattern comment none (and "#" (* comment-chr) "\n"))
+(define-peg-pattern flags all (and (ignore "#, ") (* comment-chr) (ignore "\n")))
 (define-peg-pattern entry all
-  (and (ignore (* whitespace)) (ignore "msgid ") msgid
-       (ignore (* whitespace)) (ignore "msgstr ") msgstr))
+  (and (* (or flags comment (ignore (* whitespace))))
+       (ignore "msgid ") msgid (ignore (* whitespace))
+       (ignore "msgstr ") msgstr))
 (define-peg-pattern escape body (or "\\\\" "\\\"" "\\n"))
 (define-peg-pattern str-chr body (or " " "!" (and (ignore "\\") "\"")
                                      "\\n" (and (ignore "\\") "\\")
@@ -53,7 +59,24 @@
                (append (list "\n" prefix) result)))))))
 
 (define (parse-tree->assoc parse-tree)
-  "Converts a po PARSE-TREE to an association list."
+  "Converts a po PARSE-TREE to an association list, where the key is the msgid
+and the value is the msgstr.  The result only contains non fuzzy strings."
+  (define (comments->flags comments)
+    (match comments
+      (('flags flags)
+       (map (lambda (flag) (string->symbol (string-trim-both flag #\space)))
+            (string-split flags #\,)))
+      ((? list? comments)
+       (fold
+         (lambda (comment res)
+           (match comment
+             ((? string? _) res)
+             (flags
+              (append (comments->flags flags)
+                      res))))
+         '()
+         comments))))
+
   (match parse-tree
     (() '())
     ((entry . parse-tree)
@@ -66,10 +89,22 @@
        ;; empty msgstr
        (('entry ('msgid msgid) 'msgstr)
         (parse-tree->assoc parse-tree))
+       (('entry _ ('msgid msgid) 'msgstr)
+        (parse-tree->assoc parse-tree))
+       (('entry ('msgid msgid) ('msgstr msgstr))
+        (acons (interpret-newline-escape msgid)
+               (interpret-newline-escape msgstr)
+               (parse-tree->assoc parse-tree)))
        (('entry ('msgid msgid) ('msgstr msgstr))
         (acons (interpret-newline-escape msgid)
                (interpret-newline-escape msgstr)
-               (parse-tree->assoc parse-tree)))))))
+               (parse-tree->assoc parse-tree)))
+       (('entry comments ('msgid msgid) ('msgstr msgstr))
+        (if (member 'fuzzy (comments->flags comments))
+            (parse-tree->assoc parse-tree)
+            (acons (interpret-newline-escape msgid)
+                   (interpret-newline-escape msgstr)
+                   (parse-tree->assoc parse-tree))))))))
 
 (define (read-po-file port)
   "Read a .po file from PORT and return an alist of msgid and msgstr."
@@ -77,3 +112,71 @@
                           po-file
                           (get-string-all port)))))
     (parse-tree->assoc tree)))
+
+(define (canonicalize-whitespace str)
+  "Change whitespace (newlines, etc.) in STR to @code{#\\space}."
+  (string-map (lambda (chr)
+                (if (char-set-contains? char-set:whitespace chr)
+                    #\space
+                    chr))
+              str))
+
+(define xref-regexp
+  ;; Texinfo cross-reference regexp.
+  (make-regexp "@(px|x)?ref\\{([^,}]+)"))
+
+(define (translate-cross-references texi pofile)
+  "Translate the cross-references that appear in @var{texi}, the initial
+translation of a Texinfo file, using the msgid/msgstr pairs from @var{pofile}."
+  (define translations
+    (call-with-input-file pofile read-po-file))
+
+  (define content
+    (call-with-input-file texi get-string-all))
+
+  (define matches
+    (list-matches xref-regexp content))
+
+  (define translation-map
+    (fold (match-lambda*
+            (((msgid . str) result)
+             (vhash-cons msgid str result)))
+          vlist-null
+          translations))
+
+  (define translated
+    ;; Iterate over MATCHES and replace cross-references with their
+    ;; translation found in TRANSLATION-MAP.  (We can't use
+    ;; 'substitute*' because matches can span multiple lines.)
+    (let loop ((matches matches)
+               (offset 0)
+               (result '()))
+      (match matches
+        (()
+         (string-concatenate-reverse
+          (cons (string-drop content offset) result)))
+        ((head . tail)
+         (let ((prefix (match:substring head 1))
+               (ref    (canonicalize-whitespace (match:substring head 2))))
+           (define translated
+             (string-append "@" (or prefix "")
+                            "ref{"
+                            (match (vhash-assoc ref translation-map)
+                              (#f ref)
+                              ((_ . str) str))))
+
+           (loop tail
+                 (match:end head)
+                 (append (list translated
+                               (string-take
+                                (string-drop content offset)
+                                (- (match:start head) offset)))
+                         result)))))))
+
+  (format (current-error-port)
+          "translated ~a cross-references in '~a'~%"
+          (length matches) texi)
+
+  (call-with-output-file texi
+    (lambda (port)
+      (display translated port))))
diff --git a/guix/self.scm b/guix/self.scm
index a0d448742a..bd9a71de45 100644
--- a/guix/self.scm
+++ b/guix/self.scm
@@ -316,81 +316,23 @@ the result to OUTPUT."
                               chr))
                         str))
 
-          (define xref-regexp
-            ;; Texinfo cross-reference regexp.
-            (make-regexp "@(px|x)?ref\\{([^,}]+)"))
-
-          (define (translate-cross-references texi translations)
-            ;; Translate the cross-references that appear in TEXI, a Texinfo
-            ;; file, using the msgid/msgstr pairs from TRANSLATIONS.
-            (define content
-              (call-with-input-file texi get-string-all))
-
-            (define matches
-              (list-matches xref-regexp content))
-
-            (define translation-map
-              (fold (match-lambda*
-                      (((msgid . str) result)
-                       (vhash-cons msgid str result)))
-                    vlist-null
-                    translations))
-
-            (define translated
-              ;; Iterate over MATCHES and replace cross-references with their
-              ;; translation found in TRANSLATION-MAP.  (We can't use
-              ;; 'substitute*' because matches can span multiple lines.)
-              (let loop ((matches matches)
-                         (offset 0)
-                         (result '()))
-                (match matches
-                  (()
-                   (string-concatenate-reverse
-                    (cons (string-drop content offset) result)))
-                  ((head . tail)
-                   (let ((prefix (match:substring head 1))
-                         (ref    (canonicalize-whitespace (match:substring head 2))))
-                     (define translated
-                       (string-append "@" (or prefix "")
-                                      "ref{"
-                                      (match (vhash-assoc ref translation-map)
-                                        (#f ref)
-                                        ((_ . str) str))))
-
-                     (loop tail
-                           (match:end head)
-                           (append (list translated
-                                         (string-take
-                                          (string-drop content offset)
-                                          (- (match:start head) offset)))
-                                   result)))))))
-
-            (format (current-error-port)
-                    "translated ~a cross-references in '~a'~%"
-                    (length matches) texi)
-            (call-with-output-file texi
-              (lambda (port)
-                (display translated port))))
-
           (define* (translate-texi prefix po lang
                                    #:key (extras '()))
             "Translate the manual for one language LANG using the PO file.
 PREFIX must be the prefix of the manual, 'guix' or 'guix-cookbook'.  EXTRAS is
 a list of extra files, such as '(\"contributing\")."
-            (let ((translations (call-with-input-file po read-po-file)))
-              (for-each (lambda (file)
-                          (translate-tmp-texi po (string-append file ".texi")
-                                              (string-append file "." lang
-                                                             ".texi.tmp")))
-                        (cons prefix extras))
-
-              (for-each (lambda (file)
-                          (let* ((texi (string-append file "." lang ".texi"))
-                                 (tmp  (string-append texi ".tmp")))
-                            (copy-file tmp texi)
-                            (translate-cross-references texi
-                                                        translations)))
-                        (cons prefix extras))))
+            (for-each (lambda (file)
+                        (translate-tmp-texi po (string-append file ".texi")
+                                            (string-append file "." lang
+                                                           ".texi.tmp")))
+                      (cons prefix extras))
+
+            (for-each (lambda (file)
+                        (let* ((texi (string-append file "." lang ".texi"))
+                               (tmp  (string-append texi ".tmp")))
+                          (copy-file tmp texi)
+                          (translate-cross-references texi po)))
+                      (cons prefix extras)))
 
           (define (available-translations directory domain)
             ;; Return the list of available translations under DIRECTORY for