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.

2 files changed, 122 insertions, 77 deletions

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