Internationalization of kiwix-serve's backend

debian/libkiwix-dev.manpages

@@ -1 +1,2 @@
 usr/share/man/man1/kiwix-compile-resources.1*
+usr/share/man/man1/kiwix-compile-i18n.1*

scripts/kiwix-compile-i18n

@@ -0,0 +1,161 @@
+#!/usr/bin/env python3
+
+'''
+Copyright 2022 Veloman Yunkan <veloman.yunkan@gmail.com>
+
+This program 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 any
+later version.
+
+This program 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 this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA.
+'''
+
+import argparse
+import os.path
+import re
+import json
+
+def to_identifier(name):
+    ident = re.sub(r'[^0-9a-zA-Z]', '_', name)
+    if ident[0].isnumeric():
+        return "_"+ident
+    return ident
+
+def lang_code(filename):
+    filename = os.path.basename(filename)
+    lang = to_identifier(os.path.splitext(filename)[0])
+    print(filename, '->', lang)
+    return lang
+
+from string import Template
+
+def expand_cxx_template(t, **kwargs):
+    return Template(t).substitute(**kwargs)
+
+def cxx_string_literal(s):
+    # Taking advantage of the fact the JSON string escape rules match
+    # those of C++
+    return 'u8' + json.dumps(s)
+
+string_table_cxx_template = '''
+const I18nString $TABLE_NAME[] = {
+  $TABLE_ENTRIES
+};
+'''
+
+lang_table_entry_cxx_template = '''
+    {
+        $LANG_STRING_LITERAL,
+        ARRAY_ELEMENT_COUNT($STRING_TABLE_NAME),
+        $STRING_TABLE_NAME
+    }'''
+
+cxxfile_template = '''// This file is automatically generated. Do not modify it.
+
+#include "server/i18n.h"
+
+namespace kiwix {
+namespace i18n {
+
+namespace
+{
+
+$STRING_DATA
+
+} // unnamed namespace
+
+#define ARRAY_ELEMENT_COUNT(a) (sizeof(a)/sizeof(a[0]))
+
+extern const I18nStringTable stringTables[] = {
+  $LANG_TABLE
+};
+
+extern const size_t langCount = $LANG_COUNT;
+
+} // namespace i18n
+} // namespace kiwix
+'''
+
+class Resource:
+    def __init__(self, base_dirs, filename):
+        filename = filename.strip()
+        self.filename = filename
+        self.lang_code = lang_code(filename)
+        found = False
+        for base_dir in base_dirs:
+            try:
+                with open(os.path.join(base_dir, filename), 'r') as f:
+                    self.data = f.read()
+                found = True
+                break
+            except FileNotFoundError:
+                continue
+        if not found:
+            raise Exception("Impossible to find {}".format(filename))
+
+
+    def get_string_table_name(self):
+        return "string_table_for_" + self.lang_code
+
+    def get_string_table(self):
+        table_entries = ",\n  ".join(self.get_string_table_entries())
+        return expand_cxx_template(string_table_cxx_template,
+                    TABLE_NAME=self.get_string_table_name(),
+                    TABLE_ENTRIES=table_entries)
+
+    def get_string_table_entries(self):
+        d = json.loads(self.data)
+        for k in sorted(d.keys()):
+            if k != "@metadata":
+                key_string = cxx_string_literal(k)
+                value_string = cxx_string_literal(d[k])
+                yield '{ ' + key_string + ', ' + value_string + ' }'
+
+    def get_lang_table_entry(self):
+        return expand_cxx_template(lang_table_entry_cxx_template,
+                LANG_STRING_LITERAL=cxx_string_literal(self.lang_code),
+                STRING_TABLE_NAME=self.get_string_table_name())
+
+
+
+def gen_c_file(resources):
+    string_data = []
+    lang_table = []
+    for r in resources:
+        string_data.append(r.get_string_table())
+        lang_table.append(r.get_lang_table_entry())
+
+    return expand_cxx_template(cxxfile_template,
+                STRING_DATA="\n".join(string_data),
+                LANG_TABLE=",\n  ".join(lang_table),
+                LANG_COUNT=len(resources)
+           )
+
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--cxxfile',
+                        required=True,
+                        help='The Cpp file name to generate')
+    parser.add_argument('i18n_resource_file',
+                        help='The list of resources to compile.')
+    args = parser.parse_args()
+
+    base_dir = os.path.dirname(os.path.realpath(args.i18n_resource_file))
+    with open(args.i18n_resource_file, 'r') as f:
+        resources = [Resource([base_dir], filename)
+                        for filename in f.readlines()]
+
+    with open(args.cxxfile, 'w') as f:
+        f.write(gen_c_file(resources))
+

scripts/kiwix-compile-i18n.1

@@ -0,0 +1,18 @@
+.TH KIWIX-COMPILE-I18N "1" "January 2022" "Kiwix" "User Commands"
+.SH NAME
+kiwix-compile-i18n \- helper to compile Kiwix i18n (internationalization) data
+.SH SYNOPSIS
+\fBkiwix\-compile\-i18n\fR [\-h] \-\-cxxfile CXXFILE i18n_resource_file\fR
+.SH DESCRIPTION
+.TP
+i18n_resource_file
+The list of i18n resources to compile.
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+show a help message and exit
+.TP
+\fB\-\-cxxfile\fR CXXFILE
+The Cpp file name to generate
+.TP
+.SH AUTHOR
+Veloman Yunkan <veloman.yunkan@gmail.com>

scripts/kiwix-compile-resources

@@ -102,7 +102,7 @@ class Resource:
 
 
 
-master_c_template = """//This file is automaically generated. Do not modify it.
+master_c_template = """//This file is automatically generated. Do not modify it.
 
 #include <stdlib.h>
 #include <fstream>

scripts/meson.build

@@ -4,3 +4,9 @@ res_compiler = find_program('kiwix-compile-resources')
 install_data(res_compiler.path(), install_dir:get_option('bindir'))
 
 install_man('kiwix-compile-resources.1')
+
+i18n_compiler = find_program('kiwix-compile-i18n')
+
+install_data(i18n_compiler.path(), install_dir:get_option('bindir'))
+
+install_man('kiwix-compile-i18n.1')

src/meson.build

@@ -28,10 +28,12 @@ kiwix_sources = [
   'server/response.cpp',
   'server/internalServer.cpp',
   'server/internalServer_catalog_v2.cpp',
+  'server/i18n.cpp',
   'opds_catalog.cpp',
   'version.cpp'
 ]
 kiwix_sources += lib_resources
+kiwix_sources += i18n_resources
 
 if host_machine.system() == 'windows'
   kiwix_sources += 'subprocess_windows.cpp'

src/server/i18n.cpp

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2022 Veloman Yunkan <veloman.yunkan@gmail.com>
+ *
+ * This program 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
+ * any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include "i18n.h"
+
+#include "tools/otherTools.h"
+
+#include <algorithm>
+#include <map>
+
+namespace kiwix
+{
+
+const char* I18nStringTable::get(const std::string& key) const
+{
+  const I18nString* const begin = entries;
+  const I18nString* const end = begin + entryCount;
+  const I18nString* found = std::lower_bound(begin, end, key,
+      [](const I18nString& a, const std::string& k) {
+        return a.key < k;
+  });
+  return (found == end || found->key != key) ? nullptr : found->value;
+}
+
+namespace i18n
+{
+// this data is generated by the i18n resource compiler
+extern const I18nStringTable stringTables[];
+extern const size_t langCount;
+}
+
+namespace
+{
+
+class I18nStringDB
+{
+public: // functions
+  I18nStringDB() {
+    for ( size_t i = 0; i < kiwix::i18n::langCount; ++i ) {
+      const auto& t = kiwix::i18n::stringTables[i];
+      lang2TableMap[t.lang] = &t;
+    }
+    enStrings = lang2TableMap.at("en");
+  };
+
+  std::string get(const std::string& lang, const std::string& key) const {
+    const char* s = getStringsFor(lang)->get(key);
+    if ( s == nullptr ) {
+      s = enStrings->get(key);
+      if ( s == nullptr ) {
+        throw std::runtime_error("Invalid message id");
+      }
+    }
+    return s;
+  }
+
+private: // functions
+  const I18nStringTable* getStringsFor(const std::string& lang) const {
+    try {
+      return lang2TableMap.at(lang);
+    } catch(const std::out_of_range&) {
+      return enStrings;
+    }
+  }
+
+private: // data
+  std::map<std::string, const I18nStringTable*> lang2TableMap;
+  const I18nStringTable* enStrings;
+};
+
+} // unnamed namespace
+
+std::string getTranslatedString(const std::string& lang, const std::string& key)
+{
+  static const I18nStringDB stringDb;
+
+  return stringDb.get(lang, key);
+}
+
+namespace i18n
+{
+
+std::string expandParameterizedString(const std::string& lang,
+                                      const std::string& key,
+                                      const Parameters& params)
+{
+  const std::string tmpl = getTranslatedString(lang, key);
+  return render_template(tmpl, params);
+}
+
+} // namespace i18n
+
+std::string ParameterizedMessage::getText(const std::string& lang) const
+{
+  return i18n::expandParameterizedString(lang, msgId, params);
+}
+
+} // namespace kiwix