Load translations from XLIFF format

When an <xliff> entry is present inside a locale specification,
this takes precedence over the legacy translations.

src/Main/CMakeLists.txt

@@ -28,6 +28,7 @@ set(SOURCES
     screensaver_control.cxx
     subsystemFactory.cxx
     util.cxx
+    XLIFFParser.cxx
     ${MS_RESOURCE_FILE}
 )
 
@@ -47,6 +48,7 @@ set(HEADERS
     screensaver_control.hxx
     subsystemFactory.hxx
     util.hxx
+    XLIFFParser.hxx
 )
 
 flightgear_component(Main "${SOURCES}" "${HEADERS}")

src/Main/XLIFFParser.cxx

@@ -0,0 +1,122 @@
+// XLIFFParser.cxx -- parse an XLIFF 1.2 XML file
+////
+// Copyright (C) 2018  James Turner <james@flightgear.org>
+//
+// 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 2 of the
+// License, or (at your option) 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 "config.h"
+
+#include "XLIFFParser.hxx"
+
+// simgear
+#include <simgear/debug/logstream.hxx>
+#include <simgear/props/props.hxx>
+
+using namespace flightgear;
+
+XLIFFParser::XLIFFParser(SGPropertyNode_ptr lroot) :
+    _localeRoot(lroot)
+{
+    
+}
+
+void XLIFFParser::startXML()
+{
+    
+}
+
+void XLIFFParser::endXML()
+{
+    
+}
+
+void XLIFFParser::startElement(const char *name, const XMLAttributes &atts)
+{
+    _text.clear();
+    std::string tag(name);
+    if (tag == "trans-unit") {
+        _unitId = atts.getValue("id");
+        if (_unitId.empty()) {
+            SG_LOG(SG_GENERAL, SG_WARN, "XLIFF trans-unit with missing ID: line "
+                   << getLine() << " of " << getPath());
+        }
+    } else if (tag == "group") {
+        _resource = atts.getValue("resname");
+        if (_resource.empty()) {
+            SG_LOG(SG_GENERAL, SG_WARN, "XLIFF group with missing resname: line "
+                   << getLine() << " of " << getPath());
+        } else {
+            _resourceNode = _localeRoot->getChild(_resource, 0, true /* create */);
+        }
+    }
+}
+
+void XLIFFParser::endElement(const char* name)
+{
+    std::string tag(name);
+    if (tag == "source") {
+        _source = _text;
+    } else if (tag == "target") {
+        _target = _text;
+    } else if (tag == "trans-unit") {
+        finishTransUnit();
+    }
+    
+}
+
+void XLIFFParser::finishTransUnit()
+{
+    if (!_resourceNode) {
+        SG_LOG(SG_GENERAL, SG_WARN, "XLIFF trans-unit without enclosing resource group: line "
+               << getLine() << " of " << getPath());
+        return;
+    }
+    
+    const auto slashPos = _unitId.find('/');
+    const auto indexPos = _unitId.find(':');
+
+    if (slashPos == std::string::npos)  {
+        SG_LOG(SG_GENERAL, SG_WARN, "XLIFF trans-unit id without resource: '" <<
+               _unitId << "' at line " << getLine() << " of " << getPath());
+        return;
+    }
+    
+    const auto res = _unitId.substr(0, slashPos);
+    if (res != _resource) {
+        // this implies the <group> node resname doesn't match the
+        // id resource prefix. For now just warn and skip, we could decide
+        // that one or the other takes precedence here?
+        SG_LOG(SG_GENERAL, SG_WARN, "XLIFF trans-unit with inconsistent resource: line "
+               << getLine() << " of " << getPath());
+        return;
+    }
+    
+    const auto id = _unitId.substr(slashPos + 1, indexPos - (slashPos + 1));
+    _resourceNode->setStringValue(id, _target);
+}
+
+void XLIFFParser::data (const char * s, int len)
+{
+    _text += std::string(s, len);
+}
+
+
+void XLIFFParser::pi (const char * target, const char * data) {
+    //cout << "Processing instruction " << target << ' ' << data << endl;
+}
+
+void XLIFFParser::warning (const char * message, int line, int column) {
+    SG_LOG(SG_GENERAL, SG_WARN, "Warning: " << message << " (" << line << ',' << column << ')');
+}

src/Main/XLIFFParser.hxx

@@ -0,0 +1,53 @@
+// XLIFFParser.hxx -- parse an XLIFF 1.2 XML file
+////
+// Copyright (C) 2018  James Turner <james@flightgear.org>
+//
+// 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 2 of the
+// License, or (at your option) 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 <simgear/xml/easyxml.hxx>
+
+#include <string>
+
+#include <simgear/props/propsfwd.hxx>
+
+namespace flightgear
+{
+
+class XLIFFParser : public XMLVisitor
+{
+public:
+    XLIFFParser(SGPropertyNode_ptr lroot);
+    
+protected:
+    void startXML () override;
+    void endXML   () override;
+    void startElement (const char * name, const XMLAttributes &atts) override;
+    void endElement (const char * name) override;
+    void data (const char * s, int len) override;
+    void pi (const char * target, const char * data) override;
+    void warning (const char * message, int line, int column) override;
+    
+private:
+    void finishTransUnit();
+    
+    SGPropertyNode_ptr _localeRoot;
+    SGPropertyNode_ptr _resourceNode;
+    
+    std::string _text;
+    std::string _unitId, _resource;
+    std::string _source, _target;
+};
+
+}

src/Main/locale.cxx

@@ -18,9 +18,7 @@
 // along with this program; if not, write to the Free Software
 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
 
-#ifdef HAVE_CONFIG_H
+#include <config.h>
-#  include <config.h>
-#endif
 
 #ifdef HAVE_WINDOWS_H
 #include <windows.h>
@@ -31,11 +29,13 @@
 #include <cstddef>              // std::size_t
 #include <cassert>
 
+#include <simgear/props/props.hxx>
 #include <simgear/props/props_io.hxx>
 #include <simgear/structure/exception.hxx>
 
 #include "fg_props.hxx"
 #include "locale.hxx"
+#include "XLIFFParser.hxx"
 
 using std::vector;
 using std::string;
@@ -188,7 +188,12 @@ FGLocale::selectLanguage(const char *language)
             break;
         }
     }
-
+    
+    if (_currentLocale && _currentLocale->hasChild("xliff")) {
+        parseXLIFF(_currentLocale);
+    }
+   
+    
     // load resource for system messages (translations for fgfs internal messages)
     loadResource("sys");
 
@@ -215,6 +220,28 @@ FGLocale::getPreferredLanguage() const
     return _currentLocaleString;
 }
 
+void FGLocale::parseXLIFF(SGPropertyNode* localeNode)
+{
+    SGPath path(globals->get_fg_root());
+    SGPath xliffPath = path / localeNode->getStringValue("xliff");
+    if (!xliffPath.exists()) {
+        SG_LOG(SG_GENERAL, SG_ALERT, "No XLIFF file at " << xliffPath);
+    } else {
+        SG_LOG(SG_GENERAL, SG_INFO, "Loading XLIFF file at " << xliffPath);
+        SGPropertyNode_ptr stringNode = localeNode->getNode("strings", 0, true);
+        try {
+            flightgear::XLIFFParser visitor(stringNode);
+            readXML(xliffPath, visitor);
+        } catch (sg_io_exception& ex) {
+            SG_LOG(SG_GENERAL, SG_WARN, "failure parsing XLIFF: " << path <<
+                   "\n\t" << ex.getMessage() << "\n\tat:" << ex.getLocation().asString());
+        } catch (sg_exception& ex) {
+            SG_LOG(SG_GENERAL, SG_WARN, "failure parsing XLIFF: " << path <<
+                   "\n\t" << ex.getMessage());
+        }
+    }
+}
+
 // Load strings for requested resource and locale.
 // Result is stored below "strings" in the property tree of the given locale.
 bool
@@ -222,6 +249,11 @@ FGLocale::loadResource(SGPropertyNode* localeNode, const char* resource)
 {
     SGPath path( globals->get_fg_root() );
 
+    // already loaded
+    if (localeNode->hasChild("xliff")) {
+        return true;
+    }
+    
     SGPropertyNode* stringNode = localeNode->getNode("strings", 0, true);
 
     const char *path_str = stringNode->getStringValue(resource, nullptr);

src/Main/locale.hxx

@@ -24,7 +24,11 @@
 #include <string>
 #include <cstdarg> // for va_start/_end
 
-#include <simgear/props/props.hxx>
+#include <simgear/props/propsfwd.hxx>
+#include <simgear/misc/strutils.hxx>
+
+// forward decls
+class SGPath;
 
 ///////////////////////////////////////////////////////////////////////////////
 // FGLocale  //////////////////////////////////////////////////////////////////
@@ -138,6 +142,11 @@ protected:
     SGPropertyNode_ptr _defaultLocale;
     std::string _currentLocaleString;
 
+    /**
+     * Parse an XLIFF 1.2 file into the standard property structure underneath
+     * the provided locale node
+     */
+    void parseXLIFF(SGPropertyNode* node);
 private:
     /** Return a new string with the character encoding part of the locale
      *  spec removed., i.e., "de_DE.UTF-8" becomes "de_DE". If there is no