tde-cmake/modules/TDEL10n.cmake

#################################################
#
#  (C) 2018 Slávek Banko
#  slavek (DOT) banko (AT) axis.cz
#
#  Improvements and feedback are welcome
#
#  This file is released under GPL >= 2
#
#################################################


##### include essential TDE macros ##############

set( MASTER_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}" )
include( TDEMacros )


##### verify required programs ##################

if( NOT DEFINED TDE_PREFIX AND IS_DIRECTORY /opt/trinity )
  set( TDE_PREFIX "/opt/trinity" )
else( )
  set( TDE_PREFIX "/usr" )
endif( )

if( NOT DEFINED KDE_XGETTEXT_EXECUTABLE )
  find_program( KDE_XGETTEXT_EXECUTABLE
    NAMES kde-xgettext
    HINTS "${TDE_PREFIX}/bin"
  )
  if( NOT KDE_XGETTEXT_EXECUTABLE )
    tde_message_fatal( "kde-xgettext is required but not found" )
  endif( )
endif( )

if( NOT DEFINED EXTRACTATTR_EXECUTABLE )
  find_program( EXTRACTATTR_EXECUTABLE
    NAMES extractattr
    HINTS "${TDE_PREFIX}/bin"
  )
  if( NOT EXTRACTATTR_EXECUTABLE )
    tde_message_fatal( "extractattr is required but not found" )
  endif( )
endif( )

if( NOT DEFINED XGETTEXT_EXECUTABLE )
  find_program( XGETTEXT_EXECUTABLE
    NAMES xgettext
    HINTS "${TDE_PREFIX}/bin"
  )
  if( NOT XGETTEXT_EXECUTABLE )
    tde_message_fatal( "xgettext is required but not found" )
  endif( )
  execute_process(
    COMMAND ${XGETTEXT_EXECUTABLE} --version
    OUTPUT_VARIABLE _xgettext_version
    ERROR_VARIABLE _xgettext_version
  )
  string( REGEX REPLACE "^xgettext[^\n]* ([^ ]*)\n.*" "\\1" _xgettext_version ${_xgettext_version} )
  if( "${_xgettext_version}" VERSION_LESS "0.19" )
    tde_message_fatal( "xgettext version >= 0.19 is required but found only ${_xgettext_version}" )
  endif( )
endif( )

if( NOT DEFINED MSGUNIQ_EXECUTABLE )
  find_program( MSGUNIQ_EXECUTABLE
    NAMES msguniq
    HINTS "${TDE_PREFIX}/bin"
  )
  if( NOT MSGUNIQ_EXECUTABLE )
    tde_message_fatal( "msguniq is required but not found" )
  endif( )
endif( )

if( NOT DEFINED MSGCAT_EXECUTABLE )
  find_program( MSGCAT_EXECUTABLE
    NAMES msgcat
    HINTS "${TDE_PREFIX}/bin"
  )
  if( NOT MSGCAT_EXECUTABLE )
    tde_message_fatal( "msgcat is required but not found" )
  endif( )
endif( )


#################################################
#####
##### tde_l10n_add_subdirectory
#####
##### The function simulates the add_subdirectory() behavior, but
##### the CMakeL10n.txt file is used instead of CMakeLists.txt.
#####

function( tde_l10n_add_subdirectory _dir )
  set( CMAKE_CURRENT_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/${_dir}" )
  set( CMAKE_CURRENT_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/${_dir}" )
  include( ${CMAKE_CURRENT_SOURCE_DIR}/CMakeL10n.txt )
endfunction( )


#################################################
#####
##### tde_l10n_auto_add_subdirectories
#####
##### The function is equivalent to tde_auto_add_subdirectories, but
##### the CMakeL10n.txt file is used instead of CMakeLists.txt.
#####

function( tde_l10n_auto_add_subdirectories )
  file( GLOB _dirs RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} "${CMAKE_CURRENT_SOURCE_DIR}/*" )
  foreach( _dir ${_dirs} )
    if( IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/${_dir}
        AND NOT ${_dir} STREQUAL ".svn"
        AND EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${_dir}/CMakeL10n.txt )
      tde_l10n_add_subdirectory( ${_dir} )
    endif( )
  endforeach( )
endfunction( )


#################################################
#####
##### tde_l10n_create_template
#####
##### Macro is used to generate a translation template - POT file.
#####
##### Syntax:
#####   tde_l10n_create_template(
#####     [CATALOG] file_name
#####     [SOURCES source_spec [source_spec]]
#####     [EXCLUDES regex [regex]]
#####     [KEYWORDS keyword [keyword]]
#####     [ATTRIBUTES attrib_spec [attrib_spec]]
#####     [DESTINATION directory]
#####   )
#####
##### Where:
#####   CATALOG determines the target file name (without pot suffix).
#####   SOURCES can be specified by several options:
#####     a) Do not specify anything
#####      - all usual source files will be automatically searched.
#####     b) Enter the directory name - for example, '.' or 'src'
#####      - all the usual source files in the specified directory
#####        and subdirectories will be searched.
#####     c) Enter the mask - for example '*.cpp'
#####      - all files with the specified mask will be searched.
#####     d) Specify the name of the individual file.
#####     The methods from b) to d) can be combined.
#####   EXCLUDES determines which files are to be excluded from processing
#####   KEYWORDS determines additional keywords for xgettext.
#####   ATTRIBUTES determines files and specification for extractattr:
#####     source_spec:element,attribute[,context]
#####   DESTINATION determines directory to save translation template.
#####     The destination directory is determined as follows:
#####     a) Directory is specified as an argument.
#####     b) The variable POT_SOURCE_DIR is set.
#####     c) There is a 'translations' directory.
#####     d) There is a 'po' directory.
#####
##### Note:
#####    Editing the _files list inside foreach( ${_files} ) below in the
#####    code is safe, because in CMake foreach parameters are evaluated
#####    before the loop starts. Therefore, the changes in the list inside
#####    the loop do not have an unwanted impact on the loop processing.
#####

macro( tde_l10n_create_template )

  unset( _catalog )
  unset( _sources )
  unset( _excludes )
  unset( _files )
  unset( _desktops )
  unset( _pots )
  unset( _dest )
  unset( _keywords )
  unset( _attributes )
  unset( _pot )
  unset( _directive )
  set( _var _catalog )

  foreach( _arg ${ARGN} )

    # found directive "CATALOG"
    if( "+${_arg}" STREQUAL "+CATALOG" )
      unset( _catalog )
      set( _var _catalog )
      set( _directive 1 )
    endif( )

    # found directive "SOURCES"
    if( "+${_arg}" STREQUAL "+SOURCES" )
      unset( _sources )
      set( _var _sources )
      set( _directive 1 )
    endif( )

    # found directive "EXCLUDES"
    if( "+${_arg}" STREQUAL "+EXCLUDES" )
      unset( _excludes )
      set( _var _excludes )
      set( _directive 1 )
    endif( )

    # found directive "DESTINATION"
    if( "+${_arg}" STREQUAL "+DESTINATION" )
      unset( _dest )
      set( _var _dest )
      set( _directive 1 )
    endif( )

    # found directive "KEYWORDS"
    if( "+${_arg}" STREQUAL "+KEYWORDS" )
      unset( _keywords )
      set( _var _keywords )
      set( _directive 1 )
    endif( )

    # found directive "ATTRIBUTES"
    if( "+${_arg}" STREQUAL "+ATTRIBUTES" )
      unset( _attributes )
      set( _var _attributes )
      set( _directive 1 )
    endif( )

    # collect data
    if( _directive )
      unset( _directive )
    elseif( _var )
      list( APPEND ${_var} ${_arg} )
    endif( )

  endforeach( )

  # verify catalog
  if( NOT _catalog )
    tde_message_fatal( "the name of the translation catalog is not defined" )
  endif( )

  # determine the destination directory
  if( NOT _dest )
    if( POT_SOURCE_DIR )
      set( _dest ${POT_SOURCE_DIR} )
    elseif( EXISTS "${MASTER_SOURCE_DIR}/translations" )
      set( _dest "${MASTER_SOURCE_DIR}/translations/" )
    elseif( EXISTS "${MASTER_SOURCE_DIR}/po" )
      set( _dest "${MASTER_SOURCE_DIR}/po/" )
    else( )
      tde_message_fatal( "cannot determine destination directory" )
    endif( )
  endif( )
  if( ${_dest} MATCHES "[^/]$" )
    set( _dest "${_dest}/" )
  endif( )
  if( ${_dest} MATCHES "^[^/]" )
    set( _dest "${CMAKE_CURRENT_SOURCE_DIR}/${_dest}" )
  endif( )

  get_filename_component( _potFilename "${_dest}${_catalog}.pot" ABSOLUTE )
  file( RELATIVE_PATH _potFilename ${CMAKE_SOURCE_DIR} ${_potFilename} )
  message( STATUS "Create translation template ${_potFilename}" )

  # verify sources
  if( NOT _sources AND NOT _attributes )
    # add current directory
    list( APPEND _sources "." )
  endif( )
  foreach( _src ${_sources} )

    # add all source files from directory
    if( IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/${_src} )
      if( ${_src} STREQUAL "." )
        set( _dir "${CMAKE_CURRENT_SOURCE_DIR}" )
      else( )
        set( _dir "${CMAKE_CURRENT_SOURCE_DIR}/${_src}" )
      endif( )
      file( GLOB_RECURSE _add_files
            RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}
            ${_dir}/*.c
            ${_dir}/*.cc
            ${_dir}/*.cpp
            ${_dir}/*.h
            ${_dir}/*.kcfg
            ${_dir}/*.rc
            ${_dir}/*.ui
      )
      list( SORT _add_files )
      list( APPEND _files ${_add_files} )

    # add files by the specified mask
    elseif( ${_src} MATCHES "(\\*|\\?)" )
      file( GLOB_RECURSE _add_files
            RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}
            ${CMAKE_CURRENT_SOURCE_DIR}/${_src}
      )
      list( SORT _add_files )
      list( APPEND _files ${_add_files} )

    # add a individual file
    elseif( EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${_src} )
      list( APPEND _files ${_src} )
    endif( )

  endforeach( )

  # add common translator info
  if( _files )
    set( _translatorinfo
      "i18n(\"NAME OF TRANSLATORS\", \"Your names\")\n"
      "i18n(\"EMAIL OF TRANSLATORS\", \"Your emails\")\n"
    )
    file( WRITE ${CMAKE_CURRENT_SOURCE_DIR}/_translatorinfo.tde_l10n ${_translatorinfo} )
    list( INSERT _files 0 "_translatorinfo.tde_l10n" )
  endif( )

  # filter files by excludes
  if( _excludes )
    foreach( _src ${_files} )
      foreach( _exclude ${_excludes} )
        if( ${_src} MATCHES ${_exclude} )
          list( REMOVE_ITEM _files ${_src} )
        endif( )
      endforeach( )
    endforeach( )
  endif( )
  if( NOT _files AND NOT _attributes )
    tde_message_fatal( "no source files found" )
  endif( )

  # prepare additional keywords
  unset( _add_keywords )
  foreach( _keyword ${_keywords} )
    list( APPEND _add_keywords "-k${_keyword}" )
  endforeach( )

  # prepare resource files *.kcfg, *.rc and *.ui
  foreach( _src ${_files} )
    if( ${_src} MATCHES "\\.(kcfg|rc|ui)(\\.cmake)?(\\.tde_l10n)?$" )
      tde_l10n_prepare_xml( ${_src} )
      list( REMOVE_ITEM _files ${_src} )
      list( APPEND _files "${_src}.tde_l10n" )
    endif( )
  endforeach( )

  # prepare extracted-rc.tde_l10n
  if( _attributes )
    file( WRITE ${CMAKE_CURRENT_SOURCE_DIR}/extracted-rc.tde_l10n "" )
    list( APPEND _files extracted-rc.tde_l10n )
  endif( )

  # extract attributes
  if( _attributes )
    foreach( _attrib ${_attributes} )
      if( ${_attrib} MATCHES "^([^:]+):(.+)$" )
        string( REGEX REPLACE "^([^:]+):(.+)$" "\\1" _attrib_glob ${_attrib} )
        string( REGEX REPLACE "^([^:]+):(.+)$" "\\2" _attrib_spec ${_attrib} )
        file( GLOB_RECURSE _attrib_files
              RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}
              ${CMAKE_CURRENT_SOURCE_DIR}/${_attrib_glob}
        )
        if( _attrib_files )
          list( SORT _attrib_files )
          execute_process(
            COMMAND ${EXTRACTATTR_EXECUTABLE}
              --attr=${_attrib_spec} ${_attrib_files}
            WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
            OUTPUT_VARIABLE _attrib_rc
          )
          file( APPEND ${CMAKE_CURRENT_SOURCE_DIR}/extracted-rc.tde_l10n "${_attrib_rc}" )
        endif( )
      endif( )
    endforeach( )
  endif( )

  # prepare tips
  foreach( _src ${_files} )
    if( ${_src} MATCHES "(^|/)tips$" )
      tde_l10n_preparetips( ${_src} )
      list( REMOVE_ITEM _files ${_src} )
      list( APPEND _files "${_src}.tde_l10n" )
    endif( )
  endforeach( )

  # pick desktop files *.desktop and *.protocol
  foreach( _src ${_files} )
    if( ${_src} MATCHES "\\.(desktop|protocol)(\\.cmake)?(\\.tde_l10n)?$" )
      list( APPEND _desktops ${_src} )
      list( REMOVE_ITEM _files ${_src} )
    endif( )
  endforeach( )

  # pick pot files *.pot
  foreach( _src ${_files} )
    if( ${_src} MATCHES "\\.pot(\\.cmake)?(\\.tde_l10n)?$" )
      list( APPEND _pots ${_src} )
      list( REMOVE_ITEM _files ${_src} )
    endif( )
  endforeach( )

  # create translation template
  if( _files )
    execute_process(
      COMMAND ${KDE_XGETTEXT_EXECUTABLE} --foreign-user -C
        -ki18n -ki18n:1,2 -ktr2i18n -ktr2i18n:1,2
        -kI18N_NOOP -kI18N_NOOP2 ${_add_keywords}
        -o - ${_files}
      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
      OUTPUT_VARIABLE _pot
    )

    # set charset and encoding headers
    if( _pot )
      string( REPLACE "Content-Type: text/plain; charset=CHARSET" "Content-Type: text/plain; charset=UTF-8" _pot "${_pot}" )
      string( REPLACE "Content-Transfer-Encoding: ENCODING" "Content-Transfer-Encoding: 8bit" _pot "${_pot}" )
    endif( )
  endif( )

  # process desktop files
  if( _desktops )
    # create translation template for desktop files
    if( _pot )
      set( _withPotHeader "--omit-header" )
    else( )
      set( _withPotHeader "--foreign-user" )
    endif( )
    execute_process(
      COMMAND ${XGETTEXT_EXECUTABLE} ${_withPotHeader} -L Desktop
        -kDescription -kExtraNames -kX-TDE-Submenu ${_add_keywords}
        -o - ${_desktops}
      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
      OUTPUT_VARIABLE _potDesktop
    )

    # merge translation templates
    if( _potDesktop )
      if( _pot )
        file( WRITE ${CMAKE_CURRENT_SOURCE_DIR}/extracted-pot.tmp "${_pot}" )
        file( APPEND ${CMAKE_CURRENT_SOURCE_DIR}/extracted-pot.tmp "${_potDesktop}" )
        execute_process(
          COMMAND ${MSGUNIQ_EXECUTABLE} --use-first
          INPUT_FILE ${CMAKE_CURRENT_SOURCE_DIR}/extracted-pot.tmp
          WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
          OUTPUT_VARIABLE _pot
        )
        file( REMOVE ${CMAKE_CURRENT_SOURCE_DIR}/extracted-pot.tmp )
      else( )
        set( _pot "${_potDesktop}" )

        # set charset and encoding headers
        string( REPLACE "Content-Type: text/plain; charset=CHARSET" "Content-Type: text/plain; charset=UTF-8" _pot "${_pot}" )
        string( REPLACE "Content-Transfer-Encoding: ENCODING" "Content-Transfer-Encoding: 8bit" _pot "${_pot}" )
      endif( )
    endif( )
  endif( )

  # merge additional pot files
  if( _pots )
    file( WRITE ${CMAKE_CURRENT_SOURCE_DIR}/extracted-pot.tmp "${_pot}" )
    execute_process(
      COMMAND ${MSGCAT_EXECUTABLE} --use-first extracted-pot.tmp ${_pots}
      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
      OUTPUT_VARIABLE _pot
    )
    file( REMOVE ${CMAKE_CURRENT_SOURCE_DIR}/extracted-pot.tmp )

    # set charset and encoding headers
    string( REPLACE "Content-Type: text/plain; charset=CHARSET" "Content-Type: text/plain; charset=UTF-8" _pot "${_pot}" )
    string( REPLACE "Content-Transfer-Encoding: ENCODING" "Content-Transfer-Encoding: 8bit" _pot "${_pot}" )
  endif( )

  # finalize translation template
  if( _pot )

    # update references for resources to original files and line numbers
    if( _attributes )
      file( READ "${CMAKE_CURRENT_SOURCE_DIR}/extracted-rc.tde_l10n" _extractedRC )
      string( REGEX REPLACE "[^\n]" "" _extractedRC_len "${_extractedRC}" )
      string( LENGTH "+${_extractedRC_len}" _extractedRC_len )
      set( _rcPos 0 )
      while( _rcPos LESS ${_extractedRC_len} )
        string( REGEX REPLACE "^([^\n]*)\n(.*)" "\\1" _rcLine "${_extractedRC}" )
        string( REGEX REPLACE "^([^\n]*)\n(.*)" "\\2" _extractedRC "${_extractedRC}" )
        math( EXPR _rcPos "${_rcPos}+1" )
        if( "${_rcLine}" MATCHES "^//i18n: file .* line [0-9]*$" )
          string( REGEX REPLACE "^//i18n: file (.*) line ([0-9]*)$" "\\1:\\2" _rcOrig ${_rcLine} )
        endif( )
        if( "${_rcLine}" MATCHES "^i18n\\(" AND _rcOrig )
          string( REGEX REPLACE "(^|\n)(#:.*) extracted-rc.tde_l10n:${_rcPos}( |\n)" "\\1\\2 ${_rcOrig}\\3" _pot "${_pot}" )
          unset( _rcOrig )
        endif( )
      endwhile( )
    endif( )

    # update references for modified source files (".tde_l10n" extension)
    string( REGEX REPLACE "\\.tde_l10n(:[0-9]+)" "\\1" _pot "${_pot}" )

    # save translation template
    if( EXISTS "${_dest}${_catalog}.pot" )
      file( READ "${_dest}${_catalog}.pot" _potOrig )
    else( )
      unset( _potOrig )
    endif( )
    if( _potOrig )
      string( REGEX REPLACE "\n\"POT-Creation-Date: [^\"]*\"\n" "" _potOrig "${_potOrig}" )
      string( REGEX REPLACE "\n\"POT-Creation-Date: [^\"]*\"\n" "" _potNew "${_pot}" )
    endif( )
    if( NOT _potOrig OR NOT "${_potNew}" STREQUAL "${_potOrig}" )
      file( WRITE "${_dest}${_catalog}.pot" "${_pot}" )
    endif( )

  endif( _pot )

  # cleanup
  foreach( _file ${_files} ${_desktops} )
    if( "${_file}" MATCHES "\\.tde_l10n$" )
      file( REMOVE ${CMAKE_CURRENT_SOURCE_DIR}/${_file} )
    endif( )
  endforeach( )

endmacro( )


#################################################
#####
##### tde_l10n_preparetips
#####
##### Macro is used to prepare tips file for xgettext
#####

macro( tde_l10n_preparetips _tips )

  tde_l10n_prepare_xml(
    SOURCE ${_tips}
    TAGS html
    C_FORMAT
    PRESERVE entities line-wrap spaces-leading spaces-trailing spaces-multi
  )

endmacro( )


#################################################
#####
##### tde_l10n_prepare_xml
#####
##### The function is used to prepare XML file for xgettext.
##### The default settings are identical to extractrc.
#####

function( tde_l10n_prepare_xml )

  unset( _source )
  unset( _target )
  unset( _context )
  set( _tags "[tT][eE][xX][tT]|title|string|whatsthis|tooltip|label" )
  set( _preserve "line-wrap" "lines-leading" "spaces-leading" "spaces-trailing" "spaces-multi" )
  set( _no_c_format 1 )
  unset( _directive )
  set( _var _source )

  foreach( _arg ${ARGN} )

    # found directive "SOURCE"
    if( "+${_arg}" STREQUAL "+SOURCE" )
      unset( _source )
      set( _var _source )
      set( _directive 1 )
    endif( )

    # found directive "TARGET"
    if( "+${_arg}" STREQUAL "+TARGET" )
      unset( _target )
      set( _var _target )
      set( _directive 1 )
    endif( )

    # found directive "CONTEXT"
    if( "+${_arg}" STREQUAL "+CONTEXT" )
      unset( _context )
      set( _var _context )
      set( _directive 1 )
    endif( )

    # found directive "TAGS"
    if( "+${_arg}" STREQUAL "+TAGS" )
      unset( _tags )
      set( _var _tags )
      set( _directive 1 )
    endif( )

    # found directive "PRESERVE"
    if( "+${_arg}" STREQUAL "+PRESERVE" )
      unset( _preserve )
      set( _var _preserve )
      set( _directive 1 )
    endif( )

    # found directive "C_FORMAT"
    if( "+${_arg}" STREQUAL "+C_FORMAT" )
      unset( _no_c_format )
      set( _directive 1 )
    endif( )

    # found directive "NO_C_FORMAT"
    if( "+${_arg}" STREQUAL "+NO_C_FORMAT" )
      set( _no_c_format 1 )
      set( _directive 1 )
    endif( )

    # collect data
    if( _directive )
      unset( _directive )
    elseif( _var )
      list( APPEND ${_var} ${_arg} )
    endif( )

  endforeach( )

  # verify source
  if( NOT _source )
    tde_message_fatal( "no source XML file" )
  endif( )
  if( NOT "${_source}" MATCHES "^/" )
    set( _source "${CMAKE_CURRENT_SOURCE_DIR}/${_source}" )
  endif( )
  if( NOT _target )
    set( _target "${_source}.tde_l10n" )
  endif( )
  if( NOT "${_target}" MATCHES "^/" )
    set( _target "${CMAKE_CURRENT_SOURCE_DIR}/${_target}" )
  endif( )

  # prepare tags to regexp
  string( REPLACE ";" "|" _tags "${_tags}" )

  # read file
  file( READ ${_source} _xml_data )
  string( REGEX REPLACE "[^\n]" "" _xml_len ${_xml_data} )
  string( LENGTH "+${_xml_len}" _xml_len )

  # process lines
  set( _xml_pos 0 )
  unset( _xml_l10n )
  unset( _xml_inside )
  unset( _xml_tag_empty )
  while( _xml_pos LESS ${_xml_len} )
    # pick line
    string( REGEX REPLACE "^([^\n]*)\n(.*)" "\\1" _xml_line "${_xml_data}" )
    string( REGEX REPLACE "^([^\n]*)\n(.*)" "\\2" _xml_data "${_xml_data}" )
    math( EXPR _xml_pos "${_xml_pos}+1" )
    set( _xml_newline 1 )

    # process tags on line
    while( _xml_newline OR NOT "${_xml_line}" STREQUAL "" )
      unset( _xml_newline )
      unset( _xml_line_prefix )
      unset( _xml_line_suffix )
      unset( _xml_line_rest )
      if( NOT _xml_inside )
        if( "${_xml_line}" MATCHES "<(${_tags})[^>]*>" )
          set( _xml_inside 1 )
          set( _xml_context "${_context}" )
          string( REGEX MATCH "<(${_tags})[^>]*>(.*)" _xml_line "${_xml_line}" )
          string( REGEX MATCH "^<(${_tags})( [^>]*)+>" _xml_attr "${_xml_line}" )
          if( _xml_attr AND "${_xml_attr}" MATCHES " context=\"([^\"]*)\"" )
            string( REGEX REPLACE ".* context=\"([^\"]*)\".*" "\\1" _xml_context "${_xml_attr}" )
          endif( )
          string( REGEX REPLACE "^<(${_tags})[^>]*>(.*)" "\\2" _xml_line "${_xml_line}" )
          set( _xml_line_prefix "i18n(" )
          if( _no_c_format )
            set( _xml_line_prefix "${_xml_line_prefix}/* xgettext: no-c-format */" )
          endif( )
          if( _xml_context )
            set( _xml_line_prefix "${_xml_line_prefix}\"${_xml_context}\", " )
          endif( )
          set( _xml_tag_empty 1 )
        else( )
          set( _xml_line "" )
        endif( )
      endif( )

      if( _xml_inside )
        if( "${_xml_line}" MATCHES "</(${_tags})>" )
          unset( _xml_inside )
          string( REGEX REPLACE "</(${_tags})>(.*)" "\\2" _xml_line_rest "${_xml_line}" )
          string( REGEX REPLACE "</(${_tags})>(.*)" "" _xml_line "${_xml_line}" )
          set( _xml_line_suffix ");" )
        endif( )

        string( REGEX REPLACE "\\\\" "\\\\\\\\" _xml_line "${_xml_line}" )
        string( REGEX REPLACE "\\\"" "\\\\\"" _xml_line "${_xml_line}" )
        string( REGEX REPLACE "\t" "\\\\t" _xml_line "${_xml_line}" )
        if( NOT ";${_preserve};" MATCHES ";entities;" )
          string( REGEX REPLACE "&lt;" "<" _xml_line "${_xml_line}" )
          string( REGEX REPLACE "&gt;" ">" _xml_line "${_xml_line}" )
          string( REGEX REPLACE "&amp;" "&" _xml_line "${_xml_line}" )
        endif( )
        if( NOT ";${_preserve};" MATCHES ";spaces-leading;" )
          string( REGEX REPLACE "^ +" "" _xml_line "${_xml_line}" )
        endif( )
        if( NOT ";${_preserve};" MATCHES ";spaces-trailing;" )
          string( REGEX REPLACE " +$" "" _xml_line "${_xml_line}" )
        endif( )
        if( NOT ";${_preserve};" MATCHES ";spaces-multi;" )
          string( REGEX REPLACE "  +" " " _xml_line "${_xml_line}" )
        endif( )

        if( _xml_inside )
          if( ";${_preserve};" MATCHES ";line-wrap;" )
            if( ";${_preserve};" MATCHES ";lines-leading;"
                OR NOT "${_xml_line}" STREQUAL "" OR NOT _xml_tag_empty )
              set( _xml_line "${_xml_line}\\n" )
            endif( )
          elseif( NOT "${_xml_line}" STREQUAL "" AND NOT _xml_tag_empty )
            set( _xml_line " ${_xml_line}" )
          endif( )
        endif( )
        if( NOT "${_xml_line}" STREQUAL "" )
          unset( _xml_tag_empty )
        endif( )
      endif( )

      # drop empty tag on single line
      if( _xml_line_prefix AND _xml_line_suffix AND _xml_tag_empty )
        # skip empty string for translation

      # add current tag to output
      else( )
        set( _xml_l10n "${_xml_l10n}${_xml_line_prefix}" )
        if( NOT "${_xml_line}" STREQUAL "" OR ( _xml_line_suffix AND _xml_tag_empty ) )
          set( _xml_l10n "${_xml_l10n}\"${_xml_line}\"" )
        endif( )
        set( _xml_l10n "${_xml_l10n}${_xml_line_suffix}" )
      endif( )

      # take the rest of the line for processing
      set( _xml_line "${_xml_line_rest}" )
    endwhile( )
    set( _xml_l10n "${_xml_l10n}\n" )
  endwhile( )

  # write file
  file( WRITE ${_target} "${_xml_l10n}" )

endfunction( )