inifilefeeder.hpp

Go to the documentation of this file.

//==================================================================================================
/// \file
/// This header-file is part of module \alib_variables of the \aliblong.
///
/// Copyright 2013-2026 A-Worx GmbH, Germany.
/// Published under #"mainpage_license".
//==================================================================================================
ALIB_EXPORT namespace alib {  namespace variables {
 
//==================================================================================================
/// Adapter type between class #"IniFile" and class #"Configuration".
/// INI-file contents usually are fed in with bootstrapping an application and optionally be
/// written out when an application ends (to populate empty INI-files or add new variables to
/// existing ones). For this, an instance of this type is to be created locally each time. In other
/// words, no instance of this type needs to be kept in memory during the life-span of an
/// application.
/// @see Chapter #"alib_variables_external_ini" of the Programmer's Manual of camp \alib_variables.
/// @throws alib::variables::Exceptions::ErrorWritingFile \I{CLANGDUMMY}
//==================================================================================================
class IniFileFeeder {
  //=========================================== Internals ==========================================
  protected:
    /// The configuration to work with. Set with construction.
    Configuration&          configuration;
 
    /// The priority to use to define variables. Set with construction.
    Priority                priority;
 
    /// The INI-file. Created with methods #"ImportStart" and #"ExportStart".
    IniFile*                iniFile                                                       = nullptr;
 
    /// Implements overloaded methods #".ImportSection(const String&)".
    /// @param section The section to import
    /// @return The number of variables imported.
    ALIB_DLL
    int         importSection( IniFile::Section& section );
 
 
  //========================================= Public Fields ========================================
  public:
    /// The desired maximum width of the INI-file. Defaults to <c>100</c>.
    /// This value is used with utility method #".AddResourcedSectionComments(ResourcePool&)".
    int                     LineWidth                                                         = 100;
 
    /// The prefix that is used for comment lines of sections or variables that have been
    /// added 'in code' (variables that have not been read from the file).
    /// Comments that were read from the file preserve their prefix.
    /// If comments including one of the valid prefixes are added to a variable or section
    /// 'in code', such prefix is preserved.
    String                  DefaultCommentPrefix                                      =A_CHAR("# ");
 
    /// This flag may be read after invoking the method #"ExportStart", which will try to
    /// read the file first. If the file could not be opened or is empty, this flag is set.
    /// The flag may be used to decide, for example, if a file-comment or section comments
    /// should be generated.
    bool                    DidNotExistOrWasEmpty                                            =false;
 
 
  //==================================== Constructors/destructor ===================================
  public:
    /// Constructor.
    /// @param pConfiguration Stored in the field #"configuration".
    /// @param pPriority      Stored in the field #".priority". Defaults to #"Priority::ConfigFile".
    ///
    IniFileFeeder( Configuration& pConfiguration, Priority pPriority= Priority::ConfigFile )
    : configuration(pConfiguration)
    , priority     (pPriority)                                                                    {}
 
    /// Virtual destructor. #"alib_mod_assert;Raises an ALib warning" in debug-compilations,
    /// if the internal INI-file was not disposed before deletion. Disposal is made with methods
    /// #"ImportEnd" and ExportEnd.
    virtual ~IniFileFeeder() {
        #if ALIB_DEBUG && !ALIB_DEBUG_ASSERTION_PRINTABLES
            ALIB_ASSERT_WARNING(iniFile == nullptr, "VARIABLES",
              "Export or import sequence not completed before deleting the INI-file.\n"
              "Filename of previous sequence: {}", iniFile->FileName )
            delete iniFile;
        #endif
 
    }
 
  //=========================================== Interface ==========================================
    /// Imports all entries in the section named \p{sectionName} in the underlying INI-file into
    /// the configuration.
    /// @param sectionName The name of the section to import.
    /// @return The number of variables imported.
    ALIB_DLL
    int         ImportSection( const String& sectionName );
 
    /// Imports all entries in the section named \p{sectionName} in the underlying INI-file into
    /// the configuration. This special version of the method accepts parameter \p{typeName}
    /// and hence declares the variables in case they have not been declared, yet.
    ///
    /// \note
    ///   This method is useful to load a section of variables of the same type with a) avoiding to
    ///   set preset string and b) with the advantage that a using code may use
    ///   #"Variable::Try(const String&);Variable::Try" to find the variable without declaring
    ///   it.<br>
    ///   This method may be used, for example, with camp \alib_expressions to declare nested
    ///   expressions to an #"StandardRepository".
    /// @param sectionName The name of the section to import.
    /// @param typeName    The type of the variable to declare.
    /// @return The number of variables imported.
    ALIB_DLL
    int         ImportSection( const String& sectionName, const String& typeName );
 
    /// Imports all entries found INI-file into the configuration. Variables which are already
    /// declared and have a lower priority definition, will be set with the value found.
    /// Otherwise, a #"PresetImportString(StringEscaper);preset string" is set for the
    /// variable.
    /// @return The number of variables imported.
    ALIB_DLL
    int         ImportAll();
 
    /// Creates the internal \p{iniFile} instance.
    /// @param path The filepath to the INI-file.
    /// @return The number of entries read. (The result of method #"IniFile::Read;*".)
    int ImportStart( const Path&  path ) {
        if( iniFile != nullptr ) {
            ALIB_ASSERT_WARNING(iniFile == nullptr, "VARIABLES",
              "Export or import sequence not completed before starting a new one.\n"
              "Previous filename: ", iniFile->FileName )
            delete iniFile;
        }
        iniFile= new IniFile();
        int qtyEntries= 0;
        #if ALIB_CAMP
            try { qtyEntries=  iniFile->Read(path); } catch (Exception& ) {}
        #else
            iniFile->Read(path);
        #endif
        return qtyEntries;
    }
 
    /// Creates the internal \p{iniFile} instance.
    /// @param path The filepath to the INI-file.
    /// @return The number of entries read. (The result of method #"IniFile::Read;*".)
    int ExportStart( const Path& path ) {
        int qtyEntries= 0;
        #if ALIB_CAMP
        try { qtyEntries= ImportStart(path); }
        catch (Exception& e) {
            if (e.Type() != variables::Exceptions::ErrorOpeningFile)
                throw;
        }
        #else
            qtyEntries= ImportStart(path);
        #endif
        DidNotExistOrWasEmpty= (qtyEntries == 0);
        return qtyEntries;
    }
 
    /// Closes and deletes the internal \p{iniFile} instance.
    void ImportEnd() {
        if(iniFile == nullptr) {
            ALIB_ERROR( "VARIABLES", "No INI-file loaded when trying to end import/export." )
            return;
        }
        delete iniFile;
        iniFile= nullptr;
    }
 
    /// Closes and deletes the internal \p{iniFile} instance without writing an opened INI-file.
    void ExportEnd()                                                                { ImportEnd(); }
 
    /// Writes the contents of the internal \p{iniFile} instance created with #"ExportStart" into
    /// an (optionally) different file and then deletes the instance.
    /// @param path The file path for writing.
    void ExportEnd(const Path&  path ) {
        if(iniFile == nullptr) {
            ALIB_ERROR( "VARIABLES", "No INI-file loaded when trying to import data." )
            return;
        }
        iniFile->Write(path);
        delete iniFile;
        iniFile= nullptr;
    }
 
 
    /// Writes the given variable to the internal INI-file.
    /// If an INI-file was previously loaded, only those variables which are not existing in the
    /// INI-file are written. This method can thus be used to "populate" an empty INI-file with
    /// variables and their resourced or hard-coded default values and this way present all
    /// configurable options to an end-user.
    ///
    /// Furthermore, a user can specify the word "writeback" (respectively what is resourced
    /// with to token <c>"CFGIniWB"</c>) to force overwriting the INI-file contents with the current
    /// value of the variable.
    ///
    /// @param var The variable to export.
    /// @return \c true if the variable either did not exist yet in the INI-file or if it existed
    ///            and the write-back mechanism was in place. \c false otherwise.
    ALIB_DLL
    bool        Export( const Variable& var );
 
    /// Creates a variable cursor with the given \p{cfg} and \p{path} and passes it to overloaded
    /// method #"Export(const" Variable&).
    /// @param path  The path of the variable to export.
    /// @return \c   true if the variable either did not exist yet in the INI-file or if it existed
    ///              and the write-back mechanism was in place. \c false otherwise.
    bool         Export(const String& path) {
        auto cursor= configuration.Root();
        auto remainder= cursor.GoTo(path);
        if( remainder.IsNotEmpty() ) {
            ALIB_WARNING("VARIABLES", "Configuration variable path \"{}\" to export not found.",
                                      path)
            return false;
        }
        return Export( Variable(cursor) );
    }
 
 
    /// Writes all variables below the given #"StringTree::Cursor;*"
    /// of the #"Configuration" into the #"iniFile", previously created with #"ExportStart".
    /// If an INI-file was previously loaded, only those variables which are not existing in the
    /// INI-file are written.
    /// This method can thus be used to "populate" an empty INI-file with default values and
    /// this way present all configurable options to an end-user.
    ///
    /// Furthermore, a user can specify the word "writeback" (respectively what is resourced
    /// with to token <c>"CFGIniWB"</c>) to force overwriting the INI-file contents with the current
    /// value of the variable.
    ///
    /// @param cursor              A cursor into the configuration's #"StringTree".
    /// @param directChildrenOnly  If \c true, only the direct children of this cursor are written
    ///                            as variables. Defaults to \c false.
    /// @return The number of variables exported. A negative value on error.
    ALIB_DLL
    int        ExportSubTree( Configuration::Cursor cursor, bool directChildrenOnly= false );
 
    /// Invokes #".ExportSubTree(Configuration::Cursor, bool)" by creating a cursor from the given
    /// \p{path}
    /// @param path                The path to the subtree (or single variable) to use.
    /// @param directChildrenOnly  If \c true, only the direct children of this \p{path} are written
    ///                            as variables. Defaults to \c false.
    /// @return The number of variables exported. A negative value on error.
    int        ExportSubTree( const String& path, bool directChildrenOnly= false ) {
        auto cursor= configuration.Root();
        auto remainder= cursor.GoTo(path);
        if( remainder.IsNotEmpty() ) {
            return -1;
        }
 
        return ExportSubTree( cursor, directChildrenOnly );
    }
 
    /// Searches the entry of the internal INI-file that represents the given \p{variable}
    /// @param variable   The variable to search in the INI-file.
    /// @return The section and entry if found. If not found, the second member of the pair is
    ///         emtpy.
    ALIB_DLL
    IniFile::Handle   SearchEntry ( const Variable& variable );
 
    /// Searches the entry of the internal INI-file that represents the given variable determined
    /// by parameter \p{path}
    /// @param path   The path of the variable to search in the INI-file.
    /// @return The section and entry if found. If not found, the second member of the pair is
    ///         emtpy.
    ALIB_DLL
    IniFile::Handle   SearchEntry ( const String& path );
 
    /// This method may be used to set the #"config_IniFile_writebackflag;writeback flag"
    /// of an entry in the associated INI-file. The flag is only set if the entry was
    /// programmatically created (usually with one of the <b>Export</b>-methods of this class) and
    /// if it was not present in the INI-file before.
    /// @see Chapter #"alib_variables_external_session" of the Programmer's Manual of module
    /// \alib_variables_nl.
    /// @param path  The path of the variable to export.
    /// @return \c true if the variable did exist and was newly added to the INI-file, \c false
    ///            otherwise.
    ALIB_DLL
    bool         SetWriteBackFlag( const String& path );
 
    /// Invokes overloaded method #".SetWriteBackFlag(const String& path)".
    /// @param var The variable to modifiy.
    /// @return \c true if the variable did exist and was newly added to the INI-file, \c false
    ///            otherwise.
    ALIB_DLL
    bool        SetWriteBackFlag( const Variable& var );
 
    #if ALIB_RESOURCES
    /// This is a utility function that reads section comments from
    /// #"alib_mod_resources;externalized string resources".
    ///
    /// All sections of the underlying INI-file are processed, but resourced comments
    /// are only added in the case that a section's comment string is \c nulled. This is not the
    /// case if a section was read from an INI-file, as even if no comments were given,
    /// the field is empty but not \e nulled. In other words, only sections that have been
    /// programmatically added during the run of software are changed<br>
    /// This approach allows a user to remove the comments, without the software restoring them.
    ///
    /// The resource names are assembled from given \p{resourceNamePrefix} and the section name.
    /// The resource strings found are processed using the method
    /// #"Paragraphs.AddMarked(const BoxedObjects&)".
    /// This allows using text macros like <b>'\@HL'</b> to format the text.
    ///
    /// \see
    ///    Field #".LineWidth", which is respected when formatting comment lines.
    ///
    /// @param resourcePool          The resource pool to use.
    /// @param resourceCategory      The category of the resourced comments.
    /// @param resourceNamePrefix    A prefix of the resource name.
    /// @return The number of section comments written.
    ///         This is useful to detect if the INI-file needs to be written.
    ALIB_DLL
    int       AddResourcedSectionComments( ResourcePool&    resourcePool,
                                           const NString&   resourceCategory,
                                           const NString&   resourceNamePrefix  );
 
    /// This is a shortcut to the overloaded method, accepting a #"ResourceHolder"
    /// instead of parameters \p{resourcePool} and \p{resourceCategory}.
    /// @param resourceHolder      A container holding a resource pool and a fixed category.
    /// @param resourceNamePrefix  A prefix of the resource name.
    /// @return The number of section comments written.
    ///         This is useful to detect if the INI-file needs to be written.
    int       AddResourcedSectionComments( resources::ResourceHolder&  resourceHolder,
                                           const NString&              resourceNamePrefix  ) {
        return AddResourcedSectionComments( resourceHolder.GetResourcePool(),
                                            resourceHolder.ResourceCategory,
                                            resourceNamePrefix );
    }
    #endif
 
    /// Allows access to the internal INI-file object created with either method #".ImportStart" or
    /// #".ExportStart". In debug-compilations, this method asserts that an INI-file was opened.
    /// In release-compilations, a non-existing INI-file leads to undefined behavior.
    /// @return The currently opened INI-File.
    IniFile& GetIniFile() {
        ALIB_ASSERT_ERROR( iniFile != nullptr, "VARIABLES",
            "No INI-file loaded when trying to access it." )
        return *iniFile;
    }
 
}; // class IniFileFeeder
 
 
} // namespace alib[::config]
 
/// Type alias in namespace #"%alib".
using     IniFileFeeder=       variables::IniFileFeeder;
 
} // namespace [alib]