X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/36c9828f702fb504b07968703bcd82f04196070a..50fc7dbe765947697e2ce0b95cb725f6a4f0fb77:/docs/doxygen/overviews/arc.h diff --git a/docs/doxygen/overviews/arc.h b/docs/doxygen/overviews/arc.h index 6d5b162e58..7e0bc839ac 100644 --- a/docs/doxygen/overviews/arc.h +++ b/docs/doxygen/overviews/arc.h @@ -1,5 +1,5 @@ ///////////////////////////////////////////////////////////////////////////// -// Name: arc +// Name: arc.h // Purpose: topic overview // Author: wxWidgets team // RCS-ID: $Id$ @@ -8,82 +8,49 @@ /*! - @page arc_overview Archive formats such as zip + @page overview_arc Archive formats such as zip The archive classes handle archive formats such as zip, tar, rar and cab. - Currently #wxZip - and #wxTar classes are included. + Currently #wxZip and #wxTar classes are included. + For each archive type, there are the following classes (using zip here as an example): - - - - - - #wxZipInputStream - - - - - Input stream - - - - - - #wxZipOutputStream - - - - - Output stream - - - - - - #wxZipEntry - - - - - Holds the meta-data for an - entry (e.g. filename, timestamp, etc.) - - - - + @li wxZipInputStream: input stream + @li wxZipOutputStream: output stream + @li wxZipEntry: holds the meta-data for an entry (e.g. filename, timestamp, etc.) There are also abstract wxArchive classes that can be used to write code - that can handle any of the archive types, - see '@ref arcgeneric_overview'. + that can handle any of the archive types, see @ref overview_arc_generic. + Also see #wxFileSystem for a higher level interface that can handle archive files in a generic way. + The classes are designed to handle archives on both seekable streams such as disk files, or non-seekable streams such as pipes and sockets - (see '@ref arcnoseek_overview'). - @b See also - #wxFileSystem + (see @ref overview_arc_noseek). + + See also #wxFileSystem. - @ref arccreate_overview - @ref arcextract_overview - @ref arcmodify_overview - @ref arcbyname_overview - @ref arcgeneric_overview - @ref arcnoseek_overview + @li @ref overview_arc_create + @li @ref overview_arc_extract + @li @ref overview_arc_modify + @li @ref overview_arc_byname + @li @ref overview_arc_generic + @li @ref overview_arc_noseek - @section wxarccreate Creating an archive +
- @ref arc_overview - Call #PutNextEntry() to - create each new entry in the archive, then write the entry's data. + + @section overview_arc_create Creating an archive + + Call #PutNextEntry() to create each new entry in the archive, then write the entry's data. Another call to PutNextEntry() closes the current entry and begins the next. For example: @code - wxFFileOutputStream out(_T("test.zip")); + wxFFileOutputStream out(_T("test.zip")); wxZipOutputStream zip(out); wxTextOutputStream txt(zip); wxString sep(wxFileName::GetPathSeparator()); @@ -99,18 +66,18 @@ store entries in subdirectories. - @section wxarcextract Extracting an archive + @section overview_arc_extract Extracting an archive + + #GetNextEntry() returns a pointer to entry object containing the meta-data for + the next entry in the archive (and gives away ownership). + + Reading from the input stream then returns the entry's data. + Eof() becomes @true after an attempt has been made to read past the end of the entry's data. - @ref arc_overview - #GetNextEntry() returns a pointer - to entry object containing the meta-data for the next entry in the archive - (and gives away ownership). Reading from the input stream then returns the - entry's data. Eof() becomes @true after an attempt has been made to read past - the end of the entry's data. When there are no more entries, GetNextEntry() returns @NULL and sets Eof(). @code - auto_ptrwxZipEntry entry; + auto_ptr entry; wxFFileInputStream in(_T("test.zip")); wxZipInputStream zip(in); @@ -125,31 +92,31 @@ - @section wxarcmodify Modifying an archive + @section overview_arc_modify Modifying an archive - @ref arc_overview To modify an existing archive, write a new copy of the archive to a new file, making any necessary changes along the way and transferring any unchanged entries using #CopyEntry(). + For archive types which compress entry data, CopyEntry() is likely to be much more efficient than transferring the data using Read() and Write() since it will copy them without decompressing and recompressing them. + In general modifications are not possible without rewriting the archive, though it may be possible in some limited cases. Even then, rewriting the archive is usually a better choice since a failure can be handled without - losing the whole - archive. #wxTempFileOutputStream can - be helpful to do this. + losing the whole archive. #wxTempFileOutputStream can be helpful to do this. + For example to delete all entries matching the pattern "*.txt": @code - auto_ptrwxFFileInputStream in(new wxFFileInputStream(_T("test.zip"))); + auto_ptr in(new wxFFileInputStream(_T("test.zip"))); wxTempFileOutputStream out(_T("test.zip")); wxZipInputStream inzip(*in); wxZipOutputStream outzip(out); - auto_ptrwxZipEntry entry; + auto_ptr entry; // transfer any meta-data for the archive as a whole (the zip comment // in the case of zip) @@ -171,30 +138,30 @@ - @section wxarcbyname Looking up an archive entry by name + @section overview_arc_byname Looking up an archive entry by name - @ref arc_overview Also see #wxFileSystem for a higher level interface that is more convenient for accessing archive entries by name. + To open just one entry in an archive, the most efficient way is - to simply search for it linearly by calling - #GetNextEntry() until the + to simply search for it linearly by calling #GetNextEntry() until the required entry is found. This works both for archives on seekable and non-seekable streams. + The format of filenames in the archive is likely to be different from the local filename format. For example zips and tars use unix style names, with forward slashes as the path separator, and absolute paths are not allowed. So if on Windows the file - "C:\MYDIR\MYFILE.TXT" is stored, then when reading - the entry back #GetName() will return - "MYDIR\MYFILE.TXT". The conversion into the internal format + "C:\MYDIR\MYFILE.TXT" is stored, then when reading the entry back #GetName() + will return "MYDIR\MYFILE.TXT". The conversion into the internal format and back has lost some information. + So to avoid ambiguity when searching for an entry matching a local name, it is better to convert the local name to the archive's internal format and search for that: @code - auto_ptrwxZipEntry entry; + auto_ptr entry; // convert the local name we are looking for into the internal format wxString name = wxZipEntry::GetInternalName(localname); @@ -216,11 +183,10 @@ To access several entries randomly, it is most efficient to transfer the entire catalogue of entries to a container such as a std::map or a - #wxHashMap then entries looked up by name can be - opened using the #OpenEntry() method. + #wxHashMap then entries looked up by name can be opened using the #OpenEntry() method. @code - WX_DECLARE_STRING_HASH_MAP(wxZipEntry*, ZipCatalog); + WX_DECLARE_STRING_HASH_MAP(wxZipEntry*, ZipCatalog); ZipCatalog::iterator it; wxZipEntry *entry; ZipCatalog cat; @@ -249,7 +215,7 @@ underlying stream on the same archive: @code - // opening another entry without closing the first requires another + // opening another entry without closing the first requires another // input stream for the same file wxFFileInputStream in2(_T("test.zip")); wxZipInputStream zip2(in2); @@ -259,78 +225,43 @@ - @section wxarcgeneric Generic archive programming + @section overview_arc_generic Generic archive programming - @ref arc_overview Also see #wxFileSystem for a higher level interface that can handle archive files in a generic way. + The specific archive classes, such as the wxZip classes, inherit from the following abstract classes which can be used to write code that can handle any of the archive types: - - - - - - #wxArchiveInputStream - - - - - Input stream - - - - - - #wxArchiveOutputStream - - - - - Output stream - - - - - - #wxArchiveEntry - - - - - Holds the meta-data for an - entry (e.g. filename) - - - - + @li wxArchiveInputStream: input stream + @li wxArchiveOutputStream: output stream + @li wxArchiveEntry: holds the meta-data for an entry (e.g. filename) In order to able to write generic code it's necessary to be able to create instances of the classes without knowing which archive type is being used. + To allow this there is a class factory for each archive type, derived from - #wxArchiveClassFactory, that can create - the other classes. + #wxArchiveClassFactory, that can create the other classes. + For example, given @e wxArchiveClassFactory* factory, streams and entries can be created like this: @code - // create streams without knowing their type - auto_ptrwxArchiveInputStream inarc(factory-NewStream(in)); - auto_ptrwxArchiveOutputStream outarc(factory-NewStream(out)); + // create streams without knowing their type + auto_ptr inarc(factory-NewStream(in)); + auto_ptr outarc(factory-NewStream(out)); // create an empty entry object - auto_ptrwxArchiveEntry entry(factory-NewEntry()); + auto_ptr entry(factory-NewEntry()); @endcode - For the factory itself, the static member - wxArchiveClassFactory::Find(). + For the factory itself, the static member wxArchiveClassFactory::Find(). can be used to find a class factory that can handle a given file extension or mime type. For example, given @e filename: @code - const wxArchiveClassFactory *factory; + const wxArchiveClassFactory *factory; factory = wxArchiveClassFactory::Find(filename, wxSTREAM_FILEEXT); if (factory) @@ -339,14 +270,15 @@ @e Find does not give away ownership of the returned pointer, so it does not need to be deleted. + There are similar class factories for the filter streams that handle the compression and decompression of a single stream, such as wxGzipInputStream. - These can be found using - wxFilterClassFactory::Find(). + These can be found using wxFilterClassFactory::Find(). + For example, to list the contents of archive @e filename: @code - auto_ptrwxInputStream in(new wxFFileInputStream(filename)); + auto_ptr in(new wxFFileInputStream(filename)); if (in-IsOk()) { @@ -363,8 +295,8 @@ const wxArchiveClassFactory *acf; acf = wxArchiveClassFactory::Find(filename, wxSTREAM_FILEEXT); if (acf) { - auto_ptrwxArchiveInputStream arc(acf-NewStream(in.release())); - auto_ptrwxArchiveEntry entry; + auto_ptr arc(acf-NewStream(in.release())); + auto_ptr entry; // list the contents of the archive while ((entry.reset(arc-GetNextEntry())), entry.get() != @NULL) @@ -378,94 +310,72 @@ - @section wxarcnoseek Archives on non-seekable streams + @section overview_arc_noseek Archives on non-seekable streams - @ref arc_overview In general, handling archives on non-seekable streams is done in the same way as for seekable streams, with a few caveats. - The main limitation is that accessing entries randomly using - #OpenEntry() + + The main limitation is that accessing entries randomly using #OpenEntry() is not possible, the entries can only be accessed sequentially in the order they are stored within the archive. + For each archive type, there will also be other limitations which will depend on the order the entries' meta-data is stored within the archive. These are not too difficult to deal with, and are outlined below. + @b PutNextEntry and the entry size When writing archives, some archive formats store the entry size before the entry's data (tar has this limitation, zip doesn't). In this case - the entry's size must be passed to - #PutNextEntry() or an error - occurs. + the entry's size must be passed to #PutNextEntry() or an error occurs. + This is only an issue on non-seekable streams, since otherwise the archive output stream can seek back and fix up the header once the size of the entry is known. + For generic programming, one way to handle this is to supply the size whenever it is known, and rely on the error message from the output stream when the operation is not supported. + @b GetNextEntry and the weak reference mechanism Some archive formats do not store all an entry's meta-data before the entry's data (zip is an example). In this case, when reading from a - non-seekable stream, #GetNextEntry() - can only return a partially populated #wxArchiveEntry - object - not all the fields are set. + non-seekable stream, #GetNextEntry() can only return a partially populated + #wxArchiveEntry object - not all the fields are set. + The input stream then keeps a weak reference to the entry object and updates it when more meta-data becomes available. A weak reference being one that does not prevent you from deleting the wxArchiveEntry object - the input stream only attempts to update it if it is still around. + The documentation for each archive entry type gives the details of what meta-data becomes available and when. For generic programming, when the worst case must be assumed, you can rely on all the fields of wxArchiveEntry being fully populated when GetNextEntry() returns, with the the following exceptions: + @li GetSize(): Guaranteed to be available after the entry has been read to #Eof(), + or #CloseEntry() has been called + @li IsReadOnly(): Guaranteed to be available after the end of the archive has been + reached, i.e. after GetNextEntry() returns @NULL and Eof() is @true + This mechanism allows #CopyEntry() to always fully preserve entries' meta-data. + No matter what order order the meta-data occurs within the archive, the input stream + will always have read it before the output stream must write it. - - - #GetSize() - - - - - Guaranteed to be - available after the entry has been read to #Eof(), - or #CloseEntry() has been called - - - - - - #IsReadOnly() - - - - - Guaranteed to - be available after the end of the archive has been reached, i.e. after - GetNextEntry() returns @NULL and Eof() is @true - - - - - - This mechanism allows #CopyEntry() - to always fully preserve entries' meta-data. No matter what order order - the meta-data occurs within the archive, the input stream will always - have read it before the output stream must write it. @b wxArchiveNotifier Notifier objects can be used to get a notification whenever an input stream updates a #wxArchiveEntry object's data via the weak reference mechanism. + Consider the following code which renames an entry in an archive. This is the usual way to modify an entry's meta-data, simply set the - required field before writing it with - #CopyEntry(): + required field before writing it with #CopyEntry(): @code - auto_ptrwxArchiveInputStream arc(factory-NewStream(in)); - auto_ptrwxArchiveOutputStream outarc(factory-NewStream(out)); - auto_ptrwxArchiveEntry entry; + auto_ptr arc(factory-NewStream(in)); + auto_ptr outarc(factory-NewStream(out)); + auto_ptr entry; outarc-CopyArchiveMetaData(*arc); @@ -480,10 +390,8 @@ @endcode However, for non-seekable streams, this technique cannot be used for - fields such as #IsReadOnly(), - which are not necessarily set when - #GetNextEntry() returns. In - this case a #wxArchiveNotifier can be used: + fields such as #IsReadOnly(), which are not necessarily set when + #GetNextEntry() returns. In this case a #wxArchiveNotifier can be used: @code class MyNotifier : public wxArchiveNotifier @@ -493,15 +401,13 @@ }; @endcode - The meta-data changes are done in your notifier's - #OnEntryUpdated() method, - then #SetNotifier() is called before - CopyEntry(): + The meta-data changes are done in your notifier's #OnEntryUpdated() method, + then #SetNotifier() is called before CopyEntry(): @code - auto_ptrwxArchiveInputStream arc(factory-NewStream(in)); - auto_ptrwxArchiveOutputStream outarc(factory-NewStream(out)); - auto_ptrwxArchiveEntry entry; + auto_ptr arc(factory-NewStream(in)); + auto_ptr outarc(factory-NewStream(out)); + auto_ptr entry; MyNotifier notifier; outarc-CopyArchiveMetaData(*arc); @@ -522,6 +428,5 @@ changing the entry name can be done this way too and it works on seekable streams as well as non-seekable. - */ - +*/