Slowly toward version control + comparison

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@33443 a592a061-630c-0410-9148-cb99ea01b6c8

src/VCBackend.cpp

@@ -19,6 +19,7 @@
 #include "frontends/alert.h"
 #include "frontends/Application.h"
 
+#include "support/convert.h"
 #include "support/debug.h"
 #include "support/filetools.h"
 #include "support/gettext.h"
@@ -981,6 +982,38 @@ void SVN::getLog(FileName const & tmpf)
 }
 
 
+bool SVN::prepareFileRevision(int rev, string & f)
+{
+	if (rev <= 0)
+		if (!getFileRevisionInfo())
+			return false;
+	if (rev == 0)
+		rev = convert<int>(rev_file_cache_);
+	// go back for minus rev
+	else if (rev < 0) {
+		rev = rev + convert<int>(rev_file_cache_);
+		if (rev < 1)
+			return false;
+	}
+
+	FileName tmpf = FileName::tempName("lyxvcrev");
+	if (tmpf.empty()) {
+		LYXERR(Debug::LYXVC, "Could not generate logfile " << tmpf);
+		return N_("Error: Could not generate logfile.");
+	}
+
+	doVCCommand("svn cat -r " + convert<string>(rev) + " "
+	              + quoteName(onlyFilename(owner_->absFileName()))
+		      + " > " + quoteName(tmpf.toFilesystemEncoding()),
+		FileName(owner_->filePath()));
+	if (tmpf.isFileEmpty())
+		return false;
+
+	f = tmpf.absFilename();
+	return true;
+}
+
+
 bool SVN::toggleReadOnlyEnabled()
 {
 	return false;

src/VCBackend.h

@@ -275,6 +275,14 @@ protected:
 	bool isLocked() const;
 	/// acquire/release write lock for the current file
 	void fileLock(bool lock, support::FileName const & tmpf, std::string & status);
+	/**
+	 * Prepare revision rev of the file into newly created temporary file
+	 * and save the filename into parameter f.
+	 * Parameter rev can be either revision number or negative number
+	 * which is interpreted as how many revision back from the current
+	 * one do we want. rev=0 is reserved for the last (committed) revision.
+	 */
+	bool prepareFileRevision(int rev, std::string & f);
 
 private:
 	support::FileName file_;
@@ -287,7 +295,7 @@ private:
 	 * was already unsuccessful.
 	 */
 	bool getFileRevisionInfo();
-	/// cache for file revision number, "?" if already unsuccessful
+	/// cache for file revision number, "?" if already unsuccessful, isNumber==true
 	std::string rev_file_cache_;
 	/// cache for author of last commit
 	std::string rev_author_cache_;