From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 7 Oct 2013 16:36:04 +0000 (+0300)
Subject: Rewrite BufferedFile as a standalone class
X-Git-Url: http://git.tdb.fi/?p=libs%2Fcore.git;a=commitdiff_plain;h=7b81490ae4ed6c7c8566f889d146677827f5d4a5;hp=0f5501ad79950e9658fb672ac6b97a608e3a2dd9

Rewrite BufferedFile as a standalone class

The generic Filtered template is unable to account for the complexities of
buffering a seekable object.  In particular, relative seeks were broken.

I may revisit the template form at a later date if I come up with a
workable design.  For now its use is discouraged.
---

diff --git a/source/io/file.cpp b/source/io/file.cpp
index 9069432..666b1ed 100644
--- a/source/io/file.cpp
+++ b/source/io/file.cpp
@@ -81,5 +81,66 @@ const Handle &File::get_handle(Mode m)
 	return handle;
 }
 
+
+BufferedFile::BufferedFile(const string &fn, Mode m, File::CreateMode cm):
+	file(fn, m, cm),
+	buffer(file),
+	position(0)
+{
+	mode = m;
+	file.signal_end_of_file.connect(sigc::mem_fun(this, &BufferedFile::set_eof));
+}
+
+unsigned BufferedFile::do_write(const char *buf, unsigned size)
+{
+	unsigned ret = buffer.write(buf, size);
+	position += ret;
+	return ret;
+}
+
+unsigned BufferedFile::do_read(char *buf, unsigned size)
+{
+	unsigned ret = buffer.read(buf, size);
+	position += ret;
+	return ret;
+}
+
+unsigned BufferedFile::put(char c)
+{
+	unsigned ret = buffer.put(c);
+	position += ret;
+	return ret;
+}
+
+bool BufferedFile::getline(string &line)
+{
+	bool ret = buffer.getline(line);
+	if(ret)
+		position += line.size();
+	return ret;
+}
+
+int BufferedFile::get()
+{
+	int ret = buffer.get();
+	if(ret>=0)
+		++position;
+	return ret;
+}
+
+SeekOffset BufferedFile::seek(SeekOffset offset, SeekType type)
+{
+	if(type==S_CUR)
+	{
+		offset += position;
+		type = S_BEG;
+	}
+
+	signal_flush_required.emit();
+	position = file.seek(offset, type);
+	eof_flag = false;
+	return position;
+}
+
 } // namespace IO
 } // namespace Msp
diff --git a/source/io/file.h b/source/io/file.h
index d106561..d342734 100644
--- a/source/io/file.h
+++ b/source/io/file.h
@@ -81,7 +81,29 @@ inline File::CreateMode operator&(File::CreateMode m, File::CreateMode n)
 inline File::CreateMode operator~(File::CreateMode m)
 { return File::CreateMode(~static_cast<int>(m)); }
 
-typedef Filtered<File, Buffered> BufferedFile;
+
+class BufferedFile: public Seekable
+{
+private:
+	File file;
+	Buffered buffer;
+	SeekOffset position;
+
+public:
+	BufferedFile(const std::string &, Mode = M_READ, File::CreateMode = File::C_OVERWRITE);
+
+protected:
+	virtual unsigned do_write(const char *, unsigned);
+	virtual unsigned do_read(char *, unsigned);
+public:
+	virtual unsigned put(char);
+
+	virtual bool getline(std::string &);
+	virtual int get();
+
+	virtual SeekOffset seek(SeekOffset, SeekType);
+	virtual SeekOffset tell() const { return position; }
+};
 
 } // namespace IO
 } // namespace Msp
diff --git a/source/io/filtered.h b/source/io/filtered.h
index a4a4319..2092743 100644
--- a/source/io/filtered.h
+++ b/source/io/filtered.h
@@ -4,7 +4,11 @@
 namespace Msp {
 namespace IO {
 
-// XXX This needs a redesign
+/**
+This class is broken by design.  Do not use.  It exposes base class methods in
+an unsafe and misleading way.  In particular, a Filtered<File, Buffered> causes
+seeks to behave incorrectly.
+*/
 template<typename B, typename F>
 class Filtered: public B
 {