X-Git-Url: https://git.lyx.org/gitweb/?a=blobdiff_plain;f=src%2Fsupport%2Funicode.h;h=6373e470ba0e446a192f08ea18f07f241b582437;hb=b7abd752faa1f5d4958b27045bcfb1678ec1b2ae;hp=afe0bc5858759398623cb0b8f8e9c80871a46673;hpb=d5a41946a6848e2869b6ca2c2d4f6fdbc76ae338;p=lyx.git

diff --git a/src/support/unicode.h b/src/support/unicode.h
index afe0bc5858..6373e470ba 100644
--- a/src/support/unicode.h
+++ b/src/support/unicode.h
@@ -1,3 +1,4 @@
+// -*- C++ -*-
 /**
  * \file unicode.h
  * This file is part of LyX, the document processor.
@@ -14,42 +15,61 @@
 #define LYX_SUPPORT_UNICODE_H
 
 #include "support/strfwd.h"
+#include "support/unique_ptr.h"
 
+#include <cstddef>
+#include <string>
 #include <vector>
 
 
 namespace lyx {
 
+/**
+ * Wrapper for iconv(3).
+ *
+ * According to the POSIX standard, all specified functions are thread-safe,
+ * with some exceptions. The iconv() function is not listed as an exception:
+ * http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xsh_chap02.html#tag_22_02_09_09
+ * http://man7.org/linux/man-pages/man7/pthreads.7.html
+ *
+ * Therefore, you can use as many instances of this class in parallel as you
+ * like. However, you need to ensure that each instance is only used by one
+ * thread at any given time. If this condition is not met you get nasty
+ * mixtures of different thread data as in bug 7240.
+ *
+ * From a performance point of view it is best to use one static instance
+ * per thread for each in/out encoding pair. This can e.g. be achieved by
+ * using helpers for thread-local storage such as QThreadStorage or
+ * boost::thread_specific_ptr. A single static instance protected by a mutex
+ * would work as well, and might be preferrable for exotic encoding pairs.
+ * Creating local IconvProcessor instances should be avoided because of the
+ * overhead in iconv_open().
+ */
 class IconvProcessor
 {
+	/// open iconv.
+	/// \return true if the processor is ready to use.
+	bool init();
+	std::string const tocode_;
+	std::string const fromcode_;
+	struct Handler;
+	unique_ptr<Handler> h_;
 public:
-	IconvProcessor(char const * tocode = "", char const * fromcode = "");
-	/// copy constructor needed because of pimpl_
-	IconvProcessor(IconvProcessor const &);
-	/// assignment operator needed because of pimpl_
-	void operator=(IconvProcessor const &);
-	/// destructor
-	~IconvProcessor();
-
+	IconvProcessor(std::string tocode, std::string fromcode);
 	/// convert any data from \c fromcode to \c tocode unicode format.
 	/// \return the number of bytes of the converted output buffer.
 	int convert(char const * in_buffer, size_t in_size,
 		char * out_buffer, size_t max_out_size);
-
-	/// source encoding
-	std::string from() const;
 	/// target encoding
-	std::string to() const;
-
-private:
-	/// open iconv.
-	/// \return true if the processor is ready to use.
-	bool init();
-	/// hide internals
-	struct Impl;
-	Impl * pimpl_;
+	std::string to() const { return tocode_; }
+	// required by g++ 4.7
+	IconvProcessor(IconvProcessor &&) = default;
 };
 
+/// Get the global IconvProcessor instance of the current thread for
+/// utf8->ucs4 conversions
+IconvProcessor & utf8ToUcs4();
+
 // A single codepoint conversion for utf8_to_ucs4 does not make
 // sense, so that function is left out.
 
@@ -65,6 +85,10 @@ std::vector<char_type> utf16_to_ucs4(unsigned short const * s, size_t ls);
 
 std::vector<unsigned short> ucs4_to_utf16(char_type const * s, size_t ls);
 
+/// Get the global IconvProcessor instance of the current thread for
+/// ucs4->utf8 conversions
+IconvProcessor & ucs4ToUtf8();
+
 // ucs4_to_utf8
 
 std::vector<char> ucs4_to_utf8(char_type c);