[Boost-commit] svn:boost r86613 - trunk/boost/detail

Subject: [Boost-commit] svn:boost r86613 - trunk/boost/detail
From: ramey_at_[hidden]
Date: 2013-11-10 21:19:46

Author: ramey
Date: 2013-11-10 21:19:46 EST (Sun, 10 Nov 2013)
New Revision: 86613
URL: http://svn.boost.org/trac/boost/changeset/86613

Log:
changed codecvt_utf8 so that serialization uses the standard one if available.  If there is no standard one available, it uses the one in boost/utility.

Added:
   trunk/boost/detail/utf8_codecvt_facet.ipp   (contents, props changed)

Added: trunk/boost/detail/utf8_codecvt_facet.ipp
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ trunk/boost/detail/utf8_codecvt_facet.ipp	2013-11-10 21:19:46 EST (Sun, 10 Nov 2013)	(r86613)
@@ -0,0 +1,284 @@
+/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
+// utf8_codecvt_facet.ipp
+
+// Copyright (c) 2001 Ronald Garcia, Indiana University (garcia_at_[hidden])
+// Andrew Lumsdaine, Indiana University (lums_at_[hidden]). 
+// Use, modification and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// Please see the comments in <boost/detail/utf8_codecvt_facet.hpp> to
+// learn how this file should be used.
+
+#include <boost/detail/utf8_codecvt_facet.hpp>
+
+#include <cstdlib> // for multi-byte converson routines
+#include <cassert>
+
+#include <boost/limits.hpp>
+#include <boost/config.hpp>
+
+// If we don't have wstring, then Unicode support 
+// is not available anyway, so we don't need to even
+// compiler this file. This also fixes the problem
+// with mingw, which can compile this file, but will
+// generate link error when building DLL.
+#ifndef BOOST_NO_STD_WSTRING
+
+BOOST_UTF8_BEGIN_NAMESPACE
+
+/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
+// implementation for wchar_t
+
+// Translate incoming UTF-8 into UCS-4
+std::codecvt_base::result utf8_codecvt_facet::do_in(
+    std::mbstate_t& /*state*/, 
+    const char * from,
+    const char * from_end, 
+    const char * & from_next,
+    wchar_t * to, 
+    wchar_t * to_end, 
+    wchar_t * & to_next
+) const {
+    // Basic algorithm:  The first octet determines how many
+    // octets total make up the UCS-4 character.  The remaining
+    // "continuing octets" all begin with "10". To convert, subtract
+    // the amount that specifies the number of octets from the first
+    // octet.  Subtract 0x80 (1000 0000) from each continuing octet,
+    // then mash the whole lot together.  Note that each continuing
+    // octet only uses 6 bits as unique values, so only shift by
+    // multiples of 6 to combine.
+    while (from != from_end && to != to_end) {
+
+        // Error checking   on the first octet
+        if (invalid_leading_octet(*from)){
+            from_next = from;
+            to_next = to;
+            return std::codecvt_base::error;
+        }
+
+        // The first octet is   adjusted by a value dependent upon 
+        // the number   of "continuing octets" encoding the character
+        const   int cont_octet_count = get_cont_octet_count(*from);
+        const   wchar_t octet1_modifier_table[] =   {
+            0x00, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc
+        };
+
+        // The unsigned char conversion is necessary in case char is
+        // signed   (I learned this the hard way)
+        wchar_t ucs_result = 
+            (unsigned char)(*from++) - octet1_modifier_table[cont_octet_count];
+
+        // Invariants   : 
+        //   1) At the start of the loop,   'i' continuing characters have been
+        //    processed 
+        //   2) *from   points to the next continuing character to be processed.
+        int i   = 0;
+        while(i != cont_octet_count && from != from_end) {
+
+            // Error checking on continuing characters
+            if (invalid_continuing_octet(*from)) {
+                from_next   = from;
+                to_next =   to;
+                return std::codecvt_base::error;
+            }
+
+            ucs_result *= (1 << 6); 
+
+            // each continuing character has an extra (10xxxxxx)b attached to 
+            // it that must be removed.
+            ucs_result += (unsigned char)(*from++) - 0x80;
+            ++i;
+        }
+
+        // If   the buffer ends with an incomplete unicode character...
+        if (from == from_end && i   != cont_octet_count) {
+            // rewind "from" to before the current character translation
+            from_next = from - (i+1); 
+            to_next = to;
+            return std::codecvt_base::partial;
+        }
+        *to++   = ucs_result;
+    }
+    from_next = from;
+    to_next = to;
+
+    // Were we done converting or did we run out of destination space?
+    if(from == from_end) return std::codecvt_base::ok;
+    else return std::codecvt_base::partial;
+}
+
+std::codecvt_base::result utf8_codecvt_facet::do_out(
+    std::mbstate_t& /*state*/, 
+    const wchar_t *   from,
+    const wchar_t * from_end, 
+    const wchar_t * & from_next,
+    char * to, 
+    char * to_end, 
+    char * & to_next
+) const
+{
+    // RG - consider merging this table with the other one
+    const wchar_t octet1_modifier_table[] = {
+        0x00, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc
+    };
+
+    wchar_t max_wchar = (std::numeric_limits<wchar_t>::max)();
+    while (from != from_end && to != to_end) {
+
+        // Check for invalid UCS-4 character
+        if (*from  > max_wchar) {
+            from_next = from;
+            to_next = to;
+            return std::codecvt_base::error;
+        }
+
+        int cont_octet_count = get_cont_octet_out_count(*from);
+
+        // RG  - comment this formula better
+        int shift_exponent = (cont_octet_count) *   6;
+
+        // Process the first character
+        *to++ = static_cast<char>(octet1_modifier_table[cont_octet_count] +
+            (unsigned char)(*from / (1 << shift_exponent)));
+
+        // Process the continuation characters 
+        // Invariants: At   the start of the loop:
+        //   1) 'i' continuing octets   have been generated
+        //   2) '*to'   points to the next location to place an octet
+        //   3) shift_exponent is   6 more than needed for the next octet
+        int i   = 0;
+        while   (i != cont_octet_count && to != to_end) {
+            shift_exponent -= 6;
+            *to++ = static_cast<char>(0x80 + ((*from / (1 << shift_exponent)) % (1 << 6)));
+            ++i;
+        }
+        // If   we filled up the out buffer before encoding the character
+        if(to   == to_end && i != cont_octet_count) {
+            from_next = from;
+            to_next = to - (i+1);
+            return std::codecvt_base::partial;
+        }
+        ++from;
+    }
+    from_next = from;
+    to_next = to;
+    // Were we done or did we run out of destination space
+    if(from == from_end) return std::codecvt_base::ok;
+    else return std::codecvt_base::partial;
+}
+
+// How many char objects can I process to get <= max_limit
+// wchar_t objects?
+int utf8_codecvt_facet::do_length(
+    const std::mbstate_t &,
+    const char * from,
+    const char * from_end, 
+    std::size_t max_limit
+) const
+#if BOOST_WORKAROUND(__IBMCPP__, BOOST_TESTED_AT(600))
+        throw()
+#endif
+{ 
+    // RG - this code is confusing!  I need a better way to express it.
+    // and test cases.
+
+    // Invariants:
+    // 1) last_octet_count has the size of the last measured character
+    // 2) char_count holds the number of characters shown to fit
+    // within the bounds so far (no greater than max_limit)
+    // 3) from_next points to the octet 'last_octet_count' before the
+    // last measured character.  
+    int last_octet_count=0;
+    std::size_t char_count = 0;
+    const char* from_next = from;
+    // Use "<" because the buffer may represent incomplete characters
+    while (from_next+last_octet_count <= from_end && char_count <= max_limit) {
+        from_next += last_octet_count;
+        last_octet_count = (get_octet_count(*from_next));
+        ++char_count;
+    }
+    return static_cast<int>(from_next-from_end);
+}
+
+unsigned int utf8_codecvt_facet::get_octet_count(
+    unsigned char   lead_octet
+){
+    // if the 0-bit (MSB) is 0, then 1 character
+    if (lead_octet <= 0x7f) return 1;
+
+    // Otherwise the count number of consecutive 1 bits starting at MSB
+//    assert(0xc0 <= lead_octet && lead_octet <= 0xfd);
+
+    if (0xc0 <= lead_octet && lead_octet <= 0xdf) return 2;
+    else if (0xe0 <= lead_octet && lead_octet <= 0xef) return 3;
+    else if (0xf0 <= lead_octet && lead_octet <= 0xf7) return 4;
+    else if (0xf8 <= lead_octet && lead_octet <= 0xfb) return 5;
+    else return 6;
+}
+BOOST_UTF8_END_NAMESPACE
+
+namespace {
+template<std::size_t s>
+int get_cont_octet_out_count_impl(wchar_t word){
+    if (word < 0x80) {
+        return 0;
+    }
+    if (word < 0x800) {
+        return 1;
+    }
+    return 2;
+}
+
+template<>
+int get_cont_octet_out_count_impl<4>(wchar_t word){
+    if (word < 0x80) {
+        return 0;
+    }
+    if (word < 0x800) {
+        return 1;
+    }
+
+    // Note that the following code will generate warnings on some platforms
+    // where wchar_t is defined as UCS2.  The warnings are superfluous as the
+    // specialization is never instantitiated with such compilers, but this
+    // can cause problems if warnings are being treated as errors, so we guard
+    // against that.  Including <boost/detail/utf8_codecvt_facet.hpp> as we do
+    // should be enough to get WCHAR_MAX defined.
+#if !defined(WCHAR_MAX)
+#   error WCHAR_MAX not defined!
+#endif
+    // cope with VC++ 7.1 or earlier having invalid WCHAR_MAX
+#if defined(_MSC_VER) && _MSC_VER <= 1310 // 7.1 or earlier
+    return 2;
+#elif WCHAR_MAX > 0x10000
+    
+   if (word < 0x10000) {
+        return 2;
+    }
+    if (word < 0x200000) {
+        return 3;
+    }
+    if (word < 0x4000000) {
+        return 4;
+    }
+    return 5;
+    
+#else
+    return 2;
+#endif
+}
+
+} // namespace anonymous
+
+BOOST_UTF8_BEGIN_NAMESPACE
+// How many "continuing octets" will be needed for this word
+// ==   total octets - 1.
+int utf8_codecvt_facet::get_cont_octet_out_count(
+    wchar_t word
+) const {
+    return get_cont_octet_out_count_impl<sizeof(wchar_t)>(word);
+}
+BOOST_UTF8_END_NAMESPACE
+
+#endif