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add a namespace nana::utf for UTF-8 character processing

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This commit is contained in:
Jinhao
2016-01-01 12:30:18 +08:00
parent a42ebe19b4
commit 0a4f04267e
4 changed files with 199 additions and 2 deletions
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177
source/charset.cpp
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@@ -30,6 +30,183 @@
namespace nana
{
namespace utf
{
const char* char_ptr(const char* text, unsigned pos)
{
auto ustr = reinterpret_cast<const unsigned char*>(text);
auto const end = ustr + std::strlen(text);
for (unsigned i = 0; i != pos; ++i)
{
const auto uch = *ustr;
if (uch < 0x80)
{
++ustr;
continue;
}
if (uch < 0xC0)
return nullptr;
if ((uch < 0xE0) && (ustr + 1 < end))
ustr += 2;
else if (uch < 0xF0 && (ustr + 2 <= end))
ustr += 3;
else if (uch < 0x1F && (ustr + 3 <= end))
ustr += 4;
else
return nullptr;
}
return reinterpret_cast<const char*>(ustr);
}
const char* char_ptr(const std::string& text_utf8, unsigned pos)
{
auto ustr = reinterpret_cast<const unsigned char*>(text_utf8.c_str());
auto const end = ustr + text_utf8.size();
for (unsigned i = 0; i != pos; ++i)
{
const auto uch = *ustr;
if (uch < 0x80)
{
++ustr;
continue;
}
if (uch < 0xC0)
return nullptr;
if ((uch < 0xE0) && (ustr + 1 < end))
ustr += 2;
else if (uch < 0xF0 && (ustr + 2 <= end))
ustr += 3;
else if (uch < 0x1F && (ustr + 3 <= end))
ustr += 4;
else
return nullptr;
}
return reinterpret_cast<const char*>(ustr);
}
wchar_t char_at(const char* text_utf8, unsigned pos, unsigned * len)
{
if (!text_utf8)
return 0;
if (pos)
{
text_utf8 = char_ptr(text_utf8, pos);
if (!text_utf8)
return 0;
}
const wchar_t uch = *reinterpret_cast<const unsigned char*>(text_utf8);
if (uch < 0x80)
{
if (len)
*len = 1;
return *text_utf8;
}
if (uch < 0xC0)
{
if (len)
*len = 0;
return 0;
}
const auto end = text_utf8 + std::strlen(text_utf8);
if (uch < 0xE0 && (text_utf8 + 1 <= end))
{
if (len)
*len = 2;
return (wchar_t(uch & 0x1F) << 6) | (reinterpret_cast<const unsigned char*>(text_utf8)[1] & 0x3F);
}
else if (uch < 0xF0 && (text_utf8 + 2 <= end))
{
if (len)
*len = 3;
return ((((uch & 0xF) << 6) | (reinterpret_cast<const unsigned char*>(text_utf8)[1] & 0x3F)) << 6) | (reinterpret_cast<const unsigned char*>(text_utf8)[2] & 0x3F);
}
else if (uch < 0x1F && (text_utf8 + 3 <= end))
{
if (len)
*len = 4;
return ((((((uch & 0x7) << 6) | (reinterpret_cast<const unsigned char*>(text_utf8)[1] & 0x3F)) << 6) | (reinterpret_cast<const unsigned char*>(text_utf8)[2] & 0x3F)) << 6) | (reinterpret_cast<const unsigned char*>(text_utf8)[3] & 0x3F);
}
if (len)
*len = 0;
return 0;
}
wchar_t char_at(const ::std::string& text_utf8, unsigned pos, unsigned * len)
{
const char* ptr;
if (pos)
{
ptr = char_ptr(text_utf8, pos);
if (!ptr)
return 0;
}
else
ptr = text_utf8.c_str();
const wchar_t uch = *reinterpret_cast<const unsigned char*>(ptr);
if (uch < 0x80)
{
if (len)
*len = 1;
return *ptr;
}
if (uch < 0xC0)
{
if (len)
*len = 0;
return 0;
}
const auto end = text_utf8.c_str() + text_utf8.size();
if (uch < 0xE0 && (ptr + 1 <= end))
{
if (len)
*len = 2;
return (wchar_t(uch & 0x1F) << 6) | (reinterpret_cast<const unsigned char*>(ptr)[1] & 0x3F);
}
else if (uch < 0xF0 && (ptr + 2 <= end))
{
if (len)
*len = 3;
return ((((uch & 0xF) << 6) | (reinterpret_cast<const unsigned char*>(ptr)[1] & 0x3F)) << 6) | (reinterpret_cast<const unsigned char*>(ptr)[2] & 0x3F);
}
else if (uch < 0x1F && (ptr + 3 <= end))
{
if (len)
*len = 4;
return ((((((uch & 0x7) << 6) | (reinterpret_cast<const unsigned char*>(ptr)[1] & 0x3F)) << 6) | (reinterpret_cast<const unsigned char*>(ptr)[2] & 0x3F)) << 6) | (reinterpret_cast<const unsigned char*>(ptr)[3] & 0x3F);
}
if (len)
*len = 0;
return 0;
}
}
namespace detail
{
class locale_initializer