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utf8: use an iterator style interface internally

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This commit is contained in:
Danny Robson 2017-10-02 16:15:19 +11:00
parent 35db5f0a7a
commit c61fa16316
2 changed files with 40 additions and 31 deletions
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69
utf8.cpp
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@ -74,53 +74,52 @@ operator"" _test (const char *str, size_t len)
///////////////////////////////////////////////////////////////////////////////
std::vector<util::utf8::codepoint_t>
util::utf8::decode (view<const std::byte*> src)
template <
typename InputT,
typename OutputT>
static OutputT
decode (util::view<InputT> src, OutputT dst)
{
std::vector<codepoint_t> dst;
dst.reserve (src.size ());
using namespace util::utf8;
static constexpr
test<codepoint_t> TESTS[] = {
test<codepoint_t> PREFIX[] = {
"0b0xxxxxxx"_test,
"0b110xxxxx"_test,
"0b1110xxxx"_test,
"0b11110xxx"_test
};
for (auto cursor = src.cbegin (); cursor != src.cend (); ++cursor) {
codepoint_t c = std::to_integer<codepoint_t> (*cursor);
for (auto cursor = src.cbegin (); cursor != src.cend (); ) {
codepoint_t c = std::to_integer<codepoint_t> (*cursor++);
int len = TESTS[0].valid (c) ? 0 :
TESTS[1].valid (c) ? 1 :
TESTS[2].valid (c) ? 2 :
TESTS[3].valid (c) ? 3 :
throw malformed_error {};
if (cursor + len >= src.cend ())
int len = PREFIX[0].valid (c) ? 0 :
PREFIX[1].valid (c) ? 1 :
PREFIX[2].valid (c) ? 2 :
PREFIX[3].valid (c) ? 3 :
throw malformed_error {};
// get the simple ANSI case out of the way
if (!len) {
dst.push_back (c);
*dst++ = c;
continue;
}
codepoint_t head = codepoint_t { c & ~TESTS[len].mask } << (len * 6);
codepoint_t accum = head;
codepoint_t shift = 0;
codepoint_t accum { PREFIX[len].value (c) };
// check every following data byte has the appropriate prefix
constexpr auto CONTINUATION = "0b10xxxxxx"_test;
for (int i = 1; i <= len; ++i) {
if (!CONTINUATION.valid (std::to_integer<codepoint_t> (cursor[i])))
throw malformed_error {};
}
static constexpr auto CONTINUATION = "0b10xxxxxx"_test;
switch (len) {
case 3: accum |= CONTINUATION.value (std::to_integer<codepoint_t> (cursor[3])) << (shift++ * 6u);
case 2: accum |= CONTINUATION.value (std::to_integer<codepoint_t> (cursor[2])) << (shift++ * 6u);
case 1: accum |= CONTINUATION.value (std::to_integer<codepoint_t> (cursor[1])) << (shift++ * 6u);
for (int i = 1; i <= len; ++i) {
if (cursor == src.cend ())
throw malformed_error {};
codepoint_t now = std::to_integer<codepoint_t> (*cursor++);
if (!CONTINUATION.valid (now))
throw malformed_error {};
accum <<= 6;
accum |= CONTINUATION.value (now);
}
// describes the bits required to be present for a valid minimally
@ -144,9 +143,21 @@ util::utf8::decode (view<const std::byte*> src)
if (accum == 0xfffe || accum == 0xffff)
throw illegal_codepoint {};
dst.push_back (accum);
std::advance (cursor, len);
*dst++ = accum;
}
return dst;
}
///////////////////////////////////////////////////////////////////////////////
std::vector<util::utf8::codepoint_t>
util::utf8::decode (view<const std::byte*> src)
{
std::vector<codepoint_t> dst;
dst.reserve (src.size ());
::decode (src, std::back_inserter (dst));
return dst;
}

2
utf8.hpp
View File

@ -29,8 +29,6 @@ namespace util::utf8 {
///////////////////////////////////////////////////////////////////////////
using codepoint_t = uint32_t;
constexpr codepoint_t MAX_CODEPOINT = 0x10FFFF;
///////////////////////////////////////////////////////////////////////////
std::vector<codepoint_t>