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#include "codepoint_iterator.h"
#include <cstdint>
namespace {
enum class CodeUnitType : uint8_t {
CONTINUATION = 128, // 10000000
LEADING = 64, // 01000000
THREE = 32, // 00100000
FOUR = 16, // 00010000
};
enum class CodePoint : uint8_t {
CONTINUATION = 63, // 00111111
TWO = 31, // 00011111
THREE = 15, // 00001111
FOUR = 7, // 00000111
};
inline bool match(const uint8_t& codeUnit, CodeUnitType&& type) {
return codeUnit & static_cast<uint8_t>(type);
}
inline void write(char32_t& codePoint,
const uint8_t& codeUnit,
CodePoint&& mask,
const uint8_t& offset) {
codePoint += (codeUnit & static_cast<uint8_t>(mask)) << offset;
}
}
namespace UTF8 {
CodepointIterator::CodepointIterator(std::string::const_iterator iter):
iterator_(iter),
dereferenced_(false),
codepoint_(0) { }
CodepointIterator::CodepointIterator(const CodepointIterator& src):
iterator_(src.iterator_),
dereferenced_(src.dereferenced_),
codepoint_(src.codepoint_) { }
CodepointIterator& CodepointIterator::operator=(const CodepointIterator& src) {
this->iterator_ = src.iterator_;
this->dereferenced_ = src.dereferenced_;
this->codepoint_ = src.codepoint_;
return *this;
}
bool CodepointIterator::operator==(const CodepointIterator& src) const {
return this->iterator_ == src.iterator_;
}
bool CodepointIterator::operator!=(const CodepointIterator& src) const {
return this->iterator_ != src.iterator_;
}
bool CodepointIterator::operator==(
const std::string::const_iterator& src) const {
return this->iterator_ == src;
}
bool CodepointIterator::operator!=(
const std::string::const_iterator& src) const {
return this->iterator_ != src;
}
char32_t CodepointIterator::operator*() {
if ( !this->dereferenced_ ) {
uint8_t currByte = *(this->iterator_);
this->dereferenced_ = true;
this->codepoint_ = 0;
if ( match(currByte, CodeUnitType::CONTINUATION) ) {
if ( match(currByte, CodeUnitType::THREE) ) {
if ( match(currByte, CodeUnitType::FOUR) ) {
write(this->codepoint_,
currByte,
CodePoint::FOUR,
18);
write(this->codepoint_,
*(this->iterator_ + 1),
CodePoint::CONTINUATION,
12);
write(this->codepoint_,
*(this->iterator_ + 2),
CodePoint::CONTINUATION,
6);
write(this->codepoint_,
*(this->iterator_ + 3),
CodePoint::CONTINUATION,
0);
} else {
write(this->codepoint_,
currByte,
CodePoint::THREE,
12);
write(this->codepoint_,
*(this->iterator_ + 1),
CodePoint::CONTINUATION,
6);
write(this->codepoint_,
*(this->iterator_ + 2),
CodePoint::CONTINUATION,
0);
}
} else {
write(this->codepoint_,
currByte,
CodePoint::TWO,
6);
write(this->codepoint_,
*(this->iterator_ + 1),
CodePoint::CONTINUATION,
0);
}
} else {
this->codepoint_ = currByte;
}
}
return this->codepoint_;
}
CodepointIterator& CodepointIterator::operator++() {
this->dereferenced_ = false;
uint8_t currByte = *(this->iterator_);
std::string::difference_type offset = 1;
if ( match(currByte, CodeUnitType::CONTINUATION) ) {
if ( match(currByte, CodeUnitType::THREE) ) {
if ( match(currByte, CodeUnitType::FOUR) ) {
offset = 4;
} else {
offset = 3;
}
} else {
offset = 2;
}
}
this->iterator_ += offset;
return *this;
}
CodepointIterator& CodepointIterator::operator--() {
this->dereferenced_ = false;
--this->iterator_;
if ( match(*(this->iterator_), CodeUnitType::CONTINUATION) ) {
--this->iterator_;
if ( !match(*(this->iterator_), CodeUnitType::LEADING) ) {
--this->iterator_;
if ( !match(*(this->iterator_), CodeUnitType::LEADING) ) {
--this->iterator_;
if ( !match(*(this->iterator_), CodeUnitType::LEADING) ) {
throw codepoint_invalid();
}
}
}
}
return *this;
}
CodepointIterator CodepointIterator::operator++(int) {
CodepointIterator oldIter(*this);
++(*this);
return oldIter;
}
CodepointIterator CodepointIterator::operator--(int) {
CodepointIterator oldIter(*this);
--(*this);
return oldIter;
}
}
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