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-rw-r--r--src/codepoint_iterator.cc190
-rw-r--r--src/codepoint_iterator.h49
2 files changed, 239 insertions, 0 deletions
diff --git a/src/codepoint_iterator.cc b/src/codepoint_iterator.cc
new file mode 100644
index 0000000..21a8c36
--- /dev/null
+++ b/src/codepoint_iterator.cc
@@ -0,0 +1,190 @@
+#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;
+}
+
+}
diff --git a/src/codepoint_iterator.h b/src/codepoint_iterator.h
new file mode 100644
index 0000000..938f53d
--- /dev/null
+++ b/src/codepoint_iterator.h
@@ -0,0 +1,49 @@
+#ifndef CODEPOINT_ITERATOR_H_
+#define CODEPOINT_ITERATOR_H_
+
+#include <iterator>
+#include <string>
+#include <exception>
+
+namespace UTF8 {
+
+class CodepointIterator : public std::iterator<std::bidirectional_iterator_tag,
+ char32_t,
+ std::string::difference_type,
+ const char32_t*,
+ const char32_t&> {
+ public:
+ CodepointIterator(std::string::const_iterator);
+ CodepointIterator(const CodepointIterator&);
+
+ CodepointIterator& operator=(const CodepointIterator&);
+
+ bool operator==(const CodepointIterator&) const;
+ bool operator==(const std::string::const_iterator&) const;
+
+ bool operator!=(const CodepointIterator&) const;
+ bool operator!=(const std::string::const_iterator&) const;
+
+ char32_t operator*();
+
+ CodepointIterator& operator++();
+ CodepointIterator& operator--();
+
+ CodepointIterator operator++(int);
+ CodepointIterator operator--(int);
+
+ private:
+ std::string::const_iterator iterator_;
+ bool dereferenced_;
+ char32_t codepoint_;
+};
+
+class codepoint_invalid: public std::exception {
+ virtual const char* what() const throw() {
+ return "codepoint_invalid";
+ }
+};
+
+}
+
+#endif // CODEPOINT_ITERATOR_H_