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#include <stdint.h>
#include <assert.h>
#include <stdbool.h>
class Point {
Page *page;
uint16_t index;
uint16_t index_to_offset() {
if (index < page->gap_start) {
return index;
} else {
return index + (page->gap_end - page->gap_start);
}
}
uint8_t byte() {
return index == page->element_count ? (page->next ? page->next->elements[0] : 0) : page->elements[index_to_offset()];
}
void next_byte() {
if (index < page->element_count) {
index++;
} else if (page->next) {
page = page->next;
index = 1;
}
}
void prev_byte() {
if (index > 1) {
index--;
} else if (page->prev) {
page = page->prev;
index = page->element_count;
} else {
index = 0;
}
}
size_t rune_type() {
if (byte() & 1 << 7) {
if (byte() & 1 << 6) {
if (byte() & 1 << 5) {
if (byte() & 1 << 4) {
return 4;
} else {
return 3;
}
} else {
return 2;
}
} else {
return 0;
}
} else {
return 1;
}
}
public:
Point() : page(new Page()), index(0) {}
Point(const Point& p) : page(p.page), index(p.index) {}
bool operator==(Point p) {
return page == p.page && index == p.index;
}
bool operator!=(Point p) {
return page != p.page || index != p.index;
}
bool at_start() {
return index == 0;
}
bool at_end() {
return index == page->element_count && !page->next;
}
void operator++(int) {
do {
next_byte();
} while (!rune_type());
}
void operator--(int) {
do {
prev_byte();
} while (!rune_type());
}
wchar_t element() {
size_t type = rune_type();
wchar_t rune = byte() & (0xff >> type);
Point iter(*this);
for (size_t i = 1; i < type; i++) {
rune <<= 6;
iter.next_byte();
rune |= (iter.byte() & 0x3f);
}
return rune;
}
uint64_t seek(uint8_t c, uint64_t limit) {
uint64_t travel_distance = 0;
while (!at_end() && byte() != c && travel_distance < limit) {
next_byte();
travel_distance++;
}
return travel_distance;
}
uint64_t rseek(uint8_t c, uint64_t limit) {
uint64_t travel_distance = 0;
while (!at_start() && byte() != c && travel_distance < limit) {
prev_byte();
travel_distance++;
}
return travel_distance;
}
void align_gap() {
while (page->gap_end < index_to_offset()) {
page->move_gap_forward();
}
while (page->gap_end > index_to_offset()) {
page->move_gap_backward();
}
}
void push(uint8_t c) {
if (page->is_full()) {
page->split();
if (index >= PAGE_SIZE / 2) {
page = page->next;
index -= PAGE_SIZE / 2;
}
}
align_gap();
page->push(c);
next_byte();
}
void pop() {
if (page->element_count == 1 && index == 1) {
if (page->prev) {
prev_byte();
delete page->next;
} else if (page->next) {
page->next->copy_to(page);
delete page->next;
index = 0;
} else {
page->pop();
prev_byte();
}
} else if (index > 0) {
align_gap();
page->pop();
prev_byte();
}
}
};
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