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#include <assert.h>
#include <stdio.h>
#include "piece-table.h"
/*
* We probably should have a pool of pieces and go using them and deleting them
* from there instead of malloc/free but we are lazy
*/
static void print_string(char *str, size_t size) {
size_t i;
printf("\"");
for ( i=0; i < size; i++) {
printf("%c", str[i]);
}
printf("\"");
}
void print_piece_table (piece_table *pt) {
piece *cur;
printf("piece_table {");
printf("\n\toriginal: "); print_string(pt->orig.content, pt->orig.size);
printf("\n\tadd: "); print_string(pt->add.content, pt->add.used);
printf("\n\tlength: %ld", pt->length);
printf("\n\tpieces: ");
for ( cur = pt->sentinel->next; cur != pt->sentinel; cur = cur->next ) {
printf("\n\t\ttext: "); print_string(cur->start, cur->length);
}
printf("\n\t cached_offset: %ld", pt->cached_offset);
printf("\n\t cached (piece-text):");
print_string(pt->cached->start, pt->cached->length);
printf("\n}\n");
}
static piece *make_piece() {
return malloc(sizeof(piece));
}
static piece *make_piece_list() {
/* Makes a sentinel connected to itself in a ring*/
piece *p = make_piece();
p->next = p;
p->prev = p;
p->length = 0;
p->start = NULL;
return p;
}
void init_piece_table(piece_table *pt, char *orig) {
piece *pc;
init_growable_buffer(&pt->add);
init_fixed_buffer(&pt->orig, orig);
pt->length = pt->orig.size;
pt->sentinel = make_piece_list();
pc = make_piece();
pc->start = pt->orig.content;
pc->length = pt->orig.size;
pc->prev = pt->sentinel;
pc->next = pt->sentinel;
pt->sentinel->next = pc;
pt->sentinel->prev = pc;
pt->cached_offset = 0;
pt->cached = pc;
}
static void free_piece_list(piece *p) {
piece *cur, *next;
assert(p != NULL);
for ( cur = p->next; cur != p; cur = next ) {
next = cur->next;
free(cur);
}
free(cur);
}
void free_piece_table(piece_table *pt) {
free_growable_buffer(&pt->add);
free_piece_list(pt->sentinel);
pt->sentinel = NULL;
pt->cached = NULL;
pt->cached_offset = 0;
pt->length = 0;
}
static void find_piece_by_pos(piece_table *pt, size_t pos) {
piece *cur;
assert(pos < pt->length);
if ( pos >= pt->cached_offset ) {
/* Search forward */
for ( cur = pt->cached; ; cur = cur->next ) {
if ( pt->cached_offset + cur->length > pos ) {
pt->cached = cur;
assert(pt->cached != pt->sentinel);
return;
}
pt->cached_offset += cur->length;
}
} else {
/* Search backwards */
for ( cur = pt->cached->prev; ; cur = cur->prev ) {
pt->cached_offset -= cur->length;
if ( pt->cached_offset < pos ) {
pt->cached = cur;
assert(pt->cached != pt->sentinel);
return;
}
}
}
}
char index_piece_table(piece_table *pt, size_t pos) {
assert(pos < pt->length);
find_piece_by_pos(pt, pos);
return pt->cached->start[pos - pt->cached_offset];
}
static piece *split_piece(piece *p, size_t pos) {
/* Returns the first piece */
piece *second;
assert(pos < p->length);
assert(p->start != NULL); /* Not a sentinel piece */
assert(p->start != 0); /* Not an empty piece (they should not exist) */
if ( pos == 0 ) {
return p->prev;
}
second = make_piece();
second->length = p->length - pos;
p->length = pos;
second->next = p->next;
p->next = second;
second->prev = p;
second->start = p->start + pos;
return p;
}
void insert_piece_table(piece_table *pt, size_t pos, char *in, size_t in_len) {
piece *start, *end, *new;
assert( pos <= pt->length );
assert( in_len > 0 );
append_growable_buffer(&pt->add, in, in_len);
if ( pos == 0 ) {
start = pt->sentinel;
} else if ( pos == pt->length ) {
start = pt->sentinel->prev;
} else {
find_piece_by_pos(pt, pos);
start = split_piece(pt->cached, pos - pt->cached_offset);
}
end = start->next;
/* Update cache;
* If we insert before our cached piece, the offset is not up-to-date
* anymore.
*/
if ( pt->cached_offset >= pos ) {
pt->cached = pt->cached->prev;
pt->cached_offset -= pt->cached->length;
}
new = make_piece();
new->start = pt->add.content + pt->add.used - in_len;
new->length = in_len;
start->next = new;
new->prev = start;
new->next = end;
end->prev = new;
pt->length += in_len;
}
void delete_piece_table(piece_table *pt, size_t pos, size_t len) {
piece *cur, *next, *start, *end;
size_t off_start;
assert( pos + len <= pt->length );
assert( len > 0 );
if ( pos == 0 ) {
start = pt->sentinel;
off_start = 0;
} else {
find_piece_by_pos(pt, pos);
off_start = pt->cached_offset;
start = split_piece(pt->cached, pos - pt->cached_offset);
}
if ( pos + len == pt->length ) {
end = pt->sentinel;
} else {
find_piece_by_pos(pt, pos + len);
end = split_piece(pt->cached, pos + len - pt->cached_offset)->next;
}
/* Update cache to before the start */
if ( pt->cached_offset >= pos ) {
pt->cached = start;
pt->cached_offset = off_start;
}
/* Free unneeded pieces */
for ( cur = start->next; cur != end ; cur = next ) {
next = cur->next;
free(cur);
}
start->next = end;
end->prev = start;
pt->length -= len;
}
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