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/* Copyright (C) 2018 Curtis McEnroe <june@causal.agency>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <err.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
static struct Span {
size_t at;
size_t to;
} Span(size_t at, size_t to) {
return (struct Span) { at, to };
}
static bool spanStartsIn(struct Span a, struct Span b) {
return a.at >= b.at && a.at < b.to;
}
static bool spanEndsIn(struct Span a, struct Span b) {
return a.to > b.at && a.to <= b.to;
}
static bool spanContains(struct Span a, struct Span b) {
return a.at <= b.at && a.to >= b.to;
}
static struct Seg {
struct Span span;
char *data;
} Seg(struct Span span, char *data) {
return (struct Seg) { span, data };
}
static struct Seg segBefore(struct Seg seg, size_t at) {
return Seg(Span(seg.span.at, at), seg.data);
}
static struct Seg segAfter(struct Seg seg, size_t at) {
return Seg(Span(at, seg.span.to), seg.data + (at - seg.span.at));
}
struct Table {
struct Table *next;
struct Table *prev;
size_t len;
struct Seg seg[];
};
static struct Table *tableNew(size_t cap) {
size_t size = sizeof(struct Table) + cap * sizeof(struct Seg);
struct Table *table = malloc(size);
if (!table) err(EX_OSERR, "malloc");
memset(table, 0, size);
return table;
}
static void tableAdd(struct Table *table, struct Seg seg) {
// FIXME: Make this clearer.
size_t len = seg.span.to - seg.span.at;
if (table->len) {
struct Seg last = table->seg[table->len - 1];
seg.span = Span(last.span.to, last.span.to + len);
} else {
seg.span = Span(0, len);
}
table->seg[table->len++] = seg;
}
static struct Table *tableInsert(struct Table *prev, struct Seg seg) {
struct Table *next = tableNew(prev->len + 2);
if (!prev->len) {
tableAdd(next, seg);
return next;
}
for (size_t i = 0; i < prev->len; ++i) {
if (seg.span.at == prev->seg[i].span.at) {
tableAdd(next, seg);
tableAdd(next, prev->seg[i]);
} else if (spanStartsIn(seg.span, prev->seg[i].span)) {
tableAdd(next, segBefore(prev->seg[i], seg.span.at));
tableAdd(next, seg);
tableAdd(next, segAfter(prev->seg[i], seg.span.at));
} else {
tableAdd(next, prev->seg[i]);
}
}
return next;
}
static struct Table *tableDelete(struct Table *prev, struct Span span) {
struct Table *next = tableNew(prev->len + 1);
for (size_t i = 0; i < prev->len; ++i) {
if (spanContains(span, prev->seg[i].span)) {
// drop
} else if (spanContains(prev->seg[i].span, span)) {
tableAdd(next, segBefore(prev->seg[i], span.at));
tableAdd(next, segAfter(prev->seg[i], span.to));
} else if (spanStartsIn(span, prev->seg[i].span)) {
tableAdd(next, segBefore(prev->seg[i], span.at));
} else if (spanEndsIn(span, prev->seg[i].span)) {
tableAdd(next, segAfter(prev->seg[i], span.to));
} else {
tableAdd(next, prev->seg[i]);
}
}
return next;
}
int main() {
struct Table *table = tableNew(0);
table = tableInsert(table, Seg(Span(0, 13), "Hello, world!"));
table = tableDelete(table, Span(1, 5));
table = tableInsert(table, Seg(Span(1, 5), "owdy"));
table = tableDelete(table, Span(3, 6));
table = tableInsert(table, Seg(Span(3, 6), " do"));
for (size_t i = 0; i < table->len; ++i) {
printf("%.*s", table->seg[i].span.to - table->seg[i].span.at, table->seg[i].data);
}
}
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