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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 spanEqual(struct Span a, struct Span b) {
return a.at == b.at && a.to == b.to;
}
static bool spanIn(struct Span a, struct Span b) {
return a.at > b.at && a.to < b.to;
}
static bool spanHeadIn(struct Span a, struct Span b) {
return a.at > b.at && a.at < b.to;
}
static bool spanTailIn(struct Span a, struct Span b) {
return a.to > b.at && a.to < b.to;
}
static struct Seg {
char *ptr;
size_t len;
} Seg(char *ptr, size_t len) {
return (struct Seg) { ptr, len };
}
static struct Seg segHead(struct Seg seg, size_t at) {
return Seg(seg.ptr, at);
}
static struct Seg segTail(struct Seg seg, size_t at) {
return Seg(seg.ptr + at, seg.len - at);
}
static struct Table {
struct Table *next;
struct Table *prev;
size_t len;
struct Seg seg[];
} *Table(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 struct TableIter {
size_t len;
struct Seg *seg;
struct Span span;
} TableIter(struct Table *table) {
if (table->len) {
return (struct TableIter) {
table->len,
&table->seg[0],
Span(0, table->seg[0].len),
};
} else {
return (struct TableIter) { 0, NULL, Span(0, 0) };
}
}
static void tableNext(struct TableIter *it) {
it->len--;
it->seg++;
it->span = Span(it->span.to, it->span.to + it->seg->len);
}
static struct Seg *tableAt(struct Table *table, size_t at) {
for (struct TableIter it = TableIter(table); it.len; tableNext(&it)) {
if (it.span.at == at) return it.seg;
}
return NULL;
}
static struct Table *tableInsert(struct Table *prev, size_t at, struct Seg seg) {
struct Table *next = Table(prev->len + 2);
if (!prev->len) {
next->seg[next->len++] = seg;
return next;
}
struct Span span = Span(at, at + seg.len);
for (struct TableIter it = TableIter(prev); it.len; tableNext(&it)) {
if (it.span.at == at) {
next->seg[next->len++] = seg;
next->seg[next->len++] = *it.seg;
} else if (spanHeadIn(span, it.span)) {
next->seg[next->len++] = segHead(*it.seg, at - it.span.at);
next->seg[next->len++] = seg;
next->seg[next->len++] = segTail(*it.seg, at - it.span.at);
} else {
next->seg[next->len++] = *it.seg;
}
}
return next;
}
static struct Table *tableDelete(struct Table *prev, struct Span span) {
struct Table *next = Table(prev->len + 1);
for (struct TableIter it = TableIter(prev); it.len; tableNext(&it)) {
if (spanIn(it.span, span) || spanEqual(it.span, span)) {
// drop
} else if (spanIn(span, it.span)) {
next->seg[next->len++] = segHead(*it.seg, span.at - it.span.at);
next->seg[next->len++] = segTail(*it.seg, span.to - it.span.at);
} else if (spanHeadIn(span, it.span)) {
next->seg[next->len++] = segHead(*it.seg, span.at - it.span.at);
} else if (spanTailIn(span, it.span)) {
next->seg[next->len++] = segTail(*it.seg, span.to - it.span.at);
} else {
next->seg[next->len++] = *it.seg;
}
}
return next;
}
int main() {
struct Table *table = Table(0);
table = tableInsert(table, 0, Seg("Hello, world!\n", 14));
table = tableDelete(table, Span(1, 5));
table = tableInsert(table, 1, Seg("owdy", 5));
table = tableDelete(table, Span(3, 6));
table = tableInsert(table, 3, Seg(" do", 3));
for (size_t i = 0; i < table->len; ++i) {
printf("%.*s", (int)table->seg[i].len, table->seg[i].ptr);
}
}
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