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// ed - edit text
// ed [-p string] [-s] [file]
#include <assert.h>
#include <stdio.h>
#include <string.h>
#define COMMAND_MODE 0
#define INPUT_MODE 1
int mode = COMMAND_MODE;
FILE *fp = NULL;
FILE *mem_fp = NULL;
int line_number = 1;
int ed_getline(char *buffer, size_t s) {
(void)s;
int i = 0;
char c;
for (;; i++) {
int rc = read(0, &c, 1);
assert(rc > 0);
printf("%c", c);
buffer[i] = c;
if ('\n' == c) {
break;
}
}
buffer[i] = '\0';
return i;
}
void goto_line(void) {
char c;
fseek(mem_fp, 0, SEEK_SET);
int line = 1;
if (1 != line_number) {
// Goto line
for (; fread(&c, 1, 1, mem_fp);) {
if ('\n' == c) {
line++;
}
if (line == line_number) {
return;
}
}
printf("got to line: %d\n", line);
assert(0);
}
}
void read_line(void) {
char c;
goto_line();
for (; fread(&c, 1, 1, mem_fp);) {
if ('\n' == c) {
break;
}
printf("%c", c);
}
printf("\n");
}
void goto_end_of_line(void) {
char c;
for (; fread(&c, 1, 1, mem_fp);) {
if ('\n' == c) {
break;
}
}
}
void delete_line(void) {
long s = ftell(mem_fp);
printf("s: %d\n", s);
goto_end_of_line();
long end = ftell(mem_fp);
printf("end: %d\n", end);
long offset = end - s;
for (char buffer[4096];;) {
int rc = fread(buffer, 1, 100, mem_fp);
long reset = ftell(mem_fp);
if (0 == rc) {
break;
}
fseek(mem_fp, s, SEEK_SET);
fwrite(buffer, 1, rc, mem_fp);
s += rc;
fseek(mem_fp, reset, SEEK_SET);
}
}
void read_command(void) {
char buffer[4096];
char *s = buffer;
ed_getline(buffer, 4096);
int a = -1;
int rc = sscanf(buffer, "%d", &a);
if (0 < rc) {
line_number = a;
}
for (; isdigit(*s); s++)
;
if (0 == strcmp(s, "i")) {
mode = INPUT_MODE;
return;
}
if (0 == strcmp(s, ".")) {
read_line();
return;
}
return;
}
void read_input(void) {
char buffer[4096];
int l = ed_getline(buffer, 4096);
if (0 == strcmp(buffer, ".")) {
mode = COMMAND_MODE;
return;
}
goto_line();
delete_line();
goto_line();
assert(fwrite(buffer, l, 1, mem_fp));
return;
}
int ed_main(char argc, char **argv) {
if (argc < 2) {
return 1;
}
char *buffer;
size_t size;
mem_fp = open_memstream(&buffer, &size);
assert(mem_fp);
fp = fopen(argv[1], "r");
assert(fp);
char r_buffer[4096];
for (int rc; (rc = fread(buffer, 1, 4096, fp));) {
fwrite(r_buffer, 1, rc, mem_fp);
}
for (;;) {
if (COMMAND_MODE == mode) {
read_command();
} else {
read_input();
}
}
fclose(fp);
fclose(mem_fp);
return 0;
}
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