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added limited line editing capability
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@npamnani
npamnani committed Jan 5, 2017
1 parent 98606b3 commit b68b4bd
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388 changes: 388 additions & 0 deletions coda_readline.c
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Original file line number Diff line number Diff line change
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#include <stdio.h>
#include <termios.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define LINE_LEN 1024
#define MAX_HIST_SIZE 1000

struct termios saved;
static char line[LINE_LEN];
static int prmt_len;
static int str_len;
static int cur_idx;
static char dummy_line[LINE_LEN];

struct dlist
{
struct dlist *next;
struct dlist *prev;
char *line;
};

struct history_struct {

struct dlist start;
struct dlist end;
int max_size;
int cur_size;
};

struct dlist dummy_node;
static struct history_struct history = {
.max_size = 100,
.start.next = &dummy_node,
.end.prev = &dummy_node
};

struct dlist dummy_node = {
.next = &history.end,
.prev = &history.start,
.line = dummy_line
};
static struct dlist *last_node = &dummy_node;

static inline void del_nodes(int count)
{
while (count > 0 && history.cur_size > 0)
{
struct dlist *del_node = history.start.next;
history.start.next = del_node->next;
del_node->next->prev = &history.start;
free(del_node->line);
free(del_node);
--history.cur_size;
--count;
}
}

static void add_node(char *str)
{
int len;

struct dlist *new_node;
if (history.cur_size != 0 && strcmp(dummy_node.prev->line, str) == 0)
{
return;
}

if (history.cur_size == history.max_size)
{
del_nodes(1);
}

len = strlen(str);
new_node = malloc(sizeof(*new_node));
new_node->line = malloc(len + 1);
memcpy(new_node->line, str, len + 1);

new_node->next = &dummy_node;
new_node->prev = dummy_node.prev;
dummy_node.prev->next = new_node;
dummy_node.prev = new_node;
++history.cur_size;
}

static int termsetup()
{
struct termios term;
if(tcgetattr(fileno(stdin), &term) < 0) {
perror("Error getting terminal information");
exit(1);
}
saved = term;

term.c_lflag &= ~ICANON;
term.c_lflag &= ~ECHO;
term.c_lflag |= ISIG;
term.c_cc[VMIN]=1;
term.c_cc[VTIME]=0;
term.c_cc[VINTR]=0;
term.c_cc[VQUIT]=0;

if(tcsetattr(fileno(stdin), TCSANOW, &term) < 0) {
perror("Error setting terminal information");
return 1;
}
return 0;
}

static int termrestore()
{
if(tcsetattr(fileno(stdin), TCSANOW, &saved) < 0) {
perror("Error setting terminal information");
return 1;
}
return 0;
}

static void write_stdout(char *str, int end)
{
if (end < 0)
end = 0;

while(end--)
putc('\b', stdout);
if (str != NULL)
fwrite(str, strlen(str), 1, stdout);
}

static void write_space(int count)
{
if (count < 0)
count = 0;
while(count--)
putc(' ', stdout);
}

static void display_down()
{

if (last_node->next != &history.end)
last_node = last_node->next;
else
return;

{
int len = strlen(last_node->line);
memcpy(line + prmt_len, last_node->line, len + 1);
write_stdout(line + prmt_len, cur_idx - prmt_len);
write_space(str_len - prmt_len - len);
write_stdout(0, str_len - prmt_len - len);
cur_idx = str_len = len + prmt_len;
}
}

static void display_up()
{

if (last_node->prev != &history.start)
last_node = last_node->prev;
else
return;

{
int len = strlen(last_node->line);
memcpy(line + prmt_len, last_node->line, len + 1);
write_stdout(line + prmt_len, cur_idx - prmt_len);
write_space(str_len - prmt_len - len);
write_stdout(0, str_len - prmt_len - len);
cur_idx = str_len = len + prmt_len;
}
}

static void metakey()
{
int key = getchar();

if (key == 91)
{
key = getchar();
switch(key)
{
case 65:
{
display_up();
break;
}
case 66:
{
display_down();
break;
}
case 67:
{
if (cur_idx < str_len)
{
write_stdout(line + prmt_len, cur_idx - prmt_len);
++cur_idx;
write_stdout(NULL, str_len - cur_idx);
}
break;
}
case 68:
{
if (cur_idx > prmt_len)
{
write_stdout(NULL, 1);
--cur_idx;
}
}
case 71:
break;
default:
{
while(key != 126)
{
key = getchar();
}
}
}
}
}

static char* coda_getline(const char *prompt)
{
int key;
const char *rl_prmpt = (prompt == NULL || prompt[0] == '\0') ?
"readline > " : prompt;

display_prompt:

memset(line, 0, LINE_LEN);
cur_idx = str_len = prmt_len = strlen(rl_prmpt);

memcpy(line, rl_prmpt, prmt_len);
write_stdout(line, 0);

do {
key=getchar();

switch(key)
{
case 27:
{
metakey();
break;
}
case 10:
{
last_node = &dummy_node;
dummy_node.line[0] = 0;
write_stdout("\n", 0);
return line;
}
case 1:
{
write_stdout(NULL, cur_idx - prmt_len);
cur_idx = prmt_len;
break;
}
case 5:
{
write_stdout(line + prmt_len, cur_idx - prmt_len);
cur_idx = str_len;
break;
}
case 23: //erase previous word
break;
case 28: //QUIT
{
break;
}
case 3: //INTR
{
write_stdout("^C\n", 0);
dummy_node.line[0] = 0;
last_node = &dummy_node;
goto display_prompt;
}
case 4:
{
if (prmt_len == str_len)
{
return NULL;
}
else if(cur_idx < str_len)
{
memmove(&line[cur_idx], &line[cur_idx + 1], str_len - cur_idx - 1);
line[str_len - 1] = 32;
write_stdout(line + prmt_len, cur_idx - prmt_len);
write_stdout(NULL, str_len - cur_idx);
line[--str_len] = 0;
if (last_node == &dummy_node)
{
memcpy(dummy_node.line, line + prmt_len, str_len);
}
}
break;
}
case 127:
{
if (cur_idx > prmt_len)
{
memmove(&line[cur_idx - 1], &line[cur_idx], str_len - cur_idx);
line[str_len - 1] = 32;
write_stdout(line + prmt_len, cur_idx - prmt_len);
write_stdout(NULL, str_len - cur_idx + 1);
line[--str_len] = 0;
--cur_idx;
if (last_node == &dummy_node)
{
memcpy(dummy_node.line, line + prmt_len, str_len);
}
}
break;
}
case 12:
{
putc('\f', stdout);
write_stdout(line ,0);
write_stdout(NULL, str_len - cur_idx);
break;
}
default:
{
if (iscntrl(key))
break;

if ((str_len + 1) <= LINE_LEN)
{
memmove(&line[cur_idx + 1], &line[cur_idx], str_len - cur_idx);
line[cur_idx] = (unsigned char) key;
line[str_len + 1] = 0;
write_stdout(line + prmt_len, cur_idx - prmt_len);
write_stdout(NULL, str_len - cur_idx);
++cur_idx;
++str_len;
memcpy(dummy_node.line, line + prmt_len, str_len);
}
}
}
} while(1);
}

char* coda_readline(const char *prompt)
{
char *rline;

if (!isatty(fileno(stdin)) || !isatty(fileno(stdout)))
{
perror("coda_readline: Not a terminal");
return NULL;
}

if (termsetup())
return NULL;

rline = coda_getline(prompt);

termrestore();

if (rline) {
char *new_mem = malloc(str_len - prmt_len + 1);
memcpy(new_mem, rline + prmt_len, str_len - prmt_len);
new_mem[str_len - prmt_len] = 0;
rline = new_mem;
}
return rline;
}

void coda_add_history(char *str)
{
if (str == NULL || str[0] == '\0')
return;

add_node(str);
}

void coda_history_size(int hist_size)
{
if (hist_size < 0 || hist_size > MAX_HIST_SIZE)
return;

if (history.cur_size > hist_size)
del_nodes(history.cur_size - hist_size);
history.max_size = hist_size;
}
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