history.c

#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "elist.h"
#include "history.h"

struct elist *history;
int cur_index;
int num_commands;

void hist_init(unsigned int limit)
{
    history = elist_create(limit);
    elist_clear_mem(history);
    cur_index = -1;
    num_commands= 0;
}

void hist_destroy(void)
{
    for (int i = 0; i < elist_size(history); ++i) {
        char *cmd = (char *) elist_get(history, i);
        free(cmd);
    }
    elist_destroy(history);
    cur_index = -1;
    num_commands = 0;
}

void hist_add(const char *cmd)
{
    if (elist_size(history) < 100) {
        elist_add(history, (char *) cmd);
    } else {
        elist_set(history, (cur_index + 1) % 100, (char *) cmd);
    }
    cur_index = (cur_index + 1) % 100;
    ++num_commands;
}

void hist_print(void)
{
    for (int i = elist_size(history) - 1; i >= 0 ; --i) {
        char *temp = elist_get(history, (cur_index - i + 100) % 100);
        printf("%d %s\n",num_commands - i, temp);
    }
    fflush(stdout);
}

const char *hist_search_prefix(char *prefix)
{
    for (int i = 0; i < elist_size(history); ++i) {
        char *temp = elist_get(history, (cur_index - i + 100) % 100);
        if (!strncmp(prefix, temp, strlen(prefix))) {
            return temp;
        }
    }
    return NULL;
}

const char *hist_search_cnum(int command_number)
{
    if (num_commands - command_number > 99 || command_number > num_commands) {
        return NULL;
    } else {
        int index = (cur_index - (num_commands - command_number) + 100) % 100;
        return elist_get(history, index);
    }

    // TODO: Retrieves a particular command number. Return NULL if no match
    // found.
}

unsigned int hist_last_cnum(void)
{
    return num_commands;
}