simple-editline/main.c

Basic interactive CLI with commands, help, and completion.

Demonstrates building a grammar using sequence, or, and option nodes, setting help text and callbacks on commands, and using the editline integration for interactive input with TAB completion.

Example session:

simple> hello john
you say hello to john
simple> hello mike 3
you say hello to mike 3 times
simple> bye johnny
you say bye to johnny
simple> exit
Exit !

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright 2025, Olivier MATZ <zer0@droids-corp.org>
 */

 
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <ecoli.h>
 
#define ID_NAME "id_name"
#define ID_JOHN "id_john"
#define ID_COUNT "id_count"
 
/* stop program when true */
static bool done;
 
static int hello_cb(const struct ec_pnode *parse)
{
    const char *count;
    const char *name;
 
    name = ec_strvec_val(ec_pnode_get_strvec(ec_pnode_find(parse, ID_NAME)), 0);
    count = ec_strvec_val(ec_pnode_get_strvec(ec_pnode_find(parse, ID_COUNT)), 0);
 
    printf("you say hello to %s", name);
    if (count)
        printf(" %s times", count);
    printf("\n");
 
    return 0;
}
 
static int bye_cb(const struct ec_pnode *parse)
{
    const char *name;
 
    name = ec_strvec_val(ec_pnode_get_strvec(ec_pnode_find(parse, ID_NAME)), 0);
    printf("you say bye to %s\n", name);
 
    return 0;
}
 
static int exit_cb(const struct ec_pnode *parse)
{
    (void)parse;
 
    printf("Exit !\n");
    done = true;
 
    return 0;
}
 
static int check_exit(void *opaque)
{
    (void)opaque;
    return done;
}
 
static struct ec_node *create_commands(void)
{
    struct ec_node *cmdlist = NULL, *cmd = NULL;
    struct ec_node *names = NULL;
    int ret;
 
    /* the top node containing the list of commands */
    cmdlist = ec_node("or", EC_NO_ID);
    if (cmdlist == NULL)
        goto fail;
 
    /* a common subtree containing a list of names */
    names = EC_NODE_OR(
        ID_NAME,
        ec_node_str(ID_JOHN, "john"),
        ec_node_str(EC_NO_ID, "johnny"),
        ec_node_str(EC_NO_ID, "mike")
    );
    if (names == NULL)
        goto fail;
 
    /* the hello command */
    cmd = EC_NODE_SEQ(
        EC_NO_ID,
        ec_node_str(EC_NO_ID, "hello"),
        ec_node_clone(names),
        ec_node_option(EC_NO_ID, ec_node_int(ID_COUNT, 0, 10, 10))
    );
    if (cmd == NULL)
        goto fail;
    if (ec_interact_set_callback(cmd, hello_cb) < 0)
        goto fail;
    if (ec_interact_set_help(cmd, "say hello to someone several times") < 0)
        goto fail;
    if (ec_interact_set_help(ec_node_find(cmd, ID_JOHN), "specific help for john") < 0)
        goto fail;
    if (ec_interact_set_help(ec_node_find(cmd, ID_NAME), "the name of the person") < 0)
        goto fail;
    if (ec_interact_set_help(ec_node_find(cmd, ID_COUNT), "an integer (0-10)") < 0)
        goto fail;
    ret = ec_node_or_add(cmdlist, cmd);
    cmd = NULL; /* already freed, even on error */
    if (ret < 0)
        goto fail;
 
    /* the bye command */
    cmd = EC_NODE_SEQ(EC_NO_ID, ec_node_str(EC_NO_ID, "bye"), ec_node_clone(names));
    if (ec_interact_set_callback(cmd, bye_cb) < 0)
        goto fail;
    if (ec_interact_set_help(cmd, "say bye") < 0)
        goto fail;
    ret = ec_node_or_add(cmdlist, cmd);
    cmd = NULL; /* already freed, even on error */
    if (ret < 0)
        goto fail;
 
    /* the exit command */
    cmd = ec_node_str(EC_NO_ID, "exit");
    if (ec_interact_set_callback(cmd, exit_cb) < 0)
        goto fail;
    if (ec_interact_set_help(cmd, "exit program") < 0)
        goto fail;
    ret = ec_node_or_add(cmdlist, cmd);
    cmd = NULL; /* already freed, even on error */
    if (ret < 0)
        goto fail;
 
    /* the lexer, added above the command list */
    cmdlist = ec_node_sh_lex(EC_NO_ID, cmdlist);
    if (cmdlist == NULL)
        goto fail;
 
    ec_node_free(names);
 
    return cmdlist;
 
fail:
    fprintf(stderr, "cannot initialize nodes\n");
    ec_node_free(names);
    ec_node_free(cmdlist);
    ec_node_free(cmd);
    return NULL;
}
 
int main(void)
{
    struct ec_editline *editline = NULL;
    struct ec_node *node = NULL;
 
    if (ec_init() < 0) {
        fprintf(stderr, "cannot init ecoli: %s\n", strerror(errno));
        return 1;
    }
 
    node = create_commands();
    if (node == NULL) {
        fprintf(stderr, "failed to create commands: %s\n", strerror(errno));
        goto fail;
    }
 
    editline = ec_editline("simple-editline", stdin, stdout, stderr, 0);
    if (editline == NULL) {
        fprintf(stderr, "Failed to initialize editline\n");
        goto fail;
    }
 
    if (ec_editline_set_prompt(editline, "simple> ") < 0) {
        fprintf(stderr, "Failed to set prompt\n");
        goto fail;
    }
    ec_editline_set_node(editline, node);
 
    if (ec_editline_interact(editline, check_exit, NULL) < 0)
        goto fail;
 
    ec_editline_free(editline);
    ec_node_free(node);
    return 0;
 
fail:
    ec_editline_free(editline);
    ec_node_free(node);
    return 1;
}