extension-editline/main.c

Define custom node types with specialized parsing and completion.

Demonstrates creating a custom grammar node type (bool_tuple) with its own parsing and completion logic. The bool_tuple node parses and completes tuples of booleans like "(true,false,true)" and converts them to an integer where each boolean becomes a bit (e.g. "(true,false,true)" = 101 binary = 5).

The custom node (node_bool_tuple.c) implements:

• Parsing: validates input matches the exact grammar (bool,bool,...)
• Completion: provides context-aware suggestions at each parsing state (opening paren, true/false keywords, comma, closing paren)

The main program registers two commands:

• "convert <bool_tuple>" - parses the tuple and prints its integer value
• "exit" - quits the program

Example session:

extension> convert (true,false,true)
Integer value for (true,false,true) is 5
extension> convert (false,true)
Integer value for (false,true) is 1
extension> exit
Exit !

See also node_bool_tuple.c for the node type implementation.

/* 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_BOOL_TUPLE "id_bool_tuple"
 
/* stop program when true */
static bool done;
 
static int convert_cb(const struct ec_pnode *parse)
{
    const char *bool_tuple;
    const char *next_false;
    const char *next_true;
    unsigned int val = 0;
    const char *t;
 
    bool_tuple = ec_strvec_val(ec_pnode_get_strvec(ec_pnode_find(parse, ID_BOOL_TUPLE)), 0);
    t = bool_tuple;
 
    /* convert bool tuple into an integer */
    while (1) {
        next_true = strstr(t, "true");
        next_false = strstr(t, "false");
 
        if (next_true && (next_false == NULL || next_false > next_true)) {
            val = (val << 1) | 1;
            t = next_true + 1;
        } else if (next_false && (next_true == NULL || next_true > next_false)) {
            val = val << 1;
            t = next_false + 1;
        } else {
            break;
        }
    }
    printf("Integer value for %s is %u\n", bool_tuple, val);
 
    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;
    int ret;
 
    /* the top node containing the list of commands */
    cmdlist = ec_node("or", EC_NO_ID);
    if (cmdlist == NULL)
        goto fail;
 
    /* the convert command */
    cmd = EC_NODE_SEQ(
        EC_NO_ID, ec_node_str(EC_NO_ID, "convert"), ec_node("bool_tuple", ID_BOOL_TUPLE)
    );
    if (cmd == NULL)
        goto fail;
    if (ec_interact_set_callback(cmd, convert_cb) < 0)
        goto fail;
    if (ec_interact_set_help(cmd, "Convert a tuple of boolean into its integer representation")
        < 0)
        goto fail;
    if (ec_interact_set_help(
            ec_node_find(cmd, ID_BOOL_TUPLE),
            "A tuple of booleans. Example: \"(true,false,true)\""
        )
        < 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;
 
    return cmdlist;
 
fail:
    fprintf(stderr, "cannot initialize nodes\n");
    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("extension-editline", stdin, stdout, stderr, 0);
    if (editline == NULL) {
        fprintf(stderr, "Failed to initialize editline\n");
        goto fail;
    }
 
    if (ec_editline_set_prompt(editline, "extension> ") < 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;
}