readline/main.c

Integration with GNU readline instead of libedit.

Demonstrates how to use libecoli's completion API with GNU readline by implementing custom completion functions.

Example session:

> hello john 5
parse(match=yes, len=3)
 seq(match=yes, len=3)
  str(hello)(match=yes, len=1) "hello"
  or(name)(match=yes, len=1)
   str(john)(match=yes, len=1) "john"
  int(int)(match=yes, len=1) "5"
> good morning bob
parse(match=yes, len=3)
 cmd(match=yes, len=3)
  cmd(name)(match=yes, len=1) "bob"
> buy potatoes
parse(match=yes, len=2)
 cmd(match=yes, len=2)
> bye
parse(match=yes, len=1)
 seq(match=yes, len=1)
  str(bye)(match=yes, len=1) "bye"

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright 2016, Olivier MATZ <zer0@droids-corp.org>
 */

 
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
 
#include <readline/history.h>
#include <readline/readline.h>
 
#include <ecoli.h>
 
static struct ec_node *commands;
 
static char *my_completion_entry(const char *s, int state)
{
    static struct ec_comp *c;
    static struct ec_comp_item *item;
    enum ec_comp_type item_type;
    const char *item_str, *item_display;
 
    (void)s;
 
    /* Don't append a quote. Note: there are still some bugs when
     * completing a quoted token. */
    rl_completion_suppress_quote = 1;
    rl_completer_quote_characters = "\"'";
 
    if (state == 0) {
        char *line;
 
        ec_comp_free(c);
        line = strdup(rl_line_buffer);
        if (line == NULL)
            return NULL;
        line[rl_point] = '\0';
 
        c = ec_complete(commands, line);
        free(line);
        if (c == NULL)
            return NULL;
 
        free(item);
        item = ec_comp_iter_first(c, EC_COMP_FULL | EC_COMP_PARTIAL);
        if (item == NULL)
            return NULL;
    } else {
        item = ec_comp_iter_next(item, EC_COMP_FULL | EC_COMP_PARTIAL);
        if (item == NULL)
            return NULL;
    }
 
    item_str = ec_comp_item_get_str(item);
    if (ec_comp_count(c, EC_COMP_FULL | EC_COMP_PARTIAL) == 1) {
        /* don't add the trailing space for partial completions */
        if (state == 0) {
            item_type = ec_comp_item_get_type(item);
            if (item_type == EC_COMP_FULL)
                rl_completion_suppress_append = 0;
            else
                rl_completion_suppress_append = 1;
        }
 
        return strdup(item_str);
    } else if (rl_completion_type == '?') {
        /* on second try only show the display part */
        item_display = ec_comp_item_get_display(item);
        return strdup(item_display);
    }
 
    return strdup(item_str);
}
 
static char **my_attempted_completion(const char *text, int start, int end)
{
    (void)start;
    (void)end;
 
    /* remove default file completion */
    rl_attempted_completion_over = 1;
 
    return rl_completion_matches(text, my_completion_entry);
}
 
/* this function builds the help string */
static char *get_node_help(const struct ec_comp_item *item)
{
    const struct ec_comp_group *grp;
    const struct ec_pnode *pstate;
    const struct ec_node *node;
    char *help = NULL;
    const char *node_help = NULL;
    char *node_desc = NULL;
 
    grp = ec_comp_item_get_grp(item);
    for (pstate = ec_comp_group_get_pstate(grp); pstate != NULL;
         pstate = ec_pnode_get_parent(pstate)) {
        node = ec_pnode_get_node(pstate);
        if (node_help == NULL)
            node_help = ec_dict_get(ec_node_attrs(node), "help");
        if (node_desc == NULL)
            node_desc = ec_node_desc(node);
    }
 
    if (node_help == NULL)
        node_help = "-";
    if (node_desc == NULL)
        return NULL;
 
    if (asprintf(&help, "%-20s %s", node_desc, node_help) < 0)
        return NULL;
 
    free(node_desc);
 
    return help;
}
 
static int show_help(int ignore, int invoking_key)
{
    const struct ec_comp_group *grp, *prev_grp = NULL;
    struct ec_comp_item *item = NULL;
    struct ec_comp *c = NULL;
    struct ec_pnode *p = NULL;
    char *line = NULL;
    size_t count = 0;
    char **helps = NULL;
    int match = 0;
    int ret = 1;
    int cols;
 
    (void)ignore;
    (void)invoking_key;
 
    line = strdup(rl_line_buffer);
    if (line == NULL)
        goto fail;
 
    /* check if the current line matches */
    p = ec_parse(commands, line);
    if (ec_pnode_matches(p))
        match = 1;
    ec_pnode_free(p);
    p = NULL;
 
    /* complete at current cursor position */
    line[rl_point] = '\0';
    c = ec_complete(commands, line);
    free(line);
    line = NULL;
    if (c == NULL)
        goto fail;
 
    /* strangely, rl_display_match_list() expects first index at 1 */
    helps = calloc(match + 1, sizeof(char *));
    if (helps == NULL)
        goto fail;
    if (match)
        helps[1] = "<return>";
 
    /* let's display one contextual help per node */
    EC_COMP_FOREACH (item, c, EC_COMP_UNKNOWN | EC_COMP_FULL | EC_COMP_PARTIAL) {
        char **tmp;
 
        /* keep one help per group, skip other items  */
        grp = ec_comp_item_get_grp(item);
        if (grp == prev_grp)
            continue;
 
        prev_grp = grp;
 
        tmp = realloc(helps, (count + match + 2) * sizeof(char *));
        if (tmp == NULL)
            goto fail;
        helps = tmp;
        helps[count + match + 1] = get_node_help(item);
        count++;
    }
 
    /* ensure not more than 1 entry per line */
    rl_get_screen_size(NULL, &cols);
    rl_display_match_list(helps, count + match, cols);
    rl_forced_update_display();
 
    ret = 0;
 
fail:
    free(item);
    ec_pnode_free(p);
    free(line);
    ec_comp_free(c);
    if (helps != NULL) {
        while (count--)
            free(helps[count + match + 1]);
    }
    free(helps);
 
    return ret;
}
 
static int create_commands(void)
{
    struct ec_node *cmdlist = NULL, *cmd = NULL;
 
    cmdlist = ec_node("or", EC_NO_ID);
    if (cmdlist == NULL)
        goto fail;
 
    cmd = EC_NODE_SEQ(
        EC_NO_ID,
        ec_node_str(EC_NO_ID, "hello"),
        EC_NODE_OR(
            "name",
            ec_node_str("john", "john"),
            ec_node_str(EC_NO_ID, "johnny"),
            ec_node_str(EC_NO_ID, "mike")
        ),
        ec_node_option(EC_NO_ID, ec_node_int("int", 0, 10, 10))
    );
    if (cmd == NULL)
        goto fail;
    ec_dict_set(ec_node_attrs(cmd), "help", "say hello to someone several times", NULL);
    ec_dict_set(
        ec_node_attrs(ec_node_find(cmd, "john")), "help", "specific help for john", NULL
    );
    ec_dict_set(
        ec_node_attrs(ec_node_find(cmd, "name")), "help", "the name of the person", NULL
    );
    ec_dict_set(ec_node_attrs(ec_node_find(cmd, "int")), "help", "an integer (0-10)", NULL);
    if (ec_node_or_add(cmdlist, cmd) < 0)
        goto fail;
 
    cmd = EC_NODE_CMD(
        EC_NO_ID,
        "good morning name [count]",
        EC_NODE_CMD("name", "bob|bobby|michael"),
        ec_node_int("count", 0, 10, 10)
    );
    if (cmd == NULL)
        goto fail;
    ec_dict_set(ec_node_attrs(cmd), "help", "say good morning to someone several times", NULL);
    ec_dict_set(ec_node_attrs(ec_node_find(cmd, "name")), "help", "the person to greet", NULL);
    ec_dict_set(
        ec_node_attrs(ec_node_find(cmd, "count")),
        "help",
        "how many times to greet (0-10)",
        NULL
    );
    if (ec_node_or_add(cmdlist, cmd) < 0)
        goto fail;
 
    cmd = EC_NODE_CMD(EC_NO_ID, "buy potatoes,carrots,pumpkins");
    if (cmd == NULL)
        goto fail;
    ec_dict_set(ec_node_attrs(cmd), "help", "buy some vegetables", NULL);
    if (ec_node_or_add(cmdlist, cmd) < 0)
        goto fail;
 
    cmd = EC_NODE_CMD(
        EC_NO_ID,
        "eat vegetables",
        ec_node_many(
            "vegetables",
            EC_NODE_OR(
                EC_NO_ID,
                ec_node_str(EC_NO_ID, "potatoes"),
                ec_node_once(EC_NO_ID, ec_node_str(EC_NO_ID, "carrots")),
                ec_node_once(EC_NO_ID, ec_node_str(EC_NO_ID, "pumpkins"))
            ),
            1,
            0
        )
    );
    if (cmd == NULL)
        goto fail;
    ec_dict_set(ec_node_attrs(cmd), "help", "eat vegetables (take some more potatoes)", NULL);
    if (ec_node_or_add(cmdlist, cmd) < 0)
        goto fail;
 
    cmd = EC_NODE_SEQ(EC_NO_ID, ec_node_str(EC_NO_ID, "bye"));
    ec_dict_set(ec_node_attrs(cmd), "help", "say bye", NULL);
    if (ec_node_or_add(cmdlist, cmd) < 0)
        goto fail;
 
    cmd = EC_NODE_SEQ(EC_NO_ID, ec_node_str(EC_NO_ID, "load"), ec_node("file", EC_NO_ID));
    ec_dict_set(ec_node_attrs(cmd), "help", "load a file", NULL);
    if (ec_node_or_add(cmdlist, cmd) < 0)
        goto fail;
 
    commands = ec_node_sh_lex(EC_NO_ID, cmdlist);
    if (commands == NULL)
        goto fail;
 
    return 0;
 
fail:
    fprintf(stderr, "cannot initialize nodes\n");
    ec_node_free(cmdlist);
    return -1;
}
 
int main(void)
{
    struct ec_pnode *p;
    char *line;
 
    if (ec_init() < 0) {
        fprintf(stderr, "cannot init ecoli: %s\n", strerror(errno));
        return 1;
    }
 
    if (create_commands() < 0)
        return 1;
 
    rl_bind_key('?', show_help);
    rl_attempted_completion_function = my_attempted_completion;
 
    while (1) {
        line = readline("> ");
        if (line == NULL)
            break;
 
        p = ec_parse(commands, line);
        ec_pnode_dump(stdout, p);
        add_history(line);
        ec_pnode_free(p);
    }
 
    ec_node_free(commands);
    return 0;
}