linenoise.cpp

/* linenoise.c -- guerrilla line editing library against the idea that a
 * line editing lib needs to be 20,000 lines of C code.
 *
 * You can find the latest source code at:
 * 
 *   http://github.com/antirez/linenoise
 *
 * Does a number of crazy assumptions that happen to be true in 99.9999% of
 * the 2010 UNIX computers around.
 *
 * ------------------------------------------------------------------------
 *
 * Copyright (c) 2010, Salvatore Sanfilippo <antirez at gmail dot com>
 * Copyright (c) 2010, Pieter Noordhuis <pcnoordhuis at gmail dot com>
 *
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 *  *  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *  *  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * ------------------------------------------------------------------------
 *
 * References:
 * - http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
 * - http://www.3waylabs.com/nw/WWW/products/wizcon/vt220.html
 *
 * Todo list:
 * - Switch to gets() if $TERM is something we can't support.
 * - Filter bogus Ctrl+<char> combinations.
 * - Win32 support
 *
 * Bloat:
 * - Completion?
 * - History search like Ctrl+r in readline?
 *
 * List of escape sequences used by this program, we do everything just
 * with three sequences. In order to be so cheap we may have some
 * flickering effect with some slow terminal, but the lesser sequences
 * the more compatible.
 *
 * CHA (Cursor Horizontal Absolute)
 *    Sequence: ESC [ n G
 *    Effect: moves cursor to column n
 *
 * EL (Erase Line)
 *    Sequence: ESC [ n K
 *    Effect: if n is 0 or missing, clear from cursor to end of line
 *    Effect: if n is 1, clear from beginning of line to cursor
 *    Effect: if n is 2, clear entire line
 *
 * CUF (CUrsor Forward)
 *    Sequence: ESC [ n C
 *    Effect: moves cursor forward of n chars
 *
 * The following are used to clear the screen: ESC [ H ESC [ 2 J
 * This is actually composed of two sequences:
 *
 * cursorhome
 *    Sequence: ESC [ H
 *    Effect: moves the cursor to upper left corner
 *
 * ED2 (Clear entire screen)
 *    Sequence: ESC [ 2 J
 *    Effect: clear the whole screen
 * 
 */

#include <termios.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include "linenoise.h"

#define LINENOISE_DEFAULT_HISTORY_MAX_LEN 100
#define LINENOISE_MAX_LINE 4096
static const char *unsupported_term[] = {"dumb", "cons25", NULL};
static linenoiseCompletionCallback *completionCallback = NULL;

static struct termios orig_termios; /* in order to restore at exit */
static int rawmode = 0; /* for atexit() function to check if restore is needed*/
static int atexit_registered = 0; /* register atexit just 1 time */
static int history_max_len = LINENOISE_DEFAULT_HISTORY_MAX_LEN;
static int history_len = 0;
char **history = NULL;

static void linenoiseAtExit (void);
int linenoiseHistoryAdd (const char *line);

static int isUnsupportedTerm (void) {
    char *term = getenv("TERM");
    int j;

    if (term == NULL) return 0;
    for (j = 0; unsupported_term[j]; j++)
        if (!strcasecmp(term, unsupported_term[j])) return 1;
    return 0;
}

static void freeHistory (void) {
    if (history) {
        int j;

        for (j = 0; j < history_len; j++)
            free(history[j]);
        free(history);
    }
}

static int enableRawMode (int fd) {
    struct termios raw;

    if (!isatty(STDIN_FILENO)) goto fatal;
    if (!atexit_registered) {
        atexit(linenoiseAtExit);
        atexit_registered = 1;
    }
    if (tcgetattr(fd, &orig_termios) == -1) goto fatal;

    raw = orig_termios; /* modify the original mode */
    /* input modes: no break, no CR to NL, no parity check, no strip char,
     * no start/stop output control. */
    raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
    /* output modes - disable post processing */
    raw.c_oflag &= ~(OPOST);
    /* control modes - set 8 bit chars */
    raw.c_cflag |= (CS8);
    /* local modes - choing off, canonical off, no extended functions,
     * no signal chars (^Z,^C) */
    raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
    /* control chars - set return condition: min number of bytes and timer.
     * We want read to return every single byte, without timeout. */
    raw.c_cc[VMIN] = 1;
    raw.c_cc[VTIME] = 0; /* 1 byte, no timer */

    /* put terminal in raw mode after flushing */
    if (tcsetattr(fd, TCSAFLUSH, &raw) < 0) goto fatal;
    rawmode = 1;
    return 0;

fatal:
    errno = ENOTTY;
    return -1;
}

static void disableRawMode (int fd) {
    /* Don't even check the return value as it's too late. */
    if (rawmode && tcsetattr(fd, TCSAFLUSH, &orig_termios) != -1)
        rawmode = 0;
}

/* At exit we'll try to fix the terminal to the initial conditions. */
static void linenoiseAtExit (void) {
    disableRawMode(STDIN_FILENO);
    freeHistory();
}

static int getColumns (void) {
    struct winsize ws;

    if (ioctl(1, TIOCGWINSZ, &ws) == -1) return 80;
    return ws.ws_col;
}

static void refreshLine (int fd, const char *prompt, char *buf, size_t len, size_t pos, size_t cols) {
    char seq[64];
    size_t plen = strlen(prompt);

    while ((plen + pos) >= cols) {
        buf++;
        len--;
        pos--;
    }
    while (plen + len > cols) {
        len--;
    }

    /* Cursor to left edge */
    snprintf(seq, 64, "\x1b[0G");
    if (write(fd, seq, strlen(seq)) == -1) return;
    /* Write the prompt and the current buffer content */
    if (write(fd, prompt, strlen(prompt)) == -1) return;
    if (write(fd, buf, len) == -1) return;
    /* Erase to right */
    snprintf(seq, 64, "\x1b[0K");
    if (write(fd, seq, strlen(seq)) == -1) return;
    /* Move cursor to original position. */
    snprintf(seq, 64, "\x1b[0G\x1b[%dC", (int) (pos + plen));
    if (write(fd, seq, strlen(seq)) == -1) return;
}

static void beep () {
    fprintf(stderr, "\x7");
    fflush(stderr);
}

static void freeCompletions (linenoiseCompletions *lc) {
    size_t i;
    for (i = 0; i < lc->len; i++)
        free(lc->cvec[i]);
    if (lc->cvec != NULL)
        free(lc->cvec);
}

static int completeLine (int fd, const char *prompt, char *buf, size_t buflen, size_t *len, size_t *pos, size_t cols) {
    linenoiseCompletions lc = {0, NULL};
    int nread, nwritten;
    char c = 0;

    completionCallback(buf, &lc);
    if (lc.len == 0) {
        beep();
    }
    else {
        size_t stop = 0, i = 0;
        size_t clen;

        while (!stop) {
            /* Show completion or original buffer */
            if (i < lc.len) {
                clen = strlen(lc.cvec[i]);
                refreshLine(fd, prompt, lc.cvec[i], clen, clen, cols);
            }
            else {
                refreshLine(fd, prompt, buf, *len, *pos, cols);
            }

            nread = read(fd, &c, 1);
            if (nread <= 0) {
                freeCompletions(&lc);
                return -1;
            }

            switch (c) {
                case 9: /* tab */
                    i = (i + 1) % (lc.len + 1);
                    if (i == lc.len) beep();
                    break;
                case 27: /* escape */
                    /* Re-show original buffer */
                    if (i < lc.len) {
                        refreshLine(fd, prompt, buf, *len, *pos, cols);
                    }
                    stop = 1;
                    break;
                default:
                    /* Update buffer and return */
                    if (i < lc.len) {
                        nwritten = snprintf(buf, buflen, "%s", lc.cvec[i]);
                        *len = *pos = nwritten;
                    }
                    stop = 1;
                    break;
            }
        }
    }

    freeCompletions(&lc);
    return c; /* Return last read character */
}

void linenoiseClearScreen (void) {
    if (write(STDIN_FILENO, "\x1b[H\x1b[2J", 7) <= 0) {
        /* nothing to do, just to avoid warning. */
    }
}

static int linenoisePrompt (int fd, char *buf, size_t buflen, const char *prompt) {
    size_t plen = strlen(prompt);
    size_t pos = 0;
    size_t len = 0;
    size_t cols = getColumns();
    int history_index = 0;

    buf[0] = '\0';
    buflen--; /* Make sure there is always space for the nulterm */

    /* The latest history entry is always our current buffer, that
     * initially is just an empty string. */
    linenoiseHistoryAdd("");

    if (write(fd, prompt, plen) == -1) return -1;
    while (1) {
        char c;
        int nread;
        char seq[2], seq2[2];

        nread = read(fd, &c, 1);
        if (nread <= 0) return len;

        /* Only autocomplete when the callback is set. It returns < 0 when
         * there was an error reading from fd. Otherwise it will return the
         * character that should be handled next. */
        if (c == 9 && completionCallback != NULL) {
            c = completeLine(fd, prompt, buf, buflen, &len, &pos, cols);
            /* Return on errors */
            if (c < 0) return len;
            /* Read next character when 0 */
            if (c == 0) continue;
        }

        switch (c) {
            case 13: /* enter */
                history_len--;
                free(history[history_len]);
                return (int) len;
            case 3: /* ctrl-c */
                errno = EAGAIN;
                return -1;
            case 127: /* backspace */
            case 8: /* ctrl-h */
                if (pos > 0 && len > 0) {
                    memmove(buf + pos - 1, buf + pos, len - pos);
                    pos--;
                    len--;
                    buf[len] = '\0';
                    refreshLine(fd, prompt, buf, len, pos, cols);
                }
                break;
            case 4: /* ctrl-d, remove char at right of cursor */
                if (len > 1 && pos < (len - 1)) {
                    memmove(buf + pos, buf + pos + 1, len - pos);
                    len--;
                    buf[len] = '\0';
                    refreshLine(fd, prompt, buf, len, pos, cols);
                }
                else if (len == 0) {
                    history_len--;
                    free(history[history_len]);
                    errno = EPIPE;
                    return -1;
                }
                break;
            case 20: /* ctrl-t */
                if (pos > 0 && pos < len) {
                    int aux = buf[pos - 1];
                    buf[pos - 1] = buf[pos];
                    buf[pos] = aux;
                    if (pos != len - 1) pos++;
                    refreshLine(fd, prompt, buf, len, pos, cols);
                }
                break;
            case 2: /* ctrl-b */
                goto left_arrow;
            case 6: /* ctrl-f */
                goto right_arrow;
            case 16: /* ctrl-p */
                seq[1] = 65;
                goto up_down_arrow;
            case 14: /* ctrl-n */
                seq[1] = 66;
                goto up_down_arrow;
                break;
            case 27: /* escape sequence */
                if (read(fd, seq, 2) == -1) break;
                if (seq[0] == 91 && seq[1] == 68) {
left_arrow:
                    /* left arrow */
                    if (pos > 0) {
                        pos--;
                        refreshLine(fd, prompt, buf, len, pos, cols);
                    }
                }
                else if (seq[0] == 91 && seq[1] == 67) {
right_arrow:
                    /* right arrow */
                    if (pos != len) {
                        pos++;
                        refreshLine(fd, prompt, buf, len, pos, cols);
                    }
                }
                else if (seq[0] == 91 && (seq[1] == 65 || seq[1] == 66)) {
up_down_arrow:
                    /* up and down arrow: history */
                    if (history_len > 1) {
                        /* Update the current history entry before to
                         * overwrite it with tne next one. */
                        free(history[history_len - 1 - history_index]);
                        history[history_len - 1 - history_index] = strdup(buf);
                        /* Show the new entry */
                        history_index += (seq[1] == 65) ? 1 : -1;
                        if (history_index < 0) {
                            history_index = 0;
                            break;
                        }
                        else if (history_index >= history_len) {
                            history_index = history_len - 1;
                            break;
                        }
                        strncpy(buf, history[history_len - 1 - history_index], buflen);
                        buf[buflen] = '\0';
                        len = pos = strlen(buf);
                        refreshLine(fd, prompt, buf, len, pos, cols);
                    }
                }
                else if (seq[0] == 91 && seq[1] > 48 && seq[1] < 55) {
                    /* extended escape */
                    if (read(fd, seq2, 2) == -1) break;
                    if (seq[1] == 51 && seq2[0] == 126) {
                        /* delete */
                        if (len > 0 && pos < len) {
                            memmove(buf + pos, buf + pos + 1, len - pos - 1);
                            len--;
                            buf[len] = '\0';
                            refreshLine(fd, prompt, buf, len, pos, cols);
                        }
                    }
                }
                break;
            default:
                if (len < buflen) {
                    if (len == pos) {
                        buf[pos] = c;
                        pos++;
                        len++;
                        buf[len] = '\0';
                        if (plen + len < cols) {
                            /* Avoid a full update of the line in the
                             * trivial case. */
                            if (write(fd, &c, 1) == -1) return -1;
                        }
                        else {
                            refreshLine(fd, prompt, buf, len, pos, cols);
                        }
                    }
                    else {
                        memmove(buf + pos + 1, buf + pos, len - pos);
                        buf[pos] = c;
                        len++;
                        pos++;
                        buf[len] = '\0';
                        refreshLine(fd, prompt, buf, len, pos, cols);
                    }
                }
                break;
            case 21: /* Ctrl+u, delete the whole line. */
                buf[0] = '\0';
                pos = len = 0;
                refreshLine(fd, prompt, buf, len, pos, cols);
                break;
            case 11: /* Ctrl+k, delete from current to end of line. */
                buf[pos] = '\0';
                len = pos;
                refreshLine(fd, prompt, buf, len, pos, cols);
                break;
            case 1: /* Ctrl+a, go to the start of the line */
                pos = 0;
                refreshLine(fd, prompt, buf, len, pos, cols);
                break;
            case 5: /* ctrl+e, go to the end of the line */
                pos = len;
                refreshLine(fd, prompt, buf, len, pos, cols);
                break;
            case 12: /* ctrl+l, clear screen */
                linenoiseClearScreen();
                refreshLine(fd, prompt, buf, len, pos, cols);
        }
    }
    return len;
}

static int linenoiseRaw (char *buf, size_t buflen, const char *prompt) {
    int fd = STDIN_FILENO;
    int count;

    if (buflen == 0) {
        errno = EINVAL;
        return -1;
    }
    if (!isatty(STDIN_FILENO)) {
        if (fgets(buf, buflen, stdin) == NULL) return -1;
        count = strlen(buf);
        if (count && buf[count - 1] == '\n') {
            count--;
            buf[count] = '\0';
        }
    }
    else {
        if (enableRawMode(fd) == -1) return -1;
        count = linenoisePrompt(fd, buf, buflen, prompt);
        disableRawMode(fd);
        printf("\n");
    }
    return count;
}

char *linenoise (const char *prompt) {
    char buf[LINENOISE_MAX_LINE];
    int count;

    if (isUnsupportedTerm()) {
        size_t len;

        printf("xxx %s", prompt);
        fflush(stdout);
        if (fgets(buf, LINENOISE_MAX_LINE, stdin) == NULL) return NULL;
        len = strlen(buf);
        while (len && (buf[len - 1] == '\n' || buf[len - 1] == '\r')) {
            len--;
            buf[len] = '\0';
        }
        return strdup(buf);
    }
    else {
        count = linenoiseRaw(buf, LINENOISE_MAX_LINE, prompt);
        if (count == -1) return NULL;
        return strdup(buf);
    }
}

/* Register a callback function to be called for tab-completion. */
void linenoiseSetCompletionCallback (linenoiseCompletionCallback *fn) {
    completionCallback = fn;
}

void linenoiseAddCompletion (linenoiseCompletions *lc, char *str) {
    size_t len = strlen(str);
    char *copy = (char *) malloc(len + 1);
    memcpy(copy, str, len + 1);
    lc->cvec = (char **) realloc(lc->cvec, sizeof (char*) *(lc->len + 1));
    lc->cvec[lc->len++] = copy;
}

/* Using a circular buffer is smarter, but a bit more complex to handle. */
int linenoiseHistoryAdd (const char *line) {
    char *linecopy;

    if (history_max_len == 0) return 0;
    if (history == NULL) {
        history = (char **) malloc(sizeof (char*) *history_max_len);
        if (history == NULL) return 0;
        memset(history, 0, (sizeof (char*) *history_max_len));
    }
    linecopy = strdup(line);
    if (!linecopy) return 0;
    if (history_len == history_max_len) {
        free(history[0]);
        memmove(history, history + 1, sizeof (char*) *(history_max_len - 1));
        history_len--;
    }
    history[history_len] = linecopy;
    history_len++;
    return 1;
}

int linenoiseHistorySetMaxLen (int len) {
    char **_new;

    if (len < 1) return 0;
    if (history) {
        int tocopy = history_len;

        _new = (char **) malloc(sizeof (char*) *len);
        if (_new == NULL) return 0;
        if (len < tocopy) tocopy = len;
        memcpy(_new, history + (history_max_len - tocopy), sizeof (char*) *tocopy);
        free(history);
        history = _new;
    }
    history_max_len = len;
    if (history_len > history_max_len)
        history_len = history_max_len;
    return 1;
}

/* Save the history in the specified file. On success 0 is returned
 * otherwise -1 is returned. */
int linenoiseHistorySave (char *filename) {
    FILE *fp = fopen(filename, "w");
    int j;

    if (fp == NULL) return -1;
    for (j = 0; j < history_len; j++)
        fprintf(fp, "%s\n", history[j]);
    fclose(fp);
    return 0;
}

/* Load the history from the specified file. If the file does not exist
 * zero is returned and no operation is performed.
 *
 * If the file exists and the operation succeeded 0 is returned, otherwise
 * on error -1 is returned. */
int linenoiseHistoryLoad (char *filename) {
    FILE *fp = fopen(filename, "r");
    char buf[LINENOISE_MAX_LINE];

    if (fp == NULL) return -1;

    while (fgets(buf, LINENOISE_MAX_LINE, fp) != NULL) {
        char *p;

        p = strchr(buf, '\r');
        if (!p) p = strchr(buf, '\n');
        if (p) *p = '\0';
        linenoiseHistoryAdd(buf);
    }
    fclose(fp);
    return 0;
}