linenoise.c

/* 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) 2010-2016, Salvatore Sanfilippo <antirez at gmail dot com>
 * Copyright (c) 2010-2013, 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.
 *
 * ------------------------------------------------------------------------
 */

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <conio.h>

#include "linenoise.h"

#define LINENOISE_HISTORY_MAX_LEN 20
#define LINENOISE_MAX_LINE 256

static char buf[LINENOISE_MAX_LINE];

static linenoiseCompletionCallback *completionCallback = NULL;

static int history_len = 0;
static char **history = NULL;

/* The linenoiseState structure represents the state during line editing.
 * We pass this state to functions implementing specific editing
 * functionalities. */
struct linenoiseState {
    char *buf;          /* Edited line buffer. */
    size_t buflen;      /* Edited line buffer size. */
    const char *prompt; /* Prompt to display. */
    size_t plen;        /* Prompt length. */
    size_t pos;         /* Current cursor position. */
    size_t oldpos;      /* Previous refresh cursor position. */
    size_t len;         /* Current edited line length. */
    size_t cols;        /* Number of columns in terminal. */
    int history_index;  /* The history index we are currently editing. */
};

enum KEY_ACTION {
    CTRL_A = 1,         /* Ctrl+a */
    CTRL_B = 2,         /* Ctrl-b */
    CTRL_C = 3,         /* Ctrl-c */
    CTRL_D = 4,         /* Ctrl-d */
    CTRL_E = 5,         /* Ctrl-e */
    CTRL_F = 6,         /* Ctrl-f */
    CTRL_N = 14,        /* Ctrl-n */
    CTRL_P = 16         /* Ctrl-p */
};

static void refreshLine(struct linenoiseState *l);

/* ======================= Low level terminal handling ====================== */

/* Try to get the number of columns in the current terminal, or assume 80
 * if it fails. */
static int getColumns() {
    unsigned char cols, rows;

    screensize(&cols,&rows);
    return cols;
}

/* Beep, used for completion when there is nothing to complete or when all
 * the choices were already shown. */
static void linenoiseBeep(void) {
    unsigned char x = wherex();
    putchar('\a');
    gotox(x);
}

/* ============================== Completion ================================ */

/* Free a list of completion option populated by linenoiseAddCompletion(). */
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);
}

/* This is an helper function for linenoiseEdit() and is called when the
 * user types the <tab> key in order to complete the string currently in the
 * input.
 *
 * The state of the editing is encapsulated into the pointed linenoiseState
 * structure as described in the structure definition. */
static int completeLine(register struct linenoiseState *ls) {
    linenoiseCompletions lc = { 0, NULL };
    int nwritten;
    char c = 0;

    completionCallback(ls->buf,&lc);
    if (lc.len == 0) {
        linenoiseBeep();
    } else {
        size_t stop = 0, i = 0;

        while(!stop) {
            /* Show completion or original buffer */
            if (i < lc.len) {
                struct linenoiseState saved;
                saved = *ls;

                ls->len = ls->pos = strlen(lc.cvec[i]);
                ls->buf = lc.cvec[i];
                refreshLine(ls);
                ls->len = saved.len;
                ls->pos = saved.pos;
                ls->buf = saved.buf;
            } else {
                refreshLine(ls);
            }

            c = cgetc();
            switch(c) {
                case '\t': /* tab */
                    i = (i+1) % (lc.len+1);
                    if (i == lc.len) linenoiseBeep();
                    break;
                case CTRL_C:
                    /* Re-show original buffer */
                    if (i < lc.len) refreshLine(ls);
                    stop = 1;
                    break;
                default:
                    /* Update buffer and return */
                    if (i < lc.len) {
                        nwritten = snprintf(ls->buf,ls->buflen,"%s",lc.cvec[i]);
                        ls->len = ls->pos = nwritten;
                    }
                    stop = 1;
                    break;
            }
        }
    }

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

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

/* This function is used by the callback function registered by the user
 * in order to add completion options given the input string when the
 * user typed <tab>. See the example.c source code for a very easy to
 * understand example. */
void linenoiseAddCompletion(linenoiseCompletions *lc, const char *str) {
    size_t len = strlen(str);
    char *copy, **cvec;

    copy = malloc(len+1);
    if (copy == NULL) return;
    memcpy(copy,str,len+1);
    cvec = realloc(lc->cvec,sizeof(char*)*(lc->len+1));
    if (cvec == NULL) {
        free(copy);
        return;
    }
    lc->cvec = cvec;
    lc->cvec[lc->len++] = copy;
}

/* =========================== Line editing ================================= */

/* Low level line refresh.
 *
 * Rewrite the currently edited line accordingly to the buffer content,
 * cursor position, and number of columns of the terminal. */
static void refreshLine(struct linenoiseState *l) {
    char tmp;
    unsigned char y = wherey();
    size_t plen = strlen(l->prompt);
    char *buf = l->buf;
    size_t len = l->len;
    size_t pos = l->pos;

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

    /* Cursor to left edge */
    gotox(0);
    /* Write the prompt */
    cputs(l->prompt);
    /* Write the current buffer content */
    tmp = buf[len];
    buf[len] = '\0';
    cputs(buf);
    buf[len] = tmp;
    /* Erase to right */
    if (wherex()) {
        cclear(l->cols-wherex());
    }
    /* Move cursor to original position. */
    gotoxy((unsigned char)(pos+plen),y);
}

/* Insert the character 'c' at cursor current position. */
void linenoiseEditInsert(register struct linenoiseState *l, char c) {
    if (l->len < l->buflen) {
        if (l->len == l->pos) {
            l->buf[l->pos] = c;
            l->pos++;
            l->len++;
            l->buf[l->len] = '\0';
            if ((l->plen+l->len < l->cols)) {
                /* Avoid a full update of the line in the
                 * trivial case. */
                cputc(c);
            } else {
                refreshLine(l);
            }
        } else {
            memmove(l->buf+l->pos+1,l->buf+l->pos,l->len-l->pos);
            l->buf[l->pos] = c;
            l->len++;
            l->pos++;
            l->buf[l->len] = '\0';
            refreshLine(l);
        }
    }
}

/* Move cursor on the left. */
void linenoiseEditMoveLeft(struct linenoiseState *l) {
    if (l->pos > 0) {
        l->pos--;
        refreshLine(l);
    }
}

/* Move cursor on the right. */
void linenoiseEditMoveRight(struct linenoiseState *l) {
    if (l->pos != l->len) {
        l->pos++;
        refreshLine(l);
    }
}

/* Move cursor to the start of the line. */
void linenoiseEditMoveHome(struct linenoiseState *l) {
    if (l->pos != 0) {
        l->pos = 0;
        refreshLine(l);
    }
}

/* Move cursor to the end of the line. */
void linenoiseEditMoveEnd(struct linenoiseState *l) {
    if (l->pos != l->len) {
        l->pos = l->len;
        refreshLine(l);
    }
}

/* Substitute the currently edited line with the next or previous history
 * entry as specified by 'dir'. */
#define LINENOISE_HISTORY_NEXT 0
#define LINENOISE_HISTORY_PREV 1
void linenoiseEditHistoryNext(register struct linenoiseState *l, int dir) {
    if (history_len > 1) {
        /* Update the current history entry before to
         * overwrite it with the next one. */
        free(history[history_len - 1 - l->history_index]);
        history[history_len - 1 - l->history_index] = strdup(l->buf);
        /* Show the new entry */
        l->history_index += (dir == LINENOISE_HISTORY_PREV) ? 1 : -1;
        if (l->history_index < 0) {
            l->history_index = 0;
            return;
        } else if (l->history_index >= history_len) {
            l->history_index = history_len-1;
            return;
        }
        strncpy(l->buf,history[history_len - 1 - l->history_index],l->buflen);
        l->buf[l->buflen-1] = '\0';
        l->len = l->pos = strlen(l->buf);
        refreshLine(l);
    }
}

/* Delete the character at the right of the cursor without altering the cursor
 * position. Basically this is what happens with the "Delete" keyboard key. */
void linenoiseEditDelete(register struct linenoiseState *l) {
    if (l->len > 0 && l->pos < l->len) {
        memmove(l->buf+l->pos,l->buf+l->pos+1,l->len-l->pos-1);
        l->len--;
        l->buf[l->len] = '\0';
        refreshLine(l);
    }
}

/* Backspace implementation. */
void linenoiseEditBackspace(register struct linenoiseState *l) {
    if (l->pos > 0 && l->len > 0) {
        memmove(l->buf+l->pos-1,l->buf+l->pos,l->len-l->pos);
        l->pos--;
        l->len--;
        l->buf[l->len] = '\0';
        refreshLine(l);
    }
}

/* This function is the core of the line editing capability of linenoise.
 *
 * The resulting string is put into 'buf' when the user type enter.
 *
 * The function returns the length of the current buffer. */
static int linenoiseEdit(const char *prompt)
{
    struct linenoiseState l;

    /* Populate the linenoise state that we pass to functions implementing
     * specific editing functionalities. */
    l.buf = buf;
    l.buflen = LINENOISE_MAX_LINE;
    l.prompt = prompt;
    l.plen = strlen(prompt);
    l.oldpos = l.pos = 0;
    l.len = 0;
    l.cols = getColumns();
    l.history_index = 0;

    /* Buffer starts empty. */
    l.buf[0] = '\0';
    l.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("");

    cputs(prompt);
    while(1) {
        char c;

        c = cgetc();

        /* Only autocomplete when the callback is set. It will return the
         * character that should be handled next. */
        if (c == '\t' && completionCallback != NULL) {
            c = completeLine(&l);
            /* Read next character when 0 */
            if (c == 0) continue;
        }

        switch(c) {
        case CH_ENTER:
            history_len--;
            free(history[history_len]);
            return (int)l.len;
        case CH_ESC:
            errno = EAGAIN;
            return -1;
        case CH_DEL: /* backspace */
            linenoiseEditBackspace(&l);
            break;
        case CTRL_D: /* ctrl-d, remove char at right of cursor. */
            if (l.len > 0) {
                linenoiseEditDelete(&l);
            }
            break;
        case CTRL_B: /* ctrl-b */
        case CH_CURS_LEFT:
            linenoiseEditMoveLeft(&l);
            break;
        case CTRL_F: /* ctrl-f */
        case CH_CURS_RIGHT:
            linenoiseEditMoveRight(&l);
            break;
        case CTRL_P: /* ctrl-p */
        case CH_CURS_UP:
            linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_PREV);
            break;
        case CTRL_N: /* ctrl-n */
        case CH_CURS_DOWN:
            linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_NEXT);
            break;
        case CTRL_A: /* Ctrl+a, go to the start of the line */
            linenoiseEditMoveHome(&l);
            break;
        case CTRL_E: /* ctrl+e, go to the end of the line */
            linenoiseEditMoveEnd(&l);
            break;
        default:
            if (isprint(c)) linenoiseEditInsert(&l,c);
            break;
        }
    }
    return l.len;
}

/* The high level function that is the main API of the linenoise library. */
char *linenoise(const char *prompt) {
    unsigned char oldcursor;
    int count;

    oldcursor = cursor(1);
    count = linenoiseEdit(prompt);
    cursor(oldcursor);

    if (count == -1) return NULL;
    return buf;
}

/* ================================ History ================================= */

/* Reseet the history. */
void linenoiseHistoryReset(void) {
    if (history) {
        int j;

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

        history_len = 0;
        history = NULL;
    }
}

/* This is the API call to add a new entry in the linenoise history.
 * It uses a fixed array of char pointers that are shifted (memmoved)
 * when the history max length is reached in order to remove the older
 * entry and make room for the new one, so it is not exactly suitable for huge
 * histories, but will work well for a few hundred of entries.
 *
 * Using a circular buffer is smarter, but a bit more complex to handle. */
int linenoiseHistoryAdd(const char *line) {
    char *linecopy;

    /* Initialization on first call. */
    if (history == NULL) {
        history = malloc(sizeof(char*)*LINENOISE_HISTORY_MAX_LEN);
        if (history == NULL) return 0;
        memset(history,0,(sizeof(char*)*LINENOISE_HISTORY_MAX_LEN));
    }

    /* Don't add duplicated lines. */
    if (history_len && !strcmp(history[history_len-1], line)) return 0;

    /* Add an heap allocated copy of the line in the history.
     * If we reached the max length, remove the older line. */
    linecopy = strdup(line);
    if (!linecopy) return 0;
    if (history_len == LINENOISE_HISTORY_MAX_LEN) {
        free(history[0]);
        memmove(history,history+1,sizeof(char*)*(LINENOISE_HISTORY_MAX_LEN-1));
        history_len--;
    }
    history[history_len] = linecopy;
    history_len++;
    return 1;
}

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

    fp = fopen(filename,"w");

    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(const char *filename) {
    FILE *fp = fopen(filename,"r");
 
    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;
}