[bertos.git] / bertos / mware / readline.c

/**
 * \file
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 * Copyright 2004 Develer S.r.l. (http://www.develer.com/)
 * Copyright 2004 Giovanni Bajo
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 *
 * \brief Line editing support with history
 *
 * Rationale for basic implementation choices:
 *
 * \li The history is implemented storing consecutive ASCIIZ strings within an array of memory. When
 * the history is full, the first (oldest) line is cancelled and the whole buffer is memmoved to
 * overwrite it and make room. while this is is obviously not the fastest algorithm (which would
 * require the use of a circular buffer) it is surely good enough for this module, which does not
 * aim at fast performances (line editing does not require to be blazingly fast).
 *
 * \li The first character in the history is always \c \\0, and it is used as a guard. By 'wasting' it
 * in this way, the code actually gets much simpler in that we remove many checks when moving
 * backward (\c i>0 and similar).
 *
 * \li While editing, the current index points to the position of the buffer which contains the
 * last character typed in (exactly like a stack pointer). This also allows to simplify calculations
 * and to make easier using the last byte of history.
 *
 * \li While editing, the current line is always kept null-terminated. This is important because
 * if the user press ENTER, we must have room to add a \c \\0 to terminate the line. If the line
 * is as long as the whole history buffer, there would not be space for it. By always keeping the
 * \c \\0 at the end, we properly ensure this without making index checks harder.
 *
 * \li When removing a line from the history (see \c pop_history()), instead of updating all the
 * indices we have around, we move backward the pointer to the history we use. This way, we don't
 * have to update anything. This means that we keep two pointers to the history: \c real_history
 * always points to the physical start, while \c history is the adjusted pointer (that is
 * dereference to read/write to it).
 *
 * \todo Use up/down to move through history  The history line will be copied to the current line,
 * making sure there is room for it.
 *
 * \version $Id$
 *
 * \author Giovanni Bajo <rasky@develer.com>
 */


#include "readline.h"

#include <cfg/compiler.h>
#include <cfg/debug.h>

#include <stdio.h>

/// Enable compilation of the unit test code
#define DEBUG_UNIT_TEST       0

/// Enable dump of the history after each line
#define DEBUG_DUMP_HISTORY    0


/** Special keys (escape sequences converted to a single code) */
enum RL_KEYS {
        SPECIAL_KEYS = 0x1000,

        /*
         * Three byte keys:
         * #################
         * UpArrow:     0x1B 0x5B 0X41
         * DownArrow:   0x1B 0x5B 0X42
         * RightArrow:  0x1B 0x5B 0x43
         * LeftArrow:   0x1b 0x5B 0x44
         * Beak(Pause): 0x1b 0x5B 0x50
        */
        KEY_UP_ARROW,
        KEY_DOWN_ARROW,
        KEY_LEFT_ARROW,
        KEY_RIGHT_ARROW,
        KEY_PAUSE,

        /*
         * Four byte keys:
         * ################
         * F1:          0x1b 0x5B 0x5B 0x41
         * F2:          0x1b 0x5B 0x5B 0x42
         * F3:          0x1b 0x5B 0x5B 0x43
         * F4:          0x1b 0x5B 0x5B 0x44
         * F5:          0x1b 0x5B 0x5B 0x45
         * Ins:         0x1b 0x5B 0x32 0x7E
         * Home:        0x1b 0x5B 0x31 0x7E
         * PgUp:        0x1b 0x5B 0x35 0x7E
         * Del:         0x1b 0x5B 0x33 0x7E
         * End:         0x1b 0x5B 0x34 0x7E
         * PgDn:        0x1b 0x5B 0x36 0x7E
         */
        KEY_F1, KEY_F2, KEY_F3, KEY_F4, KEY_F5,
        KEY_INS, KEY_HOME, KEY_PGUP, KEY_DEL, KEY_END, KEY_PGDN,

        /*
         * Five byte keys:
         * ################
         * F6:          0x1b 0x5B 0x31 0x37 0x7E
         * F7:          0x1b 0x5B 0x31 0x38 0x7E
         * F8:          0x1b 0x5B 0x31 0x39 0x7E
         * F9:          0x1b 0x5B 0x32 0x30 0x7E
         * F10:         0x1b 0x5B 0x32 0x31 0x7E
         * F11:         0x1b 0x5B 0x32 0x33 0x7E
         * F12:         0x1b 0x5B 0x32 0x34 0x7E
         */
        KEY_F6, KEY_F7, KEY_F8, KEY_F9,
        KEY_F10, KEY_F11, KEY_F12,
};

/** Check if \a c is a separator between words.
 *  \note Parameter \a c is evaluated multiple times
 */
#define IS_WORD_SEPARATOR(c) ((c) == ' ' || (c) == '\0')

/// Write the string \a txt to the IO output (without any kind of termination)
INLINE void rl_puts(const struct RLContext* ctx, const char* txt)
{
        if (!ctx->put)
                return;

        while (*txt)
                ctx->put(*txt++, ctx->put_param);
}

/// Write character \a ch to the IO output.
INLINE void rl_putc(const struct RLContext* ctx, char ch)
{
        if (ctx->put)
                ctx->put(ch, ctx->put_param);
}

/** Read a character from the IO into \a ch. This function also takes
 *  care of converting the ANSI escape sequences into one of the codes
 *  defined in \c RL_KEYS.
 */
static bool rl_getc(const struct RLContext* ctx, int* ch)
{
        int c = ctx->get(ctx->get_param);

        if (c == EOF)
        {
                if (ctx->clear)
                        ctx->clear(ctx->clear_param);

                return false;
        }

        if (c == 0x1B)
        {
                // Unknown ESC sequence. Ignore it and read
                //  return next character.
                if (ctx->get(ctx->get_param) != 0x5B)
                        return rl_getc(ctx, ch);

                /* To be added:
                        * Home:        0x1b 0x5B 0x31 0x7E
                        * F6:          0x1b 0x5B 0x31 0x37 0x7E
                        * F7:          0x1b 0x5B 0x31 0x38 0x7E
                        * F8:          0x1b 0x5B 0x31 0x39 0x7E
                        * Ins:         0x1b 0x5B 0x32 0x7E
                        * F9:          0x1b 0x5B 0x32 0x30 0x7E
                        * F10:         0x1b 0x5B 0x32 0x31 0x7E
                        * F11:         0x1b 0x5B 0x32 0x33 0x7E
                        * F12:         0x1b 0x5B 0x32 0x34 0x7E
                        * Del:         0x1b 0x5B 0x33 0x7E
                        * End:         0x1b 0x5B 0x34 0x7E
                        * PgUp:        0x1b 0x5B 0x35 0x7E
                        * PgDn:        0x1b 0x5B 0x36 0x7E
                */

                c = ctx->get(ctx->get_param);
                switch (c)
                {
                case 0x41: c = KEY_UP_ARROW; break;
                case 0x42: c = KEY_DOWN_ARROW; break;
                case 0x43: c = KEY_RIGHT_ARROW; break;
                case 0x44: c = KEY_LEFT_ARROW; break;
                case 0x50: c = KEY_PAUSE; break;
                case 0x5B:
                        c = ctx->get(ctx->get_param);
                        switch (c)
                        {
                        case 0x41: c = KEY_F1; break;
                        case 0x42: c = KEY_F2; break;
                        case 0x43: c = KEY_F3; break;
                        case 0x44: c = KEY_F4; break;
                        case 0x45: c = KEY_F5; break;
                        default: return rl_getc(ctx, ch);
                        }
                        break;
                default: return rl_getc(ctx, ch);
                }
        }

        *ch = c;
        return true;
}

INLINE void beep(struct RLContext* ctx)
{
        rl_putc(ctx, '\a');
}

static bool pop_history(struct RLContext* ctx, int total_len)
{
        // Compute the length of the first command (including terminator).
        int len = strlen(ctx->real_history+1)+1;

        // (the first byte of the history should always be 0)
        ASSERT(ctx->real_history[0] == '\0');

        // If it is the only one in the history, do nothing
        if (len == total_len)
                return false;

        // Overwrite the first command with the second one
        memmove(ctx->real_history, ctx->real_history+len, HISTORY_SIZE-len);

        // Move back the ctx->buffer pointer so that all the indices are still valid
        ctx->history -= len;

        return true;
}

/// Check if index \a i points to the begin of the history.
INLINE bool is_history_begin(struct RLContext* ctx, int i)
{ return ctx->history + i == ctx->real_history; }

/// Check if index \a i points to the (exclusive) end of history
INLINE bool is_history_end(struct RLContext* ctx, int i)
{ return ctx->history + i == ctx->real_history + HISTORY_SIZE; }

/// Check if index \a i points to the (exclusive) end of history, or somewhere past the end.
INLINE bool is_history_past_end(struct RLContext* ctx, int i)
{ return ctx->history + i >= ctx->real_history + HISTORY_SIZE; }

/** Insert \a num_chars characters from \a ch into the history buffer at the
 *  position indicated by \a curpos. If needed, remove old history to make room.
 *  Returns true if everything was successful, false if there was no room to
 *  add the characters.
 *  \note \a num_chars can be 0, in which case we just make sure the line is
 *  correctly zero-terminated (ASCIIZ format).
 */
static bool insert_chars(struct RLContext* ctx, size_t *curpos, const char* ch, int num_chars)
{
        ASSERT(!is_history_past_end(ctx, *curpos));

        while (is_history_past_end(ctx, *curpos+num_chars+1))
        {
                if (!pop_history(ctx, *curpos))
                        return false;
        }

        while (num_chars--)
                ctx->history[++(*curpos)] = *ch++;

        ASSERT(!is_history_past_end(ctx, *curpos + 1));
        ctx->history[*curpos+1] = '\0';
        return true;
}

/// Insert a single character \a ch into the buffer (with the same semantic of \c insert_chars())
static bool insert_char(struct RLContext* ctx, size_t *curpos, char ch)
{
        return insert_chars(ctx, curpos, &ch, 1);
}

#if DEBUG_DUMP_HISTORY
/// Dump the internal history of a context (used only for debug purposes)
static void dump_history(struct RLContext* ctx)
{
        int k;
        char buf[8];
        ASSERT(ctx->real_history[0] == '\0');
        rl_puts(ctx, "History dump:");
        rl_puts(ctx, "\r\n");
        for (k = 1;
             ctx->real_history + k != ctx->history + ctx->history_pos + 1;
             k += strlen(&ctx->real_history[k]) + 1)
        {
                rl_puts(ctx, &ctx->real_history[k]);
                rl_puts(ctx, "\r\n");
        }

        sprintf(buf, "%d\r\n", ctx->history_pos + (ctx->history - ctx->real_history));
        rl_puts(ctx, buf);
}
#endif /* DEBUG_DUMP_HISTORY */

/// Complete the current word. Return false if no unambiguous completion was found
static bool complete_word(struct RLContext *ctx, size_t *curpos)
{
        const char* completed_word;
        size_t wstart;

        // If the current character is a separator,
        //  there is nothing to complete
        wstart = *curpos;
        if (IS_WORD_SEPARATOR(ctx->history[wstart]))
        {
                beep(ctx);
                return false;
        }

        // Find the separator before the current word
        do
                --wstart;
        while (!IS_WORD_SEPARATOR(ctx->history[wstart]));

        // Complete the word through the hook
        completed_word = ctx->match(ctx->match_param, ctx->history + wstart + 1, *curpos - wstart);
        if (!completed_word)
                return false;

        // Move back the terminal cursor to the separator
        while (*curpos != wstart)
        {
                rl_putc(ctx, '\b');
                --*curpos;
        }

        // Insert the completed command
        insert_chars(ctx, curpos, completed_word, strlen(completed_word));
        rl_puts(ctx, completed_word);
        insert_char(ctx, curpos, ' ');
        rl_putc(ctx, ' ');

        return true;
}

void rl_refresh(struct RLContext* ctx)
{
        rl_puts(ctx, "\r\n");
        if (ctx->prompt)
                rl_puts(ctx, ctx->prompt);
        rl_puts(ctx, ctx->history + ctx->history_pos + 1);
}

const char* rl_readline(struct RLContext* ctx)
{
        size_t i = ctx->history_pos;

        if (ctx->prompt)
                rl_puts(ctx, ctx->prompt);

        insert_chars(ctx, &i, NULL, 0);

        while (1)
        {
                char ch;
                int c;

                ASSERT(ctx->history - ctx->real_history + ctx->line_pos < HISTORY_SIZE);

                if (!rl_getc(ctx, &c))
                        return NULL;

                // Just ignore special keys for now
                if (c > SPECIAL_KEYS)
                        continue;

                if (c == '\t')
                {
                        // Ask the match hook if available
                        if (!ctx->match)
                                return false;

                        complete_word(ctx, &ctx->line_pos);
                        continue;
                }

                if (c == '\r' || c == '\n')
                {
                        // Terminate line
                        insert_chars(ctx, &ctx->line_pos, NULL, 0);
                        rl_puts(ctx, "\r\n");
                        break;
                }

                // Backspace cancels a character, or it is ignored if at
                //  the start of the line
                if (c == '\b')
                {
                        if (ctx->history[ctx->line_pos] != '\0')
                        {
                                --ctx->line_pos;
                                rl_puts(ctx, "\b \b");
                        }
                        continue;
                }

                // Add a character to the buffer, if possible
                ch = (char)c;
                ASSERT2(ch == c, "a special key was not properly handled");
                if (insert_chars(ctx, &ctx->line_pos, &ch, 1))
                {
                        rl_putc(ctx, ch);
                }
                else
                {
                        beep(ctx);
                }
        }

        ctx->history_pos = ctx->line_pos + 1;
        while (ctx->history[ctx->line_pos] != '\0')
                --ctx->line_pos;

        // Do not store empty lines in the history
        if (ctx->line_pos == ctx->history_pos - 1)
                ctx->history_pos -= 1;

#if DEBUG_DUMP_HISTORY
        dump_history(ctx);
#endif

        // Since the current pointer now points to the separator, we need
        //  to return the first character
        return &ctx->history[ctx->line_pos + 1];
}


#if DEBUG_UNIT_TEST

/** Perform the unit test for the readline library */
void rl_test(void);

#if HISTORY_SIZE != 32
        #error This test needs HISTORY_SIZE to be set at 32
#endif

static struct RLContext test_ctx;

static char* test_getc_ptr;
static int test_getc(void* data)
{
        return *test_getc_ptr++;
}

/** Perform a readline test. The function pipes the characters from \a input_buffer
 *  through the I/O to \c rl_readline(). After the whole string is sent, \c do_test()
 *  checks if the current history within the context match \a expected_history.
 */
static bool do_test(char* input_buffer, char* expected_history)
{
        rl_init_ctx(&test_ctx);
        rl_sethook_get(&test_ctx, test_getc, NULL);

        test_getc_ptr = input_buffer;
        while (*test_getc_ptr)
                rl_readline(&test_ctx);

        if (memcmp(test_ctx.real_history, expected_history, HISTORY_SIZE) != 0)
        {
                ASSERT2(0, "history compare failed");
                return false;
        }

        return true;
}

void rl_test(void)
{
        char* test1_in = "a\nb\nc\nd\ne\nf\ng\nh\ni\nj\nk\nl\nm\nn\no\np\nq\nr\ns\nt\nu\nv\nw\nx\ny\nz\n";
        char test1_hist[HISTORY_SIZE] = "\0l\0m\0n\0o\0p\0q\0r\0s\0t\0u\0v\0w\0x\0y\0z";

        if (!do_test(test1_in, test1_hist))
                return;

        kprintf("rl_test successful\n");
}

#endif /* DEBUG_UNIT_TEST */