src/cmdexpand.c

/* vi:set ts=8 sts=4 sw=4 noet:
 *
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/*
 * cmdexpand.c: functions for command-line completion
 */

#include "vim.h"

static int	cmd_showtail;	// Only show path tail in lists ?

static void	set_expand_context(expand_T *xp);
static int	ExpandFromContext(expand_T *xp, char_u *, int *, char_u ***, int);
static int	expand_showtail(expand_T *xp);
static int	expand_shellcmd(char_u *filepat, int *num_file, char_u ***file, int flagsarg);
static int	ExpandRTDir(char_u *pat, int flags, int *num_file, char_u ***file, char *dirname[]);
static int	ExpandPackAddDir(char_u *pat, int *num_file, char_u ***file);
#if defined(FEAT_EVAL)
static int	ExpandUserDefined(expand_T *xp, regmatch_T *regmatch, int *num_file, char_u ***file);
static int	ExpandUserList(expand_T *xp, int *num_file, char_u ***file);
#endif

    static int
sort_func_compare(const void *s1, const void *s2)
{
    char_u *p1 = *(char_u **)s1;
    char_u *p2 = *(char_u **)s2;

    if (*p1 != '<' && *p2 == '<') return -1;
    if (*p1 == '<' && *p2 != '<') return 1;
    return STRCMP(p1, p2);
}

    static void
ExpandEscape(
    expand_T	*xp,
    char_u	*str,
    int		numfiles,
    char_u	**files,
    int		options)
{
    int		i;
    char_u	*p;

    // May change home directory back to "~"
    if (options & WILD_HOME_REPLACE)
	tilde_replace(str, numfiles, files);

    if (options & WILD_ESCAPE)
    {
	if (xp->xp_context == EXPAND_FILES
		|| xp->xp_context == EXPAND_FILES_IN_PATH
		|| xp->xp_context == EXPAND_SHELLCMD
		|| xp->xp_context == EXPAND_BUFFERS
		|| xp->xp_context == EXPAND_DIRECTORIES)
	{
	    // Insert a backslash into a file name before a space, \, %, #
	    // and wildmatch characters, except '~'.
	    for (i = 0; i < numfiles; ++i)
	    {
		// for ":set path=" we need to escape spaces twice
		if (xp->xp_backslash == XP_BS_THREE)
		{
		    p = vim_strsave_escaped(files[i], (char_u *)" ");
		    if (p != NULL)
		    {
			vim_free(files[i]);
			files[i] = p;
#if defined(BACKSLASH_IN_FILENAME)
			p = vim_strsave_escaped(files[i], (char_u *)" ");
			if (p != NULL)
			{
			    vim_free(files[i]);
			    files[i] = p;
			}
#endif
		    }
		}
#ifdef BACKSLASH_IN_FILENAME
		p = vim_strsave_fnameescape(files[i], FALSE);
#else
		p = vim_strsave_fnameescape(files[i], xp->xp_shell);
#endif
		if (p != NULL)
		{
		    vim_free(files[i]);
		    files[i] = p;
		}

		// If 'str' starts with "\~", replace "~" at start of
		// files[i] with "\~".
		if (str[0] == '\\' && str[1] == '~' && files[i][0] == '~')
		    escape_fname(&files[i]);
	    }
	    xp->xp_backslash = XP_BS_NONE;

	    // If the first file starts with a '+' escape it.  Otherwise it
	    // could be seen as "+cmd".
	    if (*files[0] == '+')
		escape_fname(&files[0]);
	}
	else if (xp->xp_context == EXPAND_TAGS)
	{
	    // Insert a backslash before characters in a tag name that
	    // would terminate the ":tag" command.
	    for (i = 0; i < numfiles; ++i)
	    {
		p = vim_strsave_escaped(files[i], (char_u *)"\\|\"");
		if (p != NULL)
		{
		    vim_free(files[i]);
		    files[i] = p;
		}
	    }
	}
    }
}

/*
 * Return FAIL if this is not an appropriate context in which to do
 * completion of anything, return OK if it is (even if there are no matches).
 * For the caller, this means that the character is just passed through like a
 * normal character (instead of being expanded).  This allows :s/^I^D etc.
 */
    int
nextwild(
    expand_T	*xp,
    int		type,
    int		options,	// extra options for ExpandOne()
    int		escape)		// if TRUE, escape the returned matches
{
    cmdline_info_T	*ccline = get_cmdline_info();
    int		i, j;
    char_u	*p1;
    char_u	*p2;
    int		difflen;
    int		v;

    if (xp->xp_numfiles == -1)
    {
	set_expand_context(xp);
	cmd_showtail = expand_showtail(xp);
    }

    if (xp->xp_context == EXPAND_UNSUCCESSFUL)
    {
	beep_flush();
	return OK;  // Something illegal on command line
    }
    if (xp->xp_context == EXPAND_NOTHING)
    {
	// Caller can use the character as a normal char instead
	return FAIL;
    }

    msg_puts("...");	    // show that we are busy
    out_flush();

    i = (int)(xp->xp_pattern - ccline->cmdbuff);
    xp->xp_pattern_len = ccline->cmdpos - i;

    if (type == WILD_NEXT || type == WILD_PREV)
    {
	// Get next/previous match for a previous expanded pattern.
	p2 = ExpandOne(xp, NULL, NULL, 0, type);
    }
    else
    {
	// Translate string into pattern and expand it.
	if ((p1 = addstar(xp->xp_pattern, xp->xp_pattern_len,
						     xp->xp_context)) == NULL)
	    p2 = NULL;
	else
	{
	    int use_options = options |
		    WILD_HOME_REPLACE|WILD_ADD_SLASH|WILD_SILENT;
	    if (escape)
		use_options |= WILD_ESCAPE;

	    if (p_wic)
		use_options += WILD_ICASE;
	    p2 = ExpandOne(xp, p1,
			 vim_strnsave(&ccline->cmdbuff[i], xp->xp_pattern_len),
							   use_options, type);
	    vim_free(p1);
	    // longest match: make sure it is not shorter, happens with :help
	    if (p2 != NULL && type == WILD_LONGEST)
	    {
		for (j = 0; j < xp->xp_pattern_len; ++j)
		     if (ccline->cmdbuff[i + j] == '*'
			     || ccline->cmdbuff[i + j] == '?')
			 break;
		if ((int)STRLEN(p2) < j)
		    VIM_CLEAR(p2);
	    }
	}
    }

    if (p2 != NULL && !got_int)
    {
	difflen = (int)STRLEN(p2) - xp->xp_pattern_len;
	if (ccline->cmdlen + difflen + 4 > ccline->cmdbufflen)
	{
	    v = realloc_cmdbuff(ccline->cmdlen + difflen + 4);
	    xp->xp_pattern = ccline->cmdbuff + i;
	}
	else
	    v = OK;
	if (v == OK)
	{
	    mch_memmove(&ccline->cmdbuff[ccline->cmdpos + difflen],
		    &ccline->cmdbuff[ccline->cmdpos],
		    (size_t)(ccline->cmdlen - ccline->cmdpos + 1));
	    mch_memmove(&ccline->cmdbuff[i], p2, STRLEN(p2));
	    ccline->cmdlen += difflen;
	    ccline->cmdpos += difflen;
	}
    }
    vim_free(p2);

    redrawcmd();
    cursorcmd();

    // When expanding a ":map" command and no matches are found, assume that
    // the key is supposed to be inserted literally
    if (xp->xp_context == EXPAND_MAPPINGS && p2 == NULL)
	return FAIL;

    if (xp->xp_numfiles <= 0 && p2 == NULL)
	beep_flush();
    else if (xp->xp_numfiles == 1)
	// free expanded pattern
	(void)ExpandOne(xp, NULL, NULL, 0, WILD_FREE);

    return OK;
}

/*
 * Do wildcard expansion on the string 'str'.
 * Chars that should not be expanded must be preceded with a backslash.
 * Return a pointer to allocated memory containing the new string.
 * Return NULL for failure.
 *
 * "orig" is the originally expanded string, copied to allocated memory.  It
 * should either be kept in orig_save or freed.  When "mode" is WILD_NEXT or
 * WILD_PREV "orig" should be NULL.
 *
 * Results are cached in xp->xp_files and xp->xp_numfiles, except when "mode"
 * is WILD_EXPAND_FREE or WILD_ALL.
 *
 * mode = WILD_FREE:	    just free previously expanded matches
 * mode = WILD_EXPAND_FREE: normal expansion, do not keep matches
 * mode = WILD_EXPAND_KEEP: normal expansion, keep matches
 * mode = WILD_NEXT:	    use next match in multiple match, wrap to first
 * mode = WILD_PREV:	    use previous match in multiple match, wrap to first
 * mode = WILD_ALL:	    return all matches concatenated
 * mode = WILD_LONGEST:	    return longest matched part
 * mode = WILD_ALL_KEEP:    get all matches, keep matches
 *
 * options = WILD_LIST_NOTFOUND:    list entries without a match
 * options = WILD_HOME_REPLACE:	    do home_replace() for buffer names
 * options = WILD_USE_NL:	    Use '\n' for WILD_ALL
 * options = WILD_NO_BEEP:	    Don't beep for multiple matches
 * options = WILD_ADD_SLASH:	    add a slash after directory names
 * options = WILD_KEEP_ALL:	    don't remove 'wildignore' entries
 * options = WILD_SILENT:	    don't print warning messages
 * options = WILD_ESCAPE:	    put backslash before special chars
 * options = WILD_ICASE:	    ignore case for files
 *
 * The variables xp->xp_context and xp->xp_backslash must have been set!
 */
    char_u *
ExpandOne(
    expand_T	*xp,
    char_u	*str,
    char_u	*orig,	    // allocated copy of original of expanded string
    int		options,
    int		mode)
{
    char_u	*ss = NULL;
    static int	findex;
    static char_u *orig_save = NULL;	// kept value of orig
    int		orig_saved = FALSE;
    int		i;
    long_u	len;
    int		non_suf_match;		// number without matching suffix

    // first handle the case of using an old match
    if (mode == WILD_NEXT || mode == WILD_PREV)
    {
	if (xp->xp_numfiles > 0)
	{
	    if (mode == WILD_PREV)
	    {
		if (findex == -1)
		    findex = xp->xp_numfiles;
		--findex;
	    }
	    else    // mode == WILD_NEXT
		++findex;

	    // When wrapping around, return the original string, set findex to
	    // -1.
	    if (findex < 0)
	    {
		if (orig_save == NULL)
		    findex = xp->xp_numfiles - 1;
		else
		    findex = -1;
	    }
	    if (findex >= xp->xp_numfiles)
	    {
		if (orig_save == NULL)
		    findex = 0;
		else
		    findex = -1;
	    }
#ifdef FEAT_WILDMENU
	    if (p_wmnu)
		win_redr_status_matches(xp, xp->xp_numfiles, xp->xp_files,
							findex, cmd_showtail);
#endif
	    if (findex == -1)
		return vim_strsave(orig_save);
	    return vim_strsave(xp->xp_files[findex]);
	}
	else
	    return NULL;
    }

    // free old names
    if (xp->xp_numfiles != -1 && mode != WILD_ALL && mode != WILD_LONGEST)
    {
	FreeWild(xp->xp_numfiles, xp->xp_files);
	xp->xp_numfiles = -1;
	VIM_CLEAR(orig_save);
    }
    findex = 0;

    if (mode == WILD_FREE)	// only release file name
	return NULL;

    if (xp->xp_numfiles == -1)
    {
	vim_free(orig_save);
	orig_save = orig;
	orig_saved = TRUE;

	// Do the expansion.
	if (ExpandFromContext(xp, str, &xp->xp_numfiles, &xp->xp_files,
							     options) == FAIL)
	{
#ifdef FNAME_ILLEGAL
	    // Illegal file name has been silently skipped.  But when there
	    // are wildcards, the real problem is that there was no match,
	    // causing the pattern to be added, which has illegal characters.
	    if (!(options & WILD_SILENT) && (options & WILD_LIST_NOTFOUND))
		semsg(_(e_nomatch2), str);
#endif
	}
	else if (xp->xp_numfiles == 0)
	{
	    if (!(options & WILD_SILENT))
		semsg(_(e_nomatch2), str);
	}
	else
	{
	    // Escape the matches for use on the command line.
	    ExpandEscape(xp, str, xp->xp_numfiles, xp->xp_files, options);

	    // Check for matching suffixes in file names.
	    if (mode != WILD_ALL && mode != WILD_ALL_KEEP
						      && mode != WILD_LONGEST)
	    {
		if (xp->xp_numfiles)
		    non_suf_match = xp->xp_numfiles;
		else
		    non_suf_match = 1;
		if ((xp->xp_context == EXPAND_FILES
			    || xp->xp_context == EXPAND_DIRECTORIES)
			&& xp->xp_numfiles > 1)
		{
		    // More than one match; check suffix.
		    // The files will have been sorted on matching suffix in
		    // expand_wildcards, only need to check the first two.
		    non_suf_match = 0;
		    for (i = 0; i < 2; ++i)
			if (match_suffix(xp->xp_files[i]))
			    ++non_suf_match;
		}
		if (non_suf_match != 1)
		{
		    // Can we ever get here unless it's while expanding
		    // interactively?  If not, we can get rid of this all
		    // together. Don't really want to wait for this message
		    // (and possibly have to hit return to continue!).
		    if (!(options & WILD_SILENT))
			emsg(_(e_toomany));
		    else if (!(options & WILD_NO_BEEP))
			beep_flush();
		}
		if (!(non_suf_match != 1 && mode == WILD_EXPAND_FREE))
		    ss = vim_strsave(xp->xp_files[0]);
	    }
	}
    }

    // Find longest common part
    if (mode == WILD_LONGEST && xp->xp_numfiles > 0)
    {
	int mb_len = 1;
	int c0, ci;

	for (len = 0; xp->xp_files[0][len]; len += mb_len)
	{
	    if (has_mbyte)
	    {
		mb_len = (*mb_ptr2len)(&xp->xp_files[0][len]);
		c0 =(* mb_ptr2char)(&xp->xp_files[0][len]);
	    }
	    else
		c0 = xp->xp_files[0][len];
	    for (i = 1; i < xp->xp_numfiles; ++i)
	    {
		if (has_mbyte)
		    ci =(* mb_ptr2char)(&xp->xp_files[i][len]);
		else
		    ci = xp->xp_files[i][len];
		if (p_fic && (xp->xp_context == EXPAND_DIRECTORIES
			|| xp->xp_context == EXPAND_FILES
			|| xp->xp_context == EXPAND_SHELLCMD
			|| xp->xp_context == EXPAND_BUFFERS))
		{
		    if (MB_TOLOWER(c0) != MB_TOLOWER(ci))
			break;
		}
		else if (c0 != ci)
		    break;
	    }
	    if (i < xp->xp_numfiles)
	    {
		if (!(options & WILD_NO_BEEP))
		    vim_beep(BO_WILD);
		break;
	    }
	}

	ss = alloc(len + 1);
	if (ss)
	    vim_strncpy(ss, xp->xp_files[0], (size_t)len);
	findex = -1;			    // next p_wc gets first one
    }

    // Concatenate all matching names
    if (mode == WILD_ALL && xp->xp_numfiles > 0)
    {
	len = 0;
	for (i = 0; i < xp->xp_numfiles; ++i)
	    len += (long_u)STRLEN(xp->xp_files[i]) + 1;
	ss = alloc(len);
	if (ss != NULL)
	{
	    *ss = NUL;
	    for (i = 0; i < xp->xp_numfiles; ++i)
	    {
		STRCAT(ss, xp->xp_files[i]);
		if (i != xp->xp_numfiles - 1)
		    STRCAT(ss, (options & WILD_USE_NL) ? "\n" : " ");
	    }
	}
    }

    if (mode == WILD_EXPAND_FREE || mode == WILD_ALL)
	ExpandCleanup(xp);

    // Free "orig" if it wasn't stored in "orig_save".
    if (!orig_saved)
	vim_free(orig);

    return ss;
}

/*
 * Prepare an expand structure for use.
 */
    void
ExpandInit(expand_T *xp)
{
    xp->xp_pattern = NULL;
    xp->xp_pattern_len = 0;
    xp->xp_backslash = XP_BS_NONE;
#ifndef BACKSLASH_IN_FILENAME
    xp->xp_shell = FALSE;
#endif
    xp->xp_numfiles = -1;
    xp->xp_files = NULL;
#if defined(FEAT_EVAL)
    xp->xp_arg = NULL;
#endif
    xp->xp_line = NULL;
}

/*
 * Cleanup an expand structure after use.
 */
    void
ExpandCleanup(expand_T *xp)
{
    if (xp->xp_numfiles >= 0)
    {
	FreeWild(xp->xp_numfiles, xp->xp_files);
	xp->xp_numfiles = -1;
    }
}

/*
 * Show all matches for completion on the command line.
 * Returns EXPAND_NOTHING when the character that triggered expansion should
 * be inserted like a normal character.
 */
    int
showmatches(expand_T *xp, int wildmenu UNUSED)
{
    cmdline_info_T	*ccline = get_cmdline_info();
#define L_SHOWFILE(m) (showtail ? sm_gettail(files_found[m]) : files_found[m])
    int		num_files;
    char_u	**files_found;
    int		i, j, k;
    int		maxlen;
    int		lines;
    int		columns;
    char_u	*p;
    int		lastlen;
    int		attr;
    int		showtail;

    if (xp->xp_numfiles == -1)
    {
	set_expand_context(xp);
	i = expand_cmdline(xp, ccline->cmdbuff, ccline->cmdpos,
						    &num_files, &files_found);
	showtail = expand_showtail(xp);
	if (i != EXPAND_OK)
	    return i;

    }
    else
    {
	num_files = xp->xp_numfiles;
	files_found = xp->xp_files;
	showtail = cmd_showtail;
    }

#ifdef FEAT_WILDMENU
    if (!wildmenu)
    {
#endif
	msg_didany = FALSE;		// lines_left will be set
	msg_start();			// prepare for paging
	msg_putchar('\n');
	out_flush();
	cmdline_row = msg_row;
	msg_didany = FALSE;		// lines_left will be set again
	msg_start();			// prepare for paging
#ifdef FEAT_WILDMENU
    }
#endif

    if (got_int)
	got_int = FALSE;	// only int. the completion, not the cmd line
#ifdef FEAT_WILDMENU
    else if (wildmenu)
	win_redr_status_matches(xp, num_files, files_found, -1, showtail);
#endif
    else
    {
	// find the length of the longest file name
	maxlen = 0;
	for (i = 0; i < num_files; ++i)
	{
	    if (!showtail && (xp->xp_context == EXPAND_FILES
			  || xp->xp_context == EXPAND_SHELLCMD
			  || xp->xp_context == EXPAND_BUFFERS))
	    {
		home_replace(NULL, files_found[i], NameBuff, MAXPATHL, TRUE);
		j = vim_strsize(NameBuff);
	    }
	    else
		j = vim_strsize(L_SHOWFILE(i));
	    if (j > maxlen)
		maxlen = j;
	}

	if (xp->xp_context == EXPAND_TAGS_LISTFILES)
	    lines = num_files;
	else
	{
	    // compute the number of columns and lines for the listing
	    maxlen += 2;    // two spaces between file names
	    columns = ((int)Columns + 2) / maxlen;
	    if (columns < 1)
		columns = 1;
	    lines = (num_files + columns - 1) / columns;
	}

	attr = HL_ATTR(HLF_D);	// find out highlighting for directories

	if (xp->xp_context == EXPAND_TAGS_LISTFILES)
	{
	    msg_puts_attr(_("tagname"), HL_ATTR(HLF_T));
	    msg_clr_eos();
	    msg_advance(maxlen - 3);
	    msg_puts_attr(_(" kind file\n"), HL_ATTR(HLF_T));
	}

	// list the files line by line
	for (i = 0; i < lines; ++i)
	{
	    lastlen = 999;
	    for (k = i; k < num_files; k += lines)
	    {
		if (xp->xp_context == EXPAND_TAGS_LISTFILES)
		{
		    msg_outtrans_attr(files_found[k], HL_ATTR(HLF_D));
		    p = files_found[k] + STRLEN(files_found[k]) + 1;
		    msg_advance(maxlen + 1);
		    msg_puts((char *)p);
		    msg_advance(maxlen + 3);
		    msg_outtrans_long_attr(p + 2, HL_ATTR(HLF_D));
		    break;
		}
		for (j = maxlen - lastlen; --j >= 0; )
		    msg_putchar(' ');
		if (xp->xp_context == EXPAND_FILES
					  || xp->xp_context == EXPAND_SHELLCMD
					  || xp->xp_context == EXPAND_BUFFERS)
		{
		    // highlight directories
		    if (xp->xp_numfiles != -1)
		    {
			char_u	*halved_slash;
			char_u	*exp_path;

			// Expansion was done before and special characters
			// were escaped, need to halve backslashes.  Also
			// $HOME has been replaced with ~/.
			exp_path = expand_env_save_opt(files_found[k], TRUE);
			halved_slash = backslash_halve_save(
				exp_path != NULL ? exp_path : files_found[k]);
			j = mch_isdir(halved_slash != NULL ? halved_slash
							    : files_found[k]);
			vim_free(exp_path);
			vim_free(halved_slash);
		    }
		    else
			// Expansion was done here, file names are literal.
			j = mch_isdir(files_found[k]);
		    if (showtail)
			p = L_SHOWFILE(k);
		    else
		    {
			home_replace(NULL, files_found[k], NameBuff, MAXPATHL,
									TRUE);
			p = NameBuff;
		    }
		}
		else
		{
		    j = FALSE;
		    p = L_SHOWFILE(k);
		}
		lastlen = msg_outtrans_attr(p, j ? attr : 0);
	    }
	    if (msg_col > 0)	// when not wrapped around
	    {
		msg_clr_eos();
		msg_putchar('\n');
	    }
	    out_flush();		    // show one line at a time
	    if (got_int)
	    {
		got_int = FALSE;
		break;
	    }
	}

	// we redraw the command below the lines that we have just listed
	// This is a bit tricky, but it saves a lot of screen updating.
	cmdline_row = msg_row;	// will put it back later
    }

    if (xp->xp_numfiles == -1)
	FreeWild(num_files, files_found);

    return EXPAND_OK;
}

/*
 * Private gettail for showmatches() (and win_redr_status_matches()):
 * Find tail of file name path, but ignore trailing "/".
 */
    char_u *
sm_gettail(char_u *s)
{
    char_u	*p;
    char_u	*t = s;
    int		had_sep = FALSE;

    for (p = s; *p != NUL; )
    {
	if (vim_ispathsep(*p)
#ifdef BACKSLASH_IN_FILENAME
		&& !rem_backslash(p)
#endif
	   )
	    had_sep = TRUE;
	else if (had_sep)
	{
	    t = p;
	    had_sep = FALSE;
	}
	MB_PTR_ADV(p);
    }
    return t;
}

/*
 * Return TRUE if we only need to show the tail of completion matches.
 * When not completing file names or there is a wildcard in the path FALSE is
 * returned.
 */
    static int
expand_showtail(expand_T *xp)
{
    char_u	*s;
    char_u	*end;

    // When not completing file names a "/" may mean something different.
    if (xp->xp_context != EXPAND_FILES
	    && xp->xp_context != EXPAND_SHELLCMD
	    && xp->xp_context != EXPAND_DIRECTORIES)
	return FALSE;

    end = gettail(xp->xp_pattern);
    if (end == xp->xp_pattern)		// there is no path separator
	return FALSE;

    for (s = xp->xp_pattern; s < end; s++)
    {
	// Skip escaped wildcards.  Only when the backslash is not a path
	// separator, on DOS the '*' "path\*\file" must not be skipped.
	if (rem_backslash(s))
	    ++s;
	else if (vim_strchr((char_u *)"*?[", *s) != NULL)
	    return FALSE;
    }
    return TRUE;
}

/*
 * Prepare a string for expansion.
 * When expanding file names: The string will be used with expand_wildcards().
 * Copy "fname[len]" into allocated memory and add a '*' at the end.
 * When expanding other names: The string will be used with regcomp().  Copy
 * the name into allocated memory and prepend "^".
 */
    char_u *
addstar(
    char_u	*fname,
    int		len,
    int		context)	// EXPAND_FILES etc.
{
    char_u	*retval;
    int		i, j;
    int		new_len;
    char_u	*tail;
    int		ends_in_star;

    if (context != EXPAND_FILES
	    && context != EXPAND_FILES_IN_PATH
	    && context != EXPAND_SHELLCMD
	    && context != EXPAND_DIRECTORIES)
    {
	// Matching will be done internally (on something other than files).
	// So we convert the file-matching-type wildcards into our kind for
	// use with vim_regcomp().  First work out how long it will be:

	// For help tags the translation is done in find_help_tags().
	// For a tag pattern starting with "/" no translation is needed.
	if (context == EXPAND_HELP
		|| context == EXPAND_COLORS
		|| context == EXPAND_COMPILER
		|| context == EXPAND_OWNSYNTAX
		|| context == EXPAND_FILETYPE
		|| context == EXPAND_PACKADD
		|| ((context == EXPAND_TAGS_LISTFILES
			|| context == EXPAND_TAGS)
		    && fname[0] == '/'))
	    retval = vim_strnsave(fname, len);
	else
	{
	    new_len = len + 2;		// +2 for '^' at start, NUL at end
	    for (i = 0; i < len; i++)
	    {
		if (fname[i] == '*' || fname[i] == '~')
		    new_len++;		// '*' needs to be replaced by ".*"
					// '~' needs to be replaced by "\~"

		// Buffer names are like file names.  "." should be literal
		if (context == EXPAND_BUFFERS && fname[i] == '.')
		    new_len++;		// "." becomes "\."

		// Custom expansion takes care of special things, match
		// backslashes literally (perhaps also for other types?)
		if ((context == EXPAND_USER_DEFINED
			  || context == EXPAND_USER_LIST) && fname[i] == '\\')
		    new_len++;		// '\' becomes "\\"
	    }
	    retval = alloc(new_len);
	    if (retval != NULL)
	    {
		retval[0] = '^';
		j = 1;
		for (i = 0; i < len; i++, j++)
		{
		    // Skip backslash.  But why?  At least keep it for custom
		    // expansion.
		    if (context != EXPAND_USER_DEFINED
			    && context != EXPAND_USER_LIST
			    && fname[i] == '\\'
			    && ++i == len)
			break;

		    switch (fname[i])
		    {
			case '*':   retval[j++] = '.';
				    break;
			case '~':   retval[j++] = '\\';
				    break;
			case '?':   retval[j] = '.';
				    continue;
			case '.':   if (context == EXPAND_BUFFERS)
					retval[j++] = '\\';
				    break;
			case '\\':  if (context == EXPAND_USER_DEFINED
					    || context == EXPAND_USER_LIST)
					retval[j++] = '\\';
				    break;
		    }
		    retval[j] = fname[i];
		}
		retval[j] = NUL;
	    }
	}
    }
    else
    {
	retval = alloc(len + 4);
	if (retval != NULL)
	{
	    vim_strncpy(retval, fname, len);

	    // Don't add a star to *, ~, ~user, $var or `cmd`.
	    // * would become **, which walks the whole tree.
	    // ~ would be at the start of the file name, but not the tail.
	    // $ could be anywhere in the tail.
	    // ` could be anywhere in the file name.
	    // When the name ends in '$' don't add a star, remove the '$'.
	    tail = gettail(retval);
	    ends_in_star = (len > 0 && retval[len - 1] == '*');
#ifndef BACKSLASH_IN_FILENAME
	    for (i = len - 2; i >= 0; --i)
	    {
		if (retval[i] != '\\')
		    break;
		ends_in_star = !ends_in_star;
	    }
#endif
	    if ((*retval != '~' || tail != retval)
		    && !ends_in_star
		    && vim_strchr(tail, '$') == NULL
		    && vim_strchr(retval, '`') == NULL)
		retval[len++] = '*';
	    else if (len > 0 && retval[len - 1] == '$')
		--len;
	    retval[len] = NUL;
	}
    }
    return retval;
}

/*
 * Must parse the command line so far to work out what context we are in.
 * Completion can then be done based on that context.
 * This routine sets the variables:
 *  xp->xp_pattern	    The start of the pattern to be expanded within
 *				the command line (ends at the cursor).
 *  xp->xp_context	    The type of thing to expand.  Will be one of:
 *
 *  EXPAND_UNSUCCESSFUL	    Used sometimes when there is something illegal on
 *			    the command line, like an unknown command.	Caller
 *			    should beep.
 *  EXPAND_NOTHING	    Unrecognised context for completion, use char like
 *			    a normal char, rather than for completion.	eg
 *			    :s/^I/
 *  EXPAND_COMMANDS	    Cursor is still touching the command, so complete
 *			    it.
 *  EXPAND_BUFFERS	    Complete file names for :buf and :sbuf commands.
 *  EXPAND_FILES	    After command with EX_XFILE set, or after setting
 *			    with P_EXPAND set.	eg :e ^I, :w>>^I
 *  EXPAND_DIRECTORIES	    In some cases this is used instead of the latter
 *			    when we know only directories are of interest.  eg
 *			    :set dir=^I
 *  EXPAND_SHELLCMD	    After ":!cmd", ":r !cmd"  or ":w !cmd".
 *  EXPAND_SETTINGS	    Complete variable names.  eg :set d^I
 *  EXPAND_BOOL_SETTINGS    Complete boolean variables only,  eg :set no^I
 *  EXPAND_TAGS		    Complete tags from the files in p_tags.  eg :ta a^I
 *  EXPAND_TAGS_LISTFILES   As above, but list filenames on ^D, after :tselect
 *  EXPAND_HELP		    Complete tags from the file 'helpfile'/tags
 *  EXPAND_EVENTS	    Complete event names
 *  EXPAND_SYNTAX	    Complete :syntax command arguments
 *  EXPAND_HIGHLIGHT	    Complete highlight (syntax) group names
 *  EXPAND_AUGROUP	    Complete autocommand group names
 *  EXPAND_USER_VARS	    Complete user defined variable names, eg :unlet a^I
 *  EXPAND_MAPPINGS	    Complete mapping and abbreviation names,
 *			      eg :unmap a^I , :cunab x^I
 *  EXPAND_FUNCTIONS	    Complete internal or user defined function names,
 *			      eg :call sub^I
 *  EXPAND_USER_FUNC	    Complete user defined function names, eg :delf F^I
 *  EXPAND_EXPRESSION	    Complete internal or user defined function/variable
 *			    names in expressions, eg :while s^I
 *  EXPAND_ENV_VARS	    Complete environment variable names
 *  EXPAND_USER		    Complete user names
 */
    static void
set_expand_context(expand_T *xp)
{
    cmdline_info_T	*ccline = get_cmdline_info();

    // only expansion for ':', '>' and '=' command-lines
    if (ccline->cmdfirstc != ':'
#ifdef FEAT_EVAL
	    && ccline->cmdfirstc != '>' && ccline->cmdfirstc != '='
	    && !ccline->input_fn
#endif
	    )
    {
	xp->xp_context = EXPAND_NOTHING;
	return;
    }
    set_cmd_context(xp, ccline->cmdbuff, ccline->cmdlen, ccline->cmdpos, TRUE);
}

    void
set_cmd_context(
    expand_T	*xp,
    char_u	*str,	    // start of command line
    int		len,	    // length of command line (excl. NUL)
    int		col,	    // position of cursor
    int		use_ccline UNUSED) // use ccline for info
{
#ifdef FEAT_EVAL
    cmdline_info_T	*ccline = get_cmdline_info();
#endif
    int		old_char = NUL;
    char_u	*nextcomm;

    // Avoid a UMR warning from Purify, only save the character if it has been
    // written before.
    if (col < len)
	old_char = str[col];
    str[col] = NUL;
    nextcomm = str;

#ifdef FEAT_EVAL
    if (use_ccline && ccline->cmdfirstc == '=')
    {
	// pass CMD_SIZE because there is no real command
	set_context_for_expression(xp, str, CMD_SIZE);
    }
    else if (use_ccline && ccline->input_fn)
    {
	xp->xp_context = ccline->xp_context;
	xp->xp_pattern = ccline->cmdbuff;
	xp->xp_arg = ccline->xp_arg;
    }
    else
#endif
	while (nextcomm != NULL)
	    nextcomm = set_one_cmd_context(xp, nextcomm);

    // Store the string here so that call_user_expand_func() can get to them
    // easily.
    xp->xp_line = str;
    xp->xp_col = col;

    str[col] = old_char;
}

/*
 * Expand the command line "str" from context "xp".
 * "xp" must have been set by set_cmd_context().
 * xp->xp_pattern points into "str", to where the text that is to be expanded
 * starts.
 * Returns EXPAND_UNSUCCESSFUL when there is something illegal before the
 * cursor.
 * Returns EXPAND_NOTHING when there is nothing to expand, might insert the
 * key that triggered expansion literally.
 * Returns EXPAND_OK otherwise.
 */
    int
expand_cmdline(
    expand_T	*xp,
    char_u	*str,		// start of command line
    int		col,		// position of cursor
    int		*matchcount,	// return: nr of matches
    char_u	***matches)	// return: array of pointers to matches
{
    char_u	*file_str = NULL;
    int		options = WILD_ADD_SLASH|WILD_SILENT;

    if (xp->xp_context == EXPAND_UNSUCCESSFUL)
    {
	beep_flush();
	return EXPAND_UNSUCCESSFUL;  // Something illegal on command line
    }
    if (xp->xp_context == EXPAND_NOTHING)
    {
	// Caller can use the character as a normal char instead
	return EXPAND_NOTHING;
    }

    // add star to file name, or convert to regexp if not exp. files.
    xp->xp_pattern_len = (int)(str + col - xp->xp_pattern);
    file_str = addstar(xp->xp_pattern, xp->xp_pattern_len, xp->xp_context);
    if (file_str == NULL)
	return EXPAND_UNSUCCESSFUL;

    if (p_wic)
	options += WILD_ICASE;

    // find all files that match the description
    if (ExpandFromContext(xp, file_str, matchcount, matches, options) == FAIL)
    {
	*matchcount = 0;
	*matches = NULL;
    }
    vim_free(file_str);

    return EXPAND_OK;
}

#ifdef FEAT_MULTI_LANG
/*
 * Cleanup matches for help tags:
 * Remove "@ab" if the top of 'helplang' is "ab" and the language of the first
 * tag matches it.  Otherwise remove "@en" if "en" is the only language.
 */
    static void
cleanup_help_tags(int num_file, char_u **file)
{
    int		i, j;
    int		len;
    char_u	buf[4];
    char_u	*p = buf;

    if (p_hlg[0] != NUL && (p_hlg[0] != 'e' || p_hlg[1] != 'n'))
    {
	*p++ = '@';
	*p++ = p_hlg[0];
	*p++ = p_hlg[1];
    }
    *p = NUL;

    for (i = 0; i < num_file; ++i)
    {
	len = (int)STRLEN(file[i]) - 3;
	if (len <= 0)
	    continue;
	if (STRCMP(file[i] + len, "@en") == 0)
	{
	    // Sorting on priority means the same item in another language may
	    // be anywhere.  Search all items for a match up to the "@en".
	    for (j = 0; j < num_file; ++j)
		if (j != i && (int)STRLEN(file[j]) == len + 3
			   && STRNCMP(file[i], file[j], len + 1) == 0)
		    break;
	    if (j == num_file)
		// item only exists with @en, remove it
		file[i][len] = NUL;
	}
    }

    if (*buf != NUL)
	for (i = 0; i < num_file; ++i)
	{
	    len = (int)STRLEN(file[i]) - 3;
	    if (len <= 0)
		continue;
	    if (STRCMP(file[i] + len, buf) == 0)
	    {
		// remove the default language
		file[i][len] = NUL;
	    }
	}
}
#endif

/*
 * Do the expansion based on xp->xp_context and "pat".
 */
    static int
ExpandFromContext(
    expand_T	*xp,
    char_u	*pat,
    int		*num_file,
    char_u	***file,
    int		options)  // WILD_ flags
{
    regmatch_T	regmatch;
    int		ret;
    int		flags;

    flags = EW_DIR;	// include directories
    if (options & WILD_LIST_NOTFOUND)
	flags |= EW_NOTFOUND;
    if (options & WILD_ADD_SLASH)
	flags |= EW_ADDSLASH;
    if (options & WILD_KEEP_ALL)
	flags |= EW_KEEPALL;
    if (options & WILD_SILENT)
	flags |= EW_SILENT;
    if (options & WILD_ALLLINKS)
	flags |= EW_ALLLINKS;

    if (xp->xp_context == EXPAND_FILES
	    || xp->xp_context == EXPAND_DIRECTORIES
	    || xp->xp_context == EXPAND_FILES_IN_PATH)
    {
	// Expand file or directory names.
	int	free_pat = FALSE;
	int	i;

	// for ":set path=" and ":set tags=" halve backslashes for escaped
	// space
	if (xp->xp_backslash != XP_BS_NONE)
	{
	    free_pat = TRUE;
	    pat = vim_strsave(pat);
	    for (i = 0; pat[i]; ++i)
		if (pat[i] == '\\')
		{
		    if (xp->xp_backslash == XP_BS_THREE
			    && pat[i + 1] == '\\'
			    && pat[i + 2] == '\\'
			    && pat[i + 3] == ' ')
			STRMOVE(pat + i, pat + i + 3);
		    if (xp->xp_backslash == XP_BS_ONE
			    && pat[i + 1] == ' ')
			STRMOVE(pat + i, pat + i + 1);
		}
	}

	if (xp->xp_context == EXPAND_FILES)
	    flags |= EW_FILE;
	else if (xp->xp_context == EXPAND_FILES_IN_PATH)
	    flags |= (EW_FILE | EW_PATH);
	else
	    flags = (flags | EW_DIR) & ~EW_FILE;
	if (options & WILD_ICASE)
	    flags |= EW_ICASE;

	// Expand wildcards, supporting %:h and the like.
	ret = expand_wildcards_eval(&pat, num_file, file, flags);
	if (free_pat)
	    vim_free(pat);
#ifdef BACKSLASH_IN_FILENAME
	if (p_csl[0] != NUL && (options & WILD_IGNORE_COMPLETESLASH) == 0)
	{
	    int	    i;

	    for (i = 0; i < *num_file; ++i)
	    {
		char_u	*ptr = (*file)[i];

		while (*ptr != NUL)
		{
		    if (p_csl[0] == 's' && *ptr == '\\')
			*ptr = '/';
		    else if (p_csl[0] == 'b' && *ptr == '/')
			*ptr = '\\';
		    ptr += (*mb_ptr2len)(ptr);
		}
	    }
	}
#endif
	return ret;
    }

    *file = (char_u **)"";
    *num_file = 0;
    if (xp->xp_context == EXPAND_HELP)
    {
	// With an empty argument we would get all the help tags, which is
	// very slow.  Get matches for "help" instead.
	if (find_help_tags(*pat == NUL ? (char_u *)"help" : pat,
						 num_file, file, FALSE) == OK)
	{
#ifdef FEAT_MULTI_LANG
	    cleanup_help_tags(*num_file, *file);
#endif
	    return OK;
	}
	return FAIL;
    }

    if (xp->xp_context == EXPAND_SHELLCMD)
	return expand_shellcmd(pat, num_file, file, flags);
    if (xp->xp_context == EXPAND_OLD_SETTING)
	return ExpandOldSetting(num_file, file);
    if (xp->xp_context == EXPAND_BUFFERS)
	return ExpandBufnames(pat, num_file, file, options);
    if (xp->xp_context == EXPAND_TAGS
	    || xp->xp_context == EXPAND_TAGS_LISTFILES)
	return expand_tags(xp->xp_context == EXPAND_TAGS, pat, num_file, file);
    if (xp->xp_context == EXPAND_COLORS)
    {
	char *directories[] = {"colors", NULL};
	return ExpandRTDir(pat, DIP_START + DIP_OPT, num_file, file,
								directories);
    }
    if (xp->xp_context == EXPAND_COMPILER)
    {
	char *directories[] = {"compiler", NULL};
	return ExpandRTDir(pat, 0, num_file, file, directories);
    }
    if (xp->xp_context == EXPAND_OWNSYNTAX)
    {
	char *directories[] = {"syntax", NULL};
	return ExpandRTDir(pat, 0, num_file, file, directories);
    }
    if (xp->xp_context == EXPAND_FILETYPE)
    {
	char *directories[] = {"syntax", "indent", "ftplugin", NULL};
	return ExpandRTDir(pat, 0, num_file, file, directories);
    }
# if defined(FEAT_EVAL)
    if (xp->xp_context == EXPAND_USER_LIST)
	return ExpandUserList(xp, num_file, file);
# endif
    if (xp->xp_context == EXPAND_PACKADD)
	return ExpandPackAddDir(pat, num_file, file);

    regmatch.regprog = vim_regcomp(pat, p_magic ? RE_MAGIC : 0);
    if (regmatch.regprog == NULL)
	return FAIL;

    // set ignore-case according to p_ic, p_scs and pat
    regmatch.rm_ic = ignorecase(pat);

    if (xp->xp_context == EXPAND_SETTINGS
	    || xp->xp_context == EXPAND_BOOL_SETTINGS)
	ret = ExpandSettings(xp, &regmatch, num_file, file);
    else if (xp->xp_context == EXPAND_MAPPINGS)
	ret = ExpandMappings(&regmatch, num_file, file);
# if defined(FEAT_EVAL)
    else if (xp->xp_context == EXPAND_USER_DEFINED)
	ret = ExpandUserDefined(xp, &regmatch, num_file, file);
# endif
    else
    {
	static struct expgen
	{
	    int		context;
	    char_u	*((*func)(expand_T *, int));
	    int		ic;
	    int		escaped;
	} tab[] =
	{
	    {EXPAND_COMMANDS, get_command_name, FALSE, TRUE},
	    {EXPAND_BEHAVE, get_behave_arg, TRUE, TRUE},
	    {EXPAND_MAPCLEAR, get_mapclear_arg, TRUE, TRUE},
	    {EXPAND_MESSAGES, get_messages_arg, TRUE, TRUE},
	    {EXPAND_HISTORY, get_history_arg, TRUE, TRUE},
	    {EXPAND_USER_COMMANDS, get_user_commands, FALSE, TRUE},
	    {EXPAND_USER_ADDR_TYPE, get_user_cmd_addr_type, FALSE, TRUE},
	    {EXPAND_USER_CMD_FLAGS, get_user_cmd_flags, FALSE, TRUE},
	    {EXPAND_USER_NARGS, get_user_cmd_nargs, FALSE, TRUE},
	    {EXPAND_USER_COMPLETE, get_user_cmd_complete, FALSE, TRUE},
# ifdef FEAT_EVAL
	    {EXPAND_USER_VARS, get_user_var_name, FALSE, TRUE},
	    {EXPAND_FUNCTIONS, get_function_name, FALSE, TRUE},
	    {EXPAND_USER_FUNC, get_user_func_name, FALSE, TRUE},
	    {EXPAND_EXPRESSION, get_expr_name, FALSE, TRUE},
# endif
# ifdef FEAT_MENU
	    {EXPAND_MENUS, get_menu_name, FALSE, TRUE},
	    {EXPAND_MENUNAMES, get_menu_names, FALSE, TRUE},
# endif
# ifdef FEAT_SYN_HL
	    {EXPAND_SYNTAX, get_syntax_name, TRUE, TRUE},
# endif
# ifdef FEAT_PROFILE
	    {EXPAND_SYNTIME, get_syntime_arg, TRUE, TRUE},
# endif
	    {EXPAND_HIGHLIGHT, get_highlight_name, TRUE, TRUE},
	    {EXPAND_EVENTS, get_event_name, TRUE, TRUE},
	    {EXPAND_AUGROUP, get_augroup_name, TRUE, TRUE},
# ifdef FEAT_CSCOPE
	    {EXPAND_CSCOPE, get_cscope_name, TRUE, TRUE},
# endif
# ifdef FEAT_SIGNS
	    {EXPAND_SIGN, get_sign_name, TRUE, TRUE},
# endif
# ifdef FEAT_PROFILE
	    {EXPAND_PROFILE, get_profile_name, TRUE, TRUE},
# endif
# if defined(HAVE_LOCALE_H) || defined(X_LOCALE)
	    {EXPAND_LANGUAGE, get_lang_arg, TRUE, FALSE},
	    {EXPAND_LOCALES, get_locales, TRUE, FALSE},
# endif
	    {EXPAND_ENV_VARS, get_env_name, TRUE, TRUE},
	    {EXPAND_USER, get_users, TRUE, FALSE},
	    {EXPAND_ARGLIST, get_arglist_name, TRUE, FALSE},
	};
	int	i;

	// Find a context in the table and call the ExpandGeneric() with the
	// right function to do the expansion.
	ret = FAIL;
	for (i = 0; i < (int)(sizeof(tab) / sizeof(struct expgen)); ++i)
	    if (xp->xp_context == tab[i].context)
	    {
		if (tab[i].ic)
		    regmatch.rm_ic = TRUE;
		ret = ExpandGeneric(xp, &regmatch, num_file, file,
						tab[i].func, tab[i].escaped);
		break;
	    }
    }

    vim_regfree(regmatch.regprog);

    return ret;
}

/*
 * Expand a list of names.
 *
 * Generic function for command line completion.  It calls a function to
 * obtain strings, one by one.	The strings are matched against a regexp
 * program.  Matching strings are copied into an array, which is returned.
 *
 * Returns OK when no problems encountered, FAIL for error (out of memory).
 */
    int
ExpandGeneric(
    expand_T	*xp,
    regmatch_T	*regmatch,
    int		*num_file,
    char_u	***file,
    char_u	*((*func)(expand_T *, int)),
					  // returns a string from the list
    int		escaped)
{
    int		i;
    int		count = 0;
    int		round;
    char_u	*str;

    // do this loop twice:
    // round == 0: count the number of matching names
    // round == 1: copy the matching names into allocated memory
    for (round = 0; round <= 1; ++round)
    {
	for (i = 0; ; ++i)
	{
	    str = (*func)(xp, i);
	    if (str == NULL)	    // end of list
		break;
	    if (*str == NUL)	    // skip empty strings
		continue;

	    if (vim_regexec(regmatch, str, (colnr_T)0))
	    {
		if (round)
		{
		    if (escaped)
			str = vim_strsave_escaped(str, (char_u *)" \t\\.");
		    else
			str = vim_strsave(str);
		    (*file)[count] = str;
# ifdef FEAT_MENU
		    if (func == get_menu_names && str != NULL)
		    {
			// test for separator added by get_menu_names()
			str += STRLEN(str) - 1;
			if (*str == '\001')
			    *str = '.';
		    }
# endif
		}
		++count;
	    }
	}
	if (round == 0)
	{
	    if (count == 0)
		return OK;
	    *num_file = count;
	    *file = ALLOC_MULT(char_u *, count);
	    if (*file == NULL)
	    {
		*file = (char_u **)"";
		return FAIL;
	    }
	    count = 0;
	}
    }

    // Sort the results.  Keep menu's in the specified order.
    if (xp->xp_context != EXPAND_MENUNAMES && xp->xp_context != EXPAND_MENUS)
    {
	if (xp->xp_context == EXPAND_EXPRESSION
		|| xp->xp_context == EXPAND_FUNCTIONS
		|| xp->xp_context == EXPAND_USER_FUNC)
	    // <SNR> functions should be sorted to the end.
	    qsort((void *)*file, (size_t)*num_file, sizeof(char_u *),
							   sort_func_compare);
	else
	    sort_strings(*file, *num_file);
    }

#if defined(FEAT_SYN_HL)
    // Reset the variables used for special highlight names expansion, so that
    // they don't show up when getting normal highlight names by ID.
    reset_expand_highlight();
#endif

    return OK;
}

/*
 * Complete a shell command.
 * Returns FAIL or OK;
 */
    static int
expand_shellcmd(
    char_u	*filepat,	// pattern to match with command names
    int		*num_file,	// return: number of matches
    char_u	***file,	// return: array with matches
    int		flagsarg)	// EW_ flags
{
    char_u	*pat;
    int		i;
    char_u	*path = NULL;
    int		mustfree = FALSE;
    garray_T    ga;
    char_u	*buf = alloc(MAXPATHL);
    size_t	l;
    char_u	*s, *e;
    int		flags = flagsarg;
    int		ret;
    int		did_curdir = FALSE;
    hashtab_T	found_ht;
    hashitem_T	*hi;
    hash_T	hash;

    if (buf == NULL)
	return FAIL;

    // for ":set path=" and ":set tags=" halve backslashes for escaped
    // space
    pat = vim_strsave(filepat);
    for (i = 0; pat[i]; ++i)
	if (pat[i] == '\\' && pat[i + 1] == ' ')
	    STRMOVE(pat + i, pat + i + 1);

    flags |= EW_FILE | EW_EXEC | EW_SHELLCMD;

    if (pat[0] == '.' && (vim_ispathsep(pat[1])
			       || (pat[1] == '.' && vim_ispathsep(pat[2]))))
	path = (char_u *)".";
    else
    {
	// For an absolute name we don't use $PATH.
	if (!mch_isFullName(pat))
	    path = vim_getenv((char_u *)"PATH", &mustfree);
	if (path == NULL)
	    path = (char_u *)"";
    }

    // Go over all directories in $PATH.  Expand matches in that directory and
    // collect them in "ga".  When "." is not in $PATH also expand for the
    // current directory, to find "subdir/cmd".
    ga_init2(&ga, (int)sizeof(char *), 10);
    hash_init(&found_ht);
    for (s = path; ; s = e)
    {
# if defined(MSWIN)
	e = vim_strchr(s, ';');
# else
	e = vim_strchr(s, ':');
# endif
	if (e == NULL)
	    e = s + STRLEN(s);

	if (*s == NUL)
	{
	    if (did_curdir)
		break;
	    // Find directories in the current directory, path is empty.
	    did_curdir = TRUE;
	    flags |= EW_DIR;
	}
	else if (STRNCMP(s, ".", (int)(e - s)) == 0)
	{
	    did_curdir = TRUE;
	    flags |= EW_DIR;
	}
	else
	    // Do not match directories inside a $PATH item.
	    flags &= ~EW_DIR;

	l = e - s;
	if (l > MAXPATHL - 5)
	    break;
	vim_strncpy(buf, s, l);
	add_pathsep(buf);
	l = STRLEN(buf);
	vim_strncpy(buf + l, pat, MAXPATHL - 1 - l);

	// Expand matches in one directory of $PATH.
	ret = expand_wildcards(1, &buf, num_file, file, flags);
	if (ret == OK)
	{
	    if (ga_grow(&ga, *num_file) == FAIL)
		FreeWild(*num_file, *file);
	    else
	    {
		for (i = 0; i < *num_file; ++i)
		{
		    char_u *name = (*file)[i];

		    if (STRLEN(name) > l)
		    {
			// Check if this name was already found.
			hash = hash_hash(name + l);
			hi = hash_lookup(&found_ht, name + l, hash);
			if (HASHITEM_EMPTY(hi))
			{
			    // Remove the path that was prepended.
			    STRMOVE(name, name + l);
			    ((char_u **)ga.ga_data)[ga.ga_len++] = name;
			    hash_add_item(&found_ht, hi, name, hash);
			    name = NULL;
			}
		    }
		    vim_free(name);
		}
		vim_free(*file);
	    }
	}
	if (*e != NUL)
	    ++e;
    }
    *file = ga.ga_data;
    *num_file = ga.ga_len;

    vim_free(buf);
    vim_free(pat);
    if (mustfree)
	vim_free(path);
    hash_clear(&found_ht);
    return OK;
}

# if defined(FEAT_EVAL)
/*
 * Call "user_expand_func()" to invoke a user defined Vim script function and
 * return the result (either a string or a List).
 */
    static void *
call_user_expand_func(
    void	*(*user_expand_func)(char_u *, int, typval_T *),
    expand_T	*xp,
    int		*num_file,
    char_u	***file)
{
    cmdline_info_T	*ccline = get_cmdline_info();
    int		keep = 0;
    typval_T	args[4];
    sctx_T	save_current_sctx = current_sctx;
    char_u	*pat = NULL;
    void	*ret;

    if (xp->xp_arg == NULL || xp->xp_arg[0] == '\0' || xp->xp_line == NULL)
	return NULL;
    *num_file = 0;
    *file = NULL;

    if (ccline->cmdbuff != NULL)
    {
	keep = ccline->cmdbuff[ccline->cmdlen];
	ccline->cmdbuff[ccline->cmdlen] = 0;
    }

    pat = vim_strnsave(xp->xp_pattern, xp->xp_pattern_len);

    args[0].v_type = VAR_STRING;
    args[0].vval.v_string = pat;
    args[1].v_type = VAR_STRING;
    args[1].vval.v_string = xp->xp_line;
    args[2].v_type = VAR_NUMBER;
    args[2].vval.v_number = xp->xp_col;
    args[3].v_type = VAR_UNKNOWN;

    current_sctx = xp->xp_script_ctx;

    ret = user_expand_func(xp->xp_arg, 3, args);

    current_sctx = save_current_sctx;
    if (ccline->cmdbuff != NULL)
	ccline->cmdbuff[ccline->cmdlen] = keep;

    vim_free(pat);
    return ret;
}

/*
 * Expand names with a function defined by the user.
 */
    static int
ExpandUserDefined(
    expand_T	*xp,
    regmatch_T	*regmatch,
    int		*num_file,
    char_u	***file)
{
    char_u	*retstr;
    char_u	*s;
    char_u	*e;
    int		keep;
    garray_T	ga;
    int		skip;

    retstr = call_user_expand_func(call_func_retstr, xp, num_file, file);
    if (retstr == NULL)
	return FAIL;

    ga_init2(&ga, (int)sizeof(char *), 3);
    for (s = retstr; *s != NUL; s = e)
    {
	e = vim_strchr(s, '\n');
	if (e == NULL)
	    e = s + STRLEN(s);
	keep = *e;
	*e = NUL;

	skip = xp->xp_pattern[0] && vim_regexec(regmatch, s, (colnr_T)0) == 0;
	*e = keep;

	if (!skip)
	{
	    if (ga_grow(&ga, 1) == FAIL)
		break;
	    ((char_u **)ga.ga_data)[ga.ga_len] = vim_strnsave(s, (int)(e - s));
	    ++ga.ga_len;
	}

	if (*e != NUL)
	    ++e;
    }
    vim_free(retstr);
    *file = ga.ga_data;
    *num_file = ga.ga_len;
    return OK;
}

/*
 * Expand names with a list returned by a function defined by the user.
 */
    static int
ExpandUserList(
    expand_T	*xp,
    int		*num_file,
    char_u	***file)
{
    list_T      *retlist;
    listitem_T	*li;
    garray_T	ga;

    retlist = call_user_expand_func(call_func_retlist, xp, num_file, file);
    if (retlist == NULL)
	return FAIL;

    ga_init2(&ga, (int)sizeof(char *), 3);
    // Loop over the items in the list.
    for (li = retlist->lv_first; li != NULL; li = li->li_next)
    {
	if (li->li_tv.v_type != VAR_STRING || li->li_tv.vval.v_string == NULL)
	    continue;  // Skip non-string items and empty strings

	if (ga_grow(&ga, 1) == FAIL)
	    break;

	((char_u **)ga.ga_data)[ga.ga_len] =
					 vim_strsave(li->li_tv.vval.v_string);
	++ga.ga_len;
    }
    list_unref(retlist);

    *file = ga.ga_data;
    *num_file = ga.ga_len;
    return OK;
}
# endif

/*
 * Expand color scheme, compiler or filetype names.
 * Search from 'runtimepath':
 *   'runtimepath'/{dirnames}/{pat}.vim
 * When "flags" has DIP_START: search also from 'start' of 'packpath':
 *   'packpath'/pack/ * /start/ * /{dirnames}/{pat}.vim
 * When "flags" has DIP_OPT: search also from 'opt' of 'packpath':
 *   'packpath'/pack/ * /opt/ * /{dirnames}/{pat}.vim
 * "dirnames" is an array with one or more directory names.
 */
    static int
ExpandRTDir(
    char_u	*pat,
    int		flags,
    int		*num_file,
    char_u	***file,
    char	*dirnames[])
{
    char_u	*s;
    char_u	*e;
    char_u	*match;
    garray_T	ga;
    int		i;
    int		pat_len;

    *num_file = 0;
    *file = NULL;
    pat_len = (int)STRLEN(pat);
    ga_init2(&ga, (int)sizeof(char *), 10);

    for (i = 0; dirnames[i] != NULL; ++i)
    {
	s = alloc(STRLEN(dirnames[i]) + pat_len + 7);
	if (s == NULL)
	{
	    ga_clear_strings(&ga);
	    return FAIL;
	}
	sprintf((char *)s, "%s/%s*.vim", dirnames[i], pat);
	globpath(p_rtp, s, &ga, 0);
	vim_free(s);
    }

    if (flags & DIP_START) {
	for (i = 0; dirnames[i] != NULL; ++i)
	{
	    s = alloc(STRLEN(dirnames[i]) + pat_len + 22);
	    if (s == NULL)
	    {
		ga_clear_strings(&ga);
		return FAIL;
	    }
	    sprintf((char *)s, "pack/*/start/*/%s/%s*.vim", dirnames[i], pat);
	    globpath(p_pp, s, &ga, 0);
	    vim_free(s);
	}
    }

    if (flags & DIP_OPT) {
	for (i = 0; dirnames[i] != NULL; ++i)
	{
	    s = alloc(STRLEN(dirnames[i]) + pat_len + 20);
	    if (s == NULL)
	    {
		ga_clear_strings(&ga);
		return FAIL;
	    }
	    sprintf((char *)s, "pack/*/opt/*/%s/%s*.vim", dirnames[i], pat);
	    globpath(p_pp, s, &ga, 0);
	    vim_free(s);
	}
    }

    for (i = 0; i < ga.ga_len; ++i)
    {
	match = ((char_u **)ga.ga_data)[i];
	s = match;
	e = s + STRLEN(s);
	if (e - 4 > s && STRNICMP(e - 4, ".vim", 4) == 0)
	{
	    e -= 4;
	    for (s = e; s > match; MB_PTR_BACK(match, s))
		if (s < match || vim_ispathsep(*s))
		    break;
	    ++s;
	    *e = NUL;
	    mch_memmove(match, s, e - s + 1);
	}
    }

    if (ga.ga_len == 0)
	return FAIL;

    // Sort and remove duplicates which can happen when specifying multiple
    // directories in dirnames.
    remove_duplicates(&ga);

    *file = ga.ga_data;
    *num_file = ga.ga_len;
    return OK;
}

/*
 * Expand loadplugin names:
 * 'packpath'/pack/ * /opt/{pat}
 */
    static int
ExpandPackAddDir(
    char_u	*pat,
    int		*num_file,
    char_u	***file)
{
    char_u	*s;
    char_u	*e;
    char_u	*match;
    garray_T	ga;
    int		i;
    int		pat_len;

    *num_file = 0;
    *file = NULL;
    pat_len = (int)STRLEN(pat);
    ga_init2(&ga, (int)sizeof(char *), 10);

    s = alloc(pat_len + 26);
    if (s == NULL)
    {
	ga_clear_strings(&ga);
	return FAIL;
    }
    sprintf((char *)s, "pack/*/opt/%s*", pat);
    globpath(p_pp, s, &ga, 0);
    vim_free(s);

    for (i = 0; i < ga.ga_len; ++i)
    {
	match = ((char_u **)ga.ga_data)[i];
	s = gettail(match);
	e = s + STRLEN(s);
	mch_memmove(match, s, e - s + 1);
    }

    if (ga.ga_len == 0)
	return FAIL;

    // Sort and remove duplicates which can happen when specifying multiple
    // directories in dirnames.
    remove_duplicates(&ga);

    *file = ga.ga_data;
    *num_file = ga.ga_len;
    return OK;
}

/*
 * Expand "file" for all comma-separated directories in "path".
 * Adds the matches to "ga".  Caller must init "ga".
 */
    void
globpath(
    char_u	*path,
    char_u	*file,
    garray_T	*ga,
    int		expand_options)
{
    expand_T	xpc;
    char_u	*buf;
    int		i;
    int		num_p;
    char_u	**p;

    buf = alloc(MAXPATHL);
    if (buf == NULL)
	return;

    ExpandInit(&xpc);
    xpc.xp_context = EXPAND_FILES;

    // Loop over all entries in {path}.
    while (*path != NUL)
    {
	// Copy one item of the path to buf[] and concatenate the file name.
	copy_option_part(&path, buf, MAXPATHL, ",");
	if (STRLEN(buf) + STRLEN(file) + 2 < MAXPATHL)
	{
# if defined(MSWIN)
	    // Using the platform's path separator (\) makes vim incorrectly
	    // treat it as an escape character, use '/' instead.
	    if (*buf != NUL && !after_pathsep(buf, buf + STRLEN(buf)))
		STRCAT(buf, "/");
# else
	    add_pathsep(buf);
# endif
	    STRCAT(buf, file);
	    if (ExpandFromContext(&xpc, buf, &num_p, &p,
			     WILD_SILENT|expand_options) != FAIL && num_p > 0)
	    {
		ExpandEscape(&xpc, buf, num_p, p, WILD_SILENT|expand_options);

		if (ga_grow(ga, num_p) == OK)
		{
		    for (i = 0; i < num_p; ++i)
		    {
			((char_u **)ga->ga_data)[ga->ga_len] =
					vim_strnsave(p[i], (int)STRLEN(p[i]));
			++ga->ga_len;
		    }
		}

		FreeWild(num_p, p);
	    }
	}
    }

    vim_free(buf);
}

#if defined(FEAT_EVAL) || defined(PROTO)
/*
 * "getcompletion()" function
 */
    void
f_getcompletion(typval_T *argvars, typval_T *rettv)
{
    char_u	*pat;
    expand_T	xpc;
    int		filtered = FALSE;
    int		options = WILD_SILENT | WILD_USE_NL | WILD_ADD_SLASH
					| WILD_NO_BEEP;

    if (argvars[2].v_type != VAR_UNKNOWN)
	filtered = tv_get_number_chk(&argvars[2], NULL);

    if (p_wic)
	options |= WILD_ICASE;

    // For filtered results, 'wildignore' is used
    if (!filtered)
	options |= WILD_KEEP_ALL;

    ExpandInit(&xpc);
    xpc.xp_pattern = tv_get_string(&argvars[0]);
    xpc.xp_pattern_len = (int)STRLEN(xpc.xp_pattern);
    xpc.xp_context = cmdcomplete_str_to_type(tv_get_string(&argvars[1]));
    if (xpc.xp_context == EXPAND_NOTHING)
    {
	if (argvars[1].v_type == VAR_STRING)
	    semsg(_(e_invarg2), argvars[1].vval.v_string);
	else
	    emsg(_(e_invarg));
	return;
    }

# if defined(FEAT_MENU)
    if (xpc.xp_context == EXPAND_MENUS)
    {
	set_context_in_menu_cmd(&xpc, (char_u *)"menu", xpc.xp_pattern, FALSE);
	xpc.xp_pattern_len = (int)STRLEN(xpc.xp_pattern);
    }
# endif
# ifdef FEAT_CSCOPE
    if (xpc.xp_context == EXPAND_CSCOPE)
    {
	set_context_in_cscope_cmd(&xpc, xpc.xp_pattern, CMD_cscope);
	xpc.xp_pattern_len = (int)STRLEN(xpc.xp_pattern);
    }
# endif
# ifdef FEAT_SIGNS
    if (xpc.xp_context == EXPAND_SIGN)
    {
	set_context_in_sign_cmd(&xpc, xpc.xp_pattern);
	xpc.xp_pattern_len = (int)STRLEN(xpc.xp_pattern);
    }
# endif

    pat = addstar(xpc.xp_pattern, xpc.xp_pattern_len, xpc.xp_context);
    if ((rettv_list_alloc(rettv) != FAIL) && (pat != NULL))
    {
	int	i;

	ExpandOne(&xpc, pat, NULL, options, WILD_ALL_KEEP);

	for (i = 0; i < xpc.xp_numfiles; i++)
	    list_append_string(rettv->vval.v_list, xpc.xp_files[i], -1);
    }
    vim_free(pat);
    ExpandCleanup(&xpc);
}
#endif // FEAT_EVAL