new file mode 100644
--- /dev/null
+++ b/src/beval.c
@@ -0,0 +1,280 @@
+/* vi:set ts=8 sts=4 sw=4 noet:
+ *
+ * VIM - Vi IMproved	by Bram Moolenaar
+ *			Visual Workshop integration by Gordon Prieur
+ *
+ * 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.
+ */
+
+#include "vim.h"
+
+#if defined(FEAT_BEVAL) || defined(PROTO)
+
+/*
+ * Get the text and position to be evaluated for "beval".
+ * If "getword" is true the returned text is not the whole line but the
+ * relevant word in allocated memory.
+ * Returns OK or FAIL.
+ */
+    int
+get_beval_info(
+    BalloonEval	*beval,
+    int		getword,
+    win_T	**winp,
+    linenr_T	*lnump,
+    char_u	**textp,
+    int		*colp)
+{
+    win_T	*wp;
+    int		row, col;
+    char_u	*lbuf;
+    linenr_T	lnum;
+
+    *textp = NULL;
+# ifdef FEAT_BEVAL_TERM
+#  ifdef FEAT_GUI
+    if (!gui.in_use)
+#  endif
+    {
+	row = mouse_row;
+	col = mouse_col;
+    }
+# endif
+# ifdef FEAT_GUI
+    if (gui.in_use)
+    {
+	row = Y_2_ROW(beval->y);
+	col = X_2_COL(beval->x);
+    }
+#endif
+    wp = mouse_find_win(&row, &col);
+    if (wp != NULL && row < wp->w_height && col < wp->w_width)
+    {
+	/* Found a window and the cursor is in the text.  Now find the line
+	 * number. */
+	if (!mouse_comp_pos(wp, &row, &col, &lnum))
+	{
+	    /* Not past end of the file. */
+	    lbuf = ml_get_buf(wp->w_buffer, lnum, FALSE);
+	    if (col <= win_linetabsize(wp, lbuf, (colnr_T)MAXCOL))
+	    {
+		/* Not past end of line. */
+		if (getword)
+		{
+		    /* For Netbeans we get the relevant part of the line
+		     * instead of the whole line. */
+		    int		len;
+		    pos_T	*spos = NULL, *epos = NULL;
+
+		    if (VIsual_active)
+		    {
+			if (LT_POS(VIsual, curwin->w_cursor))
+			{
+			    spos = &VIsual;
+			    epos = &curwin->w_cursor;
+			}
+			else
+			{
+			    spos = &curwin->w_cursor;
+			    epos = &VIsual;
+			}
+		    }
+
+		    col = vcol2col(wp, lnum, col);
+
+		    if (VIsual_active
+			    && wp->w_buffer == curwin->w_buffer
+			    && (lnum == spos->lnum
+				? col >= (int)spos->col
+				: lnum > spos->lnum)
+			    && (lnum == epos->lnum
+				? col <= (int)epos->col
+				: lnum < epos->lnum))
+		    {
+			/* Visual mode and pointing to the line with the
+			 * Visual selection: return selected text, with a
+			 * maximum of one line. */
+			if (spos->lnum != epos->lnum || spos->col == epos->col)
+			    return FAIL;
+
+			lbuf = ml_get_buf(curwin->w_buffer, VIsual.lnum, FALSE);
+			len = epos->col - spos->col;
+			if (*p_sel != 'e')
+			    len += MB_PTR2LEN(lbuf + epos->col);
+			lbuf = vim_strnsave(lbuf + spos->col, len);
+			lnum = spos->lnum;
+			col = spos->col;
+		    }
+		    else
+		    {
+			/* Find the word under the cursor. */
+			++emsg_off;
+			len = find_ident_at_pos(wp, lnum, (colnr_T)col, &lbuf,
+					FIND_IDENT + FIND_STRING + FIND_EVAL);
+			--emsg_off;
+			if (len == 0)
+			    return FAIL;
+			lbuf = vim_strnsave(lbuf, len);
+		    }
+		}
+
+		*winp = wp;
+		*lnump = lnum;
+		*textp = lbuf;
+		*colp = col;
+		beval->ts = wp->w_buffer->b_p_ts;
+		return OK;
+	    }
+	}
+    }
+
+    return FAIL;
+}
+
+/*
+ * Show a balloon with "mesg".
+ */
+    void
+post_balloon(BalloonEval *beval UNUSED, char_u *mesg)
+{
+# ifdef FEAT_BEVAL_TERM
+#  ifdef FEAT_GUI
+    if (!gui.in_use)
+#  endif
+	ui_post_balloon(mesg);
+# endif
+# ifdef FEAT_BEVAL_GUI
+    if (gui.in_use)
+	gui_mch_post_balloon(beval, mesg);
+# endif
+}
+
+/*
+ * Returns TRUE if the balloon eval has been enabled:
+ * 'ballooneval' for the GUI and 'balloonevalterm' for the terminal.
+ * Also checks if the screen isn't scrolled up.
+ */
+    int
+can_use_beval(void)
+{
+    return (0
+#ifdef FEAT_BEVAL_GUI
+		|| (gui.in_use && p_beval)
+#endif
+#ifdef FEAT_BEVAL_TERM
+		|| (
+# ifdef FEAT_GUI
+		    !gui.in_use &&
+# endif
+		    p_bevalterm)
+#endif
+	     ) && msg_scrolled == 0;
+}
+
+/*
+ * Common code, invoked when the mouse is resting for a moment.
+ */
+    void
+general_beval_cb(BalloonEval *beval, int state UNUSED)
+{
+#ifdef FEAT_EVAL
+    win_T	*wp;
+    int		col;
+    int		use_sandbox;
+    linenr_T	lnum;
+    char_u	*text;
+    static char_u  *result = NULL;
+    long	winnr = 0;
+    char_u	*bexpr;
+    buf_T	*save_curbuf;
+    size_t	len;
+    win_T	*cw;
+#endif
+    static int	recursive = FALSE;
+
+    /* Don't do anything when 'ballooneval' is off, messages scrolled the
+     * windows up or we have no beval area. */
+    if (!can_use_beval() || beval == NULL)
+	return;
+
+    /* Don't do this recursively.  Happens when the expression evaluation
+     * takes a long time and invokes something that checks for CTRL-C typed. */
+    if (recursive)
+	return;
+    recursive = TRUE;
+
+#ifdef FEAT_EVAL
+    if (get_beval_info(beval, TRUE, &wp, &lnum, &text, &col) == OK)
+    {
+	bexpr = (*wp->w_buffer->b_p_bexpr == NUL) ? p_bexpr
+						    : wp->w_buffer->b_p_bexpr;
+	if (*bexpr != NUL)
+	{
+	    /* Convert window pointer to number. */
+	    for (cw = firstwin; cw != wp; cw = cw->w_next)
+		++winnr;
+
+	    set_vim_var_nr(VV_BEVAL_BUFNR, (long)wp->w_buffer->b_fnum);
+	    set_vim_var_nr(VV_BEVAL_WINNR, winnr);
+	    set_vim_var_nr(VV_BEVAL_WINID, wp->w_id);
+	    set_vim_var_nr(VV_BEVAL_LNUM, (long)lnum);
+	    set_vim_var_nr(VV_BEVAL_COL, (long)(col + 1));
+	    set_vim_var_string(VV_BEVAL_TEXT, text, -1);
+	    vim_free(text);
+
+	    /*
+	     * Temporarily change the curbuf, so that we can determine whether
+	     * the buffer-local balloonexpr option was set insecurely.
+	     */
+	    save_curbuf = curbuf;
+	    curbuf = wp->w_buffer;
+	    use_sandbox = was_set_insecurely((char_u *)"balloonexpr",
+				 *curbuf->b_p_bexpr == NUL ? 0 : OPT_LOCAL);
+	    curbuf = save_curbuf;
+	    if (use_sandbox)
+		++sandbox;
+	    ++textlock;
+
+	    vim_free(result);
+	    result = eval_to_string(bexpr, NULL, TRUE);
+
+	    /* Remove one trailing newline, it is added when the result was a
+	     * list and it's hardly ever useful.  If the user really wants a
+	     * trailing newline he can add two and one remains. */
+	    if (result != NULL)
+	    {
+		len = STRLEN(result);
+		if (len > 0 && result[len - 1] == NL)
+		    result[len - 1] = NUL;
+	    }
+
+	    if (use_sandbox)
+		--sandbox;
+	    --textlock;
+
+	    set_vim_var_string(VV_BEVAL_TEXT, NULL, -1);
+	    if (result != NULL && result[0] != NUL)
+	    {
+		post_balloon(beval, result);
+		recursive = FALSE;
+		return;
+	    }
+	}
+    }
+#endif
+#ifdef FEAT_NETBEANS_INTG
+    if (bevalServers & BEVAL_NETBEANS)
+	netbeans_beval_cb(beval, state);
+#endif
+#ifdef FEAT_SUN_WORKSHOP
+    if (bevalServers & BEVAL_WORKSHOP)
+	workshop_beval_cb(beval, state);
+#endif
+
+    recursive = FALSE;
+}
+
+#endif
+