/* $Id$ */
/*
* Copyright (c) 2008 Kristaps Dzonsons <kristaps@kth.se>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the
* above copyright notice and this permission notice appear in all
* copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
* WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
* AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include <assert.h>
#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#ifdef __linux__
#include <time.h>
#endif
#include "private.h"
/* FIXME: maxlineargs should be per LINE, no per TOKEN. */
static int rewind_elem(struct mdoc *, int);
static int rewind_impblock(struct mdoc *, int);
static int rewind_expblock(struct mdoc *, int);
static int rewind_head(struct mdoc *, int);
static int rewind_body(struct mdoc *, int);
static int rewind_last(struct mdoc *, struct mdoc_node *);
static int append_delims(struct mdoc *,
int, int, int *, char *);
static int lookup(struct mdoc *, int, int, int, const char *);
static int
lookup(struct mdoc *mdoc, int line, int pos, int from, const char *p)
{
int res;
res = mdoc_find(mdoc, p);
if (MDOC_PARSED & mdoc_macros[from].flags)
return(res);
if (MDOC_MAX == res)
return(res);
if ( ! mdoc_pwarn(mdoc, line, pos, WARN_SYNTAX_MACLIKE))
return(-1);
return(MDOC_MAX);
}
static int
rewind_last(struct mdoc *mdoc, struct mdoc_node *to)
{
assert(to);
mdoc->next = MDOC_NEXT_SIBLING;
if (mdoc->last == to) {
if ( ! mdoc_valid_post(mdoc))
return(0);
if ( ! mdoc_action_post(mdoc))
return(0);
return(1);
}
do {
mdoc->last = mdoc->last->parent;
assert(mdoc->last);
if ( ! mdoc_valid_post(mdoc))
return(0);
if ( ! mdoc_action_post(mdoc))
return(0);
} while (mdoc->last != to);
return(1);
}
static int
rewind_elem(struct mdoc *mdoc, int tok)
{
struct mdoc_node *n;
n = mdoc->last;
if (MDOC_ELEM != n->type)
n = n->parent;
assert(MDOC_ELEM == n->type);
assert(tok == n->tok);
return(rewind_last(mdoc, n));
}
static int
rewind_body(struct mdoc *mdoc, int tok)
{
struct mdoc_node *n;
int t;
assert(mdoc->last);
/* LINTED */
for (n = mdoc->last; n; n = n->parent) {
if (MDOC_BODY != n->type)
continue;
if (tok == (t = n->tok))
break;
if ( ! (MDOC_EXPLICIT & mdoc_macros[t].flags))
continue;
return(mdoc_verr(mdoc, n, ERR_SCOPE_BREAK));
}
assert(n);
return(rewind_last(mdoc, n));
}
static int
rewind_head(struct mdoc *mdoc, int tok)
{
struct mdoc_node *n;
int t;
assert(mdoc->last);
/* LINTED */
for (n = mdoc->last; n; n = n->parent) {
if (MDOC_HEAD != n->type)
continue;
if (tok == (t = n->tok))
break;
if ( ! (MDOC_EXPLICIT & mdoc_macros[t].flags))
continue;
return(mdoc_verr(mdoc, n, ERR_SCOPE_BREAK));
}
assert(n);
return(rewind_last(mdoc, n));
}
static int
rewind_expblock(struct mdoc *mdoc, int tok)
{
struct mdoc_node *n;
int t;
n = mdoc->last ? mdoc->last->parent : NULL;
/* LINTED */
for ( ; n; n = n->parent) {
if (MDOC_BLOCK != n->type)
continue;
if (tok == (t = n->tok))
break;
if (MDOC_NESTED & mdoc_macros[t].flags)
continue;
return(mdoc_verr(mdoc, n, ERR_SCOPE_BREAK));
}
assert(n);
return(rewind_last(mdoc, n));
}
static int
rewind_impblock(struct mdoc *mdoc, int tok)
{
int t;
struct mdoc_node *n;
n = mdoc->last ? mdoc->last->parent : NULL;
/* LINTED */
for ( ; n; n = n->parent) {
if (MDOC_BLOCK != n->type)
continue;
if (tok == (t = n->tok))
break;
if ( ! (MDOC_EXPLICIT & mdoc_macros[t].flags))
continue;
if (MDOC_NESTED & mdoc_macros[tok].flags)
return(1);
return(mdoc_verr(mdoc, n, ERR_SCOPE_BREAK));
}
if (NULL == n)
return(1);
return(rewind_last(mdoc, n));
}
static int
append_delims(struct mdoc *mdoc, int tok,
int line, int *pos, char *buf)
{
int c, lastarg;
char *p;
if (0 == buf[*pos])
return(1);
for (;;) {
lastarg = *pos;
c = mdoc_args(mdoc, line, pos, buf, 0, &p);
if (ARGS_ERROR == c)
return(0);
else if (ARGS_EOLN == c)
break;
assert(mdoc_isdelim(p));
if ( ! mdoc_word_alloc(mdoc, line, lastarg, p))
return(0);
mdoc->next = MDOC_NEXT_SIBLING;
}
return(1);
}
/* ARGSUSED */
int
macro_close_explicit(MACRO_PROT_ARGS)
{
int tt, j, c, lastarg, maxargs, flushed;
char *p;
switch (tok) {
case (MDOC_Ac):
tt = MDOC_Ao;
break;
case (MDOC_Bc):
tt = MDOC_Bo;
break;
case (MDOC_Dc):
tt = MDOC_Do;
break;
case (MDOC_Ec):
tt = MDOC_Eo;
break;
case (MDOC_Ed):
tt = MDOC_Bd;
break;
case (MDOC_Ef):
tt = MDOC_Bf;
break;
case (MDOC_Ek):
tt = MDOC_Bk;
break;
case (MDOC_El):
tt = MDOC_Bl;
break;
case (MDOC_Fc):
tt = MDOC_Fo;
break;
case (MDOC_Oc):
tt = MDOC_Oo;
break;
case (MDOC_Pc):
tt = MDOC_Po;
break;
case (MDOC_Qc):
tt = MDOC_Qo;
break;
case (MDOC_Re):
tt = MDOC_Rs;
break;
case (MDOC_Sc):
tt = MDOC_So;
break;
case (MDOC_Xc):
tt = MDOC_Xo;
break;
default:
abort();
/* NOTREACHED */
}
switch (tok) {
case (MDOC_Ec):
maxargs = 1;
break;
default:
maxargs = 0;
break;
}
if ( ! (MDOC_CALLABLE & mdoc_macros[tok].flags)) {
if (0 == buf[*pos])
return(rewind_expblock(mdoc, tt));
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_EQ0));
}
if ( ! rewind_body(mdoc, tt))
return(0);
lastarg = ppos;
flushed = 0;
if (maxargs > 0) {
if ( ! mdoc_tail_alloc(mdoc, line, ppos, tt))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
}
for (j = 0; j < MDOC_LINEARG_MAX; j++) {
lastarg = *pos;
if (j == maxargs && ! flushed) {
if ( ! rewind_expblock(mdoc, tt))
return(0);
flushed = 1;
}
c = mdoc_args(mdoc, line, pos, buf, ARGS_DELIM, &p);
if (ARGS_ERROR == c)
return(0);
if (ARGS_PUNCT == c)
break;
if (ARGS_EOLN == c)
break;
if (-1 == (c = lookup(mdoc, line, lastarg, tok, p)))
return(0);
else if (MDOC_MAX != c) {
if ( ! flushed) {
if ( ! rewind_expblock(mdoc, tt))
return(0);
flushed = 1;
}
if ( ! mdoc_macro(mdoc, c, line, lastarg, pos, buf))
return(0);
break;
}
if ( ! mdoc_word_alloc(mdoc, line, lastarg, p))
return(0);
mdoc->next = MDOC_NEXT_SIBLING;
}
if (MDOC_LINEARG_MAX == j)
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
if ( ! flushed && ! rewind_expblock(mdoc, tt))
return(0);
if (ppos > 1)
return(1);
return(append_delims(mdoc, tok, line, pos, buf));
}
/*
* A general text domain macro. When invoked, this opens a scope that
* accepts words until either end-of-line, only-punctuation, or a
* callable macro. If the word is punctuation (not only-punctuation),
* then the scope is closed out, the punctuation appended, then the
* scope opened again. If any terminating conditions are met, the scope
* is closed out. If this is the first macro in the line and
* only-punctuation remains, this punctuation is flushed.
*/
int
macro_text(MACRO_PROT_ARGS)
{
int la, lastpunct, c, sz, fl, argc;
struct mdoc_arg argv[MDOC_LINEARG_MAX];
char *p;
la = ppos;
lastpunct = 0;
for (argc = 0; argc < MDOC_LINEARG_MAX; argc++) {
la = *pos;
c = mdoc_argv(mdoc, line, tok, &argv[argc], pos, buf);
if (ARGV_EOLN == c || ARGV_WORD == c)
break;
else if (ARGV_ARG == c)
continue;
mdoc_argv_free(argc, argv);
return(0);
}
if (MDOC_LINEARG_MAX == argc) {
mdoc_argv_free(argc, argv);
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
}
c = mdoc_elem_alloc(mdoc, line, la, tok, argc, argv);
if (0 == c) {
mdoc_argv_free(argc, argv);
return(0);
}
mdoc->next = MDOC_NEXT_CHILD;
fl = ARGS_DELIM;
if (MDOC_QUOTABLE & mdoc_macros[tok].flags)
fl |= ARGS_QUOTED;
for (lastpunct = sz = 0; sz + argc < MDOC_LINEARG_MAX; sz++) {
la = *pos;
if (lastpunct) {
c = mdoc_elem_alloc(mdoc, line,
la, tok, argc, argv);
if (0 == c) {
mdoc_argv_free(argc, argv);
return(0);
}
mdoc->next = MDOC_NEXT_CHILD;
lastpunct = 0;
}
c = mdoc_args(mdoc, line, pos, buf, fl, &p);
if (ARGS_ERROR == c) {
mdoc_argv_free(argc, argv);
return(0);
}
if (ARGS_EOLN == c)
break;
if (ARGS_PUNCT == c)
break;
if (-1 == (c = lookup(mdoc, line, la, tok, p)))
return(0);
else if (MDOC_MAX != c) {
if ( ! rewind_elem(mdoc, tok)) {
mdoc_argv_free(argc, argv);
return(0);
}
mdoc_argv_free(argc, argv);
c = mdoc_macro(mdoc, c, line, la, pos, buf);
if (0 == c)
return(0);
if (ppos > 1)
return(1);
return(append_delims(mdoc, tok, line, pos, buf));
}
if (mdoc_isdelim(p)) {
if ( ! rewind_elem(mdoc, tok)) {
mdoc_argv_free(argc, argv);
return(0);
}
lastpunct = 1;
}
if ( ! mdoc_word_alloc(mdoc, line, la, p))
return(0);
mdoc->next = MDOC_NEXT_SIBLING;
}
mdoc_argv_free(argc, argv);
if (sz == MDOC_LINEARG_MAX)
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
if ( ! rewind_elem(mdoc, tok))
return(0);
if (ppos > 1)
return(1);
return(append_delims(mdoc, tok, line, pos, buf));
}
/*
* Implicit- or explicit-end multi-line scoped macro.
*/
int
macro_scoped(MACRO_PROT_ARGS)
{
int c, lastarg, argc, j, fl;
struct mdoc_arg argv[MDOC_LINEARG_MAX];
char *p;
assert ( ! (MDOC_CALLABLE & mdoc_macros[tok].flags));
if ( ! (MDOC_EXPLICIT & mdoc_macros[tok].flags))
if ( ! rewind_impblock(mdoc, tok))
return(0);
for (argc = 0; argc < MDOC_LINEARG_MAX; argc++) {
lastarg = *pos;
c = mdoc_argv(mdoc, line, tok, &argv[argc], pos, buf);
if (ARGV_EOLN == c || ARGV_WORD == c)
break;
else if (ARGV_ARG == c)
continue;
mdoc_argv_free(argc, argv);
return(0);
}
if (MDOC_LINEARG_MAX == argc) {
mdoc_argv_free(argc, argv);
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
}
c = mdoc_block_alloc(mdoc, line, ppos,
tok, (size_t)argc, argv);
mdoc_argv_free(argc, argv);
if (0 == c)
return(0);
mdoc->next = MDOC_NEXT_CHILD;
if (0 == buf[*pos]) {
if ( ! mdoc_head_alloc(mdoc, line, ppos, tok))
return(0);
if ( ! rewind_head(mdoc, tok))
return(0);
if ( ! mdoc_body_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
return(1);
}
if ( ! mdoc_head_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
fl = ARGS_DELIM;
if (MDOC_TABSEP & mdoc_macros[tok].flags)
fl |= ARGS_TABSEP;
for (j = 0; j < MDOC_LINEARG_MAX; j++) {
lastarg = *pos;
c = mdoc_args(mdoc, line, pos, buf, fl, &p);
if (ARGS_ERROR == c)
return(0);
if (ARGS_PUNCT == c)
break;
if (ARGS_EOLN == c)
break;
if (-1 == (c = lookup(mdoc, line, lastarg, tok, p)))
return(0);
else if (MDOC_MAX == c) {
if ( ! mdoc_word_alloc(mdoc, line, lastarg, p))
return(0);
mdoc->next = MDOC_NEXT_SIBLING;
continue;
}
if ( ! mdoc_macro(mdoc, c, line, lastarg, pos, buf))
return(0);
break;
}
if (j == MDOC_LINEARG_MAX)
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
if ( ! rewind_head(mdoc, tok))
return(0);
if (1 == ppos && ! append_delims(mdoc, tok, line, pos, buf))
return(0);
if ( ! mdoc_body_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
return(1);
}
/*
* When scoped to a line, a macro encompasses all of the contents. This
* differs from constants or text macros, where a new macro will
* terminate the existing context.
*/
int
macro_scoped_line(MACRO_PROT_ARGS)
{
int lastarg, c, j;
char *p;
if ( ! mdoc_block_alloc(mdoc, line, ppos, tok, 0, NULL))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
if ( ! mdoc_head_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
/* XXX - no known argument macros. */
for (lastarg = ppos, j = 0; j < MDOC_LINEARG_MAX; j++) {
lastarg = *pos;
c = mdoc_args(mdoc, line, pos, buf, ARGS_DELIM, &p);
if (ARGS_ERROR == c)
return(0);
if (ARGS_PUNCT == c)
break;
if (ARGS_EOLN == c)
break;
if (-1 == (c = lookup(mdoc, line, lastarg, tok, p)))
return(0);
else if (MDOC_MAX == c) {
if ( ! mdoc_word_alloc(mdoc, line, lastarg, p))
return(0);
mdoc->next = MDOC_NEXT_SIBLING;
continue;
}
if ( ! mdoc_macro(mdoc, c, line, lastarg, pos, buf))
return(0);
break;
}
if (j == MDOC_LINEARG_MAX)
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
if (1 == ppos) {
if ( ! rewind_head(mdoc, tok))
return(0);
if ( ! append_delims(mdoc, tok, line, pos, buf))
return(0);
}
return(rewind_impblock(mdoc, tok));
}
/*
* Constant-scope macros accept a fixed number of arguments and behave
* like constant macros except that they're scoped across lines.
*/
int
macro_constant_scoped(MACRO_PROT_ARGS)
{
int lastarg, flushed, j, c, maxargs;
char *p;
lastarg = ppos;
flushed = 0;
switch (tok) {
case (MDOC_Eo):
maxargs = 1;
break;
default:
maxargs = 0;
break;
}
if ( ! mdoc_block_alloc(mdoc, line, ppos, tok, 0, NULL))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
if (0 == maxargs) {
if ( ! mdoc_head_alloc(mdoc, line, ppos, tok))
return(0);
if ( ! rewind_head(mdoc, tok))
return(0);
if ( ! mdoc_body_alloc(mdoc, line, ppos, tok))
return(0);
flushed = 1;
} else if ( ! mdoc_head_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
for (j = 0; j < MDOC_LINEARG_MAX; j++) {
lastarg = *pos;
if (j == maxargs && ! flushed) {
if ( ! rewind_head(mdoc, tok))
return(0);
flushed = 1;
if ( ! mdoc_body_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
}
c = mdoc_args(mdoc, line, pos, buf, ARGS_DELIM, &p);
if (ARGS_ERROR == c)
return(0);
if (ARGS_PUNCT == c)
break;
if (ARGS_EOLN == c)
break;
if (-1 == (c = lookup(mdoc, line, lastarg, tok, p)))
return(0);
else if (MDOC_MAX != c) {
if ( ! flushed) {
if ( ! rewind_head(mdoc, tok))
return(0);
flushed = 1;
if ( ! mdoc_body_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
}
if ( ! mdoc_macro(mdoc, c, line, lastarg, pos, buf))
return(0);
break;
}
if ( ! flushed && mdoc_isdelim(p)) {
if ( ! rewind_head(mdoc, tok))
return(0);
flushed = 1;
if ( ! mdoc_body_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
}
if ( ! mdoc_word_alloc(mdoc, line, lastarg, p))
return(0);
mdoc->next = MDOC_NEXT_SIBLING;
}
if (MDOC_LINEARG_MAX == j)
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
if ( ! flushed) {
if ( ! rewind_head(mdoc, tok))
return(0);
if ( ! mdoc_body_alloc(mdoc, line, ppos, tok))
return(0);
mdoc->next = MDOC_NEXT_CHILD;
}
if (ppos > 1)
return(1);
return(append_delims(mdoc, tok, line, pos, buf));
}
/*
* Delimited macros are like text macros except that, should punctuation
* be encountered, the macro isn't re-started with remaining tokens
* (it's only emitted once). Delimited macros can have a maximum number
* of arguments.
*/
int
macro_constant_delimited(MACRO_PROT_ARGS)
{
int lastarg, flushed, j, c, maxargs, argc;
struct mdoc_arg argv[MDOC_LINEARG_MAX];
char *p;
lastarg = ppos;
flushed = 0;
switch (tok) {
case (MDOC_No):
/* FALLTHROUGH */
case (MDOC_Ns):
/* FALLTHROUGH */
case (MDOC_Ux):
/* FALLTHROUGH */
case (MDOC_St):
maxargs = 0;
break;
default:
maxargs = 1;
break;
}
for (argc = 0; argc < MDOC_LINEARG_MAX; argc++) {
lastarg = *pos;
c = mdoc_argv(mdoc, line, tok, &argv[argc], pos, buf);
if (ARGV_EOLN == c || ARGV_WORD == c)
break;
else if (ARGV_ARG == c)
continue;
mdoc_argv_free(argc, argv);
return(0);
}
c = mdoc_elem_alloc(mdoc, line, lastarg, tok, argc, argv);
mdoc_argv_free(argc, argv);
if (0 == c)
return(0);
mdoc->next = MDOC_NEXT_CHILD;
for (j = 0; j < MDOC_LINEARG_MAX; j++) {
lastarg = *pos;
if (j == maxargs && ! flushed) {
if ( ! rewind_elem(mdoc, tok))
return(0);
flushed = 1;
}
c = mdoc_args(mdoc, line, pos, buf, ARGS_DELIM, &p);
if (ARGS_ERROR == c)
return(0);
if (ARGS_PUNCT == c)
break;
if (ARGS_EOLN == c)
break;
if (-1 == (c = lookup(mdoc, line, lastarg, tok, p)))
return(0);
else if (MDOC_MAX != c) {
if ( ! flushed && ! rewind_elem(mdoc, tok))
return(0);
flushed = 1;
if ( ! mdoc_macro(mdoc, c, line, lastarg, pos, buf))
return(0);
break;
}
if ( ! flushed && mdoc_isdelim(p)) {
if ( ! rewind_elem(mdoc, tok))
return(0);
flushed = 1;
}
if ( ! mdoc_word_alloc(mdoc, line, lastarg, p))
return(0);
mdoc->next = MDOC_NEXT_SIBLING;
}
if (MDOC_LINEARG_MAX == j)
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
if ( ! flushed && rewind_elem(mdoc, tok))
return(0);
if (ppos > 1)
return(1);
return(append_delims(mdoc, tok, line, pos, buf));
}
/*
* Constant macros span an entire line: they constitute a macro and all
* of its arguments and child data.
*/
int
macro_constant(MACRO_PROT_ARGS)
{
int c, lastarg, argc, sz, fl;
struct mdoc_arg argv[MDOC_LINEARG_MAX];
char *p;
/* FIXME: parsing macros! */
fl = 0;
if (MDOC_QUOTABLE & mdoc_macros[tok].flags)
fl = ARGS_QUOTED;
for (argc = 0; argc < MDOC_LINEARG_MAX; argc++) {
lastarg = *pos;
c = mdoc_argv(mdoc, line, tok, &argv[argc], pos, buf);
if (ARGV_EOLN == c)
break;
else if (ARGV_ARG == c)
continue;
else if (ARGV_WORD == c)
break;
mdoc_argv_free(argc, argv);
return(0);
}
c = mdoc_elem_alloc(mdoc, line, ppos, tok, argc, argv);
mdoc_argv_free(argc, argv);
if (0 == c)
return(0);
mdoc->next = MDOC_NEXT_CHILD;
if (MDOC_LINEARG_MAX == argc)
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
for (sz = 0; sz + argc < MDOC_LINEARG_MAX; sz++) {
lastarg = *pos;
c = mdoc_args(mdoc, line, pos, buf, fl, &p);
if (ARGS_ERROR == c)
return(0);
if (ARGS_EOLN == c)
break;
if ( ! mdoc_word_alloc(mdoc, line, lastarg, p))
return(0);
mdoc->next = MDOC_NEXT_SIBLING;
}
if (MDOC_LINEARG_MAX == sz + argc)
return(mdoc_perr(mdoc, line, ppos, ERR_ARGS_MANY));
return(rewind_elem(mdoc, tok));
}
/* ARGSUSED */
int
macro_obsolete(MACRO_PROT_ARGS)
{
return(mdoc_pwarn(mdoc, line, ppos, WARN_IGN_OBSOLETE));
}
int
macro_end(struct mdoc *mdoc)
{
assert(mdoc->first);
assert(mdoc->last);
return(rewind_last(mdoc, mdoc->first));
}