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File: [cvsweb.bsd.lv] / mandoc / mdoc_markdown.c (download)

Revision 1.37, Tue Aug 10 12:55:03 2021 UTC (2 years, 7 months ago) by schwarze
Branch: MAIN
CVS Tags: VERSION_1_14_6, HEAD
Changes since 1.36: +4 -2 lines

Support two-character font names (BI, CW, CR, CB, CI)
in the tbl(7) layout font modifier.

Get rid of the TBL_CELL_BOLD and TBL_CELL_ITALIC flags and use
the usual ESCAPE_FONT* enum mandoc_esc members from mandoc.h instead,
which simplifies and unifies some code.

While here, also support CB and CI in roff(7) \f escape sequences
and in roff(7) .ft requests for all output modes.  Using those is
certainly not recommended because portability is limited even with
groff, but supporting them makes some existing third-party manual
pages look better, in particular in HTML output mode.

Bug-compatible with groff as far as i'm aware, except that i consider
font names starting with the '\n' (ASCII 0x0a line feed) character
so insane that i decided to not support them.

Missing feature reported by nabijaczleweli dot xyz in
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=992002.
I used none of the code from the initial patch submitted by
nabijaczleweli, but some of their ideas.
Final patch tested by them, too.

/* $Id: mdoc_markdown.c,v 1.37 2021/08/10 12:55:03 schwarze Exp $ */
/*
 * Copyright (c) 2017, 2018, 2020 Ingo Schwarze <schwarze@openbsd.org>
 *
 * 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 AUTHORS DISCLAIM ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS 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.
 *
 * Markdown formatter for mdoc(7) used by mandoc(1).
 */
#include "config.h"

#include <sys/types.h>

#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "mandoc_aux.h"
#include "mandoc.h"
#include "roff.h"
#include "mdoc.h"
#include "main.h"

struct	md_act {
	int		(*cond)(struct roff_node *);
	int		(*pre)(struct roff_node *);
	void		(*post)(struct roff_node *);
	const char	 *prefix; /* pre-node string constant */
	const char	 *suffix; /* post-node string constant */
};

static	void	 md_nodelist(struct roff_node *);
static	void	 md_node(struct roff_node *);
static	const char *md_stack(char);
static	void	 md_preword(void);
static	void	 md_rawword(const char *);
static	void	 md_word(const char *);
static	void	 md_named(const char *);
static	void	 md_char(unsigned char);
static	void	 md_uri(const char *);

static	int	 md_cond_head(struct roff_node *);
static	int	 md_cond_body(struct roff_node *);

static	int	 md_pre_abort(struct roff_node *);
static	int	 md_pre_raw(struct roff_node *);
static	int	 md_pre_word(struct roff_node *);
static	int	 md_pre_skip(struct roff_node *);
static	void	 md_pre_syn(struct roff_node *);
static	int	 md_pre_An(struct roff_node *);
static	int	 md_pre_Ap(struct roff_node *);
static	int	 md_pre_Bd(struct roff_node *);
static	int	 md_pre_Bk(struct roff_node *);
static	int	 md_pre_Bl(struct roff_node *);
static	int	 md_pre_D1(struct roff_node *);
static	int	 md_pre_Dl(struct roff_node *);
static	int	 md_pre_En(struct roff_node *);
static	int	 md_pre_Eo(struct roff_node *);
static	int	 md_pre_Fa(struct roff_node *);
static	int	 md_pre_Fd(struct roff_node *);
static	int	 md_pre_Fn(struct roff_node *);
static	int	 md_pre_Fo(struct roff_node *);
static	int	 md_pre_In(struct roff_node *);
static	int	 md_pre_It(struct roff_node *);
static	int	 md_pre_Lk(struct roff_node *);
static	int	 md_pre_Mt(struct roff_node *);
static	int	 md_pre_Nd(struct roff_node *);
static	int	 md_pre_Nm(struct roff_node *);
static	int	 md_pre_No(struct roff_node *);
static	int	 md_pre_Ns(struct roff_node *);
static	int	 md_pre_Pp(struct roff_node *);
static	int	 md_pre_Rs(struct roff_node *);
static	int	 md_pre_Sh(struct roff_node *);
static	int	 md_pre_Sm(struct roff_node *);
static	int	 md_pre_Vt(struct roff_node *);
static	int	 md_pre_Xr(struct roff_node *);
static	int	 md_pre__T(struct roff_node *);
static	int	 md_pre_br(struct roff_node *);

static	void	 md_post_raw(struct roff_node *);
static	void	 md_post_word(struct roff_node *);
static	void	 md_post_pc(struct roff_node *);
static	void	 md_post_Bk(struct roff_node *);
static	void	 md_post_Bl(struct roff_node *);
static	void	 md_post_D1(struct roff_node *);
static	void	 md_post_En(struct roff_node *);
static	void	 md_post_Eo(struct roff_node *);
static	void	 md_post_Fa(struct roff_node *);
static	void	 md_post_Fd(struct roff_node *);
static	void	 md_post_Fl(struct roff_node *);
static	void	 md_post_Fn(struct roff_node *);
static	void	 md_post_Fo(struct roff_node *);
static	void	 md_post_In(struct roff_node *);
static	void	 md_post_It(struct roff_node *);
static	void	 md_post_Lb(struct roff_node *);
static	void	 md_post_Nm(struct roff_node *);
static	void	 md_post_Pf(struct roff_node *);
static	void	 md_post_Vt(struct roff_node *);
static	void	 md_post__T(struct roff_node *);

static	const struct md_act md_acts[MDOC_MAX - MDOC_Dd] = {
	{ NULL, NULL, NULL, NULL, NULL }, /* Dd */
	{ NULL, NULL, NULL, NULL, NULL }, /* Dt */
	{ NULL, NULL, NULL, NULL, NULL }, /* Os */
	{ NULL, md_pre_Sh, NULL, NULL, NULL }, /* Sh */
	{ NULL, md_pre_Sh, NULL, NULL, NULL }, /* Ss */
	{ NULL, md_pre_Pp, NULL, NULL, NULL }, /* Pp */
	{ md_cond_body, md_pre_D1, md_post_D1, NULL, NULL }, /* D1 */
	{ md_cond_body, md_pre_Dl, md_post_D1, NULL, NULL }, /* Dl */
	{ md_cond_body, md_pre_Bd, md_post_D1, NULL, NULL }, /* Bd */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ed */
	{ md_cond_body, md_pre_Bl, md_post_Bl, NULL, NULL }, /* Bl */
	{ NULL, NULL, NULL, NULL, NULL }, /* El */
	{ NULL, md_pre_It, md_post_It, NULL, NULL }, /* It */
	{ NULL, md_pre_raw, md_post_raw, "*", "*" }, /* Ad */
	{ NULL, md_pre_An, NULL, NULL, NULL }, /* An */
	{ NULL, md_pre_Ap, NULL, NULL, NULL }, /* Ap */
	{ NULL, md_pre_raw, md_post_raw, "*", "*" }, /* Ar */
	{ NULL, md_pre_raw, md_post_raw, "**", "**" }, /* Cd */
	{ NULL, md_pre_raw, md_post_raw, "**", "**" }, /* Cm */
	{ NULL, md_pre_raw, md_post_raw, "`", "`" }, /* Dv */
	{ NULL, md_pre_raw, md_post_raw, "`", "`" }, /* Er */
	{ NULL, md_pre_raw, md_post_raw, "`", "`" }, /* Ev */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ex */
	{ NULL, md_pre_Fa, md_post_Fa, NULL, NULL }, /* Fa */
	{ NULL, md_pre_Fd, md_post_Fd, "**", "**" }, /* Fd */
	{ NULL, md_pre_raw, md_post_Fl, "**-", "**" }, /* Fl */
	{ NULL, md_pre_Fn, md_post_Fn, NULL, NULL }, /* Fn */
	{ NULL, md_pre_Fd, md_post_raw, "*", "*" }, /* Ft */
	{ NULL, md_pre_raw, md_post_raw, "**", "**" }, /* Ic */
	{ NULL, md_pre_In, md_post_In, NULL, NULL }, /* In */
	{ NULL, md_pre_raw, md_post_raw, "`", "`" }, /* Li */
	{ md_cond_head, md_pre_Nd, NULL, NULL, NULL }, /* Nd */
	{ NULL, md_pre_Nm, md_post_Nm, "**", "**" }, /* Nm */
	{ md_cond_body, md_pre_word, md_post_word, "[", "]" }, /* Op */
	{ NULL, md_pre_abort, NULL, NULL, NULL }, /* Ot */
	{ NULL, md_pre_raw, md_post_raw, "*", "*" }, /* Pa */
	{ NULL, NULL, NULL, NULL, NULL }, /* Rv */
	{ NULL, NULL, NULL, NULL, NULL }, /* St */
	{ NULL, md_pre_raw, md_post_raw, "*", "*" }, /* Va */
	{ NULL, md_pre_Vt, md_post_Vt, "*", "*" }, /* Vt */
	{ NULL, md_pre_Xr, NULL, NULL, NULL }, /* Xr */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %A */
	{ NULL, md_pre_raw, md_post_pc, "*", "*" }, /* %B */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %D */
	{ NULL, md_pre_raw, md_post_pc, "*", "*" }, /* %I */
	{ NULL, md_pre_raw, md_post_pc, "*", "*" }, /* %J */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %N */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %O */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %P */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %R */
	{ NULL, md_pre__T, md_post__T, NULL, NULL }, /* %T */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %V */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ac */
	{ md_cond_body, md_pre_word, md_post_word, "<", ">" }, /* Ao */
	{ md_cond_body, md_pre_word, md_post_word, "<", ">" }, /* Aq */
	{ NULL, NULL, NULL, NULL, NULL }, /* At */
	{ NULL, NULL, NULL, NULL, NULL }, /* Bc */
	{ NULL, NULL, NULL, NULL, NULL }, /* Bf XXX not implemented */
	{ md_cond_body, md_pre_word, md_post_word, "[", "]" }, /* Bo */
	{ md_cond_body, md_pre_word, md_post_word, "[", "]" }, /* Bq */
	{ NULL, NULL, NULL, NULL, NULL }, /* Bsx */
	{ NULL, NULL, NULL, NULL, NULL }, /* Bx */
	{ NULL, NULL, NULL, NULL, NULL }, /* Db */
	{ NULL, NULL, NULL, NULL, NULL }, /* Dc */
	{ md_cond_body, md_pre_word, md_post_word, "\"", "\"" }, /* Do */
	{ md_cond_body, md_pre_word, md_post_word, "\"", "\"" }, /* Dq */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ec */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ef */
	{ NULL, md_pre_raw, md_post_raw, "*", "*" }, /* Em */
	{ md_cond_body, md_pre_Eo, md_post_Eo, NULL, NULL }, /* Eo */
	{ NULL, NULL, NULL, NULL, NULL }, /* Fx */
	{ NULL, md_pre_raw, md_post_raw, "**", "**" }, /* Ms */
	{ NULL, md_pre_No, NULL, NULL, NULL }, /* No */
	{ NULL, md_pre_Ns, NULL, NULL, NULL }, /* Ns */
	{ NULL, NULL, NULL, NULL, NULL }, /* Nx */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ox */
	{ NULL, NULL, NULL, NULL, NULL }, /* Pc */
	{ NULL, NULL, md_post_Pf, NULL, NULL }, /* Pf */
	{ md_cond_body, md_pre_word, md_post_word, "(", ")" }, /* Po */
	{ md_cond_body, md_pre_word, md_post_word, "(", ")" }, /* Pq */
	{ NULL, NULL, NULL, NULL, NULL }, /* Qc */
	{ md_cond_body, md_pre_raw, md_post_raw, "'`", "`'" }, /* Ql */
	{ md_cond_body, md_pre_word, md_post_word, "\"", "\"" }, /* Qo */
	{ md_cond_body, md_pre_word, md_post_word, "\"", "\"" }, /* Qq */
	{ NULL, NULL, NULL, NULL, NULL }, /* Re */
	{ md_cond_body, md_pre_Rs, NULL, NULL, NULL }, /* Rs */
	{ NULL, NULL, NULL, NULL, NULL }, /* Sc */
	{ md_cond_body, md_pre_word, md_post_word, "'", "'" }, /* So */
	{ md_cond_body, md_pre_word, md_post_word, "'", "'" }, /* Sq */
	{ NULL, md_pre_Sm, NULL, NULL, NULL }, /* Sm */
	{ NULL, md_pre_raw, md_post_raw, "*", "*" }, /* Sx */
	{ NULL, md_pre_raw, md_post_raw, "**", "**" }, /* Sy */
	{ NULL, md_pre_raw, md_post_raw, "`", "`" }, /* Tn */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ux */
	{ NULL, NULL, NULL, NULL, NULL }, /* Xc */
	{ NULL, NULL, NULL, NULL, NULL }, /* Xo */
	{ NULL, md_pre_Fo, md_post_Fo, "**", "**" }, /* Fo */
	{ NULL, NULL, NULL, NULL, NULL }, /* Fc */
	{ md_cond_body, md_pre_word, md_post_word, "[", "]" }, /* Oo */
	{ NULL, NULL, NULL, NULL, NULL }, /* Oc */
	{ NULL, md_pre_Bk, md_post_Bk, NULL, NULL }, /* Bk */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ek */
	{ NULL, NULL, NULL, NULL, NULL }, /* Bt */
	{ NULL, NULL, NULL, NULL, NULL }, /* Hf */
	{ NULL, md_pre_raw, md_post_raw, "*", "*" }, /* Fr */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ud */
	{ NULL, NULL, md_post_Lb, NULL, NULL }, /* Lb */
	{ NULL, md_pre_abort, NULL, NULL, NULL }, /* Lp */
	{ NULL, md_pre_Lk, NULL, NULL, NULL }, /* Lk */
	{ NULL, md_pre_Mt, NULL, NULL, NULL }, /* Mt */
	{ md_cond_body, md_pre_word, md_post_word, "{", "}" }, /* Brq */
	{ md_cond_body, md_pre_word, md_post_word, "{", "}" }, /* Bro */
	{ NULL, NULL, NULL, NULL, NULL }, /* Brc */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %C */
	{ NULL, md_pre_skip, NULL, NULL, NULL }, /* Es */
	{ md_cond_body, md_pre_En, md_post_En, NULL, NULL }, /* En */
	{ NULL, NULL, NULL, NULL, NULL }, /* Dx */
	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %Q */
	{ NULL, md_pre_Lk, md_post_pc, NULL, NULL }, /* %U */
	{ NULL, NULL, NULL, NULL, NULL }, /* Ta */
	{ NULL, md_pre_skip, NULL, NULL, NULL }, /* Tg */
};
static const struct md_act *md_act(enum roff_tok);

static	int	 outflags;
#define	MD_spc		 (1 << 0)  /* Blank character before next word. */
#define	MD_spc_force	 (1 << 1)  /* Even before trailing punctuation. */
#define	MD_nonl		 (1 << 2)  /* Prevent linebreak in markdown code. */
#define	MD_nl		 (1 << 3)  /* Break markdown code line. */
#define	MD_br		 (1 << 4)  /* Insert an output line break. */
#define	MD_sp		 (1 << 5)  /* Insert a paragraph break. */
#define	MD_Sm		 (1 << 6)  /* Horizontal spacing mode. */
#define	MD_Bk		 (1 << 7)  /* Word keep mode. */
#define	MD_An_split	 (1 << 8)  /* Author mode is "split". */
#define	MD_An_nosplit	 (1 << 9)  /* Author mode is "nosplit". */

static	int	 escflags; /* Escape in generated markdown code: */
#define	ESC_BOL	 (1 << 0)  /* "#*+-" near the beginning of a line. */
#define	ESC_NUM	 (1 << 1)  /* "." after a leading number. */
#define	ESC_HYP	 (1 << 2)  /* "(" immediately after "]". */
#define	ESC_SQU	 (1 << 4)  /* "]" when "[" is open. */
#define	ESC_FON	 (1 << 5)  /* "*" immediately after unrelated "*". */
#define	ESC_EOL	 (1 << 6)  /* " " at the and of a line. */

static	int	 code_blocks, quote_blocks, list_blocks;
static	int	 outcount;


static const struct md_act *
md_act(enum roff_tok tok)
{
	assert(tok >= MDOC_Dd && tok <= MDOC_MAX);
	return md_acts + (tok - MDOC_Dd);
}

void
markdown_mdoc(void *arg, const struct roff_meta *mdoc)
{
	outflags = MD_Sm;
	md_word(mdoc->title);
	if (mdoc->msec != NULL) {
		outflags &= ~MD_spc;
		md_word("(");
		md_word(mdoc->msec);
		md_word(")");
	}
	md_word("-");
	md_word(mdoc->vol);
	if (mdoc->arch != NULL) {
		md_word("(");
		md_word(mdoc->arch);
		md_word(")");
	}
	outflags |= MD_sp;

	md_nodelist(mdoc->first->child);

	outflags |= MD_sp;
	md_word(mdoc->os);
	md_word("-");
	md_word(mdoc->date);
	putchar('\n');
}

static void
md_nodelist(struct roff_node *n)
{
	while (n != NULL) {
		md_node(n);
		n = n->next;
	}
}

static void
md_node(struct roff_node *n)
{
	const struct md_act	*act;
	int			 cond, process_children;

	if (n->type == ROFFT_COMMENT || n->flags & NODE_NOPRT)
		return;

	if (outflags & MD_nonl)
		outflags &= ~(MD_nl | MD_sp);
	else if (outflags & MD_spc &&
	     n->flags & NODE_LINE &&
	     !roff_node_transparent(n))
		outflags |= MD_nl;

	act = NULL;
	cond = 0;
	process_children = 1;
	n->flags &= ~NODE_ENDED;

	if (n->type == ROFFT_TEXT) {
		if (n->flags & NODE_DELIMC)
			outflags &= ~(MD_spc | MD_spc_force);
		else if (outflags & MD_Sm)
			outflags |= MD_spc_force;
		md_word(n->string);
		if (n->flags & NODE_DELIMO)
			outflags &= ~(MD_spc | MD_spc_force);
		else if (outflags & MD_Sm)
			outflags |= MD_spc;
	} else if (n->tok < ROFF_MAX) {
		switch (n->tok) {
		case ROFF_br:
			process_children = md_pre_br(n);
			break;
		case ROFF_sp:
			process_children = md_pre_Pp(n);
			break;
		default:
			process_children = 0;
			break;
		}
	} else {
		act = md_act(n->tok);
		cond = act->cond == NULL || (*act->cond)(n);
		if (cond && act->pre != NULL &&
		    (n->end == ENDBODY_NOT || n->child != NULL))
			process_children = (*act->pre)(n);
	}

	if (process_children && n->child != NULL)
		md_nodelist(n->child);

	if (n->flags & NODE_ENDED)
		return;

	if (cond && act->post != NULL)
		(*act->post)(n);

	if (n->end != ENDBODY_NOT)
		n->body->flags |= NODE_ENDED;
}

static const char *
md_stack(char c)
{
	static char	*stack;
	static size_t	 sz;
	static size_t	 cur;

	switch (c) {
	case '\0':
		break;
	case (char)-1:
		assert(cur);
		stack[--cur] = '\0';
		break;
	default:
		if (cur + 1 >= sz) {
			sz += 8;
			stack = mandoc_realloc(stack, sz);
		}
		stack[cur] = c;
		stack[++cur] = '\0';
		break;
	}
	return stack == NULL ? "" : stack;
}

/*
 * Handle vertical and horizontal spacing.
 */
static void
md_preword(void)
{
	const char	*cp;

	/*
	 * If a list block is nested inside a code block or a blockquote,
	 * blank lines for paragraph breaks no longer work; instead,
	 * they terminate the list.  Work around this markdown issue
	 * by using mere line breaks instead.
	 */

	if (list_blocks && outflags & MD_sp) {
		outflags &= ~MD_sp;
		outflags |= MD_br;
	}

	/*
	 * End the old line if requested.
	 * Escape whitespace at the end of the markdown line
	 * such that it won't look like an output line break.
	 */

	if (outflags & MD_sp)
		putchar('\n');
	else if (outflags & MD_br) {
		putchar(' ');
		putchar(' ');
	} else if (outflags & MD_nl && escflags & ESC_EOL)
		md_named("zwnj");

	/* Start a new line if necessary. */

	if (outflags & (MD_nl | MD_br | MD_sp)) {
		putchar('\n');
		for (cp = md_stack('\0'); *cp != '\0'; cp++) {
			putchar(*cp);
			if (*cp == '>')
				putchar(' ');
		}
		outflags &= ~(MD_nl | MD_br | MD_sp);
		escflags = ESC_BOL;
		outcount = 0;

	/* Handle horizontal spacing. */

	} else if (outflags & MD_spc) {
		if (outflags & MD_Bk)
			fputs("&nbsp;", stdout);
		else
			putchar(' ');
		escflags &= ~ESC_FON;
		outcount++;
	}

	outflags &= ~(MD_spc_force | MD_nonl);
	if (outflags & MD_Sm)
		outflags |= MD_spc;
	else
		outflags &= ~MD_spc;
}

/*
 * Print markdown syntax elements.
 * Can also be used for constant strings when neither escaping
 * nor delimiter handling is required.
 */
static void
md_rawword(const char *s)
{
	md_preword();

	if (*s == '\0')
		return;

	if (escflags & ESC_FON) {
		escflags &= ~ESC_FON;
		if (*s == '*' && !code_blocks)
			fputs("&zwnj;", stdout);
	}

	while (*s != '\0') {
		switch(*s) {
		case '*':
			if (s[1] == '\0')
				escflags |= ESC_FON;
			break;
		case '[':
			escflags |= ESC_SQU;
			break;
		case ']':
			escflags |= ESC_HYP;
			escflags &= ~ESC_SQU;
			break;
		default:
			break;
		}
		md_char(*s++);
	}
	if (s[-1] == ' ')
		escflags |= ESC_EOL;
	else
		escflags &= ~ESC_EOL;
}

/*
 * Print text and mdoc(7) syntax elements.
 */
static void
md_word(const char *s)
{
	const char	*seq, *prevfont, *currfont, *nextfont;
	char		 c;
	int		 bs, sz, uc, breakline;

	/* No spacing before closing delimiters. */
	if (s[0] != '\0' && s[1] == '\0' &&
	    strchr("!),.:;?]", s[0]) != NULL &&
	    (outflags & MD_spc_force) == 0)
		outflags &= ~MD_spc;

	md_preword();

	if (*s == '\0')
		return;

	/* No spacing after opening delimiters. */
	if ((s[0] == '(' || s[0] == '[') && s[1] == '\0')
		outflags &= ~MD_spc;

	breakline = 0;
	prevfont = currfont = "";
	while ((c = *s++) != '\0') {
		bs = 0;
		switch(c) {
		case ASCII_NBRSP:
			if (code_blocks)
				c = ' ';
			else {
				md_named("nbsp");
				c = '\0';
			}
			break;
		case ASCII_HYPH:
			bs = escflags & ESC_BOL && !code_blocks;
			c = '-';
			break;
		case ASCII_BREAK:
			continue;
		case '#':
		case '+':
		case '-':
			bs = escflags & ESC_BOL && !code_blocks;
			break;
		case '(':
			bs = escflags & ESC_HYP && !code_blocks;
			break;
		case ')':
			bs = escflags & ESC_NUM && !code_blocks;
			break;
		case '*':
		case '[':
		case '_':
		case '`':
			bs = !code_blocks;
			break;
		case '.':
			bs = escflags & ESC_NUM && !code_blocks;
			break;
		case '<':
			if (code_blocks == 0) {
				md_named("lt");
				c = '\0';
			}
			break;
		case '=':
			if (escflags & ESC_BOL && !code_blocks) {
				md_named("equals");
				c = '\0';
			}
			break;
		case '>':
			if (code_blocks == 0) {
				md_named("gt");
				c = '\0';
			}
			break;
		case '\\':
			uc = 0;
			nextfont = NULL;
			switch (mandoc_escape(&s, &seq, &sz)) {
			case ESCAPE_UNICODE:
				uc = mchars_num2uc(seq + 1, sz - 1);
				break;
			case ESCAPE_NUMBERED:
				uc = mchars_num2char(seq, sz);
				break;
			case ESCAPE_SPECIAL:
				uc = mchars_spec2cp(seq, sz);
				break;
			case ESCAPE_UNDEF:
				uc = *seq;
				break;
			case ESCAPE_DEVICE:
				md_rawword("markdown");
				continue;
			case ESCAPE_FONTBOLD:
			case ESCAPE_FONTCB:
				nextfont = "**";
				break;
			case ESCAPE_FONTITALIC:
			case ESCAPE_FONTCI:
				nextfont = "*";
				break;
			case ESCAPE_FONTBI:
				nextfont = "***";
				break;
			case ESCAPE_FONT:
			case ESCAPE_FONTCR:
			case ESCAPE_FONTROMAN:
				nextfont = "";
				break;
			case ESCAPE_FONTPREV:
				nextfont = prevfont;
				break;
			case ESCAPE_BREAK:
				breakline = 1;
				break;
			case ESCAPE_NOSPACE:
			case ESCAPE_SKIPCHAR:
			case ESCAPE_OVERSTRIKE:
				/* XXX not implemented */
				/* FALLTHROUGH */
			case ESCAPE_ERROR:
			default:
				break;
			}
			if (nextfont != NULL && !code_blocks) {
				if (*currfont != '\0') {
					outflags &= ~MD_spc;
					md_rawword(currfont);
				}
				prevfont = currfont;
				currfont = nextfont;
				if (*currfont != '\0') {
					outflags &= ~MD_spc;
					md_rawword(currfont);
				}
			}
			if (uc) {
				if ((uc < 0x20 && uc != 0x09) ||
				    (uc > 0x7E && uc < 0xA0))
					uc = 0xFFFD;
				if (code_blocks) {
					seq = mchars_uc2str(uc);
					fputs(seq, stdout);
					outcount += strlen(seq);
				} else {
					printf("&#%d;", uc);
					outcount++;
				}
				escflags &= ~ESC_FON;
			}
			c = '\0';
			break;
		case ']':
			bs = escflags & ESC_SQU && !code_blocks;
			escflags |= ESC_HYP;
			break;
		default:
			break;
		}
		if (bs)
			putchar('\\');
		md_char(c);
		if (breakline &&
		    (*s == '\0' || *s == ' ' || *s == ASCII_NBRSP)) {
			printf("  \n");
			breakline = 0;
			while (*s == ' ' || *s == ASCII_NBRSP)
				s++;
		}
	}
	if (*currfont != '\0') {
		outflags &= ~MD_spc;
		md_rawword(currfont);
	} else if (s[-2] == ' ')
		escflags |= ESC_EOL;
	else
		escflags &= ~ESC_EOL;
}

/*
 * Print a single HTML named character reference.
 */
static void
md_named(const char *s)
{
	printf("&%s;", s);
	escflags &= ~(ESC_FON | ESC_EOL);
	outcount++;
}

/*
 * Print a single raw character and maintain certain escape flags.
 */
static void
md_char(unsigned char c)
{
	if (c != '\0') {
		putchar(c);
		if (c == '*')
			escflags |= ESC_FON;
		else
			escflags &= ~ESC_FON;
		outcount++;
	}
	if (c != ']')
		escflags &= ~ESC_HYP;
	if (c == ' ' || c == '\t' || c == '>')
		return;
	if (isdigit(c) == 0)
		escflags &= ~ESC_NUM;
	else if (escflags & ESC_BOL)
		escflags |= ESC_NUM;
	escflags &= ~ESC_BOL;
}

static int
md_cond_head(struct roff_node *n)
{
	return n->type == ROFFT_HEAD;
}

static int
md_cond_body(struct roff_node *n)
{
	return n->type == ROFFT_BODY;
}

static int
md_pre_abort(struct roff_node *n)
{
	abort();
}

static int
md_pre_raw(struct roff_node *n)
{
	const char	*prefix;

	if ((prefix = md_act(n->tok)->prefix) != NULL) {
		md_rawword(prefix);
		outflags &= ~MD_spc;
		if (*prefix == '`')
			code_blocks++;
	}
	return 1;
}

static void
md_post_raw(struct roff_node *n)
{
	const char	*suffix;

	if ((suffix = md_act(n->tok)->suffix) != NULL) {
		outflags &= ~(MD_spc | MD_nl);
		md_rawword(suffix);
		if (*suffix == '`')
			code_blocks--;
	}
}

static int
md_pre_word(struct roff_node *n)
{
	const char	*prefix;

	if ((prefix = md_act(n->tok)->prefix) != NULL) {
		md_word(prefix);
		outflags &= ~MD_spc;
	}
	return 1;
}

static void
md_post_word(struct roff_node *n)
{
	const char	*suffix;

	if ((suffix = md_act(n->tok)->suffix) != NULL) {
		outflags &= ~(MD_spc | MD_nl);
		md_word(suffix);
	}
}

static void
md_post_pc(struct roff_node *n)
{
	struct roff_node *nn;

	md_post_raw(n);
	if (n->parent->tok != MDOC_Rs)
		return;

	if ((nn = roff_node_next(n)) != NULL) {
		md_word(",");
		if (nn->tok == n->tok &&
		    (nn = roff_node_prev(n)) != NULL &&
		    nn->tok == n->tok)
			md_word("and");
	} else {
		md_word(".");
		outflags |= MD_nl;
	}
}

static int
md_pre_skip(struct roff_node *n)
{
	return 0;
}

static void
md_pre_syn(struct roff_node *n)
{
	struct roff_node *np;

	if ((n->flags & NODE_SYNPRETTY) == 0 ||
	    (np = roff_node_prev(n)) == NULL)
		return;

	if (np->tok == n->tok &&
	    n->tok != MDOC_Ft &&
	    n->tok != MDOC_Fo &&
	    n->tok != MDOC_Fn) {
		outflags |= MD_br;
		return;
	}

	switch (np->tok) {
	case MDOC_Fd:
	case MDOC_Fn:
	case MDOC_Fo:
	case MDOC_In:
	case MDOC_Vt:
		outflags |= MD_sp;
		break;
	case MDOC_Ft:
		if (n->tok != MDOC_Fn && n->tok != MDOC_Fo) {
			outflags |= MD_sp;
			break;
		}
		/* FALLTHROUGH */
	default:
		outflags |= MD_br;
		break;
	}
}

static int
md_pre_An(struct roff_node *n)
{
	switch (n->norm->An.auth) {
	case AUTH_split:
		outflags &= ~MD_An_nosplit;
		outflags |= MD_An_split;
		return 0;
	case AUTH_nosplit:
		outflags &= ~MD_An_split;
		outflags |= MD_An_nosplit;
		return 0;
	default:
		if (outflags & MD_An_split)
			outflags |= MD_br;
		else if (n->sec == SEC_AUTHORS &&
		    ! (outflags & MD_An_nosplit))
			outflags |= MD_An_split;
		return 1;
	}
}

static int
md_pre_Ap(struct roff_node *n)
{
	outflags &= ~MD_spc;
	md_word("'");
	outflags &= ~MD_spc;
	return 0;
}

static int
md_pre_Bd(struct roff_node *n)
{
	switch (n->norm->Bd.type) {
	case DISP_unfilled:
	case DISP_literal:
		return md_pre_Dl(n);
	default:
		return md_pre_D1(n);
	}
}

static int
md_pre_Bk(struct roff_node *n)
{
	switch (n->type) {
	case ROFFT_BLOCK:
		return 1;
	case ROFFT_BODY:
		outflags |= MD_Bk;
		return 1;
	default:
		return 0;
	}
}

static void
md_post_Bk(struct roff_node *n)
{
	if (n->type == ROFFT_BODY)
		outflags &= ~MD_Bk;
}

static int
md_pre_Bl(struct roff_node *n)
{
	n->norm->Bl.count = 0;
	if (n->norm->Bl.type == LIST_column)
		md_pre_Dl(n);
	outflags |= MD_sp;
	return 1;
}

static void
md_post_Bl(struct roff_node *n)
{
	n->norm->Bl.count = 0;
	if (n->norm->Bl.type == LIST_column)
		md_post_D1(n);
	outflags |= MD_sp;
}

static int
md_pre_D1(struct roff_node *n)
{
	/*
	 * Markdown blockquote syntax does not work inside code blocks.
	 * The best we can do is fall back to another nested code block.
	 */
	if (code_blocks) {
		md_stack('\t');
		code_blocks++;
	} else {
		md_stack('>');
		quote_blocks++;
	}
	outflags |= MD_sp;
	return 1;
}

static void
md_post_D1(struct roff_node *n)
{
	md_stack((char)-1);
	if (code_blocks)
		code_blocks--;
	else
		quote_blocks--;
	outflags |= MD_sp;
}

static int
md_pre_Dl(struct roff_node *n)
{
	/*
	 * Markdown code block syntax does not work inside blockquotes.
	 * The best we can do is fall back to another nested blockquote.
	 */
	if (quote_blocks) {
		md_stack('>');
		quote_blocks++;
	} else {
		md_stack('\t');
		code_blocks++;
	}
	outflags |= MD_sp;
	return 1;
}

static int
md_pre_En(struct roff_node *n)
{
	if (n->norm->Es == NULL ||
	    n->norm->Es->child == NULL)
		return 1;

	md_word(n->norm->Es->child->string);
	outflags &= ~MD_spc;
	return 1;
}

static void
md_post_En(struct roff_node *n)
{
	if (n->norm->Es == NULL ||
	    n->norm->Es->child == NULL ||
	    n->norm->Es->child->next == NULL)
		return;

	outflags &= ~MD_spc;
	md_word(n->norm->Es->child->next->string);
}

static int
md_pre_Eo(struct roff_node *n)
{
	if (n->end == ENDBODY_NOT &&
	    n->parent->head->child == NULL &&
	    n->child != NULL &&
	    n->child->end != ENDBODY_NOT)
		md_preword();
	else if (n->end != ENDBODY_NOT ? n->child != NULL :
	    n->parent->head->child != NULL && (n->child != NULL ||
	    (n->parent->tail != NULL && n->parent->tail->child != NULL)))
		outflags &= ~(MD_spc | MD_nl);
	return 1;
}

static void
md_post_Eo(struct roff_node *n)
{
	if (n->end != ENDBODY_NOT) {
		outflags |= MD_spc;
		return;
	}

	if (n->child == NULL && n->parent->head->child == NULL)
		return;

	if (n->parent->tail != NULL && n->parent->tail->child != NULL)
		outflags &= ~MD_spc;
        else
		outflags |= MD_spc;
}

static int
md_pre_Fa(struct roff_node *n)
{
	int	 am_Fa;

	am_Fa = n->tok == MDOC_Fa;

	if (am_Fa)
		n = n->child;

	while (n != NULL) {
		md_rawword("*");
		outflags &= ~MD_spc;
		md_node(n);
		outflags &= ~MD_spc;
		md_rawword("*");
		if ((n = n->next) != NULL)
			md_word(",");
	}
	return 0;
}

static void
md_post_Fa(struct roff_node *n)
{
	struct roff_node *nn;

	if ((nn = roff_node_next(n)) != NULL && nn->tok == MDOC_Fa)
		md_word(",");
}

static int
md_pre_Fd(struct roff_node *n)
{
	md_pre_syn(n);
	md_pre_raw(n);
	return 1;
}

static void
md_post_Fd(struct roff_node *n)
{
	md_post_raw(n);
	outflags |= MD_br;
}

static void
md_post_Fl(struct roff_node *n)
{
	struct roff_node *nn;

	md_post_raw(n);
	if (n->child == NULL && (nn = roff_node_next(n)) != NULL &&
	    nn->type != ROFFT_TEXT && (nn->flags & NODE_LINE) == 0)
		outflags &= ~MD_spc;
}

static int
md_pre_Fn(struct roff_node *n)
{
	md_pre_syn(n);

	if ((n = n->child) == NULL)
		return 0;

	md_rawword("**");
	outflags &= ~MD_spc;
	md_node(n);
	outflags &= ~MD_spc;
	md_rawword("**");
	outflags &= ~MD_spc;
	md_word("(");

	if ((n = n->next) != NULL)
		md_pre_Fa(n);
	return 0;
}

static void
md_post_Fn(struct roff_node *n)
{
	md_word(")");
	if (n->flags & NODE_SYNPRETTY) {
		md_word(";");
		outflags |= MD_sp;
	}
}

static int
md_pre_Fo(struct roff_node *n)
{
	switch (n->type) {
	case ROFFT_BLOCK:
		md_pre_syn(n);
		break;
	case ROFFT_HEAD:
		if (n->child == NULL)
			return 0;
		md_pre_raw(n);
		break;
	case ROFFT_BODY:
		outflags &= ~(MD_spc | MD_nl);
		md_word("(");
		break;
	default:
		break;
	}
	return 1;
}

static void
md_post_Fo(struct roff_node *n)
{
	switch (n->type) {
	case ROFFT_HEAD:
		if (n->child != NULL)
			md_post_raw(n);
		break;
	case ROFFT_BODY:
		md_post_Fn(n);
		break;
	default:
		break;
	}
}

static int
md_pre_In(struct roff_node *n)
{
	if (n->flags & NODE_SYNPRETTY) {
		md_pre_syn(n);
		md_rawword("**");
		outflags &= ~MD_spc;
		md_word("#include <");
	} else {
		md_word("<");
		outflags &= ~MD_spc;
		md_rawword("*");
	}
	outflags &= ~MD_spc;
	return 1;
}

static void
md_post_In(struct roff_node *n)
{
	if (n->flags & NODE_SYNPRETTY) {
		outflags &= ~MD_spc;
		md_rawword(">**");
		outflags |= MD_nl;
	} else {
		outflags &= ~MD_spc;
		md_rawword("*>");
	}
}

static int
md_pre_It(struct roff_node *n)
{
	struct roff_node	*bln;

	switch (n->type) {
	case ROFFT_BLOCK:
		return 1;

	case ROFFT_HEAD:
		bln = n->parent->parent;
		if (bln->norm->Bl.comp == 0 &&
		    bln->norm->Bl.type != LIST_column)
			outflags |= MD_sp;
		outflags |= MD_nl;

		switch (bln->norm->Bl.type) {
		case LIST_item:
			outflags |= MD_br;
			return 0;
		case LIST_inset:
		case LIST_diag:
		case LIST_ohang:
			outflags |= MD_br;
			return 1;
		case LIST_tag:
		case LIST_hang:
			outflags |= MD_sp;
			return 1;
		case LIST_bullet:
			md_rawword("*\t");
			break;
		case LIST_dash:
		case LIST_hyphen:
			md_rawword("-\t");
			break;
		case LIST_enum:
			md_preword();
			if (bln->norm->Bl.count < 99)
				bln->norm->Bl.count++;
			printf("%d.\t", bln->norm->Bl.count);
			escflags &= ~ESC_FON;
			break;
		case LIST_column:
			outflags |= MD_br;
			return 0;
		default:
			return 0;
		}
		outflags &= ~MD_spc;
		outflags |= MD_nonl;
		outcount = 0;
		md_stack('\t');
		if (code_blocks || quote_blocks)
			list_blocks++;
		return 0;

	case ROFFT_BODY:
		bln = n->parent->parent;
		switch (bln->norm->Bl.type) {
		case LIST_ohang:
			outflags |= MD_br;
			break;
		case LIST_tag:
		case LIST_hang:
			md_pre_D1(n);
			break;
		default:
			break;
		}
		return 1;

	default:
		return 0;
	}
}

static void
md_post_It(struct roff_node *n)
{
	struct roff_node	*bln;
	int			 i, nc;

	if (n->type != ROFFT_BODY)
		return;

	bln = n->parent->parent;
	switch (bln->norm->Bl.type) {
	case LIST_bullet:
	case LIST_dash:
	case LIST_hyphen:
	case LIST_enum:
		md_stack((char)-1);
		if (code_blocks || quote_blocks)
			list_blocks--;
		break;
	case LIST_tag:
	case LIST_hang:
		md_post_D1(n);
		break;

	case LIST_column:
		if (n->next == NULL)
			break;

		/* Calculate the array index of the current column. */

		i = 0;
		while ((n = n->prev) != NULL && n->type != ROFFT_HEAD)
			i++;

		/*
		 * If a width was specified for this column,
		 * subtract what printed, and
		 * add the same spacing as in mdoc_term.c.
		 */

		nc = bln->norm->Bl.ncols;
		i = i < nc ? strlen(bln->norm->Bl.cols[i]) - outcount +
		    (nc < 5 ? 4 : nc == 5 ? 3 : 1) : 1;
		if (i < 1)
			i = 1;
		while (i-- > 0)
			putchar(' ');

		outflags &= ~MD_spc;
		escflags &= ~ESC_FON;
		outcount = 0;
		break;

	default:
		break;
	}
}

static void
md_post_Lb(struct roff_node *n)
{
	if (n->sec == SEC_LIBRARY)
		outflags |= MD_br;
}

static void
md_uri(const char *s)
{
	while (*s != '\0') {
		if (strchr("%()<>", *s) != NULL) {
			printf("%%%2.2hhX", *s);
			outcount += 3;
		} else {
			putchar(*s);
			outcount++;
		}
		s++;
	}
}

static int
md_pre_Lk(struct roff_node *n)
{
	const struct roff_node *link, *descr, *punct;

	if ((link = n->child) == NULL)
		return 0;

	/* Find beginning of trailing punctuation. */
	punct = n->last;
	while (punct != link && punct->flags & NODE_DELIMC)
		punct = punct->prev;
	punct = punct->next;

	/* Link text. */
	descr = link->next;
	if (descr == punct)
		descr = link;  /* no text */
	md_rawword("[");
	outflags &= ~MD_spc;
	do {
		md_word(descr->string);
		descr = descr->next;
	} while (descr != punct);
	outflags &= ~MD_spc;

	/* Link target. */
	md_rawword("](");
	md_uri(link->string);
	outflags &= ~MD_spc;
	md_rawword(")");

	/* Trailing punctuation. */
	while (punct != NULL) {
		md_word(punct->string);
		punct = punct->next;
	}
	return 0;
}

static int
md_pre_Mt(struct roff_node *n)
{
	const struct roff_node *nch;

	md_rawword("[");
	outflags &= ~MD_spc;
	for (nch = n->child; nch != NULL; nch = nch->next)
		md_word(nch->string);
	outflags &= ~MD_spc;
	md_rawword("](mailto:");
	for (nch = n->child; nch != NULL; nch = nch->next) {
		md_uri(nch->string);
		if (nch->next != NULL) {
			putchar(' ');
			outcount++;
		}
	}
	outflags &= ~MD_spc;
	md_rawword(")");
	return 0;
}

static int
md_pre_Nd(struct roff_node *n)
{
	outflags &= ~MD_nl;
	outflags |= MD_spc;
	md_word("-");
	return 1;
}

static int
md_pre_Nm(struct roff_node *n)
{
	switch (n->type) {
	case ROFFT_BLOCK:
		outflags |= MD_Bk;
		md_pre_syn(n);
		break;
	case ROFFT_HEAD:
	case ROFFT_ELEM:
		md_pre_raw(n);
		break;
	default:
		break;
	}
	return 1;
}

static void
md_post_Nm(struct roff_node *n)
{
	switch (n->type) {
	case ROFFT_BLOCK:
		outflags &= ~MD_Bk;
		break;
	case ROFFT_HEAD:
	case ROFFT_ELEM:
		md_post_raw(n);
		break;
	default:
		break;
	}
}

static int
md_pre_No(struct roff_node *n)
{
	outflags |= MD_spc_force;
	return 1;
}

static int
md_pre_Ns(struct roff_node *n)
{
	outflags &= ~MD_spc;
	return 0;
}

static void
md_post_Pf(struct roff_node *n)
{
	if (n->next != NULL && (n->next->flags & NODE_LINE) == 0)
		outflags &= ~MD_spc;
}

static int
md_pre_Pp(struct roff_node *n)
{
	outflags |= MD_sp;
	return 0;
}

static int
md_pre_Rs(struct roff_node *n)
{
	if (n->sec == SEC_SEE_ALSO)
		outflags |= MD_sp;
	return 1;
}

static int
md_pre_Sh(struct roff_node *n)
{
	switch (n->type) {
	case ROFFT_BLOCK:
		if (n->sec == SEC_AUTHORS)
			outflags &= ~(MD_An_split | MD_An_nosplit);
		break;
	case ROFFT_HEAD:
		outflags |= MD_sp;
		md_rawword(n->tok == MDOC_Sh ? "#" : "##");
		break;
	case ROFFT_BODY:
		outflags |= MD_sp;
		break;
	default:
		break;
	}
	return 1;
}

static int
md_pre_Sm(struct roff_node *n)
{
	if (n->child == NULL)
		outflags ^= MD_Sm;
	else if (strcmp("on", n->child->string) == 0)
		outflags |= MD_Sm;
	else
		outflags &= ~MD_Sm;

	if (outflags & MD_Sm)
		outflags |= MD_spc;

	return 0;
}

static int
md_pre_Vt(struct roff_node *n)
{
	switch (n->type) {
	case ROFFT_BLOCK:
		md_pre_syn(n);
		return 1;
	case ROFFT_BODY:
	case ROFFT_ELEM:
		md_pre_raw(n);
		return 1;
	default:
		return 0;
	}
}

static void
md_post_Vt(struct roff_node *n)
{
	switch (n->type) {
	case ROFFT_BODY:
	case ROFFT_ELEM:
		md_post_raw(n);
		break;
	default:
		break;
	}
}

static int
md_pre_Xr(struct roff_node *n)
{
	n = n->child;
	if (n == NULL)
		return 0;
	md_node(n);
	n = n->next;
	if (n == NULL)
		return 0;
	outflags &= ~MD_spc;
	md_word("(");
	md_node(n);
	md_word(")");
	return 0;
}

static int
md_pre__T(struct roff_node *n)
{
	if (n->parent->tok == MDOC_Rs && n->parent->norm->Rs.quote_T)
		md_word("\"");
	else
		md_rawword("*");
	outflags &= ~MD_spc;
	return 1;
}

static void
md_post__T(struct roff_node *n)
{
	outflags &= ~MD_spc;
	if (n->parent->tok == MDOC_Rs && n->parent->norm->Rs.quote_T)
		md_word("\"");
	else
		md_rawword("*");
	md_post_pc(n);
}

static int
md_pre_br(struct roff_node *n)
{
	outflags |= MD_br;
	return 0;
}