Removing warning about OSNAME.

[minix.git] / external / bsd / mdocml / dist / mdoc.c

/*      $Vendor-Id: mdoc.c,v 1.177 2011/01/03 11:27:33 kristaps Exp $ */
/*
 * Copyright (c) 2008, 2009, 2010 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2010 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 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.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/types.h>

#include <assert.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "mandoc.h"
#include "libmdoc.h"
#include "libmandoc.h"

const   char *const __mdoc_macronames[MDOC_MAX] = {              
        "Ap",           "Dd",           "Dt",           "Os",
        "Sh",           "Ss",           "Pp",           "D1",
        "Dl",           "Bd",           "Ed",           "Bl",
        "El",           "It",           "Ad",           "An",
        "Ar",           "Cd",           "Cm",           "Dv",
        "Er",           "Ev",           "Ex",           "Fa",
        "Fd",           "Fl",           "Fn",           "Ft",
        "Ic",           "In",           "Li",           "Nd",
        "Nm",           "Op",           "Ot",           "Pa",
        "Rv",           "St",           "Va",           "Vt",
        /* LINTED */
        "Xr",           "%A",           "%B",           "%D",
        /* LINTED */
        "%I",           "%J",           "%N",           "%O",
        /* LINTED */
        "%P",           "%R",           "%T",           "%V",
        "Ac",           "Ao",           "Aq",           "At",
        "Bc",           "Bf",           "Bo",           "Bq",
        "Bsx",          "Bx",           "Db",           "Dc",
        "Do",           "Dq",           "Ec",           "Ef",
        "Em",           "Eo",           "Fx",           "Ms",
        "No",           "Ns",           "Nx",           "Ox",
        "Pc",           "Pf",           "Po",           "Pq",
        "Qc",           "Ql",           "Qo",           "Qq",
        "Re",           "Rs",           "Sc",           "So",
        "Sq",           "Sm",           "Sx",           "Sy",
        "Tn",           "Ux",           "Xc",           "Xo",
        "Fo",           "Fc",           "Oo",           "Oc",
        "Bk",           "Ek",           "Bt",           "Hf",
        "Fr",           "Ud",           "Lb",           "Lp",
        "Lk",           "Mt",           "Brq",          "Bro",
        /* LINTED */
        "Brc",          "%C",           "Es",           "En",
        /* LINTED */
        "Dx",           "%Q",           "br",           "sp",
        /* LINTED */
        "%U",           "Ta"
        };

const   char *const __mdoc_argnames[MDOC_ARG_MAX] = {            
        "split",                "nosplit",              "ragged",
        "unfilled",             "literal",              "file",          
        "offset",               "bullet",               "dash",          
        "hyphen",               "item",                 "enum",          
        "tag",                  "diag",                 "hang",          
        "ohang",                "inset",                "column",        
        "width",                "compact",              "std",   
        "filled",               "words",                "emphasis",
        "symbolic",             "nested",               "centered"
        };

const   char * const *mdoc_macronames = __mdoc_macronames;
const   char * const *mdoc_argnames = __mdoc_argnames;

static  void              mdoc_node_free(struct mdoc_node *);
static  void              mdoc_node_unlink(struct mdoc *, 
                                struct mdoc_node *);
static  void              mdoc_free1(struct mdoc *);
static  void              mdoc_alloc1(struct mdoc *);
static  struct mdoc_node *node_alloc(struct mdoc *, int, int, 
                                enum mdoct, enum mdoc_type);
static  int               node_append(struct mdoc *, 
                                struct mdoc_node *);
static  int               mdoc_ptext(struct mdoc *, int, char *, int);
static  int               mdoc_pmacro(struct mdoc *, int, char *, int);
static  int               mdoc_span_alloc(struct mdoc *, 
                                const struct tbl_span *);


const struct mdoc_node *
mdoc_node(const struct mdoc *m)
{

        assert( ! (MDOC_HALT & m->flags));
        return(m->first);
}


const struct mdoc_meta *
mdoc_meta(const struct mdoc *m)
{

        assert( ! (MDOC_HALT & m->flags));
        return(&m->meta);
}


/*
 * Frees volatile resources (parse tree, meta-data, fields).
 */
static void
mdoc_free1(struct mdoc *mdoc)
{

        if (mdoc->first)
                mdoc_node_delete(mdoc, mdoc->first);
        if (mdoc->meta.title)
                free(mdoc->meta.title);
        if (mdoc->meta.os)
                free(mdoc->meta.os);
        if (mdoc->meta.name)
                free(mdoc->meta.name);
        if (mdoc->meta.arch)
                free(mdoc->meta.arch);
        if (mdoc->meta.vol)
                free(mdoc->meta.vol);
        if (mdoc->meta.msec)
                free(mdoc->meta.msec);
}


/*
 * Allocate all volatile resources (parse tree, meta-data, fields).
 */
static void
mdoc_alloc1(struct mdoc *mdoc)
{

        memset(&mdoc->meta, 0, sizeof(struct mdoc_meta));
        mdoc->flags = 0;
        mdoc->lastnamed = mdoc->lastsec = SEC_NONE;
        mdoc->last = mandoc_calloc(1, sizeof(struct mdoc_node));
        mdoc->first = mdoc->last;
        mdoc->last->type = MDOC_ROOT;
        mdoc->next = MDOC_NEXT_CHILD;
}


/*
 * Free up volatile resources (see mdoc_free1()) then re-initialises the
 * data with mdoc_alloc1().  After invocation, parse data has been reset
 * and the parser is ready for re-invocation on a new tree; however,
 * cross-parse non-volatile data is kept intact.
 */
void
mdoc_reset(struct mdoc *mdoc)
{

        mdoc_free1(mdoc);
        mdoc_alloc1(mdoc);
}


/*
 * Completely free up all volatile and non-volatile parse resources.
 * After invocation, the pointer is no longer usable.
 */
void
mdoc_free(struct mdoc *mdoc)
{

        mdoc_free1(mdoc);
        free(mdoc);
}


/*
 * Allocate volatile and non-volatile parse resources.  
 */
struct mdoc *
mdoc_alloc(struct regset *regs, void *data, mandocmsg msg)
{
        struct mdoc     *p;

        p = mandoc_calloc(1, sizeof(struct mdoc));

        p->msg = msg;
        p->data = data;
        p->regs = regs;

        mdoc_hash_init();
        mdoc_alloc1(p);
        return(p);
}


/*
 * Climb back up the parse tree, validating open scopes.  Mostly calls
 * through to macro_end() in macro.c.
 */
int
mdoc_endparse(struct mdoc *m)
{

        assert( ! (MDOC_HALT & m->flags));
        if (mdoc_macroend(m))
                return(1);
        m->flags |= MDOC_HALT;
        return(0);
}

int
mdoc_addspan(struct mdoc *m, const struct tbl_span *sp)
{

        assert( ! (MDOC_HALT & m->flags));

        /* No text before an initial macro. */

        if (SEC_NONE == m->lastnamed) {
                /* FIXME: grab from span. */
                mdoc_pmsg(m, 0, 0, MANDOCERR_NOTEXT);
                return(1);
        }

        return(mdoc_span_alloc(m, sp));
}


/*
 * Main parse routine.  Parses a single line -- really just hands off to
 * the macro (mdoc_pmacro()) or text parser (mdoc_ptext()).
 */
int
mdoc_parseln(struct mdoc *m, int ln, char *buf, int offs)
{

        assert( ! (MDOC_HALT & m->flags));

        m->flags |= MDOC_NEWLINE;

        /*
         * Let the roff nS register switch SYNOPSIS mode early,
         * such that the parser knows at all times
         * whether this mode is on or off.
         * Note that this mode is also switched by the Sh macro.
         */
        if (m->regs->regs[(int)REG_nS].set) {
                if (m->regs->regs[(int)REG_nS].v.u)
                        m->flags |= MDOC_SYNOPSIS;
                else
                        m->flags &= ~MDOC_SYNOPSIS;
        }

        return(('.' == buf[offs] || '\'' == buf[offs]) ? 
                        mdoc_pmacro(m, ln, buf, offs) :
                        mdoc_ptext(m, ln, buf, offs));
}


int
mdoc_vmsg(struct mdoc *mdoc, enum mandocerr t, 
                int ln, int pos, const char *fmt, ...)
{
        char             buf[256];
        va_list          ap;

        va_start(ap, fmt);
        vsnprintf(buf, sizeof(buf) - 1, fmt, ap);
        va_end(ap);

        return((*mdoc->msg)(t, mdoc->data, ln, pos, buf));
}


int
mdoc_macro(MACRO_PROT_ARGS)
{
        assert(tok < MDOC_MAX);

        /* If we're in the body, deny prologue calls. */

        if (MDOC_PROLOGUE & mdoc_macros[tok].flags && 
                        MDOC_PBODY & m->flags) {
                mdoc_pmsg(m, line, ppos, MANDOCERR_BADBODY);
                return(1);
        }

        /* If we're in the prologue, deny "body" macros.  */

        if ( ! (MDOC_PROLOGUE & mdoc_macros[tok].flags) && 
                        ! (MDOC_PBODY & m->flags)) {
                mdoc_pmsg(m, line, ppos, MANDOCERR_BADPROLOG);
                if (NULL == m->meta.msec)
                        m->meta.msec = mandoc_strdup("1");
                if (NULL == m->meta.title)
                        m->meta.title = mandoc_strdup("UNKNOWN");
                if (NULL == m->meta.vol)
                        m->meta.vol = mandoc_strdup("LOCAL");
                if (NULL == m->meta.os)
                        m->meta.os = mandoc_strdup("LOCAL");
                if (0 == m->meta.date)
                        m->meta.date = time(NULL);
                m->flags |= MDOC_PBODY;
        }

        return((*mdoc_macros[tok].fp)(m, tok, line, ppos, pos, buf));
}


static int
node_append(struct mdoc *mdoc, struct mdoc_node *p)
{

        assert(mdoc->last);
        assert(mdoc->first);
        assert(MDOC_ROOT != p->type);

        switch (mdoc->next) {
        case (MDOC_NEXT_SIBLING):
                mdoc->last->next = p;
                p->prev = mdoc->last;
                p->parent = mdoc->last->parent;
                break;
        case (MDOC_NEXT_CHILD):
                mdoc->last->child = p;
                p->parent = mdoc->last;
                break;
        default:
                abort();
                /* NOTREACHED */
        }

        p->parent->nchild++;

        /*
         * Copy over the normalised-data pointer of our parent.  Not
         * everybody has one, but copying a null pointer is fine.
         */

        switch (p->type) {
        case (MDOC_BODY):
                /* FALLTHROUGH */
        case (MDOC_TAIL):
                /* FALLTHROUGH */
        case (MDOC_HEAD):
                p->norm = p->parent->norm;
                break;
        default:
                break;
        }

        if ( ! mdoc_valid_pre(mdoc, p))
                return(0);

        switch (p->type) {
        case (MDOC_HEAD):
                assert(MDOC_BLOCK == p->parent->type);
                p->parent->head = p;
                break;
        case (MDOC_TAIL):
                assert(MDOC_BLOCK == p->parent->type);
                p->parent->tail = p;
                break;
        case (MDOC_BODY):
                if (p->end)
                        break;
                assert(MDOC_BLOCK == p->parent->type);
                p->parent->body = p;
                break;
        default:
                break;
        }

        mdoc->last = p;

        switch (p->type) {
        case (MDOC_TBL):
                /* FALLTHROUGH */
        case (MDOC_TEXT):
                if ( ! mdoc_valid_post(mdoc))
                        return(0);
                break;
        default:
                break;
        }

        return(1);
}


static struct mdoc_node *
node_alloc(struct mdoc *m, int line, int pos, 
                enum mdoct tok, enum mdoc_type type)
{
        struct mdoc_node *p;

        p = mandoc_calloc(1, sizeof(struct mdoc_node));
        p->sec = m->lastsec;
        p->line = line;
        p->pos = pos;
        p->tok = tok;
        p->type = type;

        /* Flag analysis. */

        if (MDOC_SYNOPSIS & m->flags)
                p->flags |= MDOC_SYNPRETTY;
        else
                p->flags &= ~MDOC_SYNPRETTY;
        if (MDOC_NEWLINE & m->flags)
                p->flags |= MDOC_LINE;
        m->flags &= ~MDOC_NEWLINE;

        return(p);
}


int
mdoc_tail_alloc(struct mdoc *m, int line, int pos, enum mdoct tok)
{
        struct mdoc_node *p;

        p = node_alloc(m, line, pos, tok, MDOC_TAIL);
        if ( ! node_append(m, p))
                return(0);
        m->next = MDOC_NEXT_CHILD;
        return(1);
}


int
mdoc_head_alloc(struct mdoc *m, int line, int pos, enum mdoct tok)
{
        struct mdoc_node *p;

        assert(m->first);
        assert(m->last);

        p = node_alloc(m, line, pos, tok, MDOC_HEAD);
        if ( ! node_append(m, p))
                return(0);
        m->next = MDOC_NEXT_CHILD;
        return(1);
}


int
mdoc_body_alloc(struct mdoc *m, int line, int pos, enum mdoct tok)
{
        struct mdoc_node *p;

        p = node_alloc(m, line, pos, tok, MDOC_BODY);
        if ( ! node_append(m, p))
                return(0);
        m->next = MDOC_NEXT_CHILD;
        return(1);
}


int
mdoc_endbody_alloc(struct mdoc *m, int line, int pos, enum mdoct tok,
                struct mdoc_node *body, enum mdoc_endbody end)
{
        struct mdoc_node *p;

        p = node_alloc(m, line, pos, tok, MDOC_BODY);
        p->pending = body;
        p->end = end;
        if ( ! node_append(m, p))
                return(0);
        m->next = MDOC_NEXT_SIBLING;
        return(1);
}


int
mdoc_block_alloc(struct mdoc *m, int line, int pos, 
                enum mdoct tok, struct mdoc_arg *args)
{
        struct mdoc_node *p;

        p = node_alloc(m, line, pos, tok, MDOC_BLOCK);
        p->args = args;
        if (p->args)
                (args->refcnt)++;

        switch (tok) {
        case (MDOC_Bd):
                /* FALLTHROUGH */
        case (MDOC_Bf):
                /* FALLTHROUGH */
        case (MDOC_Bl):
                /* FALLTHROUGH */
        case (MDOC_Rs):
                p->norm = mandoc_calloc(1, sizeof(union mdoc_data));
                break;
        default:
                break;
        }

        if ( ! node_append(m, p))
                return(0);
        m->next = MDOC_NEXT_CHILD;
        return(1);
}


int
mdoc_elem_alloc(struct mdoc *m, int line, int pos, 
                enum mdoct tok, struct mdoc_arg *args)
{
        struct mdoc_node *p;

        p = node_alloc(m, line, pos, tok, MDOC_ELEM);
        p->args = args;
        if (p->args)
                (args->refcnt)++;

        switch (tok) {
        case (MDOC_An):
                p->norm = mandoc_calloc(1, sizeof(union mdoc_data));
                break;
        default:
                break;
        }

        if ( ! node_append(m, p))
                return(0);
        m->next = MDOC_NEXT_CHILD;
        return(1);
}

static int
mdoc_span_alloc(struct mdoc *m, const struct tbl_span *sp)
{
        struct mdoc_node *n;

        /* FIXME: grab from tbl_span. */
        n = node_alloc(m, 0, 0, MDOC_MAX, MDOC_TBL);
        n->span = sp;

        if ( ! node_append(m, n))
                return(0);

        m->next = MDOC_NEXT_SIBLING;
        return(1);
}


int
mdoc_word_alloc(struct mdoc *m, int line, int pos, const char *p)
{
        struct mdoc_node *n;
        size_t            sv, len;

        len = strlen(p);

        n = node_alloc(m, line, pos, MDOC_MAX, MDOC_TEXT);
        n->string = mandoc_malloc(len + 1);
        sv = strlcpy(n->string, p, len + 1);

        /* Prohibit truncation. */
        assert(sv < len + 1);

        if ( ! node_append(m, n))
                return(0);

        m->next = MDOC_NEXT_SIBLING;
        return(1);
}


static void
mdoc_node_free(struct mdoc_node *p)
{

        if (MDOC_BLOCK == p->type || MDOC_ELEM == p->type)
                free(p->norm);
        if (p->string)
                free(p->string);
        if (p->args)
                mdoc_argv_free(p->args);
        free(p);
}


static void
mdoc_node_unlink(struct mdoc *m, struct mdoc_node *n)
{

        /* Adjust siblings. */

        if (n->prev)
                n->prev->next = n->next;
        if (n->next)
                n->next->prev = n->prev;

        /* Adjust parent. */

        if (n->parent) {
                n->parent->nchild--;
                if (n->parent->child == n)
                        n->parent->child = n->prev ? n->prev : n->next;
                if (n->parent->last == n)
                        n->parent->last = n->prev ? n->prev : NULL;
        }

        /* Adjust parse point, if applicable. */

        if (m && m->last == n) {
                if (n->prev) {
                        m->last = n->prev;
                        m->next = MDOC_NEXT_SIBLING;
                } else {
                        m->last = n->parent;
                        m->next = MDOC_NEXT_CHILD;
                }
        }

        if (m && m->first == n)
                m->first = NULL;
}


void
mdoc_node_delete(struct mdoc *m, struct mdoc_node *p)
{

        while (p->child) {
                assert(p->nchild);
                mdoc_node_delete(m, p->child);
        }
        assert(0 == p->nchild);

        mdoc_node_unlink(m, p);
        mdoc_node_free(p);
}


/*
 * Parse free-form text, that is, a line that does not begin with the
 * control character.
 */
static int
mdoc_ptext(struct mdoc *m, int line, char *buf, int offs)
{
        char             *c, *ws, *end;
        struct mdoc_node *n;

        /* Ignore bogus comments. */

        if ('\\' == buf[offs] && 
                        '.' == buf[offs + 1] && 
                        '"' == buf[offs + 2]) {
                mdoc_pmsg(m, line, offs, MANDOCERR_BADCOMMENT);
                return(1);
        }

        /* No text before an initial macro. */

        if (SEC_NONE == m->lastnamed) {
                mdoc_pmsg(m, line, offs, MANDOCERR_NOTEXT);
                return(1);
        }

        assert(m->last);
        n = m->last;

        /*
         * Divert directly to list processing if we're encountering a
         * columnar MDOC_BLOCK with or without a prior MDOC_BLOCK entry
         * (a MDOC_BODY means it's already open, in which case we should
         * process within its context in the normal way).
         */

        if (MDOC_Bl == n->tok && MDOC_BODY == n->type &&
                        LIST_column == n->norm->Bl.type) {
                /* `Bl' is open without any children. */
                m->flags |= MDOC_FREECOL;
                return(mdoc_macro(m, MDOC_It, line, offs, &offs, buf));
        }

        if (MDOC_It == n->tok && MDOC_BLOCK == n->type &&
                        NULL != n->parent &&
                        MDOC_Bl == n->parent->tok &&
                        LIST_column == n->parent->norm->Bl.type) {
                /* `Bl' has block-level `It' children. */
                m->flags |= MDOC_FREECOL;
                return(mdoc_macro(m, MDOC_It, line, offs, &offs, buf));
        }

        /*
         * Search for the beginning of unescaped trailing whitespace (ws)
         * and for the first character not to be output (end).
         */

        /* FIXME: replace with strcspn(). */
        ws = NULL;
        for (c = end = buf + offs; *c; c++) {
                switch (*c) {
                case '-':
                        if (mandoc_hyph(buf + offs, c))
                                *c = ASCII_HYPH;
                        ws = NULL;
                        break;
                case ' ':
                        if (NULL == ws)
                                ws = c;
                        continue;
                case '\t':
                        /*
                         * Always warn about trailing tabs,
                         * even outside literal context,
                         * where they should be put on the next line.
                         */
                        if (NULL == ws)
                                ws = c;
                        /*
                         * Strip trailing tabs in literal context only;
                         * outside, they affect the next line.
                         */
                        if (MDOC_LITERAL & m->flags)
                                continue;
                        break;
                case '\\':
                        /* Skip the escaped character, too, if any. */
                        if (c[1])
                                c++;
                        /* FALLTHROUGH */
                default:
                        ws = NULL;
                        break;
                }
                end = c + 1;
        }
        *end = '\0';

        if (ws)
                mdoc_pmsg(m, line, (int)(ws-buf), MANDOCERR_EOLNSPACE);

        if ('\0' == buf[offs] && ! (MDOC_LITERAL & m->flags)) {
                mdoc_pmsg(m, line, (int)(c-buf), MANDOCERR_NOBLANKLN);

                /*
                 * Insert a `sp' in the case of a blank line.  Technically,
                 * blank lines aren't allowed, but enough manuals assume this
                 * behaviour that we want to work around it.
                 */
                if ( ! mdoc_elem_alloc(m, line, offs, MDOC_sp, NULL))
                        return(0);

                m->next = MDOC_NEXT_SIBLING;
                return(1);
        }

        if ( ! mdoc_word_alloc(m, line, offs, buf+offs))
                return(0);

        if (MDOC_LITERAL & m->flags)
                return(1);

        /*
         * End-of-sentence check.  If the last character is an unescaped
         * EOS character, then flag the node as being the end of a
         * sentence.  The front-end will know how to interpret this.
         */

        assert(buf < end);

        if (mandoc_eos(buf+offs, (size_t)(end-buf-offs), 0))
                m->last->flags |= MDOC_EOS;

        return(1);
}


/*
 * Parse a macro line, that is, a line beginning with the control
 * character.
 */
static int
mdoc_pmacro(struct mdoc *m, int ln, char *buf, int offs)
{
        enum mdoct        tok;
        int               i, j, sv;
        char              mac[5];
        struct mdoc_node *n;

        /* Empty lines are ignored. */

        offs++;

        if ('\0' == buf[offs])
                return(1);

        i = offs;

        /* Accept tabs/whitespace after the initial control char. */

        if (' ' == buf[i] || '\t' == buf[i]) {
                i++;
                while (buf[i] && (' ' == buf[i] || '\t' == buf[i]))
                        i++;
                if ('\0' == buf[i])
                        return(1);
        }

        sv = i;

        /* 
         * Copy the first word into a nil-terminated buffer.
         * Stop copying when a tab, space, or eoln is encountered.
         */

        j = 0;
        while (j < 4 && '\0' != buf[i] && ' ' != buf[i] && '\t' != buf[i])
                mac[j++] = buf[i++];
        mac[j] = '\0';

        tok = (j > 1 || j < 4) ? mdoc_hash_find(mac) : MDOC_MAX;
        if (MDOC_MAX == tok) {
                mdoc_vmsg(m, MANDOCERR_MACRO, ln, sv, "%s", buf + sv - 1);
                return(1);
        }

        /* Disregard the first trailing tab, if applicable. */

        if ('\t' == buf[i])
                i++;

        /* Jump to the next non-whitespace word. */

        while (buf[i] && ' ' == buf[i])
                i++;

        /* 
         * Trailing whitespace.  Note that tabs are allowed to be passed
         * into the parser as "text", so we only warn about spaces here.
         */

        if ('\0' == buf[i] && ' ' == buf[i - 1])
                mdoc_pmsg(m, ln, i - 1, MANDOCERR_EOLNSPACE);

        /*
         * If an initial macro or a list invocation, divert directly
         * into macro processing.
         */

        if (NULL == m->last || MDOC_It == tok || MDOC_El == tok) {
                if ( ! mdoc_macro(m, tok, ln, sv, &i, buf)) 
                        goto err;
                return(1);
        }

        n = m->last;
        assert(m->last);

        /*
         * If the first macro of a `Bl -column', open an `It' block
         * context around the parsed macro.
         */

        if (MDOC_Bl == n->tok && MDOC_BODY == n->type &&
                        LIST_column == n->norm->Bl.type) {
                m->flags |= MDOC_FREECOL;
                if ( ! mdoc_macro(m, MDOC_It, ln, sv, &sv, buf))
                        goto err;
                return(1);
        }

        /*
         * If we're following a block-level `It' within a `Bl -column'
         * context (perhaps opened in the above block or in ptext()),
         * then open an `It' block context around the parsed macro.
         */

        if (MDOC_It == n->tok && MDOC_BLOCK == n->type &&
                        NULL != n->parent &&
                        MDOC_Bl == n->parent->tok &&
                        LIST_column == n->parent->norm->Bl.type) {
                m->flags |= MDOC_FREECOL;
                if ( ! mdoc_macro(m, MDOC_It, ln, sv, &sv, buf)) 
                        goto err;
                return(1);
        }

        /* Normal processing of a macro. */

        if ( ! mdoc_macro(m, tok, ln, sv, &i, buf)) 
                goto err;

        return(1);

err:    /* Error out. */

        m->flags |= MDOC_HALT;
        return(0);
}