.\"	$Id: man.3,v 1.16 2010/10/23 17:11:31 schwarze Exp $
.\"
.\" Copyright (c) 2009-2010 Kristaps Dzonsons <kristaps@bsd.lv>
.\"
.\" 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.
.\"
.Dd $Mdocdate: October 23 2010 $
.Dt MAN 3
.Os
.Sh NAME
.Nm man ,
.Nm man_alloc ,
.Nm man_endparse ,
.Nm man_free ,
.Nm man_meta ,
.Nm man_node ,
.Nm man_parseln ,
.Nm man_reset
.Nd man macro compiler library
.Sh SYNOPSIS
.In mandoc.h
.In man.h
.Vt extern const char * const * man_macronames;
.Ft "struct man *"
.Fo man_alloc
.Fa "struct regset *regs"
.Fa "void *data"
.Fa "mandocmsg msgs"
.Fc
.Ft int
.Fn man_endparse "struct man *man"
.Ft void
.Fn man_free "struct man *man"
.Ft "const struct man_meta *"
.Fn man_meta "const struct man *man"
.Ft "const struct man_node *"
.Fn man_node "const struct man *man"
.Ft int
.Fo man_parseln
.Fa "struct man *man"
.Fa "int line"
.Fa "char *buf"
.Fc
.Ft void
.Fn man_reset "struct man *man"
.Sh DESCRIPTION
The
.Nm
library parses lines of
.Xr man 7
input into an abstract syntax tree (AST).
.Pp
In general, applications initiate a parsing sequence with
.Fn man_alloc ,
parse each line in a document with
.Fn man_parseln ,
close the parsing session with
.Fn man_endparse ,
operate over the syntax tree returned by
.Fn man_node
and
.Fn man_meta ,
then free all allocated memory with
.Fn man_free .
The
.Fn man_reset
function may be used in order to reset the parser for another input
sequence.
.Pp
Beyond the full set of macros defined in
.Xr man 7 ,
the
.Nm
library also accepts the following macros:
.Pp
.Bl -tag -width Ds -compact
.It PD
Has no effect.  Handled as a current-scope line macro.
.It Sp
A synonym for
.Sq sp 0.5v
.Pq part of the standard preamble for Perl documentation .
Handled as a line macro.
.It Vb
A synonym for
.Sq nf
.Pq part of the standard preamble for Perl documentation .
Handled as a current-scope line macro.
.It Ve
A synonym for
.Sq fi ,
closing
.Sq Vb
.Pq part of the standard preamble for Perl documentation .
Handled as a current-scope line macro.
.El
.Ss Types
.Bl -ohang
.It Vt struct man
An opaque type.
Its values are only used privately within the library.
.It Vt struct man_node
A parsed node.
See
.Sx Abstract Syntax Tree
for details.
.El
.Ss Functions
.Bl -ohang
.It Fn man_alloc
Allocates a parsing structure.
The
.Fa data
pointer is passed to
.Fa msgs .
Returns NULL on failure.
If non-NULL, the pointer must be freed with
.Fn man_free .
.It Fn man_reset
Reset the parser for another parse routine.
After its use,
.Fn man_parseln
behaves as if invoked for the first time.
.It Fn man_free
Free all resources of a parser.
The pointer is no longer valid after invocation.
.It Fn man_parseln
Parse a nil-terminated line of input.
This line should not contain the trailing newline.
Returns 0 on failure, 1 on success.
The input buffer
.Fa buf
is modified by this function.
.It Fn man_endparse
Signals that the parse is complete.
Note that if
.Fn man_endparse
is called subsequent to
.Fn man_node ,
the resulting tree is incomplete.
Returns 0 on failure, 1 on success.
.It Fn man_node
Returns the first node of the parse.
Note that if
.Fn man_parseln
or
.Fn man_endparse
return 0, the tree will be incomplete.
.It Fn man_meta
Returns the document's parsed meta-data.
If this information has not yet been supplied or
.Fn man_parseln
or
.Fn man_endparse
return 0, the data will be incomplete.
.El
.Ss Variables
The following variables are also defined:
.Bl -ohang
.It Va man_macronames
An array of string-ified token names.
.El
.Ss Abstract Syntax Tree
The
.Nm
functions produce an abstract syntax tree (AST) describing input in a
regular form.
It may be reviewed at any time with
.Fn man_nodes ;
however, if called before
.Fn man_endparse ,
or after
.Fn man_endparse
or
.Fn man_parseln
fail, it may be incomplete.
.Pp
This AST is governed by the ontological rules dictated in
.Xr man 7
and derives its terminology accordingly.
.Pp
The AST is composed of
.Vt struct man_node
nodes with element, root and text types as declared by the
.Va type
field.
Each node also provides its parse point (the
.Va line ,
.Va sec ,
and
.Va pos
fields), its position in the tree (the
.Va parent ,
.Va child ,
.Va next
and
.Va prev
fields) and some type-specific data.
.Pp
The tree itself is arranged according to the following normal form,
where capitalised non-terminals represent nodes.
.Pp
.Bl -tag -width "ELEMENTXX" -compact
.It ROOT
\(<- mnode+
.It mnode
\(<- ELEMENT | TEXT | BLOCK
.It BLOCK
\(<- HEAD BODY
.It HEAD
\(<- mnode*
.It BODY
\(<- mnode*
.It ELEMENT
\(<- ELEMENT | TEXT*
.It TEXT
\(<- [[:alpha:]]*
.El
.Pp
The only elements capable of nesting other elements are those with
next-lint scope as documented in
.Xr man 7 .
.Sh EXAMPLES
The following example reads lines from stdin and parses them, operating
on the finished parse tree with
.Fn parsed .
This example does not error-check nor free memory upon failure.
.Bd -literal -offset indent
struct regset regs;
struct man *man;
struct man_node *node;
char *buf;
size_t len;
int line;

bzero(&regs, sizeof(struct regset));
line = 1;
man = man_alloc(&regs, NULL, NULL);
buf = NULL;
alloc_len = 0;

while ((len = getline(&buf, &alloc_len, stdin)) >= 0) {
    if (len && buflen[len - 1] = '\en')
        buf[len - 1] = '\e0';
    if ( ! man_parseln(man, line, buf))
        errx(1, "man_parseln");
    line++;
}

free(buf);

if ( ! man_endparse(man))
    errx(1, "man_endparse");
if (NULL == (node = man_node(man)))
    errx(1, "man_node");

parsed(man, node);
man_free(man);
.Ed
.Pp
To compile this, execute
.Pp
.D1 % cc main.c libman.a libmandoc.a
.Pp
where
.Pa main.c
is the example file.
.Sh SEE ALSO
.Xr mandoc 1 ,
.Xr man 7
.Sh AUTHORS
The
.Nm
library was written by
.An Kristaps Dzonsons Aq kristaps@bsd.lv .