path: root/man.3

.\"	$Id: man.3,v 1.30 2011/02/09 09:18:15 kristaps Exp $
.\"
.\" Copyright (c) 2009-2010 Kristaps Dzonsons <kristaps@bsd.lv>
.\"
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.Dd $Mdocdate: February 9 2011 $
.Dt MAN 3
.Os
.Sh NAME
.Nm man ,
.Nm man_addeqn ,
.Nm man_addspan ,
.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 int
.Fo man_addeqn
.Fa "struct man *man"
.Fa "const struct eqn *eqn"
.Fc
.Ft int
.Fo man_addspan
.Fa "struct man *man"
.Fa "const struct tbl_span *span"
.Fc
.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 macro:
.Pp
.Bl -tag -width Ds -compact
.It PD
Has no effect.
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
If
.Fn man_addeqn ,
.Fn man_addspan ,
.Fn man_parseln ,
or
.Fn man_endparse
return 0, calls to any function but
.Fn man_reset
or
.Fn man_free
will raise an assertion.
.Bl -ohang
.It Fn man_addeqn
Add an equation to the parsing stream.
Returns 0 on failure, 1 on success.
.It Fn man_addspan
Add a table span to the parsing stream.
Returns 0 on failure, 1 on success.
.It Fn man_alloc
Allocates a parsing structure.
The
.Fa data
pointer is passed to
.Fa msgs .
Always returns a valid pointer.
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.
Returns 0 on failure, 1 on success.
.It Fn man_node
Returns the first node of the parse.
.It Fn man_meta
Returns the document's parsed meta-data.
.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
.Dl % 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 .