Considerable mdoc.3 documentation.

Added a few more escapes and macros.

1 files changed, 182 insertions, 20 deletions

diff --git a/mdoc.3 b/mdoc.3
index 8dd79ffd..76f33555 100644
--- a/mdoc.3
+++ b/mdoc.3
@@ -1,8 +1,25 @@
+.\" $Id: mdoc.3,v 1.6 2009/02/23 09:33:34 kristaps Exp $
+.\"
+.\" Copyright (c) 2009 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.
 .\" 
-.Dd $Mdocdate: January 20 2009 $
+.Dd $Mdocdate: February 23 2009 $
 .Dt mdoc 3
 .Os
-.\"
+.\" SECTION
 .Sh NAME
 .Nm mdoc_alloc ,
 .Nm mdoc_parseln ,
@@ -11,7 +28,7 @@
 .Nm mdoc_meta ,
 .Nm mdoc_free
 .Nd mdoc macro compiler library
-.\"
+.\" SECTION
 .Sh SYNOPSIS
 .Fd #include <mdoc.h>
 .Vt extern const char * const * mdoc_macronames;
@@ -28,11 +45,28 @@
 .Fn mdoc_meta "struct mdoc *mdoc"
 .Ft int
 .Fn mdoc_endparse "struct mdoc *mdoc"
-.\"
+.\" SECTION
 .Sh DESCRIPTION
 The
 .Nm mdoc
-library parses lines of mdoc-macro text into an abstract syntax tree.
+library parses lines of mdoc input into an abstract syntax tree.  
+.Dq mdoc
+is a macro package of the
+.Dq roff
+language, which is used to format BSD manual pages.  The 
+.Nm
+library implements only those macros documented in the
+.Xr mdoc 7
+and
+.Xr mdoc.samples 7
+manuals.
+.\" PARAGRAPH
+.Pp
+.Nm
+is
+.Ud
+.\" PARAGRAPH
+.Pp
 In general, applications initiate a parsing sequence with
 .Fn mdoc_alloc ,
 parse each line in a document with 
@@ -48,10 +82,46 @@ then free all allocated memory with
 See the
 .Sx EXAMPLES
 section for a full example.
+.\" PARAGRAPH
 .Pp
-.\" Function descriptions.
+This section further defines the 
+.Sx Types ,
+.Sx Functions 
+and
+.Sx Variables
+available to programmers.  The last sub-section,
+.Sx Abstract Syntax Tree ,
+documents the output tree.
+.\" SUBSECTION
+.Ss Types
+Both functions (see
+.Sx Functions )
+and variables (see
+.Sx Variables )
+may use the following types:
+.Bl -ohang
+.\" LIST-ITEM
+.It Vt struct mdoc
+An opaque type defined in
+.Pa mdoc.c .
+Its values are only used privately within the library.
+.\" LIST-ITEM
+.It Vt struct mdoc_cb
+A set of message callbacks defined in
+.Pa mdoc.h .
+.\" LIST-ITEM
+.It Vt struct mdoc_node
+A parsed node.  Defined in
+.Pa mdoc.h .
+See 
+.Sx Abstract Syntax Tree
+for details.
+.El
+.\" SUBSECTION
+.Ss Functions
 Function descriptions follow:
-.Bl -ohang -offset indent
+.Bl -ohang 
+.\" LIST-ITEM
 .It Fn mdoc_alloc
 Allocates a parsing structure.  The
 .Fa data
@@ -60,20 +130,24 @@ pointer is passed to callbacks in
 which are documented further in the header file.  Returns NULL on
 failure.  If non-NULL, the pointer must be freed with
 .Fn mdoc_free .
+.\" LIST-ITEM
 .It Fn mdoc_free
 Free all resources of a parser.  The pointer is no longer valid after
 invocation.
+.\" LIST-ITEM
 .It Fn mdoc_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.
+.\" LIST-ITEM
 .It Fn mdoc_endparse
 Signals that the parse is complete.  Note that if 
 .Fn mdoc_endparse
 is called subsequent to
 .Fn mdoc_node ,
 the resulting tree is incomplete.  Returns 0 on failure, 1 on success.
+.\" LIST-ITEM
 .It Fn mdoc_node
 Returns the first node of the parse.  Note that if 
 .Fn mdoc_parseln
@@ -88,20 +162,108 @@ or
 .Fn mdoc_endparse
 return 0, the data will be incomplete.
 .El
-.Pp
-.\" Variable descriptions.
+.\" SUBSECTION
+.Ss Variables
 The following variables are also defined:
-.Bl -ohang -offset indent
+.Bl -ohang
+.\" LIST-ITEM
 .It Va mdoc_macronames
 An array of string-ified token names.
+.\" LIST-ITEM
 .It Va mdoc_argnames
 An array of string-ified token argument names.
 .El
-.Pp
+.\" SUBSECTION
+.Ss Abstract Syntax Tree
+The 
 .Nm
-is
-.Ud
-.\" 
+functions produce an abstract syntax tree (AST) describing the input
+lines in a regular form.  It may be reviewed at any time with
+.Fn mdoc_nodes ;
+however, if called before
+.Fn mdoc_endparse ,
+or after
+.Fn mdoc_endparse 
+or
+.Fn mdoc_parseln
+fail, it may be incomplete.
+.\" PARAGRAPH
+.Pp
+The AST is composed of 
+.Vt struct mdoc_node
+nodes with block, head, body, 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 type-specific data (the
+.Va data
+field).
+.\" PARAGRAPH
+.Pp
+The tree itself is arranged according to the following normal form,
+where capitalised non-terminals represent nodes.
+.Pp
+.Bl -tag -width "ELEMENTXX" -compact
+.\" LIST-ITEM
+.It ROOT
+\(<- mnode+
+.It mnode
+\(<- BLOCK | ELEMENT | TEXT
+.It BLOCK
+\(<- (HEAD [TEXT])+ [BODY [TEXT]] [TAIL [TEXT]]
+.It BLOCK
+\(<- BODY [TEXT] [TAIL [TEXT]]
+.It ELEMENT
+\(<- TEXT*
+.It HEAD
+\(<- mnode+
+.It BODY
+\(<- mnode+
+.It TAIL
+\(<- mnode+
+.It TEXT
+\(<- [[:alpha:]]*
+.El
+.\" PARAGRAPH
+.Pp
+Of note are the TEXT nodes following the HEAD, BODY and TAIL nodes of
+the BLOCK production.  These refer to punctuation marks.  Furthermore,
+although a TEXT node will generally have a non-zero-length string, it
+certain cases, such as 
+.Dq \&.Bd \-literal ,
+an empty line will produce a zero-length string.
+.\" PARAGRAPH
+.Pp
+The rule-of-thumb for mapping node types to macros follows: in-line
+elements, such as 
+.Dq \&.Em foo ,
+are classified as ELEMENT nodes, which can only contain text.
+Multi-line elements such as
+.Dq \&.Sh
+are BLOCK elements, where the HEAD constitutes line contents and the
+BODY constitutes subsequent lines.  In-line elements with matching
+pairs, such as
+.Dq \&.So
+and
+.Dq \&.Sc ,
+are BLOCK elements with no HEAD tag.  The only exception to this is
+.Dq \&.Eo 
+and
+.Dq \&.Ec ,
+which has a HEAD and TAIL node corresponding to the enclosure string.
+TEXT nodes, obviously, constitute text; the ROOT node is the document's
+root.
+.\" SECTION
 .Sh EXAMPLES
 The following example reads lines from stdin and parses them, operating
 on the finished parse tree with 
@@ -135,21 +297,19 @@ if (NULL == (node = mdoc_node(mdoc)))
 parsed(mdoc, node);
 mdoc_free(mdoc);
 .Ed
-.\"
+.\" SECTION
 .Sh SEE ALSO
 .Xr mdoc 7 ,
 .Xr mdoc.samples 7 ,
 .Xr groff 1 ,
 .Xr mdocml 1
-.\"
-.\"
+.\" SECTION
 .Sh AUTHORS
 The
 .Nm
 utility was written by 
 .An Kristaps Dzonsons Aq kristaps@kth.se .
-.\"
-.\"
+.\" SECTION
 .Sh BUGS
 Bugs, un-implemented macros and incompabilities are documented in this
 section.  The baseline for determining whether macro parsing is 
@@ -189,4 +349,6 @@ for
 .Ox
 are supported; support for
 .Nx
-and other BSD systems is in progress.
+and other 
+.Bx
+systems is in progress.