+.\" PARAGRAPH
+.Pp
+This section further defines the
+.Sx Types ,
+.Sx Functions
+and
+.Sx Variables
+available to programmers. Following that,
+.Sx Character Encoding
+describes input format. Lastly,
+.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 -offset "XXXX"
+.\" 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 "XXXX"
+.\" LIST-ITEM
+.It Fn mdoc_alloc
+Allocates a parsing structure. The
+.Fa data
+pointer is passed to callbacks in
+.Fa cb ,
+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 The pointer is no longer valid after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
+or
+.Fn mdoc_endparse
+return 0, the tree will be incomplete.
+.It Fn mdoc_meta
+Returns the document's parsed meta-data. If this information has not
+yet been supplied or
+.Fn mdoc_parseln
+or
+.Fn mdoc_endparse
+return 0, the data will be incomplete.
+.El
+.\" SUBSECTION
+.Ss Variables
+The following variables are also defined:
+.Bl -ohang -offset "XXXX"
+.\" 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
+.\" SUBSECTION
+.Ss Character Encoding
+The
+.Xr mdoc 3
+library accepts only printable ASCII characters as defined by
+.Xr isprint 3 .
+Non-ASCII character sequences are delimited in various ways. All are
+preceeded by an escape character
+.Sq \\
+and followed by either an open-parenthesis
+.Sq \&(
+for two-character sequences; an open-bracket
+.Sq \&[
+for n-character sequences (terminated at a close-bracket
+.Sq \&] ) ;
+an asterisk and open-parenthesis
+.Sq \&*(
+for two-character sequences;
+an asterisk and non-open-parenthesis
+.Sq \&*
+for single-character sequences; or one of a small set of standalone
+single characters for other escapes.
+.\" PARAGRAPH
+.Pp
+Examples:
+.Pp
+.Bl -tag -width "XXXXXXXX" -offset "XXXX" -compact
+.\" LIST-ITEM
+.It \\*(<=
+prints
+.Dq \*(<=
+.Pq greater-equal
+.\" LIST-ITEM
+.It \\(<-
+prints
+.Dq \(<-
+.Pq left-arrow
+.\" LIST-ITEM
+.It \\[<-]
+also prints
+.Dq \(<-
+.Pq left-arrow
+.\" LIST-ITEM
+.It \\*(Ba
+prints
+.Dq \*(Ba
+.Pq bar
+.\" LIST-ITEM
+.It \\*q
+prints
+.Dq \*q
+.Pq double-quote
+.El
+.\" PARAGRAPH
+.Pp
+All escaped sequences are syntax-checked, but it's up to the front-end
+system to correctly render them to the output device.
+.\" SUBSECTION
+.Ss Abstract Syntax Tree
+The
+.Nm
+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 -offset "XXXX"
+.\" 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, in
+the specific case of
+.Sq \&.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
+.Sq \&.Em foo ,
+are classified as ELEMENT nodes, which can only contain text.
+Multi-line elements, such as
+.Sq \&.Sh ,
+are BLOCK elements, where the HEAD constitutes line contents and the
+BODY constitutes subsequent lines. In-line elements with matching
+pairs, such as
+.Sq \&.So
+and
+.Sq \&.Sc ,
+are BLOCK elements with no HEAD tag. The only exception to this is
+.Sq \&.Eo
+and
+.Sq \&.Ec ,
+which has a HEAD and TAIL node corresponding to the enclosure string.
+TEXT nodes, obviously, constitute text, and 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
+.Fn parsed .
+Note that, if the last line of the file isn't newline-terminated, this
+will truncate the file's last character (see
+.Xr fgetln 3 ) .
+Further, this example does not error-check nor free memory upon failure.
+.Bd -literal -offset "XXXX"
+struct mdoc *mdoc;
+struct mdoc_node *node;
+char *buf;
+size_t len;
+int line;
+
+line = 1;
+mdoc = mdoc_alloc(NULL, NULL);
+
+while ((buf = fgetln(fp, &len))) {
+ buf[len - 1] = '\\0';
+ if ( ! mdoc_parseln(mdoc, line, buf))
+ errx(1, "mdoc_parseln");
+ line++;
+}
+
+if ( ! mdoc_endparse(mdoc))
+ errx(1, "mdoc_endparse");
+if (NULL == (node = mdoc_node(mdoc)))
+ errx(1, "mdoc_node");
+
+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
+.Qq incompatible
+is the default
+.Xr groff 1
+system bundled with
+.Ox .
+.\" PARAGRAPH
+.Pp
+Un-implemented: the
+.Sq \&Xc
+and
+.Sq \&Xo
+macros aren't handled when used to span lines for the
+.Sq \&It
+macro. Such usage is specifically discouraged in
+.Xr mdoc.samples 7 .
+.\" PARAGRAPH
+.Pp
+Bugs: when
+.Sq \&It \-column
+is invoked, whitespace is not stripped around
+.Sq \&Ta
+or tab-character separators.
+.\" PARAGRAPH
+.Pp
+Bugs: elements within columns for
+.Sq \&It \-column
+are not yet supported.
+.\" PARAGRAPH
+.Pp
+Incompatible: the
+.Sq \&At
+macro only accepts a single parameter. Furthermore, several macros
+.Pf ( Sq \&Pp ,
+.Sq \&It ,
+and possibly others) accept multiple arguments with a warning.
+.\" PARAGRAPH
+.Pp
+Incompatible: only those macros specified by
+.Xr mdoc.samples 7
+and
+.Xr mdoc 7
+for
+.Ox
+are supported; support for
+.Nx
+and other
+.Bx
+systems is in progress.
git.ckatri.com / mandoc.git / blobdiff