Updated: 2021/Apr/14


MANDOC(3)                  Library Functions Manual                  MANDOC(3)

NAME
     mandoc, deroff, mparse_alloc, mparse_copy, mparse_free, mparse_open,
     mparse_readfd, mparse_reset, mparse_result - mandoc macro compiler
     library

SYNOPSIS
     #include <sys/types.h>
     #include <stdio.h>
     #include <mandoc.h>

     #define ASCII_NBRSP
     #define ASCII_HYPH
     #define ASCII_BREAK

     struct mparse *
     mparse_alloc(int options, enum mandoc_os oe_e, char *os_s);

     void
     mparse_free(struct mparse *parse);

     void
     mparse_copy(const struct mparse *parse);

     int
     mparse_open(struct mparse *parse, const char *fname);

     void
     mparse_readfd(struct mparse *parse, int fd, const char *fname);

     void
     mparse_reset(struct mparse *parse);

     struct roff_meta *
     mparse_result(struct mparse *parse);

     #include <roff.h>

     void
     deroff(char **dest, const struct roff_node *node);

     #include <sys/types.h>
     #include <mandoc.h>
     #include <mdoc.h>

     extern const char * const * mdoc_argnames;
     extern const char * const * mdoc_macronames;

     #include <sys/types.h>
     #include <mandoc.h>
     #include <man.h>

     extern const char * const * man_macronames;

DESCRIPTION
     The mandoc library parses a UNIX manual into an abstract syntax tree
     (AST).  UNIX manuals are composed of mdoc(7) or man(7), and may be mixed
     with roff(7), tbl(7), and eqn(7) invocations.

     The following describes a general parse sequence:

     1.   initiate a parsing sequence with mchars_alloc(3) and mparse_alloc();

     2.   open a file with open(2) or mparse_open();

     3.   parse it with mparse_readfd();

     4.   close it with close(2);

     5.   retrieve the syntax tree with mparse_result();

     6.   if information about the validity of the input is needed, fetch it
          with mparse_updaterc();

     7.   iterate over parse nodes with starting from the first member of the
          returned struct roff_meta;

     8.   free all allocated memory with mparse_free() and mchars_free(3), or
          invoke mparse_reset() and go back to step 2 to parse new files.

REFERENCE
     This section documents the functions, types, and variables available via
     <mandoc.h>, with the exception of those documented in mandoc_escape(3)
     and mchars_alloc(3).

   Types
     enum mandocerr
     An error or warning message during parsing.

     enum mandoclevel
     A classification of an enum mandocerr as regards system operation.  See
     the DIAGNOSTICS section in mandoc(1) regarding the meanings of the
     levels.

     struct mparse
     An opaque pointer to a running parse sequence.  Created with
     mparse_alloc() and freed with mparse_free().  This may be used across
     parsed input if mparse_reset() is called between parses.

   Functions
     deroff()
     Obtain a text-only representation of a struct roff_node, including text
     contained in its child nodes.  To be used on children of the first member
     of struct roff_meta.  When it is no longer needed, the pointer returned
     from deroff() can be passed to free(3).

     mparse_alloc()
     Allocate a parser.  The arguments have the following effect:

          options  When the MPARSE_MDOC or MPARSE_MAN bit is set, only that
                   parser is used.  Otherwise, the document type is
                   automatically detected.

                   When the MPARSE_SO bit is set, roff(7) so file inclusion
                   requests are always honoured.  Otherwise, if the request is
                   the only content in an input file, only the file name is
                   remembered, to be returned in the sodest field of struct
                   roff_meta.

                   When the MPARSE_QUICK bit is set, parsing is aborted after
                   the NAME section.  This is for example useful in
                   makewhatis(8) -Q to quickly build minimal databases.

                   When the MARSE_VALIDATE bit is set, mparse_result() runs
                   the validation functions before returning the syntax tree.
                   This is almost always required, except in certain debugging
                   scenarios, for example to dump unvalidated syntax trees.

          os_e     Operating system to check base system conventions for.  If
                   MANDOC_OS_OTHER, the system is automatically detected from
                   Os, -Ios, or uname(3).

          os_s     A default string for the mdoc(7) Os macro, overriding the
                   OSNAME preprocessor definition and the results of uname(3).
                   Passing NULL sets no default.

     The same parser may be used for multiple files so long as mparse_reset()
     is called between parses.  mparse_free() must be called to free the
     memory allocated by this function.  Declared in <mandoc.h>, implemented
     in read.c.

     mparse_free()
     Free all memory allocated by mparse_alloc().  Declared in <mandoc.h>,
     implemented in read.c.

     mparse_copy()
     Dump a copy of the input to the standard output; used for -man -Tman.
     Declared in <mandoc.h>, implemented in read.c.

     mparse_open()
     Open the file for reading.  If that fails and fname does not already end
     in `.gz', try again after appending `.gz'.  Save the information whether
     the file is zipped or not.  Return a file descriptor open for reading or
     -1 on failure.  It can be passed to mparse_readfd() or used directly.
     Declared in <mandoc.h>, implemented in read.c.

     mparse_readfd()
     Parse a file descriptor opened with open(2) or mparse_open().  Pass the
     associated filename in fname.  This function may be called multiple times
     with different parameters; however, close(2) and mparse_reset() should be
     invoked between parses.  Declared in <mandoc.h>, implemented in read.c.

     mparse_reset()
     Reset a parser so that mparse_readfd() may be used again.  Declared in
     <mandoc.h>, implemented in read.c.

     mparse_result()
     Obtain the result of a parse.  Declared in <mandoc.h>, implemented in
     read.c.

   Variables
     man_macronames
     The string representation of a man(7) macro as indexed by enum mant.

     mdoc_argnames
     The string representation of an mdoc(7) macro argument as indexed by enum
     mdocargt.

     mdoc_macronames
     The string representation of an mdoc(7) macro as indexed by enum mdoct.

IMPLEMENTATION NOTES
     This section consists of structural documentation for mdoc(7) and man(7)
     syntax trees and strings.

   Man and Mdoc Strings
     Strings may be extracted from mdoc and man meta-data, or from text nodes
     (MDOC_TEXT and MAN_TEXT, respectively).  These strings have special non-
     printing formatting cues embedded in the text itself, as well as roff(7)
     escapes preserved from input.  Implementing systems will need to handle
     both situations to produce human-readable text.  In general, strings may
     be assumed to consist of 7-bit ASCII characters.

     The following non-printing characters may be embedded in text strings:

     ASCII_NBRSP
             A non-breaking space character.

     ASCII_HYPH
             A soft hyphen.

     ASCII_BREAK
             A breakable zero-width space.

     Escape characters are also passed verbatim into text strings.  An escape
     character is a sequence of characters beginning with the backslash (`\').
     To construct human-readable text, these should be intercepted with
     mandoc_escape(3) and converted with one the functions described in
     mchars_alloc(3).

   Man Abstract Syntax Tree
     This AST is governed by the ontological rules dictated in man(7) and
     derives its terminology accordingly.

     The AST is composed of struct roff_node nodes with element, root and text
     types as declared by the type field.  Each node also provides its parse
     point (the line, pos, and sec fields), its position in the tree (the
     parent, child, next and prev fields) and some type-specific data.

     The tree itself is arranged according to the following normal form, where
     capitalised non-terminals represent nodes.

     ROOT       <- mnode+
     mnode      <- ELEMENT | TEXT | BLOCK
     BLOCK      <- HEAD BODY
     HEAD       <- mnode*
     BODY       <- mnode*
     ELEMENT    <- ELEMENT | TEXT*
     TEXT       <- [[:ascii:]]*

     The only elements capable of nesting other elements are those with next-
     line scope as documented in man(7).

   Mdoc Abstract Syntax Tree
     This AST is governed by the ontological rules dictated in mdoc(7) and
     derives its terminology accordingly.  "In-line" elements described in
     mdoc(7) are described simply as "elements".

     The AST is composed of struct roff_node nodes with block, head, body,
     element, root and text types as declared by the type field.  Each node
     also provides its parse point (the line, pos, and sec fields), its
     position in the tree (the parent, child, last, next and prev fields) and
     some type-specific data, in particular, for nodes generated from macros,
     the generating macro in the tok field.

     The tree itself is arranged according to the following normal form, where
     capitalised non-terminals represent nodes.

     ROOT       <- mnode+
     mnode      <- BLOCK | ELEMENT | TEXT
     BLOCK      <- HEAD [TEXT] (BODY [TEXT])+ [TAIL [TEXT]]
     ELEMENT    <- TEXT*
     HEAD       <- mnode*
     BODY       <- mnode* [ENDBODY mnode*]
     TAIL       <- mnode*
     TEXT       <- [[:ascii:]]*

     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 `.Bd -literal', an empty line will produce a zero-length
     string.  Multiple body parts are only found in invocations of `Bl
     -column', where a new body introduces a new phrase.

     The mdoc(7) syntax tree accommodates for broken block structures as well.
     The ENDBODY node is available to end the formatting associated with a
     given block before the physical end of that block.  It has a non-null end
     field, is of the BODY type, has the same tok as the BLOCK it is ending,
     and has a pending field pointing to that BLOCK's BODY node.  It is an
     indirect child of that BODY node and has no children of its own.

     An ENDBODY node is generated when a block ends while one of its child
     blocks is still open, like in the following example:

           .Ao ao
           .Bo bo ac
           .Ac bc
           .Bc end

     This example results in the following block structure:

           BLOCK Ao
               HEAD Ao
               BODY Ao
                   TEXT ao
                   BLOCK Bo, pending -> Ao
                       HEAD Bo
                       BODY Bo
                           TEXT bo
                           TEXT ac
                           ENDBODY Ao, pending -> Ao
                           TEXT bc
           TEXT end

     Here, the formatting of the Ao block extends from TEXT ao to TEXT ac,
     while the formatting of the Bo block extends from TEXT bo to TEXT bc.  It
     renders as follows in -Tascii mode:

           <ao [bo ac> bc] end

     Support for badly-nested blocks is only provided for backward
     compatibility with some older mdoc(7) implementations.  Using badly-
     nested blocks is strongly discouraged; for example, the -Thtml front-end
     to mandoc(1) is unable to render them in any meaningful way.
     Furthermore, behaviour when encountering badly-nested blocks is not
     consistent across troff implementations, especially when using multiple
     levels of badly-nested blocks.

SEE ALSO
     mandoc(1), man.cgi(3), mandoc_escape(3), mandoc_headers(3),
     mandoc_malloc(3), mansearch(3), mchars_alloc(3), tbl(3), eqn(7), man(7),
     mandoc_char(7), mdoc(7), roff(7), tbl(7)

AUTHORS
     The mandoc library was written by Kristaps Dzonsons <kristaps@bsd.lv> and
     is maintained by Ingo Schwarze <schwarze@openbsd.org>.

NetBSD 9.99                    December 30, 2018                   NetBSD 9.99