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Annotation of mandoc/mandoc.3, Revision 1.18

1.18    ! schwarze    1: .\"    $Id: mandoc.3,v 1.17 2012/01/13 15:27:14 joerg Exp $
1.1       kristaps    2: .\"
                      3: .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
                      4: .\" Copyright (c) 2010 Ingo Schwarze <schwarze@openbsd.org>
                      5: .\"
                      6: .\" Permission to use, copy, modify, and distribute this software for any
                      7: .\" purpose with or without fee is hereby granted, provided that the above
                      8: .\" copyright notice and this permission notice appear in all copies.
                      9: .\"
                     10: .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
                     11: .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
                     12: .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
                     13: .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
                     14: .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
                     15: .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
                     16: .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
                     17: .\"
1.18    ! schwarze   18: .Dd $Mdocdate: January 13 2012 $
1.1       kristaps   19: .Dt MANDOC 3
                     20: .Os
                     21: .Sh NAME
                     22: .Nm mandoc ,
1.3       kristaps   23: .Nm mandoc_escape ,
1.1       kristaps   24: .Nm man_meta ,
1.14      kristaps   25: .Nm man_mparse ,
1.1       kristaps   26: .Nm man_node ,
1.6       kristaps   27: .Nm mchars_alloc ,
                     28: .Nm mchars_free ,
                     29: .Nm mchars_num2char ,
1.7       kristaps   30: .Nm mchars_num2uc ,
1.6       kristaps   31: .Nm mchars_spec2cp ,
                     32: .Nm mchars_spec2str ,
1.1       kristaps   33: .Nm mdoc_meta ,
                     34: .Nm mdoc_node ,
                     35: .Nm mparse_alloc ,
                     36: .Nm mparse_free ,
1.14      kristaps   37: .Nm mparse_getkeep ,
                     38: .Nm mparse_keep ,
1.1       kristaps   39: .Nm mparse_readfd ,
                     40: .Nm mparse_reset ,
1.2       kristaps   41: .Nm mparse_result ,
                     42: .Nm mparse_strerror ,
                     43: .Nm mparse_strlevel
1.1       kristaps   44: .Nd mandoc macro compiler library
1.8       kristaps   45: .Sh LIBRARY
                     46: .Lb mandoc
1.1       kristaps   47: .Sh SYNOPSIS
                     48: .In man.h
                     49: .In mdoc.h
                     50: .In mandoc.h
1.3       kristaps   51: .Ft "enum mandoc_esc"
                     52: .Fo mandoc_escape
1.15      kristaps   53: .Fa "const char **end"
                     54: .Fa "const char **start"
                     55: .Fa "int *sz"
1.3       kristaps   56: .Fc
1.1       kristaps   57: .Ft "const struct man_meta *"
                     58: .Fo man_meta
                     59: .Fa "const struct man *man"
                     60: .Fc
1.14      kristaps   61: .Ft "const struct mparse *"
                     62: .Fo man_mparse
                     63: .Fa "const struct man *man"
                     64: .Fc
1.1       kristaps   65: .Ft "const struct man_node *"
                     66: .Fo man_node
                     67: .Fa "const struct man *man"
                     68: .Fc
1.6       kristaps   69: .Ft "struct mchars *"
                     70: .Fn mchars_alloc
                     71: .Ft void
                     72: .Fn mchars_free "struct mchars *p"
                     73: .Ft char
                     74: .Fn mchars_num2char "const char *cp" "size_t sz"
1.7       kristaps   75: .Ft int
                     76: .Fn mchars_num2uc "const char *cp" "size_t sz"
1.6       kristaps   77: .Ft "const char *"
                     78: .Fo mchars_spec2str
1.16      kristaps   79: .Fa "const struct mchars *p"
1.6       kristaps   80: .Fa "const char *cp"
                     81: .Fa "size_t sz"
                     82: .Fa "size_t *rsz"
                     83: .Fc
                     84: .Ft int
                     85: .Fo mchars_spec2cp
1.16      kristaps   86: .Fa "const struct mchars *p"
1.6       kristaps   87: .Fa "const char *cp"
                     88: .Fa "size_t sz"
                     89: .Ft "const char *"
                     90: .Fc
1.1       kristaps   91: .Ft "const struct mdoc_meta *"
                     92: .Fo mdoc_meta
                     93: .Fa "const struct mdoc *mdoc"
                     94: .Fc
                     95: .Ft "const struct mdoc_node *"
                     96: .Fo mdoc_node
                     97: .Fa "const struct mdoc *mdoc"
                     98: .Fc
                     99: .Ft void
                    100: .Fo mparse_alloc
                    101: .Fa "enum mparset type"
                    102: .Fa "enum mandoclevel wlevel"
                    103: .Fa "mandocmsg msg"
                    104: .Fa "void *msgarg"
                    105: .Fc
                    106: .Ft void
                    107: .Fo mparse_free
                    108: .Fa "struct mparse *parse"
                    109: .Fc
1.14      kristaps  110: .Ft void
                    111: .Fo mparse_getkeep
                    112: .Fa "const struct mparse *parse"
                    113: .Fc
                    114: .Ft void
                    115: .Fo mparse_keep
                    116: .Fa "struct mparse *parse"
                    117: .Fc
1.1       kristaps  118: .Ft "enum mandoclevel"
                    119: .Fo mparse_readfd
                    120: .Fa "struct mparse *parse"
                    121: .Fa "int fd"
                    122: .Fa "const char *fname"
                    123: .Fc
                    124: .Ft void
                    125: .Fo mparse_reset
                    126: .Fa "struct mparse *parse"
                    127: .Fc
                    128: .Ft void
                    129: .Fo mparse_result
                    130: .Fa "struct mparse *parse"
                    131: .Fa "struct mdoc **mdoc"
                    132: .Fa "struct man **man"
1.2       kristaps  133: .Fc
                    134: .Ft "const char *"
                    135: .Fo mparse_strerror
                    136: .Fa "enum mandocerr"
                    137: .Fc
                    138: .Ft "const char *"
                    139: .Fo mparse_strlevel
                    140: .Fa "enum mandoclevel"
1.1       kristaps  141: .Fc
                    142: .Vt extern const char * const * man_macronames;
                    143: .Vt extern const char * const * mdoc_argnames;
                    144: .Vt extern const char * const * mdoc_macronames;
1.4       kristaps  145: .Fd "#define ASCII_NBRSP"
                    146: .Fd "#define ASCII_HYPH"
1.1       kristaps  147: .Sh DESCRIPTION
                    148: The
                    149: .Nm mandoc
                    150: library parses a
                    151: .Ux
                    152: manual into an abstract syntax tree (AST).
                    153: .Ux
                    154: manuals are composed of
                    155: .Xr mdoc 7
                    156: or
                    157: .Xr man 7 ,
                    158: and may be mixed with
                    159: .Xr roff 7 ,
                    160: .Xr tbl 7 ,
                    161: and
                    162: .Xr eqn 7
                    163: invocations.
                    164: .Pp
                    165: The following describes a general parse sequence:
                    166: .Bl -enum
                    167: .It
                    168: initiate a parsing sequence with
                    169: .Fn mparse_alloc ;
                    170: .It
                    171: parse files or file descriptors with
                    172: .Fn mparse_readfd ;
                    173: .It
                    174: retrieve a parsed syntax tree, if the parse was successful, with
                    175: .Fn mparse_result ;
                    176: .It
                    177: iterate over parse nodes with
                    178: .Fn mdoc_node
                    179: or
                    180: .Fn man_node ;
                    181: .It
                    182: free all allocated memory with
                    183: .Fn mparse_free ,
                    184: or invoke
                    185: .Fn mparse_reset
                    186: and parse new files.
1.3       kristaps  187: .El
1.6       kristaps  188: .Pp
                    189: The
                    190: .Nm
                    191: library also contains routines for translating character strings into glyphs
                    192: .Pq see Fn mchars_alloc
                    193: and parsing escape sequences from strings
                    194: .Pq see Fn mandoc_escape .
1.3       kristaps  195: .Sh REFERENCE
                    196: This section documents the functions, types, and variables available
                    197: via
                    198: .In mandoc.h .
                    199: .Ss Types
                    200: .Bl -ohang
                    201: .It Vt "enum mandoc_esc"
1.11      kristaps  202: An escape sequence classification.
1.3       kristaps  203: .It Vt "enum mandocerr"
1.11      kristaps  204: A fatal error, error, or warning message during parsing.
1.3       kristaps  205: .It Vt "enum mandoclevel"
1.11      kristaps  206: A classification of an
                    207: .Vt "enum mandoclevel"
                    208: as regards system operation.
1.6       kristaps  209: .It Vt "struct mchars"
                    210: An opaque pointer to an object allowing for translation between
                    211: character strings and glyphs.
                    212: See
                    213: .Fn mchars_alloc .
1.3       kristaps  214: .It Vt "enum mparset"
1.11      kristaps  215: The type of parser when reading input.
                    216: This should usually be
1.12      kristaps  217: .Dv MPARSE_AUTO
1.11      kristaps  218: for auto-detection.
1.3       kristaps  219: .It Vt "struct mparse"
1.11      kristaps  220: An opaque pointer to a running parse sequence.
                    221: Created with
                    222: .Fn mparse_alloc
                    223: and freed with
                    224: .Fn mparse_free .
                    225: This may be used across parsed input if
                    226: .Fn mparse_reset
                    227: is called between parses.
1.3       kristaps  228: .It Vt "mandocmsg"
1.11      kristaps  229: A prototype for a function to handle fatal error, error, and warning
                    230: messages emitted by the parser.
1.3       kristaps  231: .El
                    232: .Ss Functions
                    233: .Bl -ohang
                    234: .It Fn mandoc_escape
1.4       kristaps  235: Scan an escape sequence, i.e., a character string beginning with
                    236: .Sq \e .
1.17      joerg     237: Pass a pointer to the character after the
                    238: .Sq \e
                    239: as
1.4       kristaps  240: .Va end ;
                    241: it will be set to the supremum of the parsed escape sequence unless
1.12      kristaps  242: returning
                    243: .Dv ESCAPE_ERROR ,
                    244: in which case the string is bogus and should be
1.4       kristaps  245: thrown away.
1.12      kristaps  246: If not
                    247: .Dv ESCAPE_ERROR
                    248: or
                    249: .Dv ESCAPE_IGNORE ,
1.4       kristaps  250: .Va start
                    251: is set to the first relevant character of the substring (font, glyph,
                    252: whatever) of length
                    253: .Va sz .
                    254: Both
                    255: .Va start
                    256: and
                    257: .Va sz
1.12      kristaps  258: may be
                    259: .Dv NULL .
1.18    ! schwarze  260: Declared in
        !           261: .In mandoc.h ,
        !           262: implemented in
        !           263: .Pa mandoc.c .
1.3       kristaps  264: .It Fn man_meta
1.4       kristaps  265: Obtain the meta-data of a successful parse.
                    266: This may only be used on a pointer returned by
                    267: .Fn mparse_result .
1.18    ! schwarze  268: Declared in
        !           269: .In man.h ,
        !           270: implemented in
        !           271: .Pa man.c .
1.14      kristaps  272: .It Fn man_mparse
                    273: Get the parser used for the current output.
1.18    ! schwarze  274: Declared in
        !           275: .In man.h ,
        !           276: implemented in
        !           277: .Pa man.c .
1.3       kristaps  278: .It Fn man_node
1.4       kristaps  279: Obtain the root node of a successful parse.
                    280: This may only be used on a pointer returned by
                    281: .Fn mparse_result .
1.18    ! schwarze  282: Declared in
        !           283: .In man.h ,
        !           284: implemented in
        !           285: .Pa man.c .
1.6       kristaps  286: .It Fn mchars_alloc
                    287: Allocate an
                    288: .Vt "struct mchars *"
                    289: object for translating special characters into glyphs.
                    290: See
                    291: .Xr mandoc_char 7
                    292: for an overview of special characters.
                    293: The object must be freed with
                    294: .Fn mchars_free .
1.18    ! schwarze  295: Declared in
        !           296: .In mandoc.h ,
        !           297: implemented in
        !           298: .Pa chars.c .
1.6       kristaps  299: .It Fn mchars_free
                    300: Free an object created with
                    301: .Fn mchars_alloc .
1.18    ! schwarze  302: Declared in
        !           303: .In mandoc.h ,
        !           304: implemented in
        !           305: .Pa chars.c .
1.6       kristaps  306: .It Fn mchars_num2char
1.7       kristaps  307: Convert a character index (e.g., the \eN\(aq\(aq escape) into a
                    308: printable ASCII character.
                    309: Returns \e0 (the nil character) if the input sequence is malformed.
1.18    ! schwarze  310: Declared in
        !           311: .In mandoc.h ,
        !           312: implemented in
        !           313: .Pa chars.c .
1.7       kristaps  314: .It Fn mchars_num2uc
                    315: Convert a hexadecimal character index (e.g., the \e[uNNNN] escape) into
                    316: a Unicode codepoint.
1.6       kristaps  317: Returns \e0 (the nil character) if the input sequence is malformed.
1.18    ! schwarze  318: Declared in
        !           319: .In mandoc.h ,
        !           320: implemented in
        !           321: .Pa chars.c .
1.6       kristaps  322: .It Fn mchars_spec2cp
                    323: Convert a special character into a valid Unicode codepoint.
1.10      kristaps  324: Returns \-1 on failure or a non-zero Unicode codepoint on success.
1.18    ! schwarze  325: Declared in
        !           326: .In mandoc.h ,
        !           327: implemented in
        !           328: .Pa chars.c .
1.6       kristaps  329: .It Fn mchars_spec2str
                    330: Convert a special character into an ASCII string.
1.12      kristaps  331: Returns
                    332: .Dv NULL
                    333: on failure.
1.18    ! schwarze  334: Declared in
        !           335: .In mandoc.h ,
        !           336: implemented in
        !           337: .Pa chars.c .
1.3       kristaps  338: .It Fn mdoc_meta
1.4       kristaps  339: Obtain the meta-data of a successful parse.
                    340: This may only be used on a pointer returned by
                    341: .Fn mparse_result .
1.18    ! schwarze  342: Declared in
        !           343: .In mdoc.h ,
        !           344: implemented in
        !           345: .Pa mdoc.c .
1.3       kristaps  346: .It Fn mdoc_node
1.4       kristaps  347: Obtain the root node of a successful parse.
                    348: This may only be used on a pointer returned by
                    349: .Fn mparse_result .
1.18    ! schwarze  350: Declared in
        !           351: .In mdoc.h ,
        !           352: implemented in
        !           353: .Pa mdoc.c .
1.3       kristaps  354: .It Fn mparse_alloc
1.4       kristaps  355: Allocate a parser.
                    356: The same parser may be used for multiple files so long as
                    357: .Fn mparse_reset
                    358: is called between parses.
                    359: .Fn mparse_free
                    360: must be called to free the memory allocated by this function.
1.18    ! schwarze  361: Declared in
        !           362: .In mandoc.h ,
        !           363: implemented in
        !           364: .Pa read.c .
1.3       kristaps  365: .It Fn mparse_free
1.4       kristaps  366: Free all memory allocated by
                    367: .Fn mparse_alloc .
1.18    ! schwarze  368: Declared in
        !           369: .In mandoc.h ,
        !           370: implemented in
        !           371: .Pa read.c .
1.14      kristaps  372: .It Fn mparse_getkeep
                    373: Acquire the keep buffer.
                    374: Must follow a call of
                    375: .Fn mparse_keep .
1.18    ! schwarze  376: Declared in
        !           377: .In mandoc.h ,
        !           378: implemented in
        !           379: .Pa read.c .
1.14      kristaps  380: .It Fn mparse_keep
                    381: Instruct the parser to retain a copy of its parsed input.
                    382: This can be acquired with subsequent
                    383: .Fn mparse_getkeep
                    384: calls.
1.18    ! schwarze  385: Declared in
        !           386: .In mandoc.h ,
        !           387: implemented in
        !           388: .Pa read.c .
1.3       kristaps  389: .It Fn mparse_readfd
1.4       kristaps  390: Parse a file or file descriptor.
                    391: If
                    392: .Va fd
                    393: is -1,
                    394: .Va fname
                    395: is opened for reading.
                    396: Otherwise,
                    397: .Va fname
                    398: is assumed to be the name associated with
                    399: .Va fd .
                    400: This may be called multiple times with different parameters; however,
                    401: .Fn mparse_reset
                    402: should be invoked between parses.
1.18    ! schwarze  403: Declared in
        !           404: .In mandoc.h ,
        !           405: implemented in
        !           406: .Pa read.c .
1.3       kristaps  407: .It Fn mparse_reset
1.4       kristaps  408: Reset a parser so that
                    409: .Fn mparse_readfd
                    410: may be used again.
1.18    ! schwarze  411: Declared in
        !           412: .In mandoc.h ,
        !           413: implemented in
        !           414: .Pa read.c .
1.3       kristaps  415: .It Fn mparse_result
1.4       kristaps  416: Obtain the result of a parse.
                    417: Only successful parses
                    418: .Po
                    419: i.e., those where
                    420: .Fn mparse_readfd
                    421: returned less than MANDOCLEVEL_FATAL
                    422: .Pc
                    423: should invoke this function, in which case one of the two pointers will
                    424: be filled in.
1.18    ! schwarze  425: Declared in
        !           426: .In mandoc.h ,
        !           427: implemented in
        !           428: .Pa read.c .
1.3       kristaps  429: .It Fn mparse_strerror
1.4       kristaps  430: Return a statically-allocated string representation of an error code.
1.18    ! schwarze  431: Declared in
        !           432: .In mandoc.h ,
        !           433: implemented in
        !           434: .Pa read.c .
1.3       kristaps  435: .It Fn mparse_strlevel
1.4       kristaps  436: Return a statically-allocated string representation of a level code.
1.18    ! schwarze  437: Declared in
        !           438: .In mandoc.h ,
        !           439: implemented in
        !           440: .Pa read.c .
1.3       kristaps  441: .El
                    442: .Ss Variables
                    443: .Bl -ohang
                    444: .It Va man_macronames
1.4       kristaps  445: The string representation of a man macro as indexed by
                    446: .Vt "enum mant" .
1.3       kristaps  447: .It Va mdoc_argnames
1.4       kristaps  448: The string representation of a mdoc macro argument as indexed by
                    449: .Vt "enum mdocargt" .
1.3       kristaps  450: .It Va mdoc_macronames
1.4       kristaps  451: The string representation of a mdoc macro as indexed by
                    452: .Vt "enum mdoct" .
1.1       kristaps  453: .El
                    454: .Sh IMPLEMENTATION NOTES
                    455: This section consists of structural documentation for
                    456: .Xr mdoc 7
                    457: and
                    458: .Xr man 7
1.11      kristaps  459: syntax trees and strings.
                    460: .Ss Man and Mdoc Strings
                    461: Strings may be extracted from mdoc and man meta-data, or from text
                    462: nodes (MDOC_TEXT and MAN_TEXT, respectively).
                    463: These strings have special non-printing formatting cues embedded in the
                    464: text itself, as well as
                    465: .Xr roff 7
                    466: escapes preserved from input.
                    467: Implementing systems will need to handle both situations to produce
                    468: human-readable text.
                    469: In general, strings may be assumed to consist of 7-bit ASCII characters.
                    470: .Pp
                    471: The following non-printing characters may be embedded in text strings:
                    472: .Bl -tag -width Ds
                    473: .It Dv ASCII_NBRSP
                    474: A non-breaking space character.
                    475: .It Dv ASCII_HYPH
                    476: A soft hyphen.
                    477: .El
                    478: .Pp
                    479: Escape characters are also passed verbatim into text strings.
                    480: An escape character is a sequence of characters beginning with the
                    481: backslash
                    482: .Pq Sq \e .
                    483: To construct human-readable text, these should be intercepted with
                    484: .Fn mandoc_escape
                    485: and converted with one of
                    486: .Fn mchars_num2char ,
                    487: .Fn mchars_spec2str ,
                    488: and so on.
1.1       kristaps  489: .Ss Man Abstract Syntax Tree
                    490: This AST is governed by the ontological rules dictated in
                    491: .Xr man 7
                    492: and derives its terminology accordingly.
                    493: .Pp
                    494: The AST is composed of
                    495: .Vt struct man_node
                    496: nodes with element, root and text types as declared by the
                    497: .Va type
                    498: field.
                    499: Each node also provides its parse point (the
                    500: .Va line ,
                    501: .Va sec ,
                    502: and
                    503: .Va pos
                    504: fields), its position in the tree (the
                    505: .Va parent ,
                    506: .Va child ,
                    507: .Va next
                    508: and
                    509: .Va prev
                    510: fields) and some type-specific data.
                    511: .Pp
                    512: The tree itself is arranged according to the following normal form,
                    513: where capitalised non-terminals represent nodes.
                    514: .Pp
                    515: .Bl -tag -width "ELEMENTXX" -compact
                    516: .It ROOT
                    517: \(<- mnode+
                    518: .It mnode
                    519: \(<- ELEMENT | TEXT | BLOCK
                    520: .It BLOCK
                    521: \(<- HEAD BODY
                    522: .It HEAD
                    523: \(<- mnode*
                    524: .It BODY
                    525: \(<- mnode*
                    526: .It ELEMENT
                    527: \(<- ELEMENT | TEXT*
                    528: .It TEXT
1.11      kristaps  529: \(<- [[:ascii:]]*
1.1       kristaps  530: .El
                    531: .Pp
                    532: The only elements capable of nesting other elements are those with
                    533: next-lint scope as documented in
                    534: .Xr man 7 .
                    535: .Ss Mdoc Abstract Syntax Tree
                    536: This AST is governed by the ontological
                    537: rules dictated in
                    538: .Xr mdoc 7
                    539: and derives its terminology accordingly.
                    540: .Qq In-line
                    541: elements described in
                    542: .Xr mdoc 7
                    543: are described simply as
                    544: .Qq elements .
                    545: .Pp
                    546: The AST is composed of
                    547: .Vt struct mdoc_node
                    548: nodes with block, head, body, element, root and text types as declared
                    549: by the
                    550: .Va type
                    551: field.
                    552: Each node also provides its parse point (the
                    553: .Va line ,
                    554: .Va sec ,
                    555: and
                    556: .Va pos
                    557: fields), its position in the tree (the
                    558: .Va parent ,
                    559: .Va child ,
                    560: .Va nchild ,
                    561: .Va next
                    562: and
                    563: .Va prev
                    564: fields) and some type-specific data, in particular, for nodes generated
                    565: from macros, the generating macro in the
                    566: .Va tok
                    567: field.
                    568: .Pp
                    569: The tree itself is arranged according to the following normal form,
                    570: where capitalised non-terminals represent nodes.
                    571: .Pp
                    572: .Bl -tag -width "ELEMENTXX" -compact
                    573: .It ROOT
                    574: \(<- mnode+
                    575: .It mnode
                    576: \(<- BLOCK | ELEMENT | TEXT
                    577: .It BLOCK
                    578: \(<- HEAD [TEXT] (BODY [TEXT])+ [TAIL [TEXT]]
                    579: .It ELEMENT
                    580: \(<- TEXT*
                    581: .It HEAD
                    582: \(<- mnode*
                    583: .It BODY
                    584: \(<- mnode* [ENDBODY mnode*]
                    585: .It TAIL
                    586: \(<- mnode*
                    587: .It TEXT
1.11      kristaps  588: \(<- [[:ascii:]]*
1.1       kristaps  589: .El
                    590: .Pp
                    591: Of note are the TEXT nodes following the HEAD, BODY and TAIL nodes of
                    592: the BLOCK production: these refer to punctuation marks.
                    593: Furthermore, although a TEXT node will generally have a non-zero-length
                    594: string, in the specific case of
                    595: .Sq \&.Bd \-literal ,
                    596: an empty line will produce a zero-length string.
                    597: Multiple body parts are only found in invocations of
                    598: .Sq \&Bl \-column ,
                    599: where a new body introduces a new phrase.
                    600: .Pp
                    601: The
                    602: .Xr mdoc 7
1.5       kristaps  603: syntax tree accommodates for broken block structures as well.
1.1       kristaps  604: The ENDBODY node is available to end the formatting associated
                    605: with a given block before the physical end of that block.
                    606: It has a non-null
                    607: .Va end
                    608: field, is of the BODY
                    609: .Va type ,
                    610: has the same
                    611: .Va tok
                    612: as the BLOCK it is ending, and has a
                    613: .Va pending
                    614: field pointing to that BLOCK's BODY node.
                    615: It is an indirect child of that BODY node
                    616: and has no children of its own.
                    617: .Pp
                    618: An ENDBODY node is generated when a block ends while one of its child
                    619: blocks is still open, like in the following example:
                    620: .Bd -literal -offset indent
                    621: \&.Ao ao
                    622: \&.Bo bo ac
                    623: \&.Ac bc
                    624: \&.Bc end
                    625: .Ed
                    626: .Pp
                    627: This example results in the following block structure:
                    628: .Bd -literal -offset indent
                    629: BLOCK Ao
                    630:     HEAD Ao
                    631:     BODY Ao
                    632:         TEXT ao
                    633:         BLOCK Bo, pending -> Ao
                    634:             HEAD Bo
                    635:             BODY Bo
                    636:                 TEXT bo
                    637:                 TEXT ac
                    638:                 ENDBODY Ao, pending -> Ao
                    639:                 TEXT bc
                    640: TEXT end
                    641: .Ed
                    642: .Pp
                    643: Here, the formatting of the
                    644: .Sq \&Ao
                    645: block extends from TEXT ao to TEXT ac,
                    646: while the formatting of the
                    647: .Sq \&Bo
                    648: block extends from TEXT bo to TEXT bc.
                    649: It renders as follows in
                    650: .Fl T Ns Cm ascii
                    651: mode:
                    652: .Pp
                    653: .Dl <ao [bo ac> bc] end
                    654: .Pp
                    655: Support for badly-nested blocks is only provided for backward
                    656: compatibility with some older
                    657: .Xr mdoc 7
                    658: implementations.
                    659: Using badly-nested blocks is
                    660: .Em strongly discouraged ;
                    661: for example, the
                    662: .Fl T Ns Cm html
                    663: and
                    664: .Fl T Ns Cm xhtml
                    665: front-ends to
                    666: .Xr mandoc 1
                    667: are unable to render them in any meaningful way.
                    668: Furthermore, behaviour when encountering badly-nested blocks is not
                    669: consistent across troff implementations, especially when using  multiple
                    670: levels of badly-nested blocks.
                    671: .Sh SEE ALSO
                    672: .Xr mandoc 1 ,
                    673: .Xr eqn 7 ,
                    674: .Xr man 7 ,
1.6       kristaps  675: .Xr mandoc_char 7 ,
1.1       kristaps  676: .Xr mdoc 7 ,
                    677: .Xr roff 7 ,
                    678: .Xr tbl 7
                    679: .Sh AUTHORS
                    680: The
                    681: .Nm
                    682: library was written by
1.13      kristaps  683: .An Kristaps Dzonsons ,
                    684: .Mt kristaps@bsd.lv .

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