1[comment {-*- tcl -*- doctools manpage}]
2[manpage_begin docidx_lang_syntax n 1.0]
3[copyright {2007-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>}]
4[moddesc   {Documentation tools}]
5[titledesc {docidx language syntax}]
6[category  {Documentation tools}]
7[description]
8[para]
9
10This document contains the formal specification of the syntax of the
11docidx markup language, version 1 in Backus-Naur-Form. This document
12is intended to be a reference, complementing the
13[term {docidx language command reference}].
14
15A beginner should read the much more informally written
16[term {docidx language introduction}] first before trying to
17understand either this document or the command reference.
18
19
20[section Fundamentals]
21
22In the broadest terms possible the [term {docidx markup language}] is
23like SGML and similar languages. A document written in this language
24consists primarily of markup commands, with text embedded into it at
25some places.
26
27[para]
28
29Each markup command is a just Tcl command surrounded by a matching
30pair of [const [lb]] and [const [rb]]. Which commands are available,
31and their arguments, i.e. syntax is specified in the
32[term {docidx language command reference}].
33
34[para]
35
36In this document we specify first the lexeme, and then the syntax,
37i.e. how we can mix text and markup commands with each other.
38
39[section {Lexical definitions}]
40
41In the syntax rules listed in the next section
42
43[list_begin enumerated]
44[enum]
45<TEXT> stands for all text except markup commands.
46
47[enum]
48Any XXX stands for the markup command [lb]xxx[rb] including its
49arguments. Each markup command is a Tcl command surrounded by a
50matching pair of [const [lb]] and [const [rb]]. Inside of these
51delimiters the usual rules for a Tcl command apply with regard to word
52quotation, nested commands, continuation lines, etc.
53
54[enum]
55<WHITE> stands for all text consisting only of spaces, newlines,
56tabulators and the [cmd comment] markup command.
57[list_end]
58
59[section Syntax]
60
61The rules listed here specify only the syntax of docidx documents. The
62lexical level of the language was covered in the previous section.
63
64[para]
65
66Regarding the syntax of the (E)BNF itself 
67
68[list_begin enumerated]
69[enum]
70The construct { X } stands for zero or more occurrences of X.
71[enum]
72The construct [lb] X [rb] stands for zero or one occurrence of X.
73[list_end]
74
75The syntax:
76
77[example {
78index     = defs
79            INDEX_BEGIN
80            [ contents ]
81            INDEX_END  
82            { <WHITE> }
83
84defs      = { INCLUDE | VSET | <WHITE> }
85contents  = keyword { keyword }
86
87keyword   = defs KEY ref { ref }
88ref       = MANPAGE | URL | defs
89}]
90
91At last a rule we were unable to capture in the EBNF syntax, as it is
92about the arguments of the markup commands, something which is not
93modeled here.
94
95[list_begin enumerated]
96[enum]
97
98The arguments of all markup commands have to be plain text, and/or text
99markup commands, i.e. one of
100
101[list_begin enumerated]
102[enum][cmd lb],
103[enum][cmd rb], or
104[enum][cmd vset] (1-argument form).
105[list_end]
106
107[list_end]
108
109
110[section {BUGS, IDEAS, FEEDBACK}]
111
112This document, will undoubtedly contain bugs and other problems.
113
114Please report such in the category [emph doctools] of the
115[uri {http://sourceforge.net/tracker/?group_id=12883} {Tcllib SF Trackers}].
116
117Please also report any ideas for enhancements you may have.
118
119[see_also docidx_intro]
120[see_also docidx_lang_intro]
121[see_also docidx_lang_cmdref]
122[see_also docidx_lang_faq]
123[keywords markup {semantic markup}]
124[keywords {docidx markup} {docidx language}]
125[keywords {docidx syntax} {docidx commands}]
126[manpage_end]
127