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ebnf2.lang
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ebnf2.lang
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--[[*****************************************************************************
* *
* EBNF2 Syntax Definition *
* *
* v1.0.1 (2018/01/18) | Highlight v3.41 | Lua 5.3 *
* *
* by Tristano Ajmone *
* *
*****************************************************************************
Associated file extensions: none
Syntax type: EBNF (Extended Backus–Naur form)
-----------------------------------------------------------------------------
I've created this EBNF syntax definition because I needed to syntax highlight
the EBNF code of Polygen Manual, which wasn't being handled properly by the
existing Highlight *BNF definitions ("ebnf", "abnf", and "bnf"). So I decided
to create my own EBNF syntax by adapting the Polygen Grammars syntax I had
just recently created. Some tweaks were required to make it parse properly
the EBNF code found in the Polygen Manual (see changelog, at the end).
Hopefully others might benefit from this new EBNF syntax too. Since there is
no universal standard for EBNF notation (EBNF being a family of notations),
this definition might be used as a starting point to tailor an ad hoc EBNF
syntax matching your needs.
-----------------------------------------------------------------------------
Written by Tristano Ajmone:
<tajmone@gmail.com>
https://github.com/tajmone
Released into the public domain according to the Unlicense terms:
http://unlicense.org/
-----------------------------------------------------------------------------
--]]
Description="EBNF2"
IgnoreCase=false
EnableIndentation=false
---------------------------------------------------------------------------------
-- DISABLE/OVERRIDE UNUSED SYNTAX ELEMENTS
---------------------------------------------------------------------------------
NEVER_MATCH_RE=[=[ \A(?!x)x ]=] -- A Never-Matching RegEx!
Digits=NEVER_MATCH_RE -- Numbers are just text in EBNF!
Identifiers=NEVER_MATCH_RE -- Highlight's default Identifiers RegEx prevents
-- capturing the Epsilon operator ('_'). Since in this syntax, all identifiers
-- are defined as RegEx Keywords, and because we don't use any Keywords lists,
-- we may as well disable Identifiers by defining them as a never-matching RegEx.
-- NOTE: Defining Identifiers as a never-matching RegEx prevents using Kewyords
-- lists (the parser will fail to capture them).
-- ==============================================================================
-- COMMENTS
-- ==============================================================================
-- OCaml style comments, no nesting: (* ...COMMENT BLOCK... *)
Comments={
{ Block=true,
Nested=false,
Delimiter = {
[=[ \(\* ]=], -- Comment start: '(*'
[=[ \*\) ]=] -- Comment end: '*)'
}
},
}
-- ==============================================================================
-- STRINGS
-- ==============================================================================
Strings={
-------------------------------------------------------------------------------
-- STRING DELIMITERS
-------------------------------------------------------------------------------
-- Only double quotes as string delimiter: "...STRING..."
Delimiter=[=[ " ]=],
--[[-----------------------------------------------------------------------------
ESCAPE SEQUENCES
------------------------------------------------------------------------------
Suppress Escape sequences via Never-Matching RegEx --]]
Escape=NEVER_MATCH_RE
}
--[[=============================================================================
OPERATORS
=============================================================================
::= := : ; ^ . , _ | + - * > < \
>> << ( ) [ ] { }
--]]
Operators=[=[ :|=|\^|\.|\*|\+|-|>|<|\(|\)|\[|]|\{|}|\||,|;|_|\\ ]=]
-- ==============================================================================
-- KEYWORDS
-- ==============================================================================
Keywords={
-------------------------------------------------------------------------------
-- Non-Terminal Symbol
-------------------------------------------------------------------------------
-- Must beging with a capital letter; must not be preceded or followed by a "-"
-- (to prevent capturing RegEx ranges like "A-Z" )
{ Id=1,
Regex=[=[ (?<!-)([A-Z][A-Za-z0-9]*)\b(?!-) ]=],
Group=1
},
}
--[[=============================================================================
CHANGELOG
=================================================================================
v1.0.1 (2018/01/18) | Highlight v3.41)
- Changed "PolyGen" to "Polygen" (the author has now officially adopted the
latter syntax).
v1.0.0 (2018/01/14) | Highlight v3.41)
- First release. Created by modifying "polygen.lang" (v1.0.0):
- Suppressed Escape Sequences (via Never-Matching RegEx)
- Deleted custom OnStateChange() hook function to handle Escape Sequences.
- Operators: added "*", and tweaked RegEx.
- Keywords:
- Removed Keywords Group 2 ("Label Identifier")
- Removed Keywords Group 3 ( "Label Selector")
- Keywords Group 1 ("Non-Terminal Symbol"): tweaked RegEx to ensure that
keyword is not preceded or followed by "-", to avoid capturing RegEx
ranges like "A-Z" in EBNF source.
--]]