vim: import leg.vim from https://github.com/Qix-/leg.vim

Signed-off-by: Alejandro Mery <amery@hanoverdisplays.com>

files/.vim/ftdetect/leg.vim

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+au BufRead,BufNewFile *.leg set ft=leg

files/.vim/syntax/leg.vim

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+" Vim syntax file
+" Language: Parser Expression Grammars (PEG) -- LEG dialect
+" Maintainer: Gianni Chiappetta, Josh Junon
+" Latest Revision: 2016-10-06
+
+if exists("b:current_syntax")
+  finish
+endif
+
+syn include @c syntax/cpp.vim
+
+syn match   legRuleIdentifier   /^\v[-a-zA-Z_][-a-zA-Z_0-9]*/ skipwhite skipnl nextgroup=legSeperator
+
+syn match   legSeperator        "=" skipwhite skipnl contained nextgroup=legExpression
+
+syn match   legExpression       /\v[^\;]*/ contained skipwhite skipnl contains=legDelimiter,legOrderedChoice,legGrouping,legSpecial,legRange,legTerminal,legNonTerminal,legQuantifier,legRuleBody
+syn match   legDelimiter        /[§]/ contained display
+syn region  legGrouping         matchgroup=legDelimiter start=/(/ end=/)/ contained skipwhite keepend contains=legExpression display
+syn match   legSpecial          /[!&ϵ^]/ contained display
+syn match   legOrderedChoice    /\v\|/ display
+syn region  legRange            matchgroup=legDelimiter start=/\[^/ start=/\[/ end=/\]/ contained skipwhite contains=legRangeValue,legUnicode display
+syn match   legRangeValue       /\d\+-\d\+/ contained display
+syn match   legRangeValue       /\a\+-\a\+/ contained display
+syn region  legTerminal         matchgroup=legDelimiter start=/"/ end=/"/ contained display
+syn region  legTerminal         matchgroup=legDelimiter start=/'/ end=/'/ contained display
+syn match   legUnicode          /U+[A-F0-9]\{4,6}/ contained display
+syn match   legNonTerminal      /\a+/ contained display
+syn match   legQuantifier       /[+\*?]/ contained display
+syn match   legQuantifier       /{\d\+,\d\+}/ contained display
+syn match   legQuantifier       /{\d\+}/ contained display
+syn match   legSpecialSymbol    /\v\$\$/ contained display
+syn region  legRuleBody         matchgroup=legCDelimiter start=/\v([@~]\s*)?\{/ end=/}/ contains=legSpecialSymbol,@c
+
+syn match   legComment          /#.*$/ contains=legTodo
+syn keyword legTodo             TODO FIXME XXX NOTE contained
+
+syn region  legCBlock           matchgroup=legCDelimiter start=/\v^\%\{/ end=/\v\%\}$/ keepend contains=@c
+syn region  legCBlock           matchgroup=legCDelimiter start=/\v\%\%/ skip=/\v.*/ end=/$/ excludenl contains=@c
+
+hi link legOrderedChoice  legSeperator
+
+hi link legRuleIdentifier Statement
+hi link legSeperator      Conditional
+hi link legDelimiter      Delimiter
+hi link legCDelimiter     Conditional
+hi link legSpecial        Special
+hi link legComment        Comment
+hi link legRangeValue     Constant
+hi link legTerminal       String
+hi link legUnicode        Constant
+hi link legQuantifier     Function
+hi link legTodo           Todo
+hi link legSpecialSymbol  Special
+
+let b:current_syntax = "leg"