Updatev2.9.1

1 files changed, 270 insertions, 117 deletions

diff --git a/syntax/ruby.vim b/syntax/ruby.vim
index 3a6ef484..0f23fc17 100644
--- a/syntax/ruby.vim
+++ b/syntax/ruby.vim
@@ -11,16 +11,41 @@ if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'ruby') == -1
 " Thanks to perl.vim authors, and to Reimer Behrends. :-) (MN)
 " ----------------------------------------------------------------------------
 
+" Prelude {{{1
 if exists("b:current_syntax")
   finish
 endif
 
+" Folding Config {{{1
 if has("folding") && exists("ruby_fold")
   setlocal foldmethod=syntax
 endif
 
+let s:foldable_groups = split(
+      \	  get(
+      \	    b:,
+      \	    'ruby_foldable_groups',
+      \	    get(g:, 'ruby_foldable_groups', 'ALL')
+      \	  )
+      \	)
+
+function! s:foldable(...) abort
+  if index(s:foldable_groups, 'ALL') > -1
+    return 1
+  endif
+
+  for l:i in a:000
+    if index(s:foldable_groups, l:i) > -1
+      return 1
+    endif
+  endfor
+
+  return 0
+endfunction " }}}
+
 syn cluster rubyNotTop contains=@rubyExtendedStringSpecial,@rubyRegexpSpecial,@rubyDeclaration,rubyConditional,rubyExceptional,rubyMethodExceptional,rubyTodo
 
+" Whitespace Errors {{{1
 if exists("ruby_space_errors")
   if !exists("ruby_no_trail_space_error")
     syn match rubySpaceError display excludenl "\s\+$"
@@ -30,14 +55,14 @@ if exists("ruby_space_errors")
   endif
 endif
 
-" Operators
+" Operators {{{1
 if exists("ruby_operators")
-  syn match  rubyOperator "[~!^|*/%+-]\|&\.\@!\|\%(class\s*\)\@<!<<\|<=>\|<=\|\%(<\|\<class\s\+\u\w*\s*\)\@<!<[^<]\@=\|===\|==\|=\~\|>>\|>=\|=\@<!>\|\*\*\|\.\.\.\|\.\.\|::"
+  syn match  rubyOperator "[~!^|*/%+-]\|&\.\@!\|\%(class\s*\)\@<!<<\|<=>\|<=\|\%(<\|\<class\s\+\u\w*\s*\)\@<!<[^<]\@=\|===\|==\|=\~\|>>\|>=\|=\@1<!>\|\*\*\|\.\.\.\|\.\.\|::"
   syn match  rubyOperator "->\|-=\|/=\|\*\*=\|\*=\|&&=\|&=\|&&\|||=\||=\|||\|%=\|+=\|!\~\|!="
-  syn region rubyBracketOperator matchgroup=rubyOperator start="\%(\w[?!]\=\|[]})]\)\@<=\[\s*" end="\s*]" contains=ALLBUT,@rubyNotTop
+  syn region rubyBracketOperator matchgroup=rubyOperator start="\%(\w[?!]\=\|[]})]\)\@2<=\[\s*" end="\s*]" contains=ALLBUT,@rubyNotTop
 endif
 
-" Expression Substitution and Backslash Notation
+" Expression Substitution and Backslash Notation {{{1
 syn match rubyStringEscape "\\\\\|\\[abefnrstv]\|\\\o\{1,3}\|\\x\x\{1,2}"						    contained display
 syn match rubyStringEscape "\%(\\M-\\C-\|\\C-\\M-\|\\M-\\c\|\\c\\M-\|\\c\|\\C-\|\\M-\)\%(\\\o\{1,3}\|\\x\x\{1,2}\|\\\=\S\)" contained display
 syn match rubyQuoteEscape  "\\[\\']"											    contained display
@@ -47,18 +72,19 @@ syn match  rubyInterpolation	      "#\%(\$\|@@\=\)\w\+"    display contained con
 syn match  rubyInterpolationDelimiter "#\ze\%(\$\|@@\=\)\w\+" display contained
 syn match  rubyInterpolation	      "#\$\%(-\w\|\W\)"       display contained contains=rubyInterpolationDelimiter,rubyPredefinedVariable,rubyInvalidVariable
 syn match  rubyInterpolationDelimiter "#\ze\$\%(-\w\|\W\)"    display contained
-syn region rubyNoInterpolation	      start="\\#{" end="}"            contained
+syn region rubyNoInterpolation	      start="\\#{" end="}"	      contained
 syn match  rubyNoInterpolation	      "\\#{"		      display contained
 syn match  rubyNoInterpolation	      "\\#\%(\$\|@@\=\)\w\+"  display contained
 syn match  rubyNoInterpolation	      "\\#\$\W"		      display contained
 
-syn match rubyDelimEscape	"\\[(<{\[)>}\]]" transparent display contained contains=NONE
+syn match rubyDelimiterEscape	"\\[(<{\[)>}\]]" transparent display contained contains=NONE
 
 syn region rubyNestedParentheses    start="("  skip="\\\\\|\\)"  matchgroup=rubyString end=")"	transparent contained
 syn region rubyNestedCurlyBraces    start="{"  skip="\\\\\|\\}"  matchgroup=rubyString end="}"	transparent contained
 syn region rubyNestedAngleBrackets  start="<"  skip="\\\\\|\\>"  matchgroup=rubyString end=">"	transparent contained
 syn region rubyNestedSquareBrackets start="\[" skip="\\\\\|\\\]" matchgroup=rubyString end="\]"	transparent contained
 
+" Regular Expression Metacharacters {{{1
 " These are mostly Oniguruma ready
 syn region rubyRegexpComment	matchgroup=rubyRegexpSpecial   start="(?#"								  skip="\\)"  end=")"  contained
 syn region rubyRegexpParens	matchgroup=rubyRegexpSpecial   start="(\(?:\|?<\=[=!]\|?>\|?<[a-z_]\w*>\|?[imx]*-[imx]*:\=\|\%(?#\)\@!\)" skip="\\)"  end=")"  contained transparent contains=@rubyRegexpSpecial
@@ -81,8 +107,8 @@ syn cluster rubyStringSpecial	      contains=rubyInterpolation,rubyNoInterpolati
 syn cluster rubyExtendedStringSpecial contains=@rubyStringSpecial,rubyNestedParentheses,rubyNestedCurlyBraces,rubyNestedAngleBrackets,rubyNestedSquareBrackets
 syn cluster rubyRegexpSpecial	      contains=rubyInterpolation,rubyNoInterpolation,rubyStringEscape,rubyRegexpSpecial,rubyRegexpEscape,rubyRegexpBrackets,rubyRegexpCharClass,rubyRegexpDot,rubyRegexpQuantifier,rubyRegexpAnchor,rubyRegexpParens,rubyRegexpComment
 
-" Numbers and ASCII Codes
-syn match rubyASCIICode "\%(\w\|[]})\"'/]\)\@<!\%(?\%(\\M-\\C-\|\\C-\\M-\|\\M-\\c\|\\c\\M-\|\\c\|\\C-\|\\M-\)\=\%(\\\o\{1,3}\|\\x\x\{1,2}\|\\\=\S\)\)"
+" Numbers and ASCII Codes {{{1
+syn match rubyASCIICode "\%(\w\|[]})\"'/]\)\@1<!\%(?\%(\\M-\\C-\|\\C-\\M-\|\\M-\\c\|\\c\\M-\|\\c\|\\C-\|\\M-\)\=\%(\\\o\{1,3}\|\\x\x\{1,2}\|\\\=\S\)\)"
 syn match rubyInteger	"\%(\%(\w\|[]})\"']\s*\)\@<!-\)\=\<0[xX]\x\+\%(_\x\+\)*r\=i\=\>"								display
 syn match rubyInteger	"\%(\%(\w\|[]})\"']\s*\)\@<!-\)\=\<\%(0[dD]\)\=\%(0\|[1-9]\d*\%(_\d\+\)*\)r\=i\=\>"						display
 syn match rubyInteger	"\%(\%(\w\|[]})\"']\s*\)\@<!-\)\=\<0[oO]\=\o\+\%(_\o\+\)*r\=i\=\>"								display
@@ -90,20 +116,26 @@ syn match rubyInteger	"\%(\%(\w\|[]})\"']\s*\)\@<!-\)\=\<0[bB][01]\+\%(_[01]\+\)
 syn match rubyFloat	"\%(\%(\w\|[]})\"']\s*\)\@<!-\)\=\<\%(0\|[1-9]\d*\%(_\d\+\)*\)\.\d\+\%(_\d\+\)*r\=i\=\>"					display
 syn match rubyFloat	"\%(\%(\w\|[]})\"']\s*\)\@<!-\)\=\<\%(0\|[1-9]\d*\%(_\d\+\)*\)\%(\.\d\+\%(_\d\+\)*\)\=\%([eE][-+]\=\d\+\%(_\d\+\)*\)r\=i\=\>"	display
 
-" Identifiers
+" Identifiers {{{1
 syn match rubyLocalVariableOrMethod "\<[_[:lower:]][_[:alnum:]]*[?!=]\=" contains=NONE display transparent
 syn match rubyBlockArgument	    "&[_[:lower:]][_[:alnum:]]"		 contains=NONE display transparent
 
 syn match  rubyConstant		"\%(\%(^\|[^.]\)\.\s*\)\@<!\<\u\%(\w\|[^\x00-\x7F]\)*\>\%(\s*(\)\@!"
 syn match  rubyClassVariable	"@@\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*" display
-syn match  rubyInstanceVariable "@\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*"  display
+syn match  rubyInstanceVariable "@\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*"	display
 syn match  rubyGlobalVariable	"$\%(\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\|-.\)"
-syn match  rubySymbol		"[]})\"':]\@<!:\%(\^\|\~@\|\~\|<<\|<=>\|<=\|<\|===\|[=!]=\|[=!]\~\|!@\|!\|>>\|>=\|>\||\|-@\|-\|/\|\[]=\|\[]\|\*\*\|\*\|&\|%\|+@\|+\|`\)"
-syn match  rubySymbol		"[]})\"':]\@<!:\$\%(-.\|[`~<=>_,;:!?/.'"@$*\&+0]\)"
-syn match  rubySymbol		"[]})\"':]\@<!:\%(\$\|@@\=\)\=\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*"
-syn match  rubySymbol		"[]})\"':]\@<!:\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\%([?!=]>\@!\)\="
-syn region rubySymbol		start="[]})\"':]\@<!:'"  end="'"  skip="\\\\\|\\'"  contains=rubyQuoteEscape fold
-syn region rubySymbol		start="[]})\"':]\@<!:\"" end="\"" skip="\\\\\|\\\"" contains=@rubyStringSpecial fold
+syn match  rubySymbol		"[]})\"':]\@1<!:\%(\^\|\~@\|\~\|<<\|<=>\|<=\|<\|===\|[=!]=\|[=!]\~\|!@\|!\|>>\|>=\|>\||\|-@\|-\|/\|\[]=\|\[]\|\*\*\|\*\|&\|%\|+@\|+\|`\)"
+syn match  rubySymbol		"[]})\"':]\@1<!:\$\%(-.\|[`~<=>_,;:!?/.'"@$*\&+0]\)"
+syn match  rubySymbol		"[]})\"':]\@1<!:\%(\$\|@@\=\)\=\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*"
+syn match  rubySymbol		"[]})\"':]\@1<!:\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\%([?!=]>\@!\)\="
+
+if s:foldable(':')
+  syn region rubySymbol		start="[]})\"':]\@1<!:'"  end="'"  skip="\\\\\|\\'"  contains=rubyQuoteEscape fold
+  syn region rubySymbol		start="[]})\"':]\@1<!:\"" end="\"" skip="\\\\\|\\\"" contains=@rubyStringSpecial fold
+else
+  syn region rubySymbol		start="[]})\"':]\@1<!:'"  end="'"  skip="\\\\\|\\'"  contains=rubyQuoteEscape
+  syn region rubySymbol		start="[]})\"':]\@1<!:\"" end="\"" skip="\\\\\|\\\"" contains=@rubyStringSpecial
+endif
 
 syn match  rubyCapitalizedMethod	"\%(\%(^\|[^.]\)\.\s*\)\@<!\<\u\%(\w\|[^\x00-\x7F]\)*\>\%(\s*(\)*\s*(\@="
 
@@ -120,96 +152,172 @@ syn match rubyPredefinedVariable "$\%(DEBUG\|FILENAME\|KCODE\|LOADED_FEATURES\|L
 syn match rubyPredefinedConstant "\%(\%(^\|[^.]\)\.\s*\)\@<!\<\%(ARGF\|ARGV\|ENV\|DATA\|FALSE\|NIL\|STDERR\|STDIN\|STDOUT\|TOPLEVEL_BINDING\|TRUE\)\>\%(\s*(\)\@!"
 syn match rubyPredefinedConstant "\%(\%(^\|[^.]\)\.\s*\)\@<!\<\%(RUBY_\%(VERSION\|RELEASE_DATE\|PLATFORM\|PATCHLEVEL\|REVISION\|DESCRIPTION\|COPYRIGHT\|ENGINE\)\)\>\%(\s*(\)\@!"
 
-" Normal Regular Expression
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\%(^\|\<\%(and\|or\|while\|until\|unless\|if\|elsif\|when\|not\|then\|else\)\|[;\~=!|&(,{[<>?:*+-]\)\s*\)\@<=/" end="/[iomxneus]*" skip="\\\\\|\\/" contains=@rubyRegexpSpecial fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\h\k*\s\+\)\@<=/[ \t=]\@!" end="/[iomxneus]*" skip="\\\\\|\\/" contains=@rubyRegexpSpecial fold
+" Normal Regular Expression {{{1
+if s:foldable('/')
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\%(^\|\<\%(and\|or\|while\|until\|unless\|if\|elsif\|when\|not\|then\|else\)\|[;\~=!|&(,{[<>?:*+-]\)\s*\)\@<=/" end="/[iomxneus]*" skip="\\\\\|\\/" contains=@rubyRegexpSpecial fold
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\h\k*\s\+\)\@<=/[ \t=]\@!" end="/[iomxneus]*" skip="\\\\\|\\/" contains=@rubyRegexpSpecial fold
+else
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\%(^\|\<\%(and\|or\|while\|until\|unless\|if\|elsif\|when\|not\|then\|else\)\|[;\~=!|&(,{[<>?:*+-]\)\s*\)\@<=/" end="/[iomxneus]*" skip="\\\\\|\\/" contains=@rubyRegexpSpecial
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\h\k*\s\+\)\@<=/[ \t=]\@!" end="/[iomxneus]*" skip="\\\\\|\\/" contains=@rubyRegexpSpecial
+endif
 
-" Generalized Regular Expression
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1[iomxneus]*" skip="\\\\\|\\\z1" contains=@rubyRegexpSpecial fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r{"				end="}[iomxneus]*"   skip="\\\\\|\\}"	 contains=@rubyRegexpSpecial fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r<"				end=">[iomxneus]*"   skip="\\\\\|\\>"	 contains=@rubyRegexpSpecial,rubyNestedAngleBrackets,rubyDelimEscape fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\["				end="\][iomxneus]*"  skip="\\\\\|\\\]"	 contains=@rubyRegexpSpecial fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r("				end=")[iomxneus]*"   skip="\\\\\|\\)"	 contains=@rubyRegexpSpecial fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\z(\s\)"				end="\z1[iomxneus]*" skip="\\\\\|\\\z1" contains=@rubyRegexpSpecial fold
+" Generalized Regular Expression {{{1
+if s:foldable('%')
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1[iomxneus]*" skip="\\\\\|\\\z1" contains=@rubyRegexpSpecial fold
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r{"				end="}[iomxneus]*"   skip="\\\\\|\\}"	 contains=@rubyRegexpSpecial fold
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r<"				end=">[iomxneus]*"   skip="\\\\\|\\>"	 contains=@rubyRegexpSpecial,rubyNestedAngleBrackets,rubyDelimiterEscape fold
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\["				end="\][iomxneus]*"  skip="\\\\\|\\\]"	 contains=@rubyRegexpSpecial fold
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r("				end=")[iomxneus]*"   skip="\\\\\|\\)"	 contains=@rubyRegexpSpecial fold
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\z(\s\)"				end="\z1[iomxneus]*" skip="\\\\\|\\\z1" contains=@rubyRegexpSpecial fold
+else
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1[iomxneus]*" skip="\\\\\|\\\z1" contains=@rubyRegexpSpecial
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r{"				end="}[iomxneus]*"   skip="\\\\\|\\}"	 contains=@rubyRegexpSpecial
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r<"				end=">[iomxneus]*"   skip="\\\\\|\\>"	 contains=@rubyRegexpSpecial,rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\["				end="\][iomxneus]*"  skip="\\\\\|\\\]"	 contains=@rubyRegexpSpecial
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r("				end=")[iomxneus]*"   skip="\\\\\|\\)"	 contains=@rubyRegexpSpecial
+  syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\z(\s\)"				end="\z1[iomxneus]*" skip="\\\\\|\\\z1" contains=@rubyRegexpSpecial
+endif
 
-" Normal String
+" Normal String {{{1
 let s:spell_cluster = exists('ruby_spellcheck_strings') ? ',@Spell' : ''
-exe 'syn region rubyString matchgroup=rubyStringDelimiter start="\"" end="\"" skip="\\\\\|\\\"" fold contains=@rubyStringSpecial' . s:spell_cluster
-exe 'syn region rubyString matchgroup=rubyStringDelimiter start="''" end="''" skip="\\\\\|\\''" fold contains=rubyQuoteEscape'    . s:spell_cluster
-
-" Shell Command Output
-syn region rubyString matchgroup=rubyStringDelimiter start="`" end="`" skip="\\\\\|\\`" contains=@rubyStringSpecial fold
-
-" Generalized Single Quoted String, Symbol and Array of Strings
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1" fold
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]{"				   end="}"   skip="\\\\\|\\}"	fold contains=rubyNestedCurlyBraces,rubyDelimEscape
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]<"				   end=">"   skip="\\\\\|\\>"	fold contains=rubyNestedAngleBrackets,rubyDelimEscape
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]\["				   end="\]"  skip="\\\\\|\\\]"	fold contains=rubyNestedSquareBrackets,rubyDelimEscape
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]("				   end=")"   skip="\\\\\|\\)"	fold contains=rubyNestedParentheses,rubyDelimEscape
-syn region rubyString matchgroup=rubyStringDelimiter start="%q\z(\s\)"				   end="\z1" skip="\\\\\|\\\z1" fold
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)"    end="\z1" skip="\\\\\|\\\z1" fold
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s{"				   end="}"   skip="\\\\\|\\}"	fold contains=rubyNestedCurlyBraces,rubyDelimEscape
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s<"				   end=">"   skip="\\\\\|\\>"	fold contains=rubyNestedAngleBrackets,rubyDelimEscape
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s\["				   end="\]"  skip="\\\\\|\\\]"	fold contains=rubyNestedSquareBrackets,rubyDelimEscape
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s("				   end=")"   skip="\\\\\|\\)"	fold contains=rubyNestedParentheses,rubyDelimEscape
-syn region rubyString matchgroup=rubyStringDelimiter start="%s\z(\s\)"				   end="\z1" skip="\\\\\|\\\z1" fold
-
-" Generalized Double Quoted String and Array of Strings and Shell Command Output
+exe 'syn region rubyString matchgroup=rubyStringDelimiter start="\"" end="\"" skip="\\\\\|\\\"" ' .
+      \ (s:foldable('%') ? 'fold' : '') . ' contains=@rubyStringSpecial' . s:spell_cluster
+exe 'syn region rubyString matchgroup=rubyStringDelimiter start="''" end="''" skip="\\\\\|\\''" ' .
+      \ (s:foldable('%') ? 'fold' : '') . ' contains=rubyQuoteEscape'	 . s:spell_cluster
+
+" Shell Command Output {{{1
+if s:foldable('%')
+  syn region rubyString matchgroup=rubyStringDelimiter start="`" end="`" skip="\\\\\|\\`" contains=@rubyStringSpecial fold
+else
+  syn region rubyString matchgroup=rubyStringDelimiter start="`" end="`" skip="\\\\\|\\`" contains=@rubyStringSpecial
+endif
+
+" Generalized Single Quoted String, Symbol and Array of Strings {{{1
+if s:foldable('%')
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1" fold
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]{"				     end="}"   skip="\\\\\|\\}"	  fold contains=rubyNestedCurlyBraces,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]<"				     end=">"   skip="\\\\\|\\>"	  fold contains=rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]\["				     end="\]"  skip="\\\\\|\\\]"  fold contains=rubyNestedSquareBrackets,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]("				     end=")"   skip="\\\\\|\\)"	  fold contains=rubyNestedParentheses,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%q\z(\s\)"			     end="\z1" skip="\\\\\|\\\z1" fold
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)"    end="\z1" skip="\\\\\|\\\z1" fold
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s{"				     end="}"   skip="\\\\\|\\}"	  fold contains=rubyNestedCurlyBraces,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s<"				     end=">"   skip="\\\\\|\\>"	  fold contains=rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s\["				     end="\]"  skip="\\\\\|\\\]"  fold contains=rubyNestedSquareBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s("				     end=")"   skip="\\\\\|\\)"	  fold contains=rubyNestedParentheses,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%s\z(\s\)"			     end="\z1" skip="\\\\\|\\\z1" fold
+else
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1"
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]{"				     end="}"   skip="\\\\\|\\}"	  contains=rubyNestedCurlyBraces,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]<"				     end=">"   skip="\\\\\|\\>"	  contains=rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]\["				     end="\]"  skip="\\\\\|\\\]"  contains=rubyNestedSquareBrackets,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[qw]("				     end=")"   skip="\\\\\|\\)"	  contains=rubyNestedParentheses,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%q\z(\s\)"			     end="\z1" skip="\\\\\|\\\z1"
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)"    end="\z1" skip="\\\\\|\\\z1"
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s{"				     end="}"   skip="\\\\\|\\}"	  contains=rubyNestedCurlyBraces,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s<"				     end=">"   skip="\\\\\|\\>"	  contains=rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s\["				     end="\]"  skip="\\\\\|\\\]"  contains=rubyNestedSquareBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%s("				     end=")"   skip="\\\\\|\\)"	  contains=rubyNestedParentheses,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%s\z(\s\)"			     end="\z1" skip="\\\\\|\\\z1"
+endif
+
+" Generalized Double Quoted String and Array of Strings and Shell Command Output {{{1
 " Note: %= is not matched here as the beginning of a double quoted string
-syn region rubyString matchgroup=rubyStringDelimiter start="%\z([~`!@#$%^&*_\-+|\:;"',.?/]\)"	    end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
-syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
-syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\={"				    end="}"   skip="\\\\\|\\}"	 contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimEscape    fold
-syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=<"				    end=">"   skip="\\\\\|\\>"	 contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimEscape  fold
-syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=\["				    end="\]"  skip="\\\\\|\\\]"	 contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimEscape fold
-syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=("				    end=")"   skip="\\\\\|\\)"	 contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimEscape    fold
-syn region rubyString matchgroup=rubyStringDelimiter start="%[Qx]\z(\s\)"			    end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
-
-" Array of Symbols
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1" fold
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i{"				end="}"   skip="\\\\\|\\}"	fold contains=rubyNestedCurlyBraces,rubyDelimEscape
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i<"				end=">"   skip="\\\\\|\\>"	fold contains=rubyNestedAngleBrackets,rubyDelimEscape
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i\["				end="\]"  skip="\\\\\|\\\]"	fold contains=rubyNestedSquareBrackets,rubyDelimEscape
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i("				end=")"   skip="\\\\\|\\)"	fold contains=rubyNestedParentheses,rubyDelimEscape
-
-" Array of interpolated Symbols
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I{"				end="}"   skip="\\\\\|\\}"	 contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimEscape    fold
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I<"				end=">"   skip="\\\\\|\\>"	 contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimEscape  fold
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I\["				end="\]"  skip="\\\\\|\\\]"	 contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimEscape fold
-syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I("				end=")"   skip="\\\\\|\\)"	 contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimEscape    fold
-
-" Here Document
+if s:foldable('%')
+  syn region rubyString matchgroup=rubyStringDelimiter start="%\z([~`!@#$%^&*_\-+|\:;"',.?/]\)"	      end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\={"			      end="}"	skip="\\\\\|\\}"   contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimiterEscape    fold
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=<"			      end=">"	skip="\\\\\|\\>"   contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimiterEscape  fold
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=\["			      end="\]"	skip="\\\\\|\\\]"  contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimiterEscape fold
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=("			      end=")"	skip="\\\\\|\\)"   contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimiterEscape    fold
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[Qx]\z(\s\)"			      end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
+else
+  syn region rubyString matchgroup=rubyStringDelimiter start="%\z([~`!@#$%^&*_\-+|\:;"',.?/]\)"	      end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\={"			      end="}"	skip="\\\\\|\\}"   contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=<"			      end=">"	skip="\\\\\|\\>"   contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=\["			      end="\]"	skip="\\\\\|\\\]"  contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=("			      end=")"	skip="\\\\\|\\)"   contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimiterEscape
+  syn region rubyString matchgroup=rubyStringDelimiter start="%[Qx]\z(\s\)"			      end="\z1" skip="\\\\\|\\\z1" contains=@rubyStringSpecial
+endif
+
+" Array of Symbols {{{1
+if s:foldable('%')
+  " Array of Symbols
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1"	fold
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i{"				  end="}"   skip="\\\\\|\\}"	fold contains=rubyNestedCurlyBraces,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i<"				  end=">"   skip="\\\\\|\\>"	fold contains=rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i\["				  end="\]"  skip="\\\\\|\\\]"	fold contains=rubyNestedSquareBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i("				  end=")"   skip="\\\\\|\\)"	fold contains=rubyNestedParentheses,rubyDelimiterEscape
+
+  " Array of interpolated Symbols
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1"	contains=@rubyStringSpecial fold
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I{"				  end="}"   skip="\\\\\|\\}"	contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimiterEscape    fold
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I<"				  end=">"   skip="\\\\\|\\>"	contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimiterEscape  fold
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I\["				  end="\]"  skip="\\\\\|\\\]"	contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimiterEscape fold
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I("				  end=")"   skip="\\\\\|\\)"	contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimiterEscape    fold
+else
+  " Array of Symbols
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1"
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i{"				  end="}"   skip="\\\\\|\\}"	contains=rubyNestedCurlyBraces,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i<"				  end=">"   skip="\\\\\|\\>"	contains=rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i\["				  end="\]"  skip="\\\\\|\\\]"	contains=rubyNestedSquareBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%i("				  end=")"   skip="\\\\\|\\)"	contains=rubyNestedParentheses,rubyDelimiterEscape
+
+  " Array of interpolated Symbols
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1"	contains=@rubyStringSpecial
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I{"				  end="}"   skip="\\\\\|\\}"	contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I<"				  end=">"   skip="\\\\\|\\>"	contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I\["				  end="\]"  skip="\\\\\|\\\]"	contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimiterEscape
+  syn region rubySymbol matchgroup=rubySymbolDelimiter start="%I("				  end=")"   skip="\\\\\|\\)"	contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimiterEscape
+endif
+
+" Here Document {{{1
 syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<[-~]\=\zs\%(\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\)+	 end=+$+ oneline contains=ALLBUT,@rubyNotTop
 syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<[-~]\=\zs"\%([^"]*\)"+ end=+$+ oneline contains=ALLBUT,@rubyNotTop
 syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<[-~]\=\zs'\%([^']*\)'+ end=+$+ oneline contains=ALLBUT,@rubyNotTop
 syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<[-~]\=\zs`\%([^`]*\)`+ end=+$+ oneline contains=ALLBUT,@rubyNotTop
 
-syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<\z(\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\)\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial fold keepend
-syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<"\z([^"]*\)"\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial fold keepend
-syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<'\z([^']*\)'\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc			fold keepend
-syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<`\z([^`]*\)`\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial fold keepend
+if s:foldable('<<')
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<\z(\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\)\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial fold keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<"\z([^"]*\)"\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial fold keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<'\z([^']*\)'\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc		    fold keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<`\z([^`]*\)`\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial fold keepend
 
-syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]\z(\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\)\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3    matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
-syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]"\z([^"]*\)"\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
-syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]'\z([^']*\)'\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart		     fold keepend
-syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]`\z([^`]*\)`\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]\z(\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\)\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3    matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]"\z([^"]*\)"\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]'\z([^']*\)'\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart		    fold keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]`\z([^`]*\)`\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+else
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<\z(\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\)\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<"\z([^"]*\)"\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<'\z([^']*\)'\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc		    keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]})"'.]\)\s\|\w\)\@<!<<`\z([^`]*\)`\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+2	matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,rubyHeredoc,@rubyStringSpecial keepend
+
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]\z(\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*\)\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3    matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]"\z([^"]*\)"\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]'\z([^']*\)'\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart		    keepend
+  syn region rubyString start=+\%(\%(class\|::\)\_s*\|\%([]}).]\)\s\|\w\)\@<!<<[-~]`\z([^`]*\)`\ze\%(.*<<[-~]\=['`"]\=\h\)\@!+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial keepend
+endif
 
+" eRuby Config {{{1
 if exists('main_syntax') && main_syntax == 'eruby'
   let b:ruby_no_expensive = 1
 end
 
+" Module, Class, Method and Alias Declarations {{{1
 syn match  rubyAliasDeclaration    "[^[:space:];#.()]\+" contained contains=rubySymbol,rubyGlobalVariable,rubyPredefinedVariable nextgroup=rubyAliasDeclaration2 skipwhite
 syn match  rubyAliasDeclaration2   "[^[:space:];#.()]\+" contained contains=rubySymbol,rubyGlobalVariable,rubyPredefinedVariable
 syn match  rubyMethodDeclaration   "[^[:space:];#(]\+"	 contained contains=rubyConstant,rubyBoolean,rubyPseudoVariable,rubyInstanceVariable,rubyClassVariable,rubyGlobalVariable
 syn match  rubyClassDeclaration    "[^[:space:];#<]\+"	 contained contains=rubyConstant,rubyOperator
 syn match  rubyModuleDeclaration   "[^[:space:];#<]\+"	 contained contains=rubyConstant,rubyOperator
 syn match  rubyFunction "\<[_[:alpha:]][_[:alnum:]]*[?!=]\=[[:alnum:]_.:?!=]\@!" contained containedin=rubyMethodDeclaration
-syn match  rubyFunction "\%(\s\|^\)\@<=[_[:alpha:]][_[:alnum:]]*[?!=]\=\%(\s\|$\)\@=" contained containedin=rubyAliasDeclaration,rubyAliasDeclaration2
-syn match  rubyFunction "\%([[:space:].]\|^\)\@<=\%(\[\]=\=\|\*\*\|[-+!~]@\=\|[*/%|&^~]\|<<\|>>\|[<>]=\=\|<=>\|===\|[=!]=\|[=!]\~\|!\|`\)\%([[:space:];#(]\|$\)\@=" contained containedin=rubyAliasDeclaration,rubyAliasDeclaration2,rubyMethodDeclaration
+syn match  rubyFunction "\%(\s\|^\)\@1<=[_[:alpha:]][_[:alnum:]]*[?!=]\=\%(\s\|$\)\@=" contained containedin=rubyAliasDeclaration,rubyAliasDeclaration2
+syn match  rubyFunction "\%([[:space:].]\|^\)\@2<=\%(\[\]=\=\|\*\*\|[-+!~]@\=\|[*/%|&^~]\|<<\|>>\|[<>]=\=\|<=>\|===\|[=!]=\|[=!]\~\|!\|`\)\%([[:space:];#(]\|$\)\@=" contained containedin=rubyAliasDeclaration,rubyAliasDeclaration2,rubyMethodDeclaration
 
 syn cluster rubyDeclaration contains=rubyAliasDeclaration,rubyAliasDeclaration2,rubyMethodDeclaration,rubyModuleDeclaration,rubyClassDeclaration,rubyFunction,rubyBlockParameter
 
-" Keywords
+" Keywords {{{1
 " Note: the following keywords have already been defined:
 " begin case class def do end for if module unless until while
 syn match   rubyControl	       "\<\%(and\|break\|in\|next\|not\|or\|redo\|rescue\|retry\|return\)\>[?!]\@!"
@@ -219,8 +327,9 @@ syn match   rubyBoolean	       "\<\%(true\|false\)\>[?!]\@!"
 syn match   rubyPseudoVariable "\<\%(nil\|self\|__ENCODING__\|__dir__\|__FILE__\|__LINE__\|__callee__\|__method__\)\>[?!]\@!" " TODO: reorganise
 syn match   rubyBeginEnd       "\<\%(BEGIN\|END\)\>[?!]\@!"
 
-" Expensive Mode - match 'end' with the appropriate opening keyword for syntax
-" based folding and special highlighting of module/class/method definitions
+" Expensive Mode {{{1
+" Match 'end' with the appropriate opening keyword for syntax based folding
+" and special highlighting of module/class/method definitions
 if !exists("b:ruby_no_expensive") && !exists("ruby_no_expensive")
   syn match  rubyDefine "\<alias\>"  nextgroup=rubyAliasDeclaration  skipwhite skipnl
   syn match  rubyDefine "\<def\>"    nextgroup=rubyMethodDeclaration skipwhite skipnl
@@ -228,23 +337,66 @@ if !exists("b:ruby_no_expensive") && !exists("ruby_no_expensive")
   syn match  rubyClass	"\<class\>"  nextgroup=rubyClassDeclaration  skipwhite skipnl
   syn match  rubyModule "\<module\>" nextgroup=rubyModuleDeclaration skipwhite skipnl
 
-  syn region rubyMethodBlock start="\<def\>"	matchgroup=rubyDefine end="\%(\<def\_s\+\)\@<!\<end\>" contains=ALLBUT,@rubyNotTop fold
-  syn region rubyBlock	     start="\<class\>"	matchgroup=rubyClass  end="\<end\>"		       contains=ALLBUT,@rubyNotTop fold
-  syn region rubyBlock	     start="\<module\>" matchgroup=rubyModule end="\<end\>"		       contains=ALLBUT,@rubyNotTop fold
+  if s:foldable('def')
+    syn region rubyMethodBlock start="\<def\>"	matchgroup=rubyDefine end="\%(\<def\_s\+\)\@<!\<end\>" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyMethodBlock start="\<def\>"	matchgroup=rubyDefine end="\%(\<def\_s\+\)\@<!\<end\>" contains=ALLBUT,@rubyNotTop
+  endif
+
+  if s:foldable('class')
+    syn region rubyBlock start="\<class\>"	matchgroup=rubyClass end="\<end\>" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyBlock start="\<class\>"	matchgroup=rubyClass end="\<end\>" contains=ALLBUT,@rubyNotTop
+  endif
+
+  if s:foldable('module')
+    syn region rubyBlock start="\<module\>" matchgroup=rubyModule end="\<end\>" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyBlock start="\<module\>" matchgroup=rubyModule end="\<end\>" contains=ALLBUT,@rubyNotTop
+  endif
 
   " modifiers
-  syn match rubyConditionalModifier "\<\%(if\|unless\)\>"    display
-  syn match rubyRepeatModifier	     "\<\%(while\|until\)\>" display
+  syn match rubyLineContinuation    "\\$" nextgroup=rubyConditionalModifier,rubyRepeatModifier skipwhite skipnl
+  syn match rubyConditionalModifier "\<\%(if\|unless\)\>"
+  syn match rubyRepeatModifier	    "\<\%(while\|until\)\>"
+
+  if s:foldable('do')
+    syn region rubyDoBlock matchgroup=rubyControl start="\<do\>" end="\<end\>" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyDoBlock matchgroup=rubyControl start="\<do\>" end="\<end\>" contains=ALLBUT,@rubyNotTop
+  endif
 
-  syn region rubyDoBlock      matchgroup=rubyControl start="\<do\>" end="\<end\>"                 contains=ALLBUT,@rubyNotTop fold
   " curly bracket block or hash literal
-  syn region rubyCurlyBlock	matchgroup=rubyCurlyBlockDelimiter  start="{" end="}"				contains=ALLBUT,@rubyNotTop fold
-  syn region rubyArrayLiteral	matchgroup=rubyArrayDelimiter	    start="\%(\w\|[\]})]\)\@<!\[" end="]"	contains=ALLBUT,@rubyNotTop fold
+  if s:foldable('{')
+    syn region rubyCurlyBlock matchgroup=rubyCurlyBlockDelimiter start="{" end="}" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyCurlyBlock matchgroup=rubyCurlyBlockDelimiter start="{" end="}" contains=ALLBUT,@rubyNotTop
+  endif
+
+  if s:foldable('[')
+    syn region rubyArrayLiteral	matchgroup=rubyArrayDelimiter start="\%(\w\|[\]})]\)\@<!\[" end="]" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyArrayLiteral	matchgroup=rubyArrayDelimiter start="\%(\w\|[\]})]\)\@<!\[" end="]" contains=ALLBUT,@rubyNotTop
+  endif
 
   " statements without 'do'
-  syn region rubyBlockExpression       matchgroup=rubyControl	  start="\<begin\>" end="\<end\>" contains=ALLBUT,@rubyNotTop fold
-  syn region rubyCaseExpression	       matchgroup=rubyConditional start="\<case\>"  end="\<end\>" contains=ALLBUT,@rubyNotTop fold
-  syn region rubyConditionalExpression matchgroup=rubyConditional start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*%&^|+=-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![?!]\)\s*\)\@<=\%(\\\n\s*\)\@<!\%(if\|unless\)\>" end="\%(\%(\%(\.\@<!\.\)\|::\)\s*\)\@<!\<end\>" contains=ALLBUT,@rubyNotTop fold
+  if s:foldable('begin')
+    syn region rubyBlockExpression matchgroup=rubyControl start="\<begin\>" end="\<end\>" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyBlockExpression matchgroup=rubyControl start="\<begin\>" end="\<end\>" contains=ALLBUT,@rubyNotTop
+  endif
+
+  if s:foldable('case')
+    syn region rubyCaseExpression matchgroup=rubyConditional start="\<case\>" end="\<end\>" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyCaseExpression matchgroup=rubyConditional start="\<case\>" end="\<end\>" contains=ALLBUT,@rubyNotTop
+  endif
+
+  if s:foldable('if')
+    syn region rubyConditionalExpression matchgroup=rubyConditional start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*%&^|+=-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![?!]\)\s*\)\@<=\%(if\|unless\)\>" end="\%(\%(\%(\.\@1<!\.\)\|::\)\s*\)\@<!\<end\>" contains=ALLBUT,@rubyNotTop fold
+  else
+    syn region rubyConditionalExpression matchgroup=rubyConditional start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*%&^|+=-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![?!]\)\s*\)\@<=\%(if\|unless\)\>" end="\%(\%(\%(\.\@1<!\.\)\|::\)\s*\)\@<!\<end\>" contains=ALLBUT,@rubyNotTop
+  endif
 
   syn match rubyConditional "\<\%(then\|else\|when\)\>[?!]\@!"	contained containedin=rubyCaseExpression
   syn match rubyConditional "\<\%(then\|else\|elsif\)\>[?!]\@!" contained containedin=rubyConditionalExpression
@@ -254,7 +406,12 @@ if !exists("b:ruby_no_expensive") && !exists("ruby_no_expensive")
 
   " statements with optional 'do'
   syn region rubyOptionalDoLine   matchgroup=rubyRepeat start="\<for\>[?!]\@!" start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!=?]\)\s*\)\@<=\<\%(until\|while\)\>" matchgroup=rubyOptionalDo end="\%(\<do\>\)" end="\ze\%(;\|$\)" oneline contains=ALLBUT,@rubyNotTop
-  syn region rubyRepeatExpression start="\<for\>[?!]\@!" start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!=?]\)\s*\)\@<=\<\%(until\|while\)\>" matchgroup=rubyRepeat end="\<end\>" contains=ALLBUT,@rubyNotTop nextgroup=rubyOptionalDoLine fold
+
+  if s:foldable('for')
+    syn region rubyRepeatExpression start="\<for\>[?!]\@!" start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!=?]\)\s*\)\@<=\<\%(until\|while\)\>" matchgroup=rubyRepeat end="\<end\>" contains=ALLBUT,@rubyNotTop nextgroup=rubyOptionalDoLine fold
+  else
+    syn region rubyRepeatExpression start="\<for\>[?!]\@!" start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!=?]\)\s*\)\@<=\<\%(until\|while\)\>" matchgroup=rubyRepeat end="\<end\>" contains=ALLBUT,@rubyNotTop nextgroup=rubyOptionalDoLine
+  endif
 
   if !exists("ruby_minlines")
     let ruby_minlines = 500
@@ -269,7 +426,7 @@ else
   syn match rubyKeyword "\<\%(alias\|undef\)\>[?!]\@!"
 endif
 
-" Special Methods
+" Special Methods {{{1
 if !exists("ruby_no_special_methods")
   syn keyword rubyAccess    public protected private public_class_method private_class_method public_constant private_constant module_function
   " attr is a common variable name
@@ -284,41 +441,36 @@ if !exists("ruby_no_special_methods")
   syn keyword rubyKeyword   callcc caller lambda proc
 endif
 
-" Comments and Documentation
+" Comments and Documentation {{{1
 syn match   rubySharpBang "\%^#!.*" display
 syn keyword rubyTodo	  FIXME NOTE TODO OPTIMIZE HACK REVIEW XXX todo contained
 syn match   rubyComment   "#.*" contains=rubySharpBang,rubySpaceError,rubyTodo,@Spell
-if !exists("ruby_no_comment_fold")
+if !exists("ruby_no_comment_fold") && s:foldable('#')
   syn region rubyMultilineComment start="^\s*#.*\n\%(^\s*#\)\@=" end="^\s*#.*\n\%(^\s*#\)\@!" contains=rubyComment transparent fold keepend
   syn region rubyDocumentation	  start="^=begin\ze\%(\s.*\)\=$" end="^=end\%(\s.*\)\=$" contains=rubySpaceError,rubyTodo,@Spell fold
 else
   syn region rubyDocumentation	  start="^=begin\s*$" end="^=end\s*$" contains=rubySpaceError,rubyTodo,@Spell
 endif
 
+" Keyword Nobbling {{{1
 " Note: this is a hack to prevent 'keywords' being highlighted as such when called as methods with an explicit receiver
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(alias\|and\|begin\|break\|case\|class\|def\|defined\|do\|else\)\>"		  transparent contains=NONE
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(elsif\|end\|ensure\|false\|for\|if\|in\|module\|next\|nil\)\>"		  transparent contains=NONE
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(not\|or\|redo\|refine\|rescue\|retry\|return\|self\|super\|then\|true\)\>"		  transparent contains=NONE
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(undef\|unless\|until\|when\|while\|yield\|BEGIN\|END\|__FILE__\|__LINE__\)\>" transparent contains=NONE
-
-syn match rubyKeywordAsMethod "\<\%(alias\|begin\|case\|class\|def\|do\|end\)[?!]" transparent contains=NONE
-syn match rubyKeywordAsMethod "\<\%(if\|module\|refine\|undef\|unless\|until\|while\)[?!]" transparent contains=NONE
-
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(abort\|at_exit\|attr\|attr_accessor\|attr_reader\)\>"	transparent contains=NONE
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(attr_writer\|autoload\|callcc\|catch\|caller\)\>"		transparent contains=NONE
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(eval\|class_eval\|instance_eval\|module_eval\|exit\)\>"	transparent contains=NONE
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(extend\|fail\|fork\|include\|lambda\)\>"			transparent contains=NONE
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(load\|loop\|prepend\|private\|proc\|protected\)\>"		transparent contains=NONE
-syn match rubyKeywordAsMethod "\%(\%(\.\@<!\.\)\|::\)\_s*\%(public\|require\|require_relative\|raise\|throw\|trap\|using\)\>"	transparent contains=NONE
+syn match rubyKeywordAsMethod "\%(\%(\.\@1<!\.\)\|::\)\_s*\%([_[:lower:]][_[:alnum:]]*\|\<\%(BEGIN\|END\)\>\)" transparent contains=NONE
+syn match rubyKeywordAsMethod "\(defined?\|exit!\)\@!\<[_[:lower:]][_[:alnum:]]*[?!]"			       transparent contains=NONE
 
+" More Symbols {{{1
 syn match  rubySymbol		"\%([{(,]\_s*\)\@<=\l\w*[!?]\=::\@!"he=e-1
-syn match  rubySymbol		"[]})\"':]\@<!\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*[!?]\=:[[:space:],]\@="he=e-1
+syn match  rubySymbol		"[]})\"':]\@1<!\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*[!?]\=:[[:space:],]\@="he=e-1
 syn match  rubySymbol		"\%([{(,]\_s*\)\@<=[[:space:],{]\l\w*[!?]\=::\@!"hs=s+1,he=e-1
 syn match  rubySymbol		"[[:space:],{(]\%(\h\|[^\x00-\x7F]\)\%(\w\|[^\x00-\x7F]\)*[!?]\=:[[:space:],]\@="hs=s+1,he=e-1
 
-" __END__ Directive
-syn region rubyData matchgroup=rubyDataDirective start="^__END__$" end="\%$" fold
+" __END__ Directive {{{1
+if s:foldable('__END__')
+  syn region rubyData matchgroup=rubyDataDirective start="^__END__$" end="\%$" fold
+else
+  syn region rubyData matchgroup=rubyDataDirective start="^__END__$" end="\%$"
+endif
 
+" Default Highlighting {{{1
 hi def link rubyClass			rubyDefine
 hi def link rubyModule			rubyDefine
 hi def link rubyMethodExceptional	rubyDefine
@@ -389,8 +541,9 @@ hi def link rubyInvalidVariable		Error
 hi def link rubyError			Error
 hi def link rubySpaceError		rubyError
 
+" Postscript {{{1
 let b:current_syntax = "ruby"
 
-" vim: nowrap sw=2 sts=2 ts=8 noet:
+" vim: nowrap sw=2 sts=2 ts=8 noet fdm=marker:
 
 endif