diff --git a/runtime/syntax/ruby.vim b/runtime/syntax/ruby.vim
index c45aae2..42a88f4 100644
--- a/runtime/syntax/ruby.vim
+++ b/runtime/syntax/ruby.vim
@@ -11,11 +11,7 @@
 " Thanks to perl.vim authors, and to Reimer Behrends. :-) (MN)
 " ----------------------------------------------------------------------------
 
-" For version 5.x: Clear all syntax items
-" For version 6.x: Quit when a syntax file was already loaded
-if version < 600
-  syntax clear
-elseif exists("b:current_syntax")
+if exists("b:current_syntax")
   finish
 endif
 
@@ -34,9 +30,9 @@
 
 " Operators
 if exists("ruby_operators")
-  syn match  rubyOperator	 "\%(\^\|\~\|\%(class\s*\)\@<!<<\|<=>\|<=\|\%(<\|\<class\s\+\u\w*\s*\)\@<!<[^<]\@=\|===\|==\|=\~\|>>\|>=\|>\||\|-\|/\|\*\*\|\*\|&\|%\|+\)"
-  syn match  rubyPseudoOperator  "\%(-=\|/=\|\*\*=\|\*=\|&&\|&=\|&&=\|||\||=\|||=\|%=\|+=\|!\~\|!=\)"
-  syn region rubyBracketOperator matchgroup=rubyOperator start="\%([_[:lower:]]\w*[?!=]\=\|}\)\@<=\[\s*" end="\s*]"
+  syn match  rubyOperator	 "\%([~!^&|*/%+-]\|\%(class\s*\)\@<!<<\|<=>\|<=\|\%(<\|\<class\s\+\u\w*\s*\)\@<!<[^<]\@=\|===\|==\|=\~\|>>\|>=\|=\@<!>\|\*\*\|\.\.\.\|\.\.\|::\)"
+  syn match  rubyPseudoOperator  "\%(-=\|/=\|\*\*=\|\*=\|&&=\|&=\|&&\|||=\||=\|||\|%=\|+=\|!\~\|!=\)"
+  syn region rubyBracketOperator matchgroup=rubyOperator start="\%([_[:lower:]]\w*[?!=]\=\|[})]\)\@<=\[\s*" end="\s*]" contains=TOP
 endif
 
 " Expression Substitution and Backslash Notation
@@ -46,22 +42,29 @@
 syn region rubyInterpolation	      matchgroup=rubyInterpolationDelimiter start="#{" end="}" contained contains=TOP
 syn match  rubyInterpolation	      "#\%(\$\|@@\=\)\w\+"    display contained  contains=rubyInterpolationDelimiter,rubyInstanceVariable,rubyClassVariable,rubyGlobalVariable,rubyPredefinedVariable
 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 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 region rubyNestedParentheses	start="("	end=")"		skip="\\\\\|\\)"	transparent contained contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimEscape
 syn region rubyNestedCurlyBraces	start="{"	end="}"		skip="\\\\\|\\}"	transparent contained contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimEscape
 syn region rubyNestedAngleBrackets	start="<"	end=">"		skip="\\\\\|\\>"	transparent contained contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimEscape
-syn region rubyNestedSquareBrackets	start="\["	end="\]"	skip="\\\\\|\\\]"	transparent contained contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimEscape
+if exists("ruby_operators")
+  syn region rubyNestedSquareBrackets	start="\["	end="\]"	skip="\\\\\|\\\]"	transparent contained contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimEscape
+else
+  syn region rubyNestedSquareBrackets	start="\["	end="\]"	skip="\\\\\|\\\]"	transparent containedin=rubyArrayLiteral contained contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimEscape
+endif
 
 syn cluster rubyStringSpecial		contains=rubyInterpolation,rubyNoInterpolation,rubyEscape
 syn cluster rubyExtendedStringSpecial	contains=@rubyStringSpecial,rubyNestedParentheses,rubyNestedCurlyBraces,rubyNestedAngleBrackets,rubyNestedSquareBrackets
 
 " 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\)\)"
+syn match rubyASCIICode	"\%(\w\|[]})\"'/]\)\@<!\%(?\%(\\M-\\C-\|\\C-\\M-\|\\M-\\c\|\\c\\M-\|\\c\|\\C-\|\\M-\)\=\%(\\\o\{1,3}\|\\x\x\{1,2}\|\\\=\S\)\)"
 syn match rubyInteger	"\<0[xX]\x\+\%(_\x\+\)*\>"								display
 syn match rubyInteger	"\<\%(0[dD]\)\=\%(0\|[1-9]\d*\%(_\d\+\)*\)\>"						display
 syn match rubyInteger	"\<0[oO]\=\o\+\%(_\o\+\)*\>"								display
@@ -77,17 +80,17 @@
 syn match  rubyClassVariable		"@@\h\w*" display
 syn match  rubyInstanceVariable		"@\h\w*"  display
 syn match  rubyGlobalVariable		"$\%(\h\w*\|-.\)"
-syn match  rubySymbol			":\@<!:\%(\^\|\~\|<<\|<=>\|<=\|<\|===\|==\|=\~\|>>\|>=\|>\||\|-@\|-\|/\|\[]=\|\[]\|\*\*\|\*\|&\|%\|+@\|+\|`\)"
-syn match  rubySymbol			":\@<!:\$\%(-.\|[`~<=>_,;:!?/.'"@$*\&+0]\)"
-syn match  rubySymbol			":\@<!:\%(\$\|@@\=\)\=\h\w*[?!=]\="
-syn region rubySymbol			start=":\@<!:\"" end="\"" skip="\\\\\|\\\""
-syn region rubySymbol			start=":\@<!:\"" end="\"" skip="\\\\\|\\\"" contains=@rubyStringSpecial fold
-if exists("ruby_operators")
-  syn match  rubyBlockParameter		"\%(\%(\%(\<do\>\|{\)\s*\)|\s*\)\@<=[( ,a-zA-Z0-9_*)]\+\%(\s*|\)\@=" display
-else
-  syn match  rubyBlockParameter		"\%(\%(\<do\>\|{\)\s*\)\@<=|\s*\zs[( ,a-zA-Z0-9_*)]\+\ze\s*|" display
-endif
+syn match  rubySymbol			"[]})\"':]\@<!:\%(\^\|\~\|<<\|<=>\|<=\|<\|===\|==\|=\~\|>>\|>=\|>\||\|-@\|-\|/\|\[]=\|\[]\|\*\*\|\*\|&\|%\|+@\|+\|`\)"
+syn match  rubySymbol			"[]})\"':]\@<!:\$\%(-.\|[`~<=>_,;:!?/.'"@$*\&+0]\)"
+syn match  rubySymbol			"[]})\"':]\@<!:\%(\$\|@@\=\)\=\h\w*"
+syn match  rubySymbol			"[]})\"':]\@<!:\h\w*[?!=]\="
+syn region rubySymbol			start="[]})\"':]\@<!:\"" end="\"" skip="\\\\\|\\\""
+syn region rubySymbol			start="[]})\"':]\@<!:\"" end="\"" skip="\\\\\|\\\"" contains=@rubyStringSpecial fold
 
+syn match  rubyBlockParameter		"\h\w*" contained
+syn region rubyBlockParameterList	start="\%(\%(\<do\>\|{\)\s*\)\@<=|" end="|" oneline display contains=rubyBlockParameter
+
+syn match rubyInvalidVariable    "$[^ A-Za-z-]"
 syn match rubyPredefinedVariable #$[!$&"'*+,./0:;<=>?@\`~1-9]#
 syn match rubyPredefinedVariable "$_\>"											   display
 syn match rubyPredefinedVariable "$-[0FIKadilpvw]\>"									   display
@@ -101,8 +104,8 @@
 "syn match rubyPredefinedConstant "\%(::\)\=\zs\%(NotImplementError\)\>"
 
 " Normal Regular Expression
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\%(^\|\<\%(and\|or\|while\|until\|unless\|if\|elsif\|when\|not\|then\)\|[;\~=!|&(,[>]\)\s*\)\@<=/" end="/[iomx]*" skip="\\\\\|\\/" contains=@rubyStringSpecial fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\<\%(split\|scan\|gsub\|sub\)\s*\)\@<=/" end="/[iomx]*" skip="\\\\\|\\/" contains=@rubyStringSpecial fold
+syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\%(^\|\<\%(and\|or\|while\|until\|unless\|if\|elsif\|when\|not\|then\|else\)\|[;\~=!|&(,[>]\)\s*\)\@<=/" end="/[iomxneus]*" skip="\\\\\|\\/" contains=@rubyStringSpecial fold
+syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="\%(\<\%(split\|scan\|gsub\|sub\)\s*\)\@<=/" end="/[iomxneus]*" skip="\\\\\|\\/" contains=@rubyStringSpecial fold
 
 " Normal String and Shell Command Output
 syn region rubyString matchgroup=rubyStringDelimiter start="\"" end="\"" skip="\\\\\|\\\"" contains=@rubyStringSpecial fold
@@ -110,18 +113,23 @@
 syn region rubyString matchgroup=rubyStringDelimiter start="`"	end="`"  skip="\\\\\|\\`"  contains=@rubyStringSpecial fold
 
 " Generalized Regular Expression
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)"	end="\z1[iomx]*" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r{"				end="}[iomx]*"	 skip="\\\\\|\\}"   contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimEscape fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r<"				end=">[iomx]*"	 skip="\\\\\|\\>"   contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimEscape fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\["				end="\][iomx]*"	 skip="\\\\\|\\\]"  contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimEscape fold
-syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r("				end=")[iomx]*"	 skip="\\\\\|\\)"   contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimEscape fold
+syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)"	end="\z1[iomxneus]*" skip="\\\\\|\\\z1" contains=@rubyStringSpecial fold
+syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r{"				end="}[iomxneus]*"	 skip="\\\\\|\\}"   contains=@rubyStringSpecial,rubyNestedCurlyBraces,rubyDelimEscape fold
+syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r<"				end=">[iomxneus]*"	 skip="\\\\\|\\>"   contains=@rubyStringSpecial,rubyNestedAngleBrackets,rubyDelimEscape fold
+syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r\["				end="\][iomxneus]*"	 skip="\\\\\|\\\]"  contains=@rubyStringSpecial,rubyNestedSquareBrackets,rubyDelimEscape fold
+syn region rubyRegexp matchgroup=rubyRegexpDelimiter start="%r("				end=")[iomxneus]*"	 skip="\\\\\|\\)"   contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimEscape fold
 
 " Generalized Single Quoted String, Symbol and Array of Strings
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qsw]\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)" end="\z1" skip="\\\\\|\\\z1" fold
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qsw]{"				    end="}"   skip="\\\\\|\\}"	 fold	contains=rubyNestedCurlyBraces,rubyDelimEscape
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qsw]<"				    end=">"   skip="\\\\\|\\>"	 fold	contains=rubyNestedAngleBrackets,rubyDelimEscape
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qsw]\["				    end="\]"  skip="\\\\\|\\\]"	 fold	contains=rubyNestedSquareBrackets,rubyDelimEscape
-syn region rubyString matchgroup=rubyStringDelimiter start="%[qsw]("				    end=")"   skip="\\\\\|\\)"	 fold	contains=rubyNestedParentheses,rubyDelimEscape
+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 rubySymbol				     start="%[s]\z([~`!@#$%^&*_\-+=|\:;"',.?/]\)"   end="\z1" skip="\\\\\|\\\z1" fold
+syn region rubySymbol				     start="%[s]{"				    end="}"   skip="\\\\\|\\}"	 fold	contains=rubyNestedCurlyBraces,rubyDelimEscape
+syn region rubySymbol				     start="%[s]<"				    end=">"   skip="\\\\\|\\>"	 fold	contains=rubyNestedAngleBrackets,rubyDelimEscape
+syn region rubySymbol				     start="%[s]\["				    end="\]"  skip="\\\\\|\\\]"	 fold	contains=rubyNestedSquareBrackets,rubyDelimEscape
+syn region rubySymbol				     start="%[s]("				    end=")"   skip="\\\\\|\\)"	 fold	contains=rubyNestedParentheses,rubyDelimEscape
 
 " Generalized Double Quoted String and Array of Strings and Shell Command Output
 " Note: %= is not matched here as the beginning of a double quoted string
@@ -133,20 +141,20 @@
 syn region rubyString matchgroup=rubyStringDelimiter start="%[QWx]\=("				    end=")"   skip="\\\\\|\\)"	 contains=@rubyStringSpecial,rubyNestedParentheses,rubyDelimEscape fold
 
 " Here Document
-syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<-\=\zs\%(\h\w*\)+   end=+$+ oneline contains=TOP
-syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<-\=\zs"\%([^"]*\)"+ end=+$+ oneline contains=TOP
-syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<-\=\zs'\%([^']*\)'+ end=+$+ oneline contains=TOP
-syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<-\=\zs`\%([^`]*\)`+ end=+$+ oneline contains=TOP
+syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<-\=\zs\%(\h\w*\)+   end=+$+ oneline contains=TOP
+syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<-\=\zs"\%([^"]*\)"+ end=+$+ oneline contains=TOP
+syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<-\=\zs'\%([^']*\)'+ end=+$+ oneline contains=TOP
+syn region rubyHeredocStart matchgroup=rubyStringDelimiter start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<-\=\zs`\%([^`]*\)`+ end=+$+ oneline contains=TOP
 
-syn region rubyString start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<\z(\h\w*\)\ze+hs=s+2    matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
-syn region rubyString start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<"\z([^"]*\)"\ze+hs=s+2  matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
-syn region rubyString start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<'\z([^']*\)'\ze+hs=s+2  matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart		      fold keepend
-syn region rubyString start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<`\z([^`]*\)`\ze+hs=s+2  matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+syn region rubyString start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<\z(\h\w*\)\ze+hs=s+2    matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+syn region rubyString start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<"\z([^"]*\)"\ze+hs=s+2  matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+syn region rubyString start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<'\z([^']*\)'\ze+hs=s+2  matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart		      fold keepend
+syn region rubyString start=+\%(\%(class\s*\|\%([]})"'.]\|::\)\)\_s*\|\w\)\@<!<<`\z([^`]*\)`\ze+hs=s+2  matchgroup=rubyStringDelimiter end=+^\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
 
-syn region rubyString start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<-\z(\h\w*\)\ze+hs=s+3    matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
-syn region rubyString start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<-"\z([^"]*\)"\ze+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
-syn region rubyString start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<-'\z([^']*\)'\ze+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart		     fold keepend
-syn region rubyString start=+\%(\%(class\s*\|\%(\.\|::\)\)\_s*\)\@<!<<-`\z([^`]*\)`\ze+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+syn region rubyString start=+\%(\%(class\s*\|\%([]}).]\|::\)\)\_s*\|\w\)\@<!<<-\z(\h\w*\)\ze+hs=s+3    matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+syn region rubyString start=+\%(\%(class\s*\|\%([]}).]\|::\)\)\_s*\|\w\)\@<!<<-"\z([^"]*\)"\ze+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
+syn region rubyString start=+\%(\%(class\s*\|\%([]}).]\|::\)\)\_s*\|\w\)\@<!<<-'\z([^']*\)'\ze+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart		     fold keepend
+syn region rubyString start=+\%(\%(class\s*\|\%([]}).]\|::\)\)\_s*\|\w\)\@<!<<-`\z([^`]*\)`\ze+hs=s+3  matchgroup=rubyStringDelimiter end=+^\s*\zs\z1$+ contains=rubyHeredocStart,@rubyStringSpecial fold keepend
 
 if exists('main_syntax') && main_syntax == 'eruby'
   let b:ruby_no_expensive = 1
@@ -160,7 +168,9 @@
 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
-" Expensive Mode - colorize *end* according to opening statement
+
+" Expensive Mode - 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
@@ -171,25 +181,25 @@
   syn region rubyBlock start="\<module\>"	matchgroup=rubyModule end="\<end\>" contains=TOP fold
 
   " modifiers
-  syn match  rubyConditional "\<\%(if\|unless\)\>"   display
-  syn match  rubyRepeat	     "\<\%(while\|until\)\>" display
+  syn match  rubyConditionalModifier "\<\%(if\|unless\)\>"   display
+  syn match  rubyRepeatModifier	     "\<\%(while\|until\)\>" display
 
-  " *do* requiring *end*
   syn region rubyDoBlock matchgroup=rubyControl start="\<do\>" end="\<end\>" contains=TOP fold
+  " curly bracket block or hash literal
+  syn region rubyCurlyBlock   start="{" end="}" contains=TOP fold
+  syn region rubyArrayLiteral matchgroup=rubyArrayDelimiter start="\%(\w\|[\]})]\)\@<!\[" end="]" contains=TOP fold
 
-  " *{* requiring *}*
-  syn region rubyCurlyBlock start="{" end="}" contains=TOP fold
+  " statements without 'do'
+  syn region rubyBlockExpression       matchgroup=rubyControl	  start="\<begin\>" end="\<end\>" contains=TOP fold
+  syn region rubyCaseExpression	       matchgroup=rubyConditional start="\<case\>"  end="\<end\>" contains=TOP fold
+  syn region rubyConditionalExpression matchgroup=rubyConditional start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+=-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!?]\)\s*\)\@<=\%(if\|unless\)\>" end="\<end\>" contains=TOP fold
 
-  " statements without *do*
-  syn region rubyNoDoBlock	  matchgroup=rubyControl     start="\<begin\>" end="\<end\>" contains=TOP fold
-  syn region rubyCaseBlock	  matchgroup=rubyConditional start="\<case\>"  end="\<end\>" contains=TOP fold
-  syn region rubyConditionalBlock matchgroup=rubyConditional start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!=?]\)\s*\)\@<=\%(if\|unless\)\>" end="\<end\>" contains=TOP fold
-  syn keyword rubyConditional then else when  contained containedin=rubyCaseBlock
-  syn keyword rubyConditional then else elsif contained containedin=rubyConditionalBlock
+  syn keyword rubyConditional then else when  contained containedin=rubyCaseExpression
+  syn keyword rubyConditional then else elsif contained containedin=rubyConditionalExpression
 
-  " statement with optional *do*
-  syn region rubyOptDoLine matchgroup=rubyRepeat start="\<for\>" start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!=?]\)\s*\)\@<=\<\%(until\|while\)\>" end="\%(\<do\>\|:\)" end="\ze\%(;\|$\)" oneline contains=TOP
-  syn region rubyOptDoBlock start="\<for\>" start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!=?]\)\s*\)\@<=\<\%(until\|while\)\>" matchgroup=rubyRepeat end="\<end\>" contains=TOP nextgroup=rubyOptDoLine fold
+  " 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=TOP
+  syn region rubyRepeatExpression start="\<for\>" start="\%(\%(^\|\.\.\.\=\|[{:,;([<>~\*/%&^|+-]\|\%(\<[_[:lower:]][_[:alnum:]]*\)\@<![!=?]\)\s*\)\@<=\<\%(until\|while\)\>" matchgroup=rubyRepeat end="\<end\>" contains=TOP nextgroup=rubyOptionalDoLine fold
 
   if !exists("ruby_minlines")
     let ruby_minlines = 50
@@ -227,11 +237,11 @@
 
 " Comments and Documentation
 syn match   rubySharpBang     "\%^#!.*" display
-syn keyword rubyTodo	      FIXME NOTE TODO XXX contained
+syn keyword rubyTodo	      FIXME NOTE TODO OPTIMIZE XXX contained
 syn match   rubyComment       "#.*" contains=rubySharpBang,rubySpaceError,rubyTodo,@Spell
 if !exists("ruby_no_comment_fold")
   syn region rubyMultilineComment start="\%(\%(^\s*#.*\n\)\@<!\%(^\s*#.*\n\)\)\%(\(^\s*#.*\n\)\{1,}\)\@=" end="\%(^\s*#.*\n\)\@<=\%(^\s*#.*\n\)\%(^\s*#\)\@!" contains=rubyComment transparent fold keepend
-  syn region rubyDocumentation	  start="^=begin\s*$" end="^=end\s*$" contains=rubySpaceError,rubyTodo,@Spell fold
+  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
@@ -252,72 +262,62 @@
 " __END__ Directive
 syn region rubyData matchgroup=rubyDataDirective start="^__END__$" end="\%$" fold
 
-" Define the default highlighting.
-" For version 5.7 and earlier: only when not done already
-" For version 5.8 and later: only when an item doesn't have highlighting yet
-if version >= 508 || !exists("did_ruby_syntax_inits")
-  if version < 508
-    let did_ruby_syntax_inits = 1
-    command -nargs=+ HiLink hi link <args>
-  else
-    command -nargs=+ HiLink hi def link <args>
-  endif
-
-  HiLink rubyClass			rubyDefine
-  HiLink rubyModule			rubyDefine
-  HiLink rubyDefine			Define
-  HiLink rubyFunction			Function
-  HiLink rubyConditional		Conditional
-  HiLink rubyRepeat			Repeat
-  HiLink rubyControl			Statement
-  HiLink rubyInclude			Include
-  HiLink rubyInteger			Number
-  HiLink rubyASCIICode			Character
-  HiLink rubyFloat			Float
-  HiLink rubyBoolean			Boolean
-  HiLink rubyException			Exception
-  if !exists("ruby_no_identifiers")
-    HiLink rubyIdentifier		Identifier
-  else
-    HiLink rubyIdentifier		NONE
-  endif
-  HiLink rubyClassVariable		rubyIdentifier
-  HiLink rubyConstant			Type
-  HiLink rubyGlobalVariable		rubyIdentifier
-  HiLink rubyBlockParameter		rubyIdentifier
-  HiLink rubyInstanceVariable		rubyIdentifier
-  HiLink rubyPredefinedIdentifier	rubyIdentifier
-  HiLink rubyPredefinedConstant		rubyPredefinedIdentifier
-  HiLink rubyPredefinedVariable		rubyPredefinedIdentifier
-  HiLink rubySymbol			Constant
-  HiLink rubyKeyword			Keyword
-  HiLink rubyOperator			Operator
-  HiLink rubyPseudoOperator		rubyOperator
-  HiLink rubyBeginEnd			Statement
-  HiLink rubyAccess			Statement
-  HiLink rubyAttribute			Statement
-  HiLink rubyEval			Statement
-  HiLink rubyPseudoVariable		Constant
-
-  HiLink rubyComment			Comment
-  HiLink rubyData			Comment
-  HiLink rubyDataDirective		Delimiter
-  HiLink rubyDocumentation		Comment
-  HiLink rubyEscape			Special
-  HiLink rubyInterpolationDelimiter	Delimiter
-  HiLink rubyNoInterpolation		rubyString
-  HiLink rubySharpBang			PreProc
-  HiLink rubyRegexpDelimiter		rubyStringDelimiter
-  HiLink rubyStringDelimiter		Delimiter
-  HiLink rubyRegexp			rubyString
-  HiLink rubyString			String
-  HiLink rubyTodo			Todo
-
-  HiLink rubyError			Error
-  HiLink rubySpaceError			rubyError
-
-  delcommand HiLink
+hi def link rubyClass			rubyDefine
+hi def link rubyModule			rubyDefine
+hi def link rubyDefine			Define
+hi def link rubyFunction		Function
+hi def link rubyConditional		Conditional
+hi def link rubyConditionalModifier	rubyConditional
+hi def link rubyRepeat			Repeat
+hi def link rubyRepeatModifier		rubyRepeat
+hi def link rubyOptionalDo		rubyRepeat
+hi def link rubyControl			Statement
+hi def link rubyInclude			Include
+hi def link rubyInteger			Number
+hi def link rubyASCIICode		Character
+hi def link rubyFloat			Float
+hi def link rubyBoolean			Boolean
+hi def link rubyException		Exception
+if !exists("ruby_no_identifiers")
+  hi def link rubyIdentifier		Identifier
+else
+  hi def link rubyIdentifier		NONE
 endif
+hi def link rubyClassVariable		rubyIdentifier
+hi def link rubyConstant		Type
+hi def link rubyGlobalVariable		rubyIdentifier
+hi def link rubyBlockParameter		rubyIdentifier
+hi def link rubyInstanceVariable	rubyIdentifier
+hi def link rubyPredefinedIdentifier	rubyIdentifier
+hi def link rubyPredefinedConstant	rubyPredefinedIdentifier
+hi def link rubyPredefinedVariable	rubyPredefinedIdentifier
+hi def link rubySymbol			Constant
+hi def link rubyKeyword			Keyword
+hi def link rubyOperator		Operator
+hi def link rubyPseudoOperator		rubyOperator
+hi def link rubyBeginEnd		Statement
+hi def link rubyAccess			Statement
+hi def link rubyAttribute		Statement
+hi def link rubyEval			Statement
+hi def link rubyPseudoVariable		Constant
+
+hi def link rubyComment			Comment
+hi def link rubyData			Comment
+hi def link rubyDataDirective		Delimiter
+hi def link rubyDocumentation		Comment
+hi def link rubyEscape			Special
+hi def link rubyInterpolationDelimiter	Delimiter
+hi def link rubyNoInterpolation		rubyString
+hi def link rubySharpBang		PreProc
+hi def link rubyRegexpDelimiter		rubyStringDelimiter
+hi def link rubyStringDelimiter		Delimiter
+hi def link rubyRegexp			rubyString
+hi def link rubyString			String
+hi def link rubyTodo			Todo
+
+hi def link rubyInvalidVariable		Error
+hi def link rubyError			Error
+hi def link rubySpaceError		rubyError
 
 let b:current_syntax = "ruby"