Ruby heredoc syntax highlighting

ruby.vim

let s:bcs = b:current_syntax
unlet b:current_syntax
syntax include @SQL syntax/sql.vim

unlet b:current_syntax
syntax include @SHELL syntax/sh.vim

unlet b:current_syntax
syntax include @CONF syntax/conf.vim

unlet b:current_syntax
syntax include @PHP syntax/php.vim

let b:current_syntax = s:bcs

syntax region hereDocText matchgroup=Statement start=+<<[-~.]*\z([A-Z]\+\)+ end=+^\s*\z1+ contains=NONE
syntax region hereDocDashSQL matchgroup=Statement start=+<<[-~.]*\z(SQL\)+  end=+^\s*\z1+ contains=@SQL
syntax region hereDocDashSHELL matchgroup=Statement start=+<<[-~.]*\z(SHELL\)+  end=+^\s*\z1+ contains=@SHELL
syntax region hereDocDashCONF matchgroup=Statement start=+<<[-~.]*\z(CONF\)+  end=+^\s*\z1+ contains=@CONF
syntax region hereDocDashPHP matchgroup=Statement start=+<<[-~.]*\z(PHP\)+  end=+^\s*\z1+ contains=@PHP