Not completely finished hook to add fragment tags to RMarkdown code chunks (slidify, revealjs, R)

knitr_hook.R

s0 <- knitr::knit_hooks$get('source')
o0 <- knitr::knit_hooks$get('output')
p0 <- knitr::knit_hooks$get('plot')

knitr::knit_hooks$set(
  list(


    source=function(x,options){
      if (is.null(options$class)) s0(x, options)
      else
          
          paste0("<pre class='", options$class, "'><code class='r'>",paste0(x, collapse="\n"))          

    },
    output = function(x,options){
      if (is.null(options$class)) o0(x, options)
      else 
        print(x)
        paste0('\n',x,'</code></pre>')
    },
#    plot = function(x, options){
#      print(p0(x, options))
#    },
     chunk=function(x,options){
       print(x)
       
       
       if (is.null(options$class)){
         return(x)
         }else{
           # if we already have closing tags (from the output) then we're done
           if(grepl('</code></pre>',x)==1){return(x)}
           
           # if not we add them here
           if(grepl('</code></pre>',x)!=1){return(paste0(x,'</code></pre>'))}

         }
#        }else{
#          #if no image and closing tags exist
#         if(grepl("!\\[", x)!=1 & grepl('</code></pre>',x)==1){return(x)}
#         #if image and no closing tags exist
#         if(grepl("!\\[", x)==1 & grepl('</code></pre>',x)!=1){
#           x<-gsub("!\\[", '</code></pre>\n![',x)
#           
#         return(x)
#         }
#            
#          
#        }
       return(x)
     }
  )
)