Fix #340 cache error

autoload/neosnippet/helpers.vim

@@ -181,6 +181,13 @@ function! neosnippet#helpers#substitute_selected_text(type, text) abort "{{{
   endtry
 endfunction"}}}
 
+function! neosnippet#helpers#vim2json(expr) abort "{{{
+  return has('patch-7.4.1498') ? js_encode(a:expr) : string(a:expr)
+endfunction "}}}
+function! neosnippet#helpers#json2vim(expr) abort "{{{
+  sandbox return has('patch-7.4.1498') ? js_decode(a:expr) : eval(a:expr)
+endfunction "}}}
+
 function! s:is_beginning_of_line(cur_text) abort "{{{
   let keyword_pattern = '\S\+'
   let cur_keyword_str = matchstr(a:cur_text, keyword_pattern.'$')

autoload/neosnippet/parser.vim

@@ -36,15 +36,21 @@ function! neosnippet#parser#_parse_snippets(filename) abort "{{{
   endif
 
   let cache_dir = neosnippet#variables#data_dir()
-  if s:Cache.check_old_cache(cache_dir, a:filename)
+  let snippets = {}
+  if !s:Cache.check_old_cache(cache_dir, a:filename)
+    try
+      let snippets = neosnippet#helpers#json2vim(
+            \ s:Cache.readfile(cache_dir, a:filename)[0])
+    catch
+    endtry
+  endif
+  if empty(snippets) || s:Cache.check_old_cache(cache_dir, a:filename)
     let [snippets, sourced] = s:parse(a:filename)
     if len(snippets) > 5 && !neosnippet#util#is_sudo() && !sourced
       call s:Cache.writefile(
-            \ cache_dir, a:filename, [string(snippets)])
+            \ cache_dir, a:filename,
+            \ [neosnippet#helpers#vim2json(snippets)])
     endif
-  else
-    sandbox let snippets = eval(
-          \ s:Cache.readfile(cache_dir, a:filename)[0])
   endif
 
   return snippets