Fix json api

autoload/SpaceVim/api/data/json.vim

@@ -1,25 +1,97 @@
 let s:json = {}
 
-function! s:json_encode(expr) abort
-    " TODO
-    " support old vim version
-    return json_encode(a:expr)
+
+if exists('*json_decode') && 0
+    let g:spacevim_api_json_true = v:true
+    let g:spacevim_api_json_true = v:false
+    let g:spacevim_api_json_true = v:null
+    function! s:json_decode(json) abort
+        if a:json ==# ''
+            return []
+        endif
+        return json_decode(a:json)
+    endfunction
+else
+    function! s:json_null() abort
+    endfunction
+
+    function! s:json_true() abort
+    endfunction
+
+    function! s:json_false() abort
+    endfunction
+
+    let g:spacevim_api_json_true = [function('s:json_true')]
+    let g:spacevim_api_json_false = [function('s:json_false')]
+    let g:spacevim_api_json_null = [function('s:json_null')]
+
+    function! s:json_decode(json) abort
+        let true = g:spacevim_api_json_true
+        let false = g:spacevim_api_json_false
+        let null = g:spacevim_api_json_null
+        if substitute(a:json, '\v\"%(\\.|[^"\\])*\"|true|false|null|[+-]?\d+%(\.\d+%([Ee][+-]?\d+)?)?', '', 'g') !~# "[^,:{}[\\] \t]"
+
+            try
+                let object = eval(a:json)
+            catch
+                " malformed JSON
+                let object = ''
+            endtry
+        else
+            let object = ''
+        endif
+
+        return object
+    endfunction
+endif
+
+lockvar g:spacevim_api_json_true
+lockvar g:spacevim_api_json_false
+lockvar g:spacevim_api_json_null
+
+let s:json['json_decode'] = function('s:json_decode')
+
+function! s:json_encode(val) abort
+    if exists('*json_decode') && 0
+        return json_encode(a:val)
+    else
+        if type(a:val) == type(0)
+            return a:val
+        elseif type(a:val) == type('')
+            let json = '"' . escape(a:val, '\"') . '"'
+            let json = substitute(json, "\r", '\\r', 'g')
+            let json = substitute(json, "\n", '\\n', 'g')
+            let json = substitute(json, "\t", '\\t', 'g')
+            let json = substitute(json, '\([[:cntrl:]]\)', '\=printf("\x%02d", char2nr(submatch(1)))', 'g')
+            return iconv(json, &encoding, 'utf-8')
+        elseif type(a:val) == 2
+            let s = string(a:val)
+            if s == string(g:spacevim_api_json_null)
+                return 'null'
+            elseif s == string(g:spacevim_api_json_true)
+                return 'true'
+            elseif s == string(g:spacevim_api_json_false)
+                return 'false'
+            endif
+        elseif type(a:val) == type([])
+            if len(a:val) == 1 && a:val[0] == g:spacevim_api_json_false[0]
+                return 'false'
+            elseif len(a:val) == 1 && a:val[0] == g:spacevim_api_json_true[0]
+                return 'true'
+            elseif len(a:val) == 1 && a:val[0] == g:spacevim_api_json_null[0]
+                return 'null'
+            endif
+            return '[' . join(map(copy(a:val), 's:json_encode(v:val)'), ',') . ']'
+        elseif type(a:val) == 4
+            return '{' . join(map(keys(a:val), "s:json_encode(v:val) . ':' . s:json_encode(a:val[v:val])"), ',') . '}'
+        else
+            return string(a:val)
+        endif
+    endif
 endfunction
 
 let s:json['json_encode'] = function('s:json_encode')
 
-function! s:json_decode(json) abort
-    if empty(a:json) && type(a:json) == type('')
-        return ''
-    endif
-    " TODO
-    " support old vim version
-    return json_decode(a:json)
-endfunction
-
-let s:json['json_decode'] = function('s:json_decode')
-
-
 function! SpaceVim#api#data#json#get() abort
     return deepcopy(s:json)
 endfunction