Web.JSON: Add 'allow_nan' setting to encode() and decode().

Author: Milly

autoload/vital/__vital__/Web/JSON.vim

@@ -1,6 +1,16 @@
 let s:save_cpo = &cpo
 set cpo&vim
 
+let s:float_constants = {
+    \   'nan': 'NaN',
+    \   '-nan': 'NaN',
+    \   'inf': 'Infinity',
+    \   '-inf': '-Infinity',
+    \ }
+let s:float_nan = 0.0 / 0
+let s:float_inf = 1.0 / 0
+lockvar s:float_constants s:float_nan s:float_inf
+
 function! s:_true() abort
   return 1
 endfunction
@@ -51,14 +61,20 @@ endfunction
 " @vimlint(EVL102, 1, l:null)
 " @vimlint(EVL102, 1, l:true)
 " @vimlint(EVL102, 1, l:false)
+" @vimlint(EVL102, 1, l:NaN)
+" @vimlint(EVL102, 1, l:Infinity)
 function! s:decode(json, ...) abort
   let settings = extend({
         \ 'use_token': 0,
+        \ 'allow_nan': 1,
         \}, get(a:000, 0, {}))
   let json = iconv(a:json, 'utf-8', &encoding)
   let json = join(split(json, "\n"), '')
   let json = substitute(json, '\\u34;', '\\"', 'g')
   let json = substitute(json, '\\u\(\x\x\x\x\)', '\=s:string.nr2enc_char("0x".submatch(1))', 'g')
+  if settings.allow_nan
+    let [NaN,Infinity] = [s:float_nan,s:float_inf]
+  endif
   if settings.use_token
     let prefix = '__Web.JSON__'
     while stridx(json, prefix) != -1
@@ -74,10 +90,13 @@ endfunction
 " @vimlint(EVL102, 0, l:null)
 " @vimlint(EVL102, 0, l:true)
 " @vimlint(EVL102, 0, l:false)
+" @vimlint(EVL102, 0, l:NaN)
+" @vimlint(EVL102, 0, l:Infinity)
 
 function! s:encode(val, ...) abort
   let settings = extend({
         \ 'indent': 0,
+        \ 'allow_nan': 1,
         \}, get(a:000, 0, {})
         \)
   let t = type(a:val)
@@ -104,6 +123,14 @@ function! s:encode(val, ...) abort
     return s:_encode_list(a:val, settings)
   elseif t == 4
     return s:_encode_dict(a:val, settings)
+  elseif t == 5
+    let val = string(a:val)
+    if settings.allow_nan
+      let val = get(s:float_constants, val, val)
+    elseif has_key(s:float_constants, val)
+      throw 'vital: Web.JSON: Invalid float value: ' . val
+    endif
+    return val
   else
     return string(a:val)
   endif

doc/vital/Web/JSON.txt

@@ -65,6 +65,18 @@ encode({object}[, {settings}])		*Vital.Web.JSON.encode()*
 	"   "a": 0,
 	"   "b": 1
 	" }'
+<
+        'allow_nan'
+        If 'allows_nan' is 0, it will raise an exception when serializing
+        out of range float values (nan, inf, -inf).
+        Otherwise 'NaN', 'Infinity' or '-Infinity' are used to represent these.
+	The default value is 1.
+	Note that NaN and Infinity are not the JSON standard.
+>
+	echo s:JSON.encode([0.0/0, 1.0/0, -1.0/0])
+	" => [NaN,Infinity,-Infinity]
+	echo s:JSON.encode([0.0/0], {'allow_nan': 0})
+        " => vital: Web.JSON: Invalid float value: nan
 <
 decode({json}[, {settings}])		*Vital.Web.JSON.decode()*
 	Decode a JSON string into an object that vim can treat.
@@ -81,6 +93,17 @@ decode({json}[, {settings}])		*Vital.Web.JSON.decode()*
 	echo s:JSON.decode('[true, false, null]', {'use_token': 1})
 	" => [s:JSON.true, s:JSON.false, s:JSON.null]
 <
+        'allow_nan'
+        If 'allows_nan' is 0, it will raise an exception when deserializing
+        float constants ('NaN', 'Infinity', '-Infinity').
+        Otherwise nan, inf or -inf are used to represent these.
+	The default value is 1.
+>
+	echo s:JSON.decode('[NaN, Infinity, -Infinity]')
+	" => [nan, inf, -inf]
+	echo s:JSON.decode('[NaN]', {'allow_nan': 0})
+	" => E121: Undefined variable: NaN
+<
 
 =============================================================================
 vim:tw=78:fo=tcq2mM:ts=8:ft=help:norl

test/Web/JSON.vimspec

@@ -71,6 +71,17 @@ Describe Web.JSON
       Assert Equals(JSON.decode('false', s), JSON.false)
       Assert Equals(JSON.decode('null', s), JSON.null)
     End
+
+    It decodes special floats (NaN/Infinity/-Infinity)
+      Assert Equals(string(JSON.decode('NaN')), 'nan')
+      Assert Equals(string(JSON.decode('Infinity')), 'inf')
+      Assert Equals(string(JSON.decode('-Infinity')), '-inf')
+
+      let s = { 'allow_nan': 0 }
+      Throws /^Vim(\w\+):E121:/ JSON.decode('NaN', s)
+      Throws /^Vim(\w\+):E121:/ JSON.decode('Infinity', s)
+      Throws /^Vim(\w\+):E121:/ JSON.decode('-Infinity', s)
+    End
   End
 
   Describe .encode()
@@ -213,5 +224,16 @@ Describe Web.JSON
       Assert Equals(JSON.encode(JSON.false), 'false')
       Assert Equals(JSON.encode(JSON.null), 'null')
     End
+
+    It encodes special floats (NaN/Infinity/-Infinity)
+      Assert Equals(JSON.encode(0.0/0), 'NaN')
+      Assert Equals(JSON.encode(1.0/0), 'Infinity')
+      Assert Equals(JSON.encode(-1.0/0), '-Infinity')
+
+      let s = { 'allow_nan': 0 }
+      Throws /^vital: Web.JSON:/ JSON.encode(0.0/0, s)
+      Throws /^vital: Web.JSON:/ JSON.encode(1.0/0, s)
+      Throws /^vital: Web.JSON:/ JSON.encode(-1.0/0, s)
+    End
   End
 End