Web.JSON: Add 'ensure_ascii' setting to encode().

Author: Milly

autoload/vital/__vital__/Web/JSON.vim

@@ -143,9 +143,25 @@ function! s:encode(val, ...) abort
         \ 'indent': 0,
         \ 'allow_nan': 1,
         \ 'from_encoding': &encoding,
+        \ 'ensure_ascii': 0,
         \}, get(a:000, 0, {})
         \)
-  return s:_encode(a:val, settings)
+  let json = s:_encode(a:val, settings)
+  if settings.ensure_ascii
+    let json = substitute(json, '[\U0000007f-\U0010ffff]',
+        \ {m -> s:_escape_unicode_chars(m[0])}, 'g')
+  endif
+  return json
+endfunction
+
+function! s:_escape_unicode_chars(char) abort
+  let n = char2nr(a:char)
+  if n < 0x10000
+    return printf('\u%04x', n)
+  else
+    let n -= 0x10000
+    return printf('\u%04x%\u%04x', 0xd800 + n / 0x400, 0xdc00 + and(0x3ff, n))
+  endif
 endfunction
 
 function! s:_encode(val, settings) abort

doc/vital/Web/JSON.txt

@@ -77,6 +77,18 @@ encode({object}[, {settings}])		*Vital.Web.JSON.encode()*
 	" => [NaN,Infinity,-Infinity]
 	echo s:JSON.encode([0.0/0], {'allow_nan': 0})
         " => vital: Web.JSON: Invalid float value: nan
+<
+        'ensure_ascii'
+        If 'ensure_ascii' is 0, all characters without control-chars
+        (0x01-0x1f) will be output as-is.
+        Otherwise the output is guaranteed to have all incoming non-ASCII
+        characters escaped.
+	The default value is 0.
+>
+	echo s:JSON.encode(["foo", "bár", "\n"])
+	" => '["foo","bár","\n"]'
+	echo s:JSON.encode(["foo", "bár", "\n"], {'ensure_ascii': 1})
+	" => '["foo","b\u00e1r","\n"]'
 <
 decode({json}[, {settings}])		*Vital.Web.JSON.decode()*
 	Decode a JSON string into an object that vim can treat.

test/Web/JSON.vimspec

@@ -157,6 +157,14 @@ Describe Web.JSON
       Assert Equals(JSON.encode(str_sjis, s), '"sあc漢g"')
     End
 
+    It encodes strings with {settings.ensure_ascii} = true
+      let s = { 'ensure_ascii': v:true }
+      " multibyte
+      Assert Equals(JSON.encode("s¢cĴgё", s), '"s\u00a2c\u0134g\u0451"')
+      " UTF-16 surrogate pair
+      Assert Equals(JSON.encode("su\xf0\x9f\x8d\xa3shi", s), '"su\ud83c\udf63shi"')
+    End
+
     It encodes lists
       Assert Equals(JSON.encode([]), '[]')
       Assert Equals(JSON.encode([0, 1, 2]), '[0,1,2]')