--- util-jsn.lua.orig	2013-07-08 00:09:21.834400224 +0200
+++ util-jsn.lua	2013-07-08 00:54:25.889668771 +0200
@@ -15,7 +15,7 @@
 -- Reminder for me: check usage in framework and extend when needed. Also document
 -- it in the cld lib documentation.
 
-local P, V, R, S, C, Cc, Cs, Ct, Cf, Cg = lpeg.P, lpeg.V, lpeg.R, lpeg.S, lpeg.C, lpeg.Cc, lpeg.Cs, lpeg.Ct, lpeg.Cf, lpeg.Cg
+local P, V, R, S, C, Cc, Cs, Ct, Cf, Cg, Cp = lpeg.P, lpeg.V, lpeg.R, lpeg.S, lpeg.C, lpeg.Cc, lpeg.Cs, lpeg.Ct, lpeg.Cf, lpeg.Cg, lpeg.Cp
 local lpegmatch = lpeg.match
 local format = string.format
 local utfchar = utf.char
@@ -42,7 +42,15 @@
 local whitespace = lpeg.patterns.whitespace
 local optionalws = whitespace^0
 
-local escape     = C(P("\\u") / "0x" * S("09","AF","af")) / function(s) return utfchar(tonumber(s)) end
+local escape_a   = C(P("\\u") / "0x" * S("09","AF","af")) / function(s) return utfchar(tonumber(s)) end
+local escape_b   = P([[\]]) / "" * S([["\/]]) --> represent themselves
+local escape_c   = P([[\b]]) / "\010"         --> backspace
+                 + P([[\f]]) / "\014"         --> form feed
+                 + P([[\n]]) / "\n"
+                 + P([[\r]]) / "\r"
+                 + P([[\t]]) / "\t"
+local invalid    = P([[\]]) / "" * (Cp() * P(1) / function (pos, chr) --[[ bug_user_about_invalid_escape (chr, pos) ]] return "" end)
+local escape     = escape_a + escape_b + escape_c + invalid
 local jstring    = dquote * Cs((escape + (1-dquote))^0) * dquote
 local jtrue      = P("true")  * Cc(true)
 local jfalse     = P("false") * Cc(false)