jbe/bsw@0: --[[--
jbe/bsw@0: json_string =  -- JavaScript code representing the given datum (with quotes, if needed)
jbe/bsw@0: encode.json(
jbe/bsw@0:   obj          -- true, false, nil or a number or string
jbe/bsw@0: )
jbe/bsw@0: 
jbe@10: This function encodes any native datatype or atom in JavaScript object notation (JSON). It ensures that the returned string can be safely included in inline scripts both in HTML and XHTML (within CDATA section).
jbe@10: 
jbe@1: TODO: can't distinguish unambiguously between empty object and empty list!
jbe/bsw@0: 
jbe@223: TODO: replace with JSON library
jbe@223: 
jbe/bsw@0: --]]--
jbe/bsw@0: 
jbe@1: -- TODO: check if numeric representations are JSON compatible
jbe@1: 
jbe/bsw@0: function encode.json(obj)
jbe/bsw@0:   if obj == nil then
jbe/bsw@0:     return "null";
jbe/bsw@0:   elseif atom.has_type(obj, atom.boolean) then
jbe/bsw@0:     return tostring(obj)
jbe/bsw@0:   elseif atom.has_type(obj, atom.number) then
jbe/bsw@0:     return tostring(obj)
jbe@1:   elseif type(obj) == "table" then
jbe@1:     local parts = {}
jbe@1:     local first = true
jbe@1:     if #obj > 0 then
jbe@1:       parts[#parts+1] = "["
jbe@1:       for idx, value in ipairs(obj) do
jbe@1:         if first then
jbe@1:           first = false
jbe@1:         else
jbe@1:           parts[#parts+1] = ","
jbe@1:         end
jbe@1:         parts[#parts+1] = tostring(value)
jbe@1:       end
jbe@1:       parts[#parts+1] = "]"
jbe@1:     else
jbe@1:       parts[#parts+1] = "{"
jbe@1:       for key, value in pairs(obj) do
jbe@1:         if first then
jbe@1:           first = false
jbe@1:         else
jbe@1:           parts[#parts+1] = ","
jbe@1:         end
jbe@1:         parts[#parts+1] = encode.json(key)
jbe@1:         parts[#parts+1] = ":"
jbe@1:         parts[#parts+1] = encode.json(value)
jbe@1:       end
jbe@1:       parts[#parts+1] = "}"
jbe@1:     end
jbe@1:     return table.concat(parts)
jbe/bsw@0:   else
jbe@10:     local str = atom.dump(obj)
jbe@10:     str = string.gsub(str, ".",
jbe@10:       function (char)
jbe@10:         if char == '\r' then return '\\r'  end
jbe@10:         if char == '\n' then return '\\n'  end
jbe@10:         if char == '\\' then return '\\\\' end
jbe@10:         if char == '"'  then return '\\"'  end
jbe@10:         local byte = string.byte(char)
jbe@10:         if byte < 32 then return string.format("\\u%04x", byte) end
jbe@10:       end
jbe@10:     )
jbe@10:     str = string.gsub(str, "</", "<\\/")
jbe@10:     str = string.gsub(str, "<!%[CDATA%[", "\\u003c![CDATA[")
jbe@10:     str = string.gsub(str, "]]>", "]]\\u003e")
jbe@10:     return '"' .. str .. '"'
jbe/bsw@0:   end
jbe/bsw@0: end