jbe/bsw@0: local function map_2digit_year(y2)
jbe/bsw@0:   local current_year = atom.date:get_current().year
jbe/bsw@0:   local guess2 = math.floor(current_year / 100) * 100 + tonumber(y2)
jbe/bsw@0:   local guess1 = guess2 - 100
jbe/bsw@0:   local guess3 = guess2 + 100
jbe/bsw@0:   if guess1 >= current_year - 80 and guess1 <= current_year + 10 then
jbe/bsw@0:     return guess1
jbe/bsw@0:   elseif guess2 >= current_year - 80 and guess2 <= current_year + 10 then
jbe/bsw@0:     return guess2
jbe/bsw@0:   elseif guess3 >= current_year - 80 and guess3 <= current_year + 10 then
jbe/bsw@0:     return guess3
jbe/bsw@0:   end
jbe/bsw@0: end
jbe/bsw@0: 
jbe/bsw@0: function parse.date(str, dest_type, options)
jbe/bsw@0:   if dest_type ~= atom.date then
jbe/bsw@0:     error("parse.date(...) can only return dates, but a different destination type than atom.date was given.")
jbe/bsw@0:   end
jbe/bsw@0:   local date_format = locale.get("date_format")
jbe/bsw@0:   if date_format and string.find(date_format, "Y+%-D+%-M+") then
jbe/bsw@0:     error("Date format collision with ISO standard.")
jbe/bsw@0:   end
jbe/bsw@0:   if string.match(str, "^%s*$") then
jbe/bsw@0:     return nil
jbe/bsw@0:   end
jbe/bsw@0:   -- first try ISO format
jbe/bsw@0:   local year, month, day = string.match(
jbe/bsw@0:     str, "^%s*([0-9][0-9][0-9][0-9])%-([0-9][0-9])%-([0-9][0-9])%s*$"
jbe/bsw@0:   )
jbe/bsw@0:   if year then
jbe/bsw@0:     return atom.date{
jbe/bsw@0:       year = tonumber(year),
jbe/bsw@0:       month = tonumber(month),
jbe/bsw@0:       day = tonumber(day)
jbe/bsw@0:     }
jbe/bsw@0:   end
jbe/bsw@0:   if not date_format then
jbe/bsw@0:     return atom.date.invalid
jbe/bsw@0:   end
jbe/bsw@0:   local format_parts = {}
jbe/bsw@0:   local numeric_parts = {}
jbe/bsw@0:   for part in string.gmatch(date_format, "[YMD]+") do
jbe/bsw@0:     format_parts[#format_parts+1] = part
jbe/bsw@0:   end
jbe/bsw@0:   for part in string.gmatch(str, "[0-9]+") do
jbe/bsw@0:     numeric_parts[#numeric_parts+1] = part
jbe/bsw@0:   end
jbe/bsw@0:   if #format_parts ~= #numeric_parts then
jbe/bsw@0:     return atom.date.invalid
jbe/bsw@0:   end
jbe/bsw@0:   local year, month, day
jbe/bsw@0:   local function process_part(format_part, numeric_part)
jbe/bsw@0:     if string.find(format_part, "^Y+$") then
jbe/bsw@0:       if #numeric_part == 4 then
jbe/bsw@0:         year = tonumber(numeric_part)
jbe/bsw@0:       elseif #numeric_part == 2 then
jbe/bsw@0:         year = map_2digit_year(numeric_part)
jbe/bsw@0:       else
jbe/bsw@0:         return atom.date.invalid
jbe/bsw@0:       end
jbe/bsw@0:     elseif string.find(format_part, "^M+$") then
jbe/bsw@0:       month = tonumber(numeric_part)
jbe/bsw@0:     elseif string.find(format_part, "^D+$") then
jbe/bsw@0:       day = tonumber(numeric_part)
jbe/bsw@0:     else
jbe/bsw@0:       if not #format_part == #numeric_part then
jbe/bsw@0:         return atom.date.invalid
jbe/bsw@0:       end
jbe/bsw@0:       local year_str  = ""
jbe/bsw@0:       local month_str = ""
jbe/bsw@0:       local day_str   = ""
jbe/bsw@0:       for i = 1, #format_part do
jbe/bsw@0:         local format_char = string.sub(format_part, i, i)
jbe/bsw@0:         local number_char = string.sub(numeric_part, i, i)
jbe/bsw@0:         if format_char == "Y" then
jbe/bsw@0:           year_str = year_str .. number_char
jbe/bsw@0:         elseif format_char == "M" then
jbe/bsw@0:           month_str = month_str .. number_char
jbe/bsw@0:         elseif format_char == "D" then
jbe/bsw@0:           day_str = day_str .. number_char
jbe/bsw@0:         else
jbe/bsw@0:           error("Assertion failed.")
jbe/bsw@0:         end
jbe/bsw@0:       end
jbe/bsw@0:       if #year_str == 2 then
jbe/bsw@0:         year = map_2digit_year(year_str)
jbe/bsw@0:       else
jbe/bsw@0:         year = tonumber(year_str)
jbe/bsw@0:       end
jbe/bsw@0:       month = tonumber(month_str)
jbe/bsw@0:       day = tonumber(day_str)
jbe/bsw@0:     end
jbe/bsw@0:   end
jbe/bsw@0:   for i = 1, #format_parts do
jbe/bsw@0:     process_part(format_parts[i], numeric_parts[i])
jbe/bsw@0:   end
jbe/bsw@0:   if not year or not month or not day then
jbe/bsw@0:     error("Date parser did not determine year, month and day. Maybe the 'date_format' locale is erroneous?")
jbe/bsw@0:   end
jbe/bsw@0:   return atom.date{ year = year, month = month, day = day }
jbe/bsw@0: end