AppleScripts to increment/decrement date values in TaskPaper. Contains improvements made on top of http://www.hogbaysoftware.com/wiki/IncrementDateValue and http://www.hogbaysoftware.com/wiki/DecrementDateValue - Works well with http://gist.github.com/648

TaskPaper-BetterDecrementDateValue.scpt

on getTextFromDate(vDate)
	set dText to ((year of vDate) as text) & "-"
	set dayText to (month of vDate as number) as text
	if length of dayText is 1 then
		set dayText to "0" & dayText
	end if
	set dText to dText & dayText & "-"
	set dayText to (day of vDate as number) as text
	if length of dayText is 1 then
		set dayText to "0" & dayText
	end if
	return dText & dayText
end getTextFromDate

on parse_date(s)
	return date ((text 9 thru 10 of s) & "/" & (text 6 thru 7 of s) & "/" & (text 1 thru 4 of s))
end parse_date

on valid_date(s)
	if s = missing value then return false
	try
		parse_date(s)
	on error
		return false
	end try
	return true
end valid_date


on run
	tell application "TaskPaper"
		tell selected entry
			if (exists tag named "due") and ¬
				not my valid_date(value of tag named "due") then
				delete tag named "due"
			end if
			if (exists tag named "due") then
				set _date to my parse_date(value of tag named "due")
				set _date to _date - (1 * days)
				set value of tag named "due" to my getTextFromDate(_date)
			else
				make tag with properties {name:"due", value:my getTextFromDate(current date)}
			end if
		end tell
	end tell
end run

TaskPaper-BetterIncrementDateValue.scpt

on getTextFromDate(vDate)
	set dText to ((year of vDate) as text) & "-"
	set dayText to (month of vDate as number) as text
	if length of dayText is 1 then
		set dayText to "0" & dayText
	end if
	set dText to dText & dayText & "-"
	set dayText to (day of vDate as number) as text
	if length of dayText is 1 then
		set dayText to "0" & dayText
	end if
	return dText & dayText
end getTextFromDate

on parse_date(s)
	return date ((text 9 thru 10 of s) & "/" & (text 6 thru 7 of s) & "/" & (text 1 thru 4 of s))
end parse_date

on valid_date(s)
	if s = missing value then return false
	try
		parse_date(s)
	on error
		return false
	end try
	return true
end valid_date


on run
	tell application "TaskPaper"
		tell selected entry
			if (exists tag named "due") and ¬
				not my valid_date(value of tag named "due") then
				delete tag named "due"
			end if
			if (exists tag named "due") then
				set _date to my parse_date(value of tag named "due")
				set _date to _date + (1 * days)
				set value of tag named "due" to my getTextFromDate(_date)
			else
				make tag with properties {name:"due", value:my getTextFromDate(current date)}
			end if
		end tell
	end tell
end run