property NSArray : a reference to current application’s NSArray
property NSString : a reference to current application’s NSString
property NSLocale : a reference to current application’s NSLocale
property NSDictionary : a reference to current application’s NSDictionary
property NSCountedSet : a reference to current application’s NSCountedSet
property NSMutableArray : a reference to current application’s NSMutableArray
property NSSortDescriptor : a reference to current application’s NSSortDescriptor
property NSDateFormatter : a reference to current application’s NSDateFormatter

set tmpArray to NSMutableArray’s new()

–変換元（テキストから自動取得できるとよかったのに）
set dFfromStr to text returned of (display dialog "Input Date Format:(年=yyyy, 月=MM, 日=dd)" default answer "MM月 dd, yyyy")

–変換先
set dOutFormStr to "yyyy/MM/dd"

tell application "CotEditor"
　　tell front document
　　　　set aRes to contents of it
　　end tell
　　
　　set aList to paragraphs of aRes
end tell

repeat with i in aList
　　set j to contents of i
　　set theDate to dateFromStringWithDateFormat(j, dFfromStr) of me
　　if theDate is not equal to missing value then
　　　　set newDateStr to convDateObjToStrWithFormat(theDate, dOutFormStr) of me
　　　　(tmpArray’s addObject:newDateStr)
　　else
　　　　(tmpArray’s addObject:j)
　　end if
end repeat

–NSArrayを指定デリミタをはさんでテキスト化
set tRes to tmpArray’s componentsJoinedByString:(return)
set ttRes to tRes as string

tell application "CotEditor"
　　tell front document
　　　　set (contents of it) to ttRes
　　end tell
end tell

–日付文字列からdate objectを作成する
on dateFromStringWithDateFormat(dateString as string, dateFormat as string)
　　set dStr to NSString’s stringWithString:dateString
　　set dateFormatStr to NSString’s stringWithString:dateFormat
　　
　　set aDateFormatter to NSDateFormatter’s alloc()’s init()
　　aDateFormatter’s setDateFormat:dateFormatStr
　　aDateFormatter’s setLocale:(NSLocale’s alloc()’s initWithLocaleIdentifier:"en_US_POSIX")
　　
　　set aDestDate to (aDateFormatter’s dateFromString:dStr)
　　
　　return aDestDate as list of string or string
end dateFromStringWithDateFormat

–date objectから指定の日付文字列を作成する
on convDateObjToStrWithFormat(aDateO as date, aFormatStr as string)
　　set aDF to NSDateFormatter’s alloc()’s init()
　　
　　set aLoc to NSLocale’s currentLocale()
　　set aLocStr to (aLoc’s localeIdentifier()) as string
　　
　　aDF’s setLocale:(NSLocale’s alloc()’s initWithLocaleIdentifier:aLocStr)
　　aDF’s setDateFormat:aFormatStr
　　set dRes to (aDF’s stringFromDate:aDateO) as string
　　return dRes
end convDateObjToStrWithFormat