I prefer all my calendar items to be available in one text file, which is easily handled with Vim. You can map a key to open your calendar file when using Vim.

The function Calendar() below generates the following output (extract):

----- Week 1 -----

Mo 30

Tu 31

==================== 2003 ========================================

==================== Q 1 ========================================

-------------------- Jan 2003 ----------------------------------------

We 01

Th 02

Fr 03

Sa 04

Su 05

----- Week 2 -----

Mo 06

Tu 07

function! Calendar(year, month, day, weekday, week, daycount)
  " output daycount calendar days starting from given date
  " into new buffer
  new
  set buftype=nofile bufhidden=hide noswapfile
  let year = a:year
  let month = a:month
  let day = a:day
  let wd = a:weekday
  let week = a:week
  let index = 0
  let date = ''
  let diy = 777 " day in year, wrong before next year
  while (index < a:daycount) " no of days to output
    let diy = diy + 1
    if (wd > 7)
      let wd = 1
      let week = week + 1
      if (week >= 53)
        if (week >= 54)
          let week = 1
        elseif (day >= 28 || day <= 3)
          let week = 1
        endif
      endif
    endif
    if (wd == 1) " day name
      let dn = "Mo"
    elseif (wd == 2)
      let dn = "Tu"
    elseif (wd == 3)
      let dn = "We"
    elseif (wd == 4)
      let dn = "Th"
    elseif (wd == 5)
      let dn = "Fr"
    elseif (wd == 6)
      let dn = "Sa"
    elseif (wd == 7)
      let dn = "Su"
    else
      let dn = "** ERROR: Unknown day name ** "
    endif
    if ((day > 31) || (month == 2 && (day > 29 || day > 28 && year % 4))
          \ || (month == 4 && day > 30) || (month == 6 && day > 30)
          \ || (month == 9 && day > 30) || (month == 11 && day > 30))
      let day = 1
      let month = month + 1
      if (month > 12)
        let month = 1
        let diy = 1
        let year = year + 1
        if (wd <= 3)
          let week = 1
        endif
      endif
      if (month == 1)
        let yline = "===================="
        call append(line("$"), yline . "    " . year . "    " . yline . yline )
        call append(line("$"), yline . "    Q 1     " . yline . yline )
        let monthn = "Jan" " month name
      elseif (month == 2)
        let monthn = "Feb"
      elseif (month == 3)
        let monthn = "Mar"
      elseif (month == 4)
        let monthn = "Apr"
        call append(line("$"), yline . "    Q 2     " . yline . yline )
      elseif (month == 5)
        let monthn = "May"
      elseif (month == 6)
        let monthn = "Jun"
      elseif (month == 7)
        let monthn = "Jul"
        call append(line("$"), yline . "    Q 3     " . yline . yline )
      elseif (month == 8)
        let monthn = "Aug"
      elseif (month == 9)
        let monthn = "Sep"
      elseif (month == 10)
        let monthn = "Oct"
        call append(line("$"), yline . "    Q 4     " . yline . yline )
      elseif (month == 11)
        let monthn = "Nov"
      elseif (month == 12)
        let monthn = "Dec"
      else
        let monthn = "** ERROR: Unknown month ** "
      endif
      let mline = "--------------------"
      call append(line("$"), mline . "  " . monthn . " " . year . "  " . mline . mline )
    endif
    if (wd == 1)
      "call append(line("$"), "----- Week " . week . " (" . diy . "..) -----")
      call append(line("$"), "----- Week " . week . " -----")
    endif
    let date = dn . " " " begin with name of day of week
    if (month < 10)
      let date = date . year . '-0' . month
    else
      let date = date . year . '-' . month
    endif
    " skip month, year
    let date = dn . " " " not interested in year, month
    if (day < 10)
      let date = date . '0' . day
    else
      let date = date . day
    endif
    " let date = date . " (" . diy . ")"
    call append(line("$"), date)
    let index = index + 1
    let day = day + 1
    let wd = wd + 1
  endwhile
endfunction

map <S-F7> :call Calendar(2002, 12, 30, 1, 1, 1000)<CR><CR>
" Dec 30, 2003 is Monday (day 1 in week), week 1 in 2003

Put the above code in your vimrc and call the function, here it is shown with entries for 1000 days. Of course, if you do not use correct arguments matching an existing day, all output will be mess.

CommentsEdit

The computation of the leap years is a little careless; the code will regard year 2100 as a leapyear, which it is not.

Maybe it is better to substitute the code part

if ((day > 31) || (month == 2 && (day > 29 || day > 28 && year % 4))
\ || (month == 4 && day > 30) || (month == 6 && day > 30)
\ || (month == 9 && day > 30) || (month == 11 && day > 30))

with this

if ((day > 31) || (day > 30 &&
\ (month == 4 || month == 6 || month == 9 || month == 11))
\ || (month == 2 &&
\ (day > 29 || (day > 28 && (year%4 || (!(year%100) && year%400))))))

but you have more than 90 years time to do this.

If you want to go to the current day with one keystroke, you can do the following.

Assuming the calendar is contained in a file pointed to by the global variable cal and the formatting of month and days is as generated, this should work by just pressing Shift-F4:

function! Today()
  let calfile = g:cal
  if (bufnr(calfile) > 0)
  exe ":bu " . bufnr(calfile)
  else
  exe "edit " . calfile
  endif
  let a = search("- " . strftime("%b %Y") . " -", "w")
  let a = search("^.. " . strftime("%d"), "w")
endfunction
map <S-F4> :call Today()<CR>