url unescape for vim

gistfile1.vim

function GetCode(pos,str)
  let s:pos = a:pos
  let s:n_code = str2nr(strpart(a:str,s:pos,2),16)
  let s:pos = s:pos + 2
  "in a certain sns
  "if s:n_code == 37
  "  let s:n_code = str2nr(strpart(s:line,s:pos,2),16)
  "  let s:pos = s:pos + 2
  "endif
  return [s:pos,s:n_code]
endfunction

function Unescape()
  let s:line = getline(".")
  let s:out = ""
  let s:pos = 0
  while s:pos < strlen(s:line)
    let s:moji =strpart(s:line,s:pos,1)
    let s:pos = s:pos + 1
    if s:moji == "%"
      let s:rc = GetCode(s:pos,s:line)
      let s:pos = s:rc[0]
      let s:f_code = s:rc[1]
      if s:f_code >= 0xe0
        "disregard %
        let s:pos = s:pos + 1
        let s:rc = GetCode(s:pos,s:line)
        let s:pos = s:rc[0]
        let s:s_code = s:rc[1]
        "disregard %
        let s:pos = s:pos + 1
        let s:rc = GetCode(s:pos,s:line)
        let s:pos = s:rc[0]
        let s:t_code = s:rc[1]
        let s:out = s:out . nr2char(float2nr((s:f_code - 0xe0) * pow(2,12) + (s:s_code - 0x80) * pow(2,6) + (s:t_code - 0x80)))
      else
        if s:n_code >= 0xc0
          "disregard %
          let s:pos = s:pos + 1
          let s:rc = GetCode(s:pos,s:line)
          let s:pos = s:rc[0]
          let s:s_code = s:rc[1]
          let s:out = s:out . nr2char(float2nr((s:f_code - 0xc0) * pow(2,6) + (s:s_code - 0x80)))
        else
          let s:out = s:out . nr2char(s:n_code)
        endif
      endif
    else
      let s:out = s:out . s:moji
    endif
  endwhile
  echo s:out
endfunction