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@verb #51:"parse_insert" this none this rxdo #60
@program #51:"parse_insert" this none this
"parse_ins(who,string)  interprets string as an insertion point, i.e., a position between lines and returns the number of the following line or 0 if bogus."
if (!(corrupt = this:ok(who = args[1])))
  return corrupt
endif
{who, string} = args
if (!string)
  string = "."
endif
last = length(this.texts[who]) + 1
ins = this.inserting[who]
if (i = index("-+", string[1]))
  rest = string[2..length(string)]
  return (n = toint(rest)) || rest == "0" ? {ins - n, ins + n}[i] | E_INVARG
else
  if (!(j = index(string, "^") || index(string, "_")))
    offset = 0
  else
    offset = j == 1 || toint(string[1..j - 1])
    if (!offset)
      return E_INVARG
    elseif (string[j] == "^")
      offset = -offset
    endif
  endif
  rest = string[j + 1..length(string)]
  if (i = rest in {".", "$"})
    return offset + {ins, last}[i]
  elseif (!(n = toint(rest)))
    return E_INVARG
  else
    return offset + (j && string[j] == "^") + n
  endif
endif
"Last modified by Dax (#789) on Tue May  3 14:09:30 2005 MDT."
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