String expression parsing

[sky_khan]

I've used your problem for trying [npeg](https://github.com/zevv/npeg) out . I 
guess I have too much time :)

Disclaimer: This is my first try using Npeg. Use at your own risk

Here you're:
    
    
    import npeg, strutils, tables
    
    type Dict = Table[string, string]
    
    let parser = peg("pad", d: Dict):
      pad <- ?padstr * sep * x1 * sep * y1 * sep * x2 * sep * y2 * sep * 
?radius * sep * ?dx * sep * ?dy * sep * ?n * sep * ?number * sep * ?name
      padstr <- >*Alnum:
        d["pad"] = $1
      sep <- *' ' * ?{',',';'} * *' '
      integer <- +Digit
      real <- +Digit * '.' * +Digit
      numeric <- real | integer
      x1 <- >numeric:
          d["x1"] = $1
      y1 <- >numeric:
          d["y1"] = $1
      x2 <- >(?'+' * numeric ):
          d["x2"] = $1
      y2 <- >(?'+' * numeric):
          d["y2"] = $1
      radius <- >numeric:
          d["radius"] = $1
      dx <- >numeric:
          d["dx"] = $1
      dy <- >numeric:
          d["dy"] = $1
      n <- >numeric:
          d["n"] = $1
      number <- >*Alnum:
          d["number"] = $1
      name <- >*Alnum:
          d["name"] = $1
    
    var data: Table[string, string]
    data["pad"] = "pad"
    data["radius"] = "0.0"
    data["dx"] = "0.0"
    data["dy"] = "0.0"
    
    doAssert parser.match("Pad 100, 100 120.5,140.5 7.5 100 0 8 0 PAD", data).ok
    echo data
    
    
    Run