lec 10

lectures/10/utils.ml

@@ -0,0 +1,42 @@
+open Angstrom
+
+let is_digit = function | '0'..'9' -> true | _ -> false
+
+let is_space = function | ' ' | '\t' -> true | _ -> false
+
+let ws = take_while is_space
+
+let ws1 = take_while1 is_space
+
+let uint_str = take_while1 is_digit
+
+let uint_num = uint_str >>| int_of_string
+
+let sign =
+  peek_char >>= function
+  | Some '+' -> advance 1 >>| fun () -> "+"
+  | Some '-' -> advance 1 >>| fun () -> "-"
+  | Some c when is_digit c -> return "+"
+  | _ -> fail "digit or sign expected"
+
+let int_str =
+  let* s = sign in
+  let* n = uint_str in
+  return (s ^ n)
+
+let int_num = int_str >>| int_of_string
+
+let dot =
+  peek_char >>= function
+  | Some '.' -> advance 1 >>| fun () -> true
+  | _ -> return false
+
+let float_str =
+  let* n = int_str in
+  let* is_dot = dot in
+  if is_dot then 
+    let* f = uint_str in return (n ^ "." ^ f)
+  else
+    return n
+
+let float_num = float_str >>| float_of_string