# str.ludic — the string handling a compiler lives on: comparison, copying,
# slicing out substrings, and integer<->text. All over raw NUL-terminated
# byte buffers reached with peek8/poke8.

# a fresh NUL-terminated copy of src[start .. start+n]

function char_is_digit(c: int) -> bool { return c >= 48 and c <= 57 }
function char_is_alpha(c: int) -> bool {
  if c >= 65 and c <= 90 { return true }
  if c >= 97 and c <= 122 { return true }
  return c == 95
}
function char_is_alnum(c: int) -> bool { return char_is_alpha(c) or char_is_digit(c) }

# integer -> fresh decimal string
function itoa(v: int) -> pointer {
  if v == 0 { let z = bytes(2); z[0] = 48; z[1] = 0; return z }
  var neg = false
  var x = v
  if x < 0 { neg = true;  x = 0 - x }
  let tmp = bytes(16)
  var n = 0
  while x > 0 { tmp[n] = 48 + x % 10;  x = x / 10;  n = n + 1 }
  var total = n
  if neg { total = total + 1 }
  let out = bytes(total + 1)
  var k = 0
  if neg { out[0] = 45;  k = 1 }
  var i = 0
  while i < n { out[k + i] = tmp[n - 1 - i];  i = i + 1 }
  out[total] = 0
  return out
}