# line.ludic - a request: one line of stdin, cut into words. A word is a JSON value (a string, an
# object or a list, read whole) or a run of anything but spaces (a name, a number)
# the next line without its end (a \r before it is dropped too), or null at the end of the input
@alloc_ok("a request read: the studio's input, never a frame")
function pv_read_line(b: PvOut) -> string {
  b.n = 0
  var c = read_char()
  if c < 0 { return null }
  while c >= 0 and c != 10 {
    if c != 13 { pv_byte(b, c) }
    c = read_char()
  }
  var s: pointer = null
  unsafe {
    s = bytes(b.n + 1)
    for i in 0 .. b.n { s[i] = b.p[i] }
    s[b.n] = 0
  }
  return s
}
@alloc_ok("a request's words: one list kept, each word a slice of the line")
function pv_words(s: string, out: []string) -> void {
  List.clear(out)
  let n = len(s)
  var i = 0
  while i < n {
    while i < n and (s[i] == 32 or s[i] == 9) { i += 1 }
    if i >= n { break }
    var j = i
    let c = s[i]
    if c == 34 or c == 123 or c == 91 { j = pv_json_end(s, i) } else {
      while j < n and s[j] != 32 and s[j] != 9 { j += 1 }
    }
    push(out, s[i..j])
    i = j
  }
}
# where the JSON value starting at i ends: its closing quote or bracket, strings and escapes skipped
function pv_json_end(s: string, i: int) -> int {
  let n = len(s)
  var depth = 0
  var ins = false
  var j = i
  while j < n {
    let c = s[j]
    if ins {
      if c == 92 { j += 1 } else if c == 34 {
        ins = false
        if depth == 0 { return j + 1 }
      }
    } else if c == 34 { ins = true } else if c == 123 or c == 91 { depth += 1 } else if c == 125 or c == 93 {
      depth -= 1
      if depth == 0 { return j + 1 }
    }
    j += 1
  }
  return n
}
# a word as text: a JSON string unquoted, anything else as it stands
@alloc_ok("a request's word read")
function pv_text(w: string) -> string {
  if len(w) > 0 and w[0] == 34 { return Value.as_str(Json.parse(w)) }
  return w
}
# a word as a number (0 when it is not one)
@alloc_ok("a request's word read")
function pv_float(w: string) -> float {
  if len(w) == 0 { return 0.0 }
  let c = w[0]
  if not ((c >= 48 and c <= 57) or c == 45 or c == 46) { return 0.0 }
  return Value.as_float(Json.parse(w))
}
function pv_int_of(w: string) -> int { return int(pv_float(w)) }
# a word as a JSON value (a bare word is a string)
@alloc_ok("a request's word read")
function pv_val(w: string) -> Val {
  if len(w) == 0 { return Value.null() }
  let c = w[0]
  if c == 34 or c == 123 or c == 91 or (c >= 48 and c <= 57) or c == 45 { return Json.parse(w) }
  if w == "true" { return Value.bool(1) }
  if w == "false" { return Value.bool(0) }
  if w == "null" { return Value.null() }
  return Value.str(w)
}
# whether s holds p at `at`, compared where it stands
function pv_sat(s: string, at: int, p: string) -> bool {
  if at + len(p) > len(s) { return false }
  for i in 0 .. len(p) {
    if s[at + i] != p[i] { return false }
  }
  return true
}