fn initialize-word _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  allocate data-ah
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  initialize-gap-buffer data
  # TODO: sometimes initialize box-data rather than scalar-data
}

## some helpers for creating words. mostly for tests

fn initialize-word-with _self: (addr word), s: (addr array byte) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  allocate data-ah
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  initialize-gap-buffer-with data, s
}

fn allocate-word-with _out: (addr handle word), s: (addr array byte) {
  var out/eax: (addr handle word) <- copy _out
  allocate out
  var out-addr/eax: (addr word) <- lookup *out
  initialize-word-with out-addr, s
}

# just for tests for now
# TODO: handle existing next
# one implication of handles: append must take a handle
fn append-word-with self-h: (handle word), s: (addr array byte) {
  var self/eax: (addr word) <- lookup self-h
  var next-ah/eax: (addr handle word) <- get self, next
  allocate-word-with next-ah, s
  var next/eax: (addr word) <- lookup *next-ah
  var prev-ah/eax: (addr handle word) <- get next, prev
  copy-handle self-h, prev-ah
}

# just for tests for now
# TODO: handle existing prev
fn prepend-word-with self-h: (handle word), s: (addr array byte) {
  var self/eax: (addr word) <- lookup self-h
  var prev-ah/eax: (addr handle word) <- get self, prev
  allocate-word-with prev-ah, s
  var prev/eax: (addr word) <- lookup *prev-ah
  var next-ah/eax: (addr handle word) <- get prev, next
  copy-handle self-h, next-ah
}

## real primitives

fn word-equal? _self: (addr word), s: (addr array byte) -> result/eax: boolean {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-buffer-equal? data, s
}

fn word-length _self: (addr word) -> result/eax: int {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-buffer-length data
}

fn first-word _self: (addr word) -> result/eax: (addr word) {
  var self/esi: (addr word) <- copy _self
  var out/edi: (addr word) <- copy self
  var prev/esi: (addr handle word) <- get self, prev
  {
    var curr/eax: (addr word) <- lookup *prev
    compare curr, 0
    break-if-=
    out <- copy curr
    prev <- get curr, prev
    loop
  }
  result <- copy out
}

fn final-word _self: (addr word) -> result/eax: (addr word) {
  var self/esi: (addr word) <- copy _self
  var out/edi: (addr word) <- copy self
  var next/esi: (addr handle word) <- get self, next
  {
    var curr/eax: (addr word) <- lookup *next
    compare curr, 0
    break-if-=
    out <- copy curr
    next <- get curr, next
    loop
  }
  result <- copy out
}

fn first-grapheme _self: (addr word) -> result/eax: grapheme {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- first-grapheme-in-gap-buffer data
}

fn add-grapheme-to-word _self: (addr word), c: grapheme {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  add-grapheme-at-gap data, c
}

fn cursor-at-start? _self: (addr word) -> result/eax: boolean {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-at-start? data
}

fn cursor-at-end? _self: (addr word) -> result/eax: boolean {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-at-end? data
}

fn cursor-left _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  var dummy/eax: grapheme <- gap-left data
}

fn cursor-right _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  var dummy/eax: grapheme <- gap-right data
}

fn cursor-to-start _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  gap-to-start data
}

fn cursor-to-end _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  gap-to-end data
}

fn cursor-index _self: (addr word) -> result/eax: int {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-index data
}

fn delete-before-cursor _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  delete-before-gap data
}

fn delete-next _self: (addr word) {
$delete-next:body: {
  var self/esi: (addr word) <- copy _self
  var next-ah/edi: (addr handle word) <- get self, next
  var next/eax: (addr word) <- lookup *next-ah
  compare next, 0
  break-if-= $delete-next:body
  var next-next-ah/ecx: (addr handle word) <- get next, next
  var self-ah/esi: (addr handle word) <- get next, prev
  copy-object next-next-ah, next-ah
  var new-next/eax: (addr word) <- lookup *next-next-ah
  compare new-next, 0
  break-if-= $delete-next:body
  var dest/eax: (addr handle word) <- get new-next, prev
  copy-object self-ah, dest
}
}

fn print-word screen: (addr screen), _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  render-gap-buffer screen, data
}

# one implication of handles: append must take a handle
fn append-word _self-ah: (addr handle word) {
  var self-ah/esi: (addr handle word) <- copy _self-ah
  var _self/eax: (addr word) <- lookup *self-ah
  var self/ebx: (addr word) <- copy _self
  # allocate new handle
  var new: (handle word)
  var new-ah/ecx: (addr handle word) <- address new
  allocate new-ah
  var new-addr/eax: (addr word) <- lookup new
  initialize-word new-addr
  # new->next = self->next
  var src/esi: (addr handle word) <- get self, next
  var dest/edi: (addr handle word) <- get new-addr, next
  copy-object src, dest
  # new->next->prev = new
  {
    var next-addr/eax: (addr word) <- lookup *src
    compare next-addr, 0
    break-if-=
    dest <- get next-addr, prev
    copy-object new-ah, dest
  }
  # new->prev = self
  dest <- get new-addr, prev
  copy-object _self-ah, dest
  # self->next = new
  dest <- get self, next
  copy-object new-ah, dest
}

fn emit-word _self: (addr word), out: (addr stream byte) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  emit-gap-buffer data, out
}

fn word-to-string _self: (addr word), out: (addr handle array byte) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  gap-buffer-to-string data, out
}