1 files changed, 140 insertions, 2 deletions
diff --git a/lua/clever_f/testing/memory_host.lua b/lua/clever_f/testing/memory_host.lua
index 57af1f1..8b473ad 100644
--- a/lua/clever_f/testing/memory_host.lua
+++ b/lua/clever_f/testing/memory_host.lua
@@ -1,5 +1,6 @@
 local capabilities = require("clever_f.capabilities")
 local domain = require("clever_f.domain")
+local text_topology = require("clever_f.text_topology")
 
 local M = {}
 local MemoryHost = {}
@@ -383,11 +384,148 @@ function MemoryHost:_emit_movement_event(previous)
   end
 end
 
-function MemoryHost:apply_cursor(position)
+local function motion_descriptor(motion)
+  if domain.Descriptor.is(motion) then
+    return motion
+  end
+  if type(motion) == "table" and motion.descriptor ~= nil then
+    return domain.Descriptor.from_string(motion.descriptor)
+  end
+  return nil
+end
+
+local function character_boundary(view, position)
+  if view:line_is_empty(position.line) then
+    return 1
+  end
+  return view:character_index_for_position(position)
+end
+
+local function character_lines(snapshot)
+  local result = {}
+  for line_number, line in ipairs(snapshot:lines()) do
+    result[line_number] = text_topology.split_editor_characters(line)
+  end
+  return result
+end
+
+local function joined_range(characters, first, last)
+  local result = {}
+  for index = first, last do
+    result[#result + 1] = characters[index]
+  end
+  return table.concat(result)
+end
+
+local function delete_character_range(
+  snapshot,
+  start_line,
+  start_index,
+  finish_line,
+  finish_index
+)
+  local source = character_lines(snapshot)
+  local lines = snapshot:lines()
+  local result = {}
+
+  for line_number = 1, start_line - 1 do
+    result[#result + 1] = lines[line_number]
+  end
+
+  local prefix = joined_range(source[start_line], 1, start_index - 1)
+  if start_line == finish_line then
+    result[#result + 1] = prefix
+      .. joined_range(
+        source[start_line],
+        finish_index,
+        #source[start_line]
+      )
+  else
+    result[#result + 1] = prefix
+      .. joined_range(
+        source[finish_line],
+        finish_index,
+        #source[finish_line]
+      )
+  end
+
+  for line_number = finish_line + 1, #lines do
+    result[#result + 1] = lines[line_number]
+  end
+  return domain.TextSnapshot.new(result)
+end
+
+local function normalized_cursor(snapshot, encoding, position)
+  local line_number = math.min(position.line, snapshot.line_count)
+  local view = text_topology.new(snapshot, encoding)
+  return view:normalize_endpoint(line_number, position.byte_column)
+end
+
+function MemoryHost:_apply_pending_delete(origin, destination, descriptor)
+  if self._pending_operator ~= "delete" and self._pending_operator ~= "d" then
+    return false
+  end
+
+  local view = text_topology.new(self._text, self._encoding)
+  local origin_index = character_boundary(view, origin)
+  local destination_index = character_boundary(view, destination)
+  local start_line
+  local start_index
+  local finish_line
+  local finish_index
+  local final_cursor
+
+  if descriptor.direction == domain.Direction.FORWARD then
+    start_line = origin.line
+    start_index = origin_index
+    finish_line = destination.line
+    finish_index = destination_index + (self._operator_inclusive and 1 or 0)
+    final_cursor = origin
+  elseif descriptor.family == domain.Family.FIND then
+    start_line = destination.line
+    start_index = destination_index + 1
+    finish_line = origin.line
+    finish_index = origin_index + 1
+    final_cursor = destination
+  else
+    start_line = destination.line
+    start_index = destination_index
+    finish_line = origin.line
+    finish_index = origin_index
+    final_cursor = view:predecessor(destination) or destination
+  end
+
+  self._text = delete_character_range(
+    self._text,
+    start_line,
+    start_index,
+    finish_line,
+    finish_index
+  )
+  self._cursor = normalized_cursor(self._text, self._encoding, final_cursor)
+  self:_record("apply_operator", {
+    operator = self._pending_operator,
+    descriptor = descriptor.value,
+    origin = origin,
+    endpoint = destination,
+    position = self._cursor,
+  })
+  return true
+end
+
+function MemoryHost:apply_cursor(position, motion)
   position = domain.Position.coerce(position)
   local previous = self._cursor
+  local descriptor = motion_descriptor(motion)
   self._cursor = position
-  self:_record("apply_cursor", { position = position })
+  self:_record("apply_cursor", {
+    position = position,
+    descriptor = descriptor and descriptor.value or nil,
+  })
+  if descriptor ~= nil then
+    local origin = type(motion) == "table" and motion.origin or previous
+    self:_apply_pending_delete(domain.Position.coerce(origin), position, descriptor)
+  end
   self:_emit_movement_event(previous)
 end