1 files changed, 302 insertions, 0 deletions
diff --git a/lua/clever_tee/sequence_state.lua b/lua/clever_tee/sequence_state.lua
new file mode 100644
index 0000000..5c66a42
--- /dev/null
+++ b/lua/clever_tee/sequence_state.lua
@@ -0,0 +1,302 @@
+local domain = require("clever_tee.domain")
+
+local M = {}
+local State = {}
+M.State = State
+
+local MAP_FIELDS = {
+  "previous_descriptor",
+  "previous_landing",
+  "first_move",
+  "previous_target",
+}
+
+local MAP_FIELD_SET = {}
+for _, field in ipairs(MAP_FIELDS) do
+  MAP_FIELD_SET[field] = true
+end
+
+local data = {
+  previous_descriptor = {},
+  previous_landing = {},
+  first_move = {},
+  previous_target = {},
+  known_contexts = {},
+  last_input_context = nil,
+  moved_forward = false,
+  moved_forward_initialized = false,
+  migemo_cache = {},
+  repeat_timestamp_ms = 0,
+  highlight_timer = nil,
+  target_overlays = {},
+  temporary_overlays = {},
+  finalizers = {},
+}
+
+local function fail(message, level)
+  error(message, (level or 1) + 1)
+end
+
+local function normalize_context(context, name)
+  if domain.ModeContext.is(context) then
+    return domain.ModeContext.from_full_mode(context.full_mode)
+  end
+  if type(context) ~= "string" or context == "" then
+    fail((name or "context") .. " must be a ModeContext or full mode string", 2)
+  end
+  return domain.ModeContext.from_full_mode(context)
+end
+
+local function copy_map(source)
+  local result = {}
+  for key, value in pairs(source) do
+    result[key] = value
+  end
+  return result
+end
+
+local function copy_resource(resource)
+  local result = {}
+  for key, value in pairs(resource) do
+    result[key] = value
+  end
+  return result
+end
+
+local function copy_resources(resources)
+  local result = {}
+  for index, resource in ipairs(resources) do
+    result[index] = copy_resource(resource)
+  end
+  return result
+end
+
+local function sorted_contexts()
+  local result = {}
+  for context in pairs(data.known_contexts) do
+    result[#result + 1] = context
+  end
+  table.sort(result, function(left, right)
+    return left.key < right.key
+  end)
+  return result
+end
+
+local function context_record(context)
+  return {
+    context = context,
+    previous_descriptor = data.previous_descriptor[context],
+    previous_landing = data.previous_landing[context],
+    first_move = data.first_move[context],
+    previous_target = data.previous_target[context],
+  }
+end
+
+local function context_records()
+  local result = {}
+  for _, context in ipairs(sorted_contexts()) do
+    result[context.key] = context_record(context)
+  end
+  return result
+end
+
+function State:get_previous_descriptor(context)
+  context = normalize_context(context)
+  return data.previous_descriptor[context]
+end
+
+function State:get_previous_landing(context)
+  context = normalize_context(context)
+  return data.previous_landing[context]
+end
+
+function State:get_first_move(context)
+  context = normalize_context(context)
+  return data.first_move[context]
+end
+
+function State:get_previous_target(context)
+  context = normalize_context(context)
+  return data.previous_target[context]
+end
+
+function State:get_context(context)
+  context = normalize_context(context)
+  return context_record(context)
+end
+
+State.context = State.get_context
+
+function State:has_previous_landing(context)
+  return self:get_previous_landing(context) ~= nil
+end
+
+function State:get_migemo(encoding)
+  if type(encoding) ~= "string" or encoding == "" then
+    fail("encoding must be a nonempty string", 2)
+  end
+  return data.migemo_cache[encoding]
+end
+
+function State:target_overlay_identities()
+  local result = {}
+  for index, resource in ipairs(data.target_overlays) do
+    result[index] = resource.identity
+  end
+  return result
+end
+
+function State:temporary_overlay_identities()
+  local result = {}
+  for index, resource in ipairs(data.temporary_overlays) do
+    result[index] = resource.identity
+  end
+  return result
+end
+
+function State:finalizer_identities()
+  local result = {}
+  for index, resource in ipairs(data.finalizers) do
+    result[index] = resource.identity
+  end
+  return result
+end
+
+function State:resources()
+  return {
+    highlight_timer = data.highlight_timer,
+    target_overlays = copy_resources(data.target_overlays),
+    temporary_overlays = copy_resources(data.temporary_overlays),
+    finalizers = copy_resources(data.finalizers),
+  }
+end
+
+function State:snapshot()
+  local snapshot = {
+    contexts = context_records(),
+    last_input_context = data.last_input_context,
+    moved_forward = data.moved_forward,
+    moved_forward_initialized = data.moved_forward_initialized,
+    migemo_cache = copy_map(data.migemo_cache),
+    repeat_timestamp_ms = data.repeat_timestamp_ms,
+    highlight_timer = data.highlight_timer,
+    target_overlays = copy_resources(data.target_overlays),
+    temporary_overlays = copy_resources(data.temporary_overlays),
+    finalizers = copy_resources(data.finalizers),
+  }
+  for _, field in ipairs(MAP_FIELDS) do
+    snapshot[field] = copy_map(data[field])
+  end
+  return snapshot
+end
+
+local function target_to_table(target)
+  return target and target:to_table() or nil
+end
+
+function State:to_table()
+  local contexts = {}
+  for _, context in ipairs(sorted_contexts()) do
+    local record = context_record(context)
+    contexts[context.key] = {
+      previous_descriptor = record.previous_descriptor
+          and record.previous_descriptor.value
+        or nil,
+      previous_landing = record.previous_landing
+          and record.previous_landing:to_table()
+        or nil,
+      first_move = record.first_move,
+      previous_target = target_to_table(record.previous_target),
+    }
+  end
+
+  local cache_keys = {}
+  for encoding in pairs(data.migemo_cache) do
+    cache_keys[#cache_keys + 1] = encoding
+  end
+  table.sort(cache_keys)
+
+  return {
+    contexts = contexts,
+    last_input_context = data.last_input_context and data.last_input_context.key or nil,
+    moved_forward = data.moved_forward,
+    moved_forward_initialized = data.moved_forward_initialized,
+    migemo_cache = cache_keys,
+    repeat_timestamp_ms = data.repeat_timestamp_ms,
+    highlight_timer = data.highlight_timer,
+    target_overlays = self:target_overlay_identities(),
+    temporary_overlays = self:temporary_overlay_identities(),
+    finalizers = self:finalizer_identities(),
+  }
+end
+
+local state
+local state_metatable = {
+  __index = function(_, key)
+    local method = State[key]
+    if method ~= nil then
+      return method
+    end
+    if MAP_FIELD_SET[key] then
+      return copy_map(data[key])
+    end
+    if key == "contexts" then
+      return context_records()
+    end
+    if key == "last_input_context"
+      or key == "moved_forward"
+      or key == "moved_forward_initialized"
+      or key == "highlight_timer"
+    then
+      return data[key]
+    end
+    if key == "repeat_timestamp" or key == "repeat_timestamp_ms" then
+      return data.repeat_timestamp_ms
+    end
+    if key == "migemo_cache" then
+      return copy_map(data.migemo_cache)
+    end
+    if key == "target_overlays"
+      or key == "temporary_overlays"
+      or key == "finalizers"
+    then
+      return copy_resources(data[key])
+    end
+    return nil
+  end,
+  __newindex = function()
+    fail("SequenceState is read-only; use StateTransitions", 2)
+  end,
+  __metatable = "clever_tee.sequence_state.State",
+}
+state = setmetatable({}, state_metatable)
+
+function M.get()
+  return state
+end
+
+function M.new()
+  return state
+end
+
+function M.is(value)
+  return value == state
+end
+
+M.global = state
+
+function M._mutate(target, mutation)
+  if target ~= state then
+    fail("StateTransitions must use the plugin-global SequenceState", 2)
+  end
+  if type(mutation) ~= "function" then
+    fail("state mutation must be a function", 2)
+  end
+  return mutation(data)
+end
+
+function M._normalize_context(context)
+  return normalize_context(context)
+end
+
+return M