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local domain = require("clever_f.domain")
local text_topology = require("clever_f.text_topology")
local M = {}
local DestinationEngine = {}
M.DestinationEngine = DestinationEngine
local engines = setmetatable({}, { __mode = "k" })
local function fail(message, level)
error(message, (level or 1) + 1)
end
local engine_metatable = {
__index = DestinationEngine,
__newindex = function()
fail("DestinationEngine values are immutable", 2)
end,
__tostring = function()
return "destination-engine"
end,
__metatable = "clever_f.destination_engine.DestinationEngine",
}
function DestinationEngine.new()
local engine = setmetatable({}, engine_metatable)
engines[engine] = true
return engine
end
function DestinationEngine.is(value)
return type(value) == "table" and engines[value] == true
end
local function calculation_inputs(view, origin, plan, count, first_move)
if not text_topology.TextView.is(view) then
fail("destination calculation view must be a TextView", 3)
end
origin = domain.Position.coerce(origin)
if not view:is_valid_cursor_position(origin) then
fail("destination calculation origin must be a valid cursor position", 3)
end
if not domain.ResolvedMotionPlan.is(plan) then
fail("destination calculation plan must be a ResolvedMotionPlan", 3)
end
count = domain.Count.new(count)
if type(first_move) ~= "boolean" then
fail("destination calculation first_move must be a Boolean", 3)
end
local bounds = view:match_start_bounds(plan.search_scope, origin)
return {
view = view,
origin = origin,
plan = plan,
count = count,
first_move = first_move,
bounds = bounds,
}
end
local function candidate_starts(request, origin)
return request.view:iter_strict(
origin,
request.plan.descriptor.direction,
request.bounds
)
end
local function regular_destination(request, target_position)
local descriptor = request.plan.descriptor
if descriptor.family == domain.Family.FIND then
return target_position
end
if descriptor.direction == domain.Direction.FORWARD then
return request.view:predecessor(target_position)
end
return request.view:successor(target_position)
end
local function target_destination(request, target_position)
local descriptor = request.plan.descriptor
if request.plan.endpoint_policy == domain.EndpointPolicy.VISUAL_EXCLUSIVE
and descriptor.direction == domain.Direction.FORWARD
then
if descriptor.family == domain.Family.FIND then
return request.view:successor(target_position)
end
return target_position
end
return regular_destination(request, target_position)
end
local function strict_destination(descriptor, destination, origin)
local comparison = domain.Position.compare(destination, origin)
if descriptor.direction == domain.Direction.FORWARD then
return comparison > 0
end
return comparison < 0
end
local function acceptable_destination(
request,
destination,
origin,
allow_till_equality
)
local descriptor = request.plan.descriptor
if strict_destination(descriptor, destination, origin) then
return true
end
return descriptor.family == domain.Family.TILL
and allow_till_equality
and domain.Position.equal(destination, origin)
end
local function next_destination(request, origin, allow_till_equality)
local candidates = candidate_starts(request, origin)
while true do
local target_position, character = candidates()
if target_position == nil then
return nil
end
if request.plan.target_plan:matches(
character,
target_position,
request.view
) then
local destination = target_destination(request, target_position)
if destination ~= nil
and acceptable_destination(
request,
destination,
origin,
allow_till_equality
)
then
return destination
end
end
end
end
local function till_equality_allowed(request, successful_steps)
return request.first_move and successful_steps == 0
end
local function boundary_outcome(request, endpoint, successful_steps)
if successful_steps > 0 then
return domain.SearchOutcome.boundary_after_partial(
endpoint,
successful_steps
)
end
return domain.SearchOutcome.boundary_before_any(request.origin)
end
function DestinationEngine:calculate(view, origin, plan, count, first_move)
local request = calculation_inputs(view, origin, plan, count, first_move)
local current_origin = request.origin
local successful_steps = 0
while successful_steps < request.count.value do
local destination = next_destination(
request,
current_origin,
till_equality_allowed(request, successful_steps)
)
if destination == nil then
break
end
current_origin = destination
successful_steps = successful_steps + 1
end
if successful_steps == request.count.value then
return domain.SearchOutcome.complete(current_origin, successful_steps)
end
return boundary_outcome(request, current_origin, successful_steps)
end
function M.new()
return DestinationEngine.new()
end
function M.calculate(view, origin, plan, count, first_move)
return DestinationEngine.new():calculate(view, origin, plan, count, first_move)
end
M.resolve = M.calculate
M.search = M.calculate
setmetatable(M, {
__call = function()
return DestinationEngine.new()
end,
})
return M
|
