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# frozen_string_literal: true
# Released under the MIT License.
# Copyright, 2025, by Samuel Williams.
require "fiber"
require "console"
module Async
# Raised when a task is explicitly stopped.
class Stop < Exception
# Represents the source of the stop operation.
class Cause < Exception
if RUBY_VERSION >= "3.4"
# @returns [Array(Thread::Backtrace::Location)] The backtrace of the caller.
def self.backtrace
caller_locations(2..-1)
end
else
# @returns [Array(String)] The backtrace of the caller.
def self.backtrace
caller(2..-1)
end
end
# Create a new cause of the stop operation, with the given message.
#
# @parameter message [String] The error message.
# @returns [Cause] The cause of the stop operation.
def self.for(message = "Task was stopped")
instance = self.new(message)
instance.set_backtrace(self.backtrace)
return instance
end
end
if RUBY_VERSION < "3.5"
# Create a new stop operation.
#
# This is a compatibility method for Ruby versions before 3.5 where cause is not propagated correctly when using {Fiber#raise}
#
# @parameter message [String | Hash] The error message or a hash containing the cause.
def initialize(message = "Task was stopped")
if message.is_a?(Hash)
@cause = message[:cause]
message = "Task was stopped"
end
super(message)
end
# @returns [Exception] The cause of the stop operation.
#
# This is a compatibility method for Ruby versions before 3.5 where cause is not propagated correctly when using {Fiber#raise}, we explicitly capture the cause here.
def cause
super || @cause
end
end
# Used to defer stopping the current task until later.
class Later
# Create a new stop later operation.
#
# @parameter task [Task] The task to stop later.
# @parameter cause [Exception] The cause of the stop operation.
def initialize(task, cause = nil)
@task = task
@cause = cause
end
# @returns [Boolean] Whether the task is alive.
def alive?
true
end
# Transfer control to the operation - this will stop the task.
def transfer
@task.stop(false, cause: @cause)
end
end
end
end
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