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require 'rake/invocation_exception_mixin'
module Rake
# #########################################################################
# A Task is the basic unit of work in a Rakefile. Tasks have associated
# actions (possibly more than one) and a list of prerequisites. When
# invoked, a task will first ensure that all of its prerequisites have an
# opportunity to run and then it will execute its own actions.
#
# Tasks are not usually created directly using the new method, but rather
# use the +file+ and +task+ convenience methods.
#
class Task
# List of prerequisites for a task.
attr_reader :prerequisites
# List of actions attached to a task.
attr_reader :actions
# Application owning this task.
attr_accessor :application
# Comment for this task. Restricted to a single line of no more than 50
# characters.
attr_reader :comment
# Full text of the (possibly multi-line) comment.
attr_reader :full_comment
# Array of nested namespaces names used for task lookup by this task.
attr_reader :scope
# File/Line locations of each of the task definitions for this
# task (only valid if the task was defined with the detect
# location option set).
attr_reader :locations
# Return task name
def to_s
name
end
def inspect
"<#{self.class} #{name} => [#{prerequisites.join(', ')}]>"
end
# List of sources for task.
attr_writer :sources
def sources
@sources ||= []
end
# List of prerequisite tasks
def prerequisite_tasks
prerequisites.collect { |pre| lookup_prerequisite(pre) }
end
def lookup_prerequisite(prerequisite_name)
application[prerequisite_name, @scope]
end
private :lookup_prerequisite
# First source from a rule (nil if no sources)
def source
@sources.first if defined?(@sources)
end
# Create a task named +task_name+ with no actions or prerequisites. Use
# +enhance+ to add actions and prerequisites.
def initialize(task_name, app)
@name = task_name.to_s
@prerequisites = []
@actions = []
@already_invoked = false
@full_comment = nil
@comment = nil
@lock = Monitor.new
@application = app
@scope = app.current_scope
@arg_names = nil
@locations = []
end
# Enhance a task with prerequisites or actions. Returns self.
def enhance(deps=nil, &block)
@prerequisites |= deps if deps
@actions << block if block_given?
self
end
# Name of the task, including any namespace qualifiers.
def name
@name.to_s
end
# Name of task with argument list description.
def name_with_args # :nodoc:
if arg_description
"#{name}#{arg_description}"
else
name
end
end
# Argument description (nil if none).
def arg_description # :nodoc:
@arg_names ? "[#{(arg_names || []).join(',')}]" : nil
end
# Name of arguments for this task.
def arg_names
@arg_names || []
end
# Reenable the task, allowing its tasks to be executed if the task
# is invoked again.
def reenable
@already_invoked = false
end
# Clear the existing prerequisites and actions of a rake task.
def clear
clear_prerequisites
clear_actions
self
end
# Clear the existing prerequisites of a rake task.
def clear_prerequisites
prerequisites.clear
self
end
# Clear the existing actions on a rake task.
def clear_actions
actions.clear
self
end
# Invoke the task if it is needed. Prerequisites are invoked first.
def invoke(*args)
task_args = TaskArguments.new(arg_names, args)
invoke_with_call_chain(task_args, InvocationChain::EMPTY)
end
# Same as invoke, but explicitly pass a call chain to detect
# circular dependencies.
def invoke_with_call_chain(task_args, invocation_chain) # :nodoc:
new_chain = InvocationChain.append(self, invocation_chain)
@lock.synchronize do
if application.options.trace
$stderr.puts "** Invoke #{name} #{format_trace_flags}"
end
return if @already_invoked
@already_invoked = true
invoke_prerequisites(task_args, new_chain)
execute(task_args) if needed?
end
rescue Exception => ex
add_chain_to(ex, new_chain)
raise ex
end
protected :invoke_with_call_chain
def add_chain_to(exception, new_chain)
exception.extend(InvocationExceptionMixin) unless exception.respond_to?(:chain)
exception.chain = new_chain if exception.chain.nil?
end
private :add_chain_to
# Invoke all the prerequisites of a task.
def invoke_prerequisites(task_args, invocation_chain) # :nodoc:
prerequisite_tasks.each { |prereq|
prereq_args = task_args.new_scope(prereq.arg_names)
prereq.invoke_with_call_chain(prereq_args, invocation_chain)
}
end
# Format the trace flags for display.
def format_trace_flags
flags = []
flags << "first_time" unless @already_invoked
flags << "not_needed" unless needed?
flags.empty? ? "" : "(" + flags.join(", ") + ")"
end
private :format_trace_flags
# Execute the actions associated with this task.
def execute(args=nil)
args ||= EMPTY_TASK_ARGS
if application.options.dryrun
$stderr.puts "** Execute (dry run) #{name}"
return
end
if application.options.trace
$stderr.puts "** Execute #{name}"
end
application.enhance_with_matching_rule(name) if @actions.empty?
@actions.each do |act|
case act.arity
when 1
act.call(self)
else
act.call(self, args)
end
end
end
# Is this task needed?
def needed?
true
end
# Timestamp for this task. Basic tasks return the current time for their
# time stamp. Other tasks can be more sophisticated.
def timestamp
prerequisite_tasks.collect { |pre| pre.timestamp }.max || Time.now
end
# Add a description to the task. The description can consist of an option
# argument list (enclosed brackets) and an optional comment.
def add_description(description)
return if ! description
comment = description.strip
add_comment(comment) if comment && ! comment.empty?
end
# Writing to the comment attribute is the same as adding a description.
def comment=(description)
add_description(description)
end
# Add a comment to the task. If a comment already exists, separate
# the new comment with " / ".
def add_comment(comment)
if @full_comment
@full_comment << " / "
else
@full_comment = ''
end
@full_comment << comment
if @full_comment =~ /\A([^.]+?\.)( |$)/
@comment = $1
else
@comment = @full_comment
end
end
private :add_comment
# Set the names of the arguments for this task. +args+ should be
# an array of symbols, one for each argument name.
def set_arg_names(args)
@arg_names = args.map { |a| a.to_sym }
end
# Return a string describing the internal state of a task. Useful for
# debugging.
def investigation
result = "------------------------------\n"
result << "Investigating #{name}\n"
result << "class: #{self.class}\n"
result << "task needed: #{needed?}\n"
result << "timestamp: #{timestamp}\n"
result << "pre-requisites: \n"
prereqs = prerequisite_tasks
prereqs.sort! {|a,b| a.timestamp <=> b.timestamp}
prereqs.each do |p|
result << "--#{p.name} (#{p.timestamp})\n"
end
latest_prereq = prerequisite_tasks.collect { |pre| pre.timestamp }.max
result << "latest-prerequisite time: #{latest_prereq}\n"
result << "................................\n\n"
return result
end
# ----------------------------------------------------------------
# Rake Module Methods
#
class << self
# Clear the task list. This cause rake to immediately forget all the
# tasks that have been assigned. (Normally used in the unit tests.)
def clear
Rake.application.clear
end
# List of all defined tasks.
def tasks
Rake.application.tasks
end
# Return a task with the given name. If the task is not currently
# known, try to synthesize one from the defined rules. If no rules are
# found, but an existing file matches the task name, assume it is a file
# task with no dependencies or actions.
def [](task_name)
Rake.application[task_name]
end
# TRUE if the task name is already defined.
def task_defined?(task_name)
Rake.application.lookup(task_name) != nil
end
# Define a task given +args+ and an option block. If a rule with the
# given name already exists, the prerequisites and actions are added to
# the existing task. Returns the defined task.
def define_task(*args, &block)
Rake.application.define_task(self, *args, &block)
end
# Define a rule for synthesizing tasks.
def create_rule(*args, &block)
Rake.application.create_rule(*args, &block)
end
# Apply the scope to the task name according to the rules for
# this kind of task. Generic tasks will accept the scope as
# part of the name.
def scope_name(scope, task_name)
(scope + [task_name]).join(':')
end
end # class << Rake::Task
end # class Rake::Task
end
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