module Rake
##
# TaskArguments manage the arguments passed to a task.
#
class TaskArguments
include Enumerable
# Argument names
attr_reader :names
# Create a TaskArgument object with a list of argument +names+ and a set
# of associated +values+. +parent+ is the parent argument object.
def initialize(names, values, parent=nil)
@names = names
@parent = parent
@hash = {}
@values = values
names.each_with_index { |name, i|
@hash[name.to_sym] = values[i] unless values[i].nil?
}
end
# Retrieve the complete array of sequential values
def to_a
@values.dup
end
# Retrieve the list of values not associated with named arguments
def extras
@values[@names.length..-1] || []
end
# Create a new argument scope using the prerequisite argument
# names.
def new_scope(names)
values = names.map { |n| self[n] }
self.class.new(names, values + extras, self)
end
# Find an argument value by name or index.
def [](index)
lookup(index.to_sym)
end
# Specify a hash of default values for task arguments. Use the
# defaults only if there is no specific value for the given
# argument.
def with_defaults(defaults)
@hash = defaults.merge(@hash)
end
# Enumerates the arguments and their values
def each(&block)
@hash.each(&block)
end
# Extracts the argument values at +keys+
def values_at(*keys)
keys.map { |k| lookup(k) }
end
# Returns the value of the given argument via method_missing
def method_missing(sym, *args)
lookup(sym.to_sym)
end
# Returns a Hash of arguments and their values
def to_hash
@hash
end
def to_s # :nodoc:
@hash.inspect
end
def inspect # :nodoc:
to_s
end
# Returns true if +key+ is one of the arguments
def has_key?(key)
@hash.has_key?(key)
end
protected
def lookup(name) # :nodoc:
if @hash.has_key?(name)
@hash[name]
elsif @parent
@parent.lookup(name)
end
end
end
EMPTY_TASK_ARGS = TaskArguments.new([], []) # :nodoc:
end
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