lib/optimism/util.rb
require "rbconfig"
class Optimism
# In order to reduce the dependencies, this Util class contains some util functions.
class Util
module Concern
def included(base)
base.extend const_get(:ClassMethods) if const_defined?(:ClassMethods)
end
end
class << self
# Extracts options from a set of arguments.
#
# @example
#
# dirs, o = Util.extract_options(["foo", "bar", {a: 1}], b: 2)
# -> ["foo", "bar"], {a: 1, b: 2}
#
# (dir,) o = Util.extract_options(["foo", {a: 1}])
# -> "foo", {a: 1}
#
# @return [Array<Array,Hash>]
def extract_options(args, default={})
if args.last.instance_of?(Hash)
[args[0...-1], default.merge(args[-1])]
else
[args, default]
end
end
# Wraps its argument in an array unless it is already an array (or array-like).
#
# Specifically:
#
# * If the argument is +nil+ an empty list is returned.
# * Otherwise, if the argument responds to +to_ary+ it is invoked, and its result returned.
# * Otherwise, returns an array with the argument as its single element.
#
# Array.wrap(nil) # => []
# Array.wrap([1, 2, 3]) # => [1, 2, 3]
# Array.wrap(0) # => [0]
#
# This method is similar in purpose to <tt>Kernel#Array</tt>, but there are some differences:
#
# * If the argument responds to +to_ary+ the method is invoked. <tt>Kernel#Array</tt>
# moves on to try +to_a+ if the returned value is +nil+, but <tt>Array.wrap</tt> returns
# such a +nil+ right away.
# * If the returned value from +to_ary+ is neither +nil+ nor an +Array+ object, <tt>Kernel#Array</tt>
# raises an exception, while <tt>Array.wrap</tt> does not, it just returns the value.
# * It does not call +to_a+ on the argument, though special-cases +nil+ to return an empty array.
#
# The last point is particularly worth comparing for some enumerables:
#
# Array(:foo => :bar) # => [[:foo, :bar]]
# Array.wrap(:foo => :bar) # => [{:foo => :bar}]
#
# Array("foo\nbar") # => ["foo\n", "bar"], in Ruby 1.8
# Array.wrap("foo\nbar") # => ["foo\nbar"]
#
# There's also a related idiom that uses the splat operator:
#
# [*object]
#
# which returns <tt>[nil]</tt> for +nil+, and calls to <tt>Array(object)</tt> otherwise.
#
# Thus, in this case the behavior is different for +nil+, and the differences with
# <tt>Kernel#Array</tt> explained above apply to the rest of +object+s.
def wrap_array(object)
if object.nil?
[]
elsif object.respond_to?(:to_ary)
object.to_ary || [object]
else
[object]
end
end
# Slice a hash to include only the given keys. This is useful for
# limiting an options hash to valid keys before passing to a method:
#
# @example
#
# a = {a: 1, b: 2, c: 3}
# a.slaice(:a, :b) -> {a: 1, b: 2}
def slice(hash, *keys)
keys = keys.map! { |key| hash.convert_key(key) } if hash.respond_to?(:convert_key)
h = hash.class.new
keys.each { |k| h[k] = hash[k] if hash.has_key?(k) }
h
end
# different to File.join.
#
# @example
#
# join_path(".", "foo") -> "foo" not "./foo"
#
def join_path(dir, *names)
dir == "." ? File.join(*names) : File.join(dir, *names)
end
def linux?
RbConfig::CONFIG["host_os"] =~ /linux|cygwin/
end
def mac?
RbConfig::CONFIG["host_os"] =~ /mac|darwin/
end
def bsd?
RbConfig::CONFIG["host_os"] =~ /bsd/
end
def windows?
RbConfig::CONFIG["host_os"] =~ /mswin|mingw/
end
def solaris?
RbConfig::CONFIG["host_os"] =~ /solaris|sunos/
end
# TODO: who knows what symbian returns?
def symbian?
RbConfig::CONFIG["host_os"] =~ /symbian/
end
def posix?
linux? or mac? or bsd? or solaris? or begin
fork do end
true
rescue NotImplementedError, NoMethodError
false
end
end
end
end
end