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#--
# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
# All rights reserved.
# See LICENSE.txt for permissions.
#++
require 'rubygems/source_index'
module Kernel
alias gem_original_require require # :nodoc:
#
# We replace Ruby's require with our own, which is capable of
# loading gems on demand.
#
# When you call <tt>require 'x'</tt>, this is what happens:
# * If the file can be loaded from the existing Ruby loadpath, it
# is.
# * Otherwise, installed gems are searched for a file that matches.
# If it's found in gem 'y', that gem is activated (added to the
# loadpath).
#
# The normal <tt>require</tt> functionality of returning false if
# that file has already been loaded is preserved.
#
def require(path) # :nodoc:
gem_original_require path
rescue LoadError => load_error
begin
if spec = Gem.searcher.find(path)
Gem.activate(spec.name, false, "= #{spec.version}")
gem_original_require path
else
raise load_error
end
end
end
end # module Kernel
module Gem
#
# GemPathSearcher has the capability to find loadable files inside
# gems. It generates data up front to speed up searches later.
#
class GemPathSearcher
#
# Initialise the data we need to make searches later.
#
def initialize
# We want a record of all the installed gemspecs, in the order
# we wish to examine them.
@gemspecs = init_gemspecs
# Map gem spec to glob of full require_path directories.
# Preparing this information may speed up searches later.
@lib_dirs = {}
@gemspecs.each do |spec|
@lib_dirs[spec.object_id] = lib_dirs(spec)
end
end
#
# Look in all the installed gems until a matching _path_ is found.
# Return the _gemspec_ of the gem where it was found. If no match
# is found, return nil.
#
# The gems are searched in alphabetical order, and in reverse
# version order.
#
# For example:
#
# find('log4r') # -> (log4r-1.1 spec)
# find('log4r.rb') # -> (log4r-1.1 spec)
# find('rake/rdoctask') # -> (rake-0.4.12 spec)
# find('foobarbaz') # -> nil
#
# Matching paths can have various suffixes ('.rb', '.so', and
# others), which may or may not already be attached to _file_.
# This method doesn't care about the full filename that matches;
# only that there is a match.
#
def find(path)
@gemspecs.each do |spec|
return spec if matching_file(spec, path)
end
nil
end
private
# Attempts to find a matching path using the require_paths of the
# given _spec_.
#
# Some of the intermediate results are cached in @lib_dirs for
# speed.
def matching_file(spec, path) # :doc:
glob = File.join @lib_dirs[spec.object_id], "#{path}#{Gem.suffix_pattern}"
return true unless Dir[glob].select { |f| File.file?(f.untaint) }.empty?
end
# Return a list of all installed gemspecs, sorted by alphabetical
# order and in reverse version order.
def init_gemspecs
Gem.source_index.map { |_, spec| spec }.sort { |a,b|
(a.name <=> b.name).nonzero? || (b.version <=> a.version)
}
end
# Returns library directories glob for a gemspec. For example,
# '/usr/local/lib/ruby/gems/1.8/gems/foobar-1.0/{lib,ext}'
def lib_dirs(spec)
"#{spec.full_gem_path}/{#{spec.require_paths.join(',')}}"
end
end # class Gem::GemPathLoader
end # module Gem
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