Make PATH enumerable.

Library/Homebrew/PATH.rb

@@ -1,4 +1,9 @@
 class PATH
+  include Enumerable
+  extend Forwardable
+
+  def_delegator :@paths, :each
+
   def initialize(*paths)
     @paths = parse(*paths)
   end
@@ -13,6 +18,11 @@ class PATH
     self
   end
 
+  def insert(index, *paths)
+    @paths = parse(*@paths.insert(index, *paths))
+    self
+  end
+
   def to_ary
     @paths
   end

Library/Homebrew/cmd/sh.rb

@@ -23,7 +23,7 @@ module Homebrew
     ENV.setup_build_environment
     if superenv?
       # superenv stopped adding brew's bin but generally users will want it
-      ENV["PATH"] = PATH.new(PATH.new(ENV["PATH"]).to_a.insert(1, HOMEBREW_PREFIX/"bin"))
+      ENV["PATH"] = PATH.new(ENV["PATH"]).insert(1, HOMEBREW_PREFIX/"bin")
     end
     ENV["PS1"] = 'brew \[\033[1;32m\]\w\[\033[0m\]$ '
     ENV["VERBOSE"] = "1"

Library/Homebrew/diagnostic.rb

@@ -100,8 +100,7 @@ module Homebrew
 
       # See https://github.com/Homebrew/legacy-homebrew/pull/9986
       def check_path_for_trailing_slashes
-        all_paths = PATH.new(ENV["PATH"]).to_a
-        bad_paths = all_paths.select { |p| p[-1..-1] == "/" }
+        bad_paths = PATH.new(ENV["PATH"]).select { |p| p[-1..-1] == "/" }
         return if bad_paths.empty?
 
         inject_file_list bad_paths, <<-EOS.undent

Library/Homebrew/global.rb

@@ -56,7 +56,7 @@ HOMEBREW_PULL_OR_COMMIT_URL_REGEX = %r[https://github\.com/([\w-]+)/([\w-]+)?/(?
 require "compat" unless ARGV.include?("--no-compat") || ENV["HOMEBREW_NO_COMPAT"]
 
 ENV["HOMEBREW_PATH"] ||= ENV["PATH"]
-ORIGINAL_PATHS = PATH.new(ENV["HOMEBREW_PATH"]).to_a.map do |p|
+ORIGINAL_PATHS = PATH.new(ENV["HOMEBREW_PATH"]).map do |p|
   begin
     Pathname.new(p).expand_path
   rescue

Library/Homebrew/requirement.rb

@@ -96,7 +96,7 @@ class Requirement
     # PATH.
     parent = satisfied_result_parent
     return unless parent
-    return if PATH.new(ENV["PATH"]).to_a.include?(parent.to_s)
+    return if PATH.new(ENV["PATH"]).include?(parent.to_s)
     ENV.append_path("PATH", parent)
   end
 

Library/Homebrew/test/PATH_spec.rb

@@ -51,6 +51,41 @@ describe PATH do
     end
   end
 
+  describe "#insert" do
+    it "inserts a path at a given index" do
+      expect(described_class.new("/path1").insert(0, "/path2").to_str).to eq("/path2:/path1")
+    end
+
+    it "can insert multiple paths" do
+      expect(described_class.new("/path1").insert(0, "/path2", "/path3")).to eq("/path2:/path3:/path1")
+    end
+  end
+
+  describe "#include?" do
+    it "returns true if a path is included" do
+      path = described_class.new("/path1", "/path2")
+      expect(path).to include("/path1")
+      expect(path).to include("/path2")
+    end
+
+    it "returns false if a path is not included" do
+      expect(described_class.new("/path1")).not_to include("/path2")
+    end
+
+    it "returns false if the given string contains a separator" do
+      expect(described_class.new("/path1", "/path2")).not_to include("/path1:")
+    end
+  end
+
+  describe "#each" do
+    it "loops through each path" do
+      enum = described_class.new("/path1", "/path2").each
+
+      expect(enum.next).to eq("/path1")
+      expect(enum.next).to eq("/path2")
+    end
+  end
+
   describe "#validate" do
     it "returns a new PATH without non-existent paths" do
       allow(File).to receive(:directory?).with("/path1").and_return(true)

Library/Homebrew/utils.rb

@@ -293,7 +293,7 @@ def quiet_system(cmd, *args)
 end
 
 def which(cmd, path = ENV["PATH"])
-  PATH.new(path).to_a.each do |p|
+  PATH.new(path).each do |p|
     begin
       pcmd = File.expand_path(cmd, p)
     rescue ArgumentError
@@ -307,7 +307,7 @@ def which(cmd, path = ENV["PATH"])
 end
 
 def which_all(cmd, path = ENV["PATH"])
-  PATH.new(path).to_a.map do |p|
+  PATH.new(path).map do |p|
     begin
       pcmd = File.expand_path(cmd, p)
     rescue ArgumentError
@@ -416,7 +416,7 @@ def nostdout
 end
 
 def paths(env_path = ENV["PATH"])
-  @paths ||= PATH.new(env_path).to_a.collect do |p|
+  @paths ||= PATH.new(env_path).collect do |p|
     begin
       File.expand_path(p).chomp("/")
     rescue ArgumentError