1 files changed, 63 insertions, 0 deletions
diff --git a/Library/Homebrew/compat/requirements/language_module_requirement.rb b/Library/Homebrew/compat/requirements/language_module_requirement.rb
new file mode 100644
index 000000000..5ddce7a66
--- /dev/null
+++ b/Library/Homebrew/compat/requirements/language_module_requirement.rb
@@ -0,0 +1,63 @@
+require "requirement"
+
+class LanguageModuleRequirement < Requirement
+  fatal true
+
+  def initialize(language, module_name, import_name = nil)
+    @language = language
+    @module_name = module_name
+    @import_name = import_name || module_name
+    super([language, module_name, import_name])
+  end
+
+  satisfy(build_env: false) { quiet_system(*the_test) }
+
+  def message
+    s = <<~EOS
+      Unsatisfied dependency: #{@module_name}
+      Homebrew does not provide special #{@language.to_s.capitalize} dependencies; install with:
+        `#{command_line} #{@module_name}`
+    EOS
+
+    unless [:python, :perl, :ruby].include? @language
+      s += <<~EOS
+        You may need to: `brew install #{@language}`
+
+      EOS
+    end
+
+    s
+  end
+
+  def the_test
+    case @language
+    when :lua
+      ["/usr/bin/env", "luarocks-5.2", "show", @import_name.to_s]
+    when :lua51
+      ["/usr/bin/env", "luarocks-5.1", "show", @import_name.to_s]
+    when :perl
+      ["/usr/bin/env", "perl", "-e", "use #{@import_name}"]
+    when :python
+      ["/usr/bin/env", "python", "-c", "import #{@import_name}"]
+    when :python3
+      ["/usr/bin/env", "python3", "-c", "import #{@import_name}"]
+    when :ruby
+      ["/usr/bin/env", "ruby", "-rubygems", "-e", "require '#{@import_name}'"]
+    end
+  end
+
+  def command_line
+    case @language
+    when :lua     then "luarocks-5.2 install"
+    when :lua51   then "luarocks-5.1 install"
+    when :perl    then "cpan -i"
+    when :python  then "pip install"
+    when :python3 then "pip3 install"
+    when :ruby    then "gem install"
+    end
+  end
+
+  def display_s
+    "#{@module_name} (#{@language} module)"
+  end
+end