1 files changed, 70 insertions, 0 deletions
diff --git a/Library/Homebrew/utils/link.rb b/Library/Homebrew/utils/link.rb
new file mode 100644
index 000000000..095dba209
--- /dev/null
+++ b/Library/Homebrew/utils/link.rb
@@ -0,0 +1,70 @@
+module Utils
+  module Link
+    module_function
+
+    def link_src_dst_dirs(src_dir, dst_dir, command, link_dir: false)
+      return unless src_dir.exist?
+      conflicts = []
+      src_paths = link_dir ? [src_dir] : src_dir.find
+      src_paths.each do |src|
+        next if src.directory? && !link_dir
+        dst = dst_dir/src.relative_path_from(src_dir)
+        if dst.symlink?
+          next if src == dst.resolved_path
+          dst.unlink
+        end
+        if dst.exist?
+          conflicts << dst
+          next
+        end
+        dst_dir.parent.mkpath
+        dst.make_relative_symlink(src)
+      end
+
+      return if conflicts.empty?
+      onoe <<-EOS.undent
+        Could not link:
+        #{conflicts.join("\n")}
+
+        Please delete these paths and run `#{command}`.
+      EOS
+    end
+    private_class_method :link_src_dst_dirs
+
+    def unlink_src_dst_dirs(src_dir, dst_dir, unlink_dir: false)
+      return unless src_dir.exist?
+      src_paths = unlink_dir ? [src_dir] : src_dir.find
+      src_paths.each do |src|
+        next if src.directory? && !unlink_dir
+        dst = dst_dir/src.relative_path_from(src_dir)
+        dst.delete if dst.symlink? && src == dst.resolved_path
+        dst.parent.rmdir_if_possible
+      end
+    end
+    private_class_method :unlink_src_dst_dirs
+
+    def link_manpages(path, command)
+      link_src_dst_dirs(path/"manpages", HOMEBREW_PREFIX/"share/man/man1", command)
+    end
+
+    def unlink_manpages(path)
+      unlink_src_dst_dirs(path/"manpages", HOMEBREW_PREFIX/"share/man/man1")
+    end
+
+    def link_completions(path, command)
+      link_src_dst_dirs(path/"completions/bash", HOMEBREW_PREFIX/"etc/bash_completion.d", command)
+      link_src_dst_dirs(path/"completions/zsh", HOMEBREW_PREFIX/"share/zsh/site-functions", command)
+      link_src_dst_dirs(path/"completions/fish", HOMEBREW_PREFIX/"share/fish/vendor_completions.d", command)
+    end
+
+    def unlink_completions(path)
+      unlink_src_dst_dirs(path/"completions/bash", HOMEBREW_PREFIX/"etc/bash_completion.d")
+      unlink_src_dst_dirs(path/"completions/zsh", HOMEBREW_PREFIX/"share/zsh/site-functions")
+      unlink_src_dst_dirs(path/"completions/fish", HOMEBREW_PREFIX/"share/fish/vendor_completions.d")
+    end
+
+    def link_docs(path, command)
+      link_src_dst_dirs(path/"docs", HOMEBREW_PREFIX/"share/doc/homebrew", command, link_dir: true)
+    end
+  end
+end