Utils: add shortened_brew_path

Library/Homebrew/test/utils/path_spec.rb

@@ -0,0 +1,33 @@
+# typed: false
+# frozen_string_literal: true
+
+require "utils/path"
+
+describe Utils do
+  describe "::path_is_parent_of?" do
+    it "returns true when child path is a descendant of the parent" do
+      expect(described_class.path_is_parent_of?("/foo", "/foo/bar/baz")).to eq(true)
+    end
+
+    it "returns false when child path is not a descendant of the parent" do
+      expect(described_class.path_is_parent_of?("/foo/bar/baz/qux", "/foo/bar")).to eq(false)
+    end
+  end
+
+  describe "::shortened_brew_path" do
+    it "returns shortened path when the path can be expressed with the output of a brew command" do
+      expect(described_class.shortened_brew_path("#{HOMEBREW_PREFIX}/foo/bar")).to eq("$(brew --prefix)/foo/bar")
+    end
+
+    it "returns shortened path with $(brew --prefix <formula>) when path is in a linked keg", :integration_test do
+      install_test_formula "testball"
+      f = Formula["testball"]
+
+      expect(described_class.shortened_brew_path("#{f.opt_prefix}/main.c")).to eq("$(brew --prefix testball)/main.c")
+    end
+
+    it "returns the original path when the path cannot be shortened" do
+      expect(described_class.shortened_brew_path("/foo/bar/baz")).to eq("/foo/bar/baz")
+    end
+  end
+end

Library/Homebrew/utils.rb

@@ -13,6 +13,7 @@ require "utils/git_repository"
 require "utils/github"
 require "utils/inreplace"
 require "utils/link"
+require "utils/path"
 require "utils/popen"
 require "utils/repology"
 require "utils/svn"

Library/Homebrew/utils/path.rb

@@ -0,0 +1,51 @@
+# typed: strict
+# frozen_string_literal: true
+
+# Helper functions for working with paths
+module Utils
+  extend T::Sig
+
+  # Checks if a a child path is a descendant of a given parent path
+  sig { params(parent_path: T.any(String, Pathname), child_path: T.any(String, Pathname)).returns(T::Boolean) }
+  def self.path_is_parent_of?(parent_path, child_path)
+    parent_component_array = Pathname(parent_path).each_filename.to_a
+    child_component_array = Pathname(child_path).each_filename.to_a
+
+    child_component_array.first(parent_component_array.length) == parent_component_array
+  end
+
+  # Gets a condensed short brew path for a given path, or the original path if it cannot be condensed
+  sig { params(long_path: T.any(String, Pathname)).returns(String) }
+  def self.shortened_brew_path(long_path)
+    short_path = long_path.to_s
+    long_path = Pathname(long_path)
+
+    if long_path.exist?
+      begin
+        k = Keg.for(long_path)
+        opt_record = k.opt_record
+        formula_name = k.to_formula.name
+      rescue FormulaUnavailableError, NotAKegError
+        nil
+      else
+        short_path = short_path.sub(/\A#{Regexp.escape(opt_record.to_s)}/, "$(brew --prefix #{formula_name})")
+      end
+    end
+
+    try_paths = {
+      HOMEBREW_CACHE      => "--cache",
+      HOMEBREW_CELLAR     => "--cellar",
+      HOMEBREW_REPOSITORY => "--repository",
+      HOMEBREW_PREFIX     => "--prefix",
+    }
+
+    try_paths.each do |try_path, flag|
+      if path_is_parent_of?(try_path, long_path)
+        short_path = short_path.sub(/\A#{Regexp.escape(try_path.to_s)}/, "$(brew #{flag})")
+        break
+      end
+    end
+
+    short_path
+  end
+end