Better handling of filename/extension changes.

lib/build/files/path.rb

@@ -22,6 +22,14 @@ module Build
 	module Files
 		# Represents a file path with an absolute root and a relative offset:
 		class Path
+			def self.split(path)
+				# Effectively dirname and basename:
+				dirname, separator, filename = path.rpartition(File::SEPARATOR)
+				filename, dot, extension = filename.rpartition('.')
+
+				return dirname + separator, filename, dot + extension
+			end
+
 			# Returns the length of the prefix which is shared by two strings.
 			def self.prefix_length(a, b)
 				[a.size, b.size].min.times{|i| return i if a[i] != b[i]}
@@ -128,9 +136,21 @@ def rebase(root)
 				self.class.new(File.join(root, relative_path), root)
 			end
 
-			def with(root: @root, extension: nil)
-				# self.relative_path should be a string so using + to add an extension should be fine.
-				relative_path = extension ? self.relative_path + extension : self.relative_path
+			def with(root: @root, extension: nil, basename: false)
+				relative_path = self.relative_path
+
+				if basename
+					dirname, filename, _ = self.class.split(relative_path)
+
+					# Replace the filename if the basename is supplied:
+					filename = basename if basename.is_a? String
+
+					relative_path = dirname + filename
+				end
+
+				if extension
+					relative_path = relative_path + extension
+				end
 
 				self.class.new(File.join(root, relative_path), root, relative_path)
 			end

lib/build/files/version.rb

@@ -20,6 +20,6 @@
 
 module Build
 	module Files
-		VERSION = "1.0.4"
+		VERSION = "1.0.5"
 	end
 end

spec/build/files/path_spec.rb

@@ -42,6 +42,20 @@ module Build::Files::PathSpec
 		end
 	end
 
+	describe Build::Files::Path.new("/foo/bar.txt") do
+		it "should replace existing file extension" do
+			expect(subject.with(extension: '.jpeg', basename: true)).to be == "/foo/bar.jpeg"
+		end
+
+		it "should append file extension" do
+			expect(subject.with(extension: '.jpeg')).to be == "/foo/bar.txt.jpeg"
+		end
+
+		it "should change basename" do
+			expect(subject.with(basename: 'baz', extension: '.txt')).to be == "/foo/baz.txt"
+		end
+	end
+
 	describe Build::Files::Path.new("/foo/bar/baz", "/foo") do
 		it "should be inspectable" do
 			expect(subject.inspect).to be_include subject.root.to_s