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diff --git a/lib/sbom/package_url.rb b/lib/sbom/package_url.rb
new file mode 100644
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+++ b/lib/sbom/package_url.rb
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+# frozen_string_literal: true
+
+# MIT License
+#
+# Copyright (c) 2021 package-url
+# Portions Copyright 2022 Gitlab B.V.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+module Sbom
+  # A package URL, or _purl_, is a URL string used to
+  # identify and locate a software package in a mostly universal and uniform way
+  # across programing languages, package managers, packaging conventions, tools,
+  # APIs and databases.
+  #
+  # A purl is a URL composed of seven components:
+  #
+  # ```
+  # scheme:type/namespace/name@version?qualifiers#subpath
+  # ```
+  #
+  # For example,
+  # the package URL for this Ruby package at version 0.1.0 is
+  # `pkg:ruby/mattt/packageurl-ruby@0.1.0`.
+  #
+  # More details on the package URL format can be found in the purl specification:
+  # https://github.com/package-url/purl-spec/blob/0b1559f76b79829e789c4f20e6d832c7314762c5/PURL-SPECIFICATION.rst
+  class PackageUrl
+    # Raised when attempting to parse an invalid package URL string.
+    # @see #parse
+    InvalidPackageUrl = Class.new(ArgumentError)
+
+    # The URL scheme, which has a constant value of `"pkg"`.
+    def scheme
+      'pkg'
+    end
+
+    # The package type or protocol, such as `"gem"`, `"npm"`, and `"github"`.
+    attr_reader :type
+
+    # A name prefix, specific to the type of package.
+    # For example, an npm scope, a Docker image owner, or a GitHub user.
+    attr_reader :namespace
+
+    # The name of the package.
+    attr_reader :name
+
+    # The version of the package.
+    attr_reader :version
+
+    # Extra qualifying data for a package, specific to the type of package.
+    # For example, the operating system or architecture.
+    attr_reader :qualifiers
+
+    # An extra subpath within a package, relative to the package root.
+    attr_reader :subpath
+
+    # Constructs a package URL from its components
+    # @param type [String] The package type or protocol.
+    # @param namespace [String] A name prefix, specific to the type of package.
+    # @param name [String] The name of the package.
+    # @param version [String] The version of the package.
+    # @param qualifiers [Hash] Extra qualifying data for a package, specific to the type of package.
+    # @param subpath [String] An extra subpath within a package, relative to the package root.
+    def initialize(type:, name:, namespace: nil, version: nil, qualifiers: nil, subpath: nil)
+      @type = type&.downcase
+      @namespace = namespace
+      @name = name
+      @version = version
+      @qualifiers = qualifiers
+      @subpath = subpath
+
+      ArgumentValidator.new(self).validate!
+    end
+
+    # Creates a new PackageUrl from a string.
+    # @param [String] string The package URL string.
+    # @raise [InvalidPackageUrl] If the string is not a valid package URL.
+    # @return [PackageUrl]
+    def self.parse(string)
+      Decoder.new(string).decode!
+    end
+
+    # Returns a hash containing the
+    # scheme, type, namespace, name, version, qualifiers, and subpath components
+    # of the package URL.
+    def to_h
+      {
+        scheme: scheme,
+        type: @type,
+        namespace: @namespace,
+        name: @name,
+        version: @version,
+        qualifiers: @qualifiers,
+        subpath: @subpath
+      }
+    end
+
+    # Returns a string representation of the package URL.
+    # Package URL representations are created according to the instructions from
+    # https://github.com/package-url/purl-spec/blob/0b1559f76b79829e789c4f20e6d832c7314762c5/PURL-SPECIFICATION.rst#how-to-build-purl-string-from-its-components.
+    def to_s
+      Encoder.new(self).encode
+    end
+  end
+end