1 files changed, 203 insertions, 0 deletions
diff --git a/lib/bundler/index.rb b/lib/bundler/index.rb
new file mode 100644
index 0000000000..9aef2dfa12
--- /dev/null
+++ b/lib/bundler/index.rb
@@ -0,0 +1,203 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Index
+    include Enumerable
+
+    def self.build
+      i = new
+      yield i
+      i
+    end
+
+    attr_reader :specs, :duplicates, :sources
+    protected :specs, :duplicates
+
+    RUBY = "ruby"
+    NULL = "\0"
+
+    def initialize
+      @sources = []
+      @cache = {}
+      @specs = {}
+      @duplicates = {}
+    end
+
+    def initialize_copy(o)
+      @sources = o.sources.dup
+      @cache = {}
+      @specs = {}
+      @duplicates = {}
+
+      o.specs.each do |name, hash|
+        @specs[name] = hash.dup
+      end
+      o.duplicates.each do |name, array|
+        @duplicates[name] = array.dup
+      end
+    end
+
+    def inspect
+      "#<#{self.class}:0x#{object_id} sources=#{sources.map(&:inspect)} specs.size=#{specs.size}>"
+    end
+
+    def empty?
+      each { return false }
+      true
+    end
+
+    # Search this index's specs, and any source indexes that this index knows
+    # about, returning all of the results.
+    def search(query)
+      results = local_search(query)
+      return results unless @sources.any?
+
+      @sources.each do |source|
+        results = safe_concat(results, source.search(query))
+      end
+      results.uniq!(&:full_name) unless results.empty? # avoid modifying frozen EMPTY_SEARCH
+      results
+    end
+
+    alias_method :[], :search
+
+    def local_search(query)
+      case query
+      when Gem::Specification, RemoteSpecification, LazySpecification, EndpointSpecification then search_by_spec(query)
+      when String then specs_by_name(query)
+      when Array then specs_by_name_and_version(*query)
+      else
+        raise "You can't search for a #{query.inspect}."
+      end
+    end
+
+    def add(spec)
+      (@specs[spec.name] ||= {}).store(spec.full_name, spec)
+    end
+    alias_method :<<, :add
+
+    def each(&blk)
+      return enum_for(:each) unless blk
+      specs.values.each do |spec_sets|
+        spec_sets.values.each(&blk)
+      end
+      sources.each {|s| s.each(&blk) }
+      self
+    end
+
+    def spec_names
+      names = specs.keys + sources.map(&:spec_names)
+      names.uniq!
+      names
+    end
+
+    def unmet_dependency_names
+      dependency_names.select do |name|
+        search(name).empty?
+      end
+    end
+
+    def dependency_names
+      names = []
+      each do |spec|
+        spec.dependencies.each do |dep|
+          next if dep.type == :development
+          names << dep.name
+        end
+      end
+      names.uniq
+    end
+
+    # Combines indexes proritizing existing specs, like `Hash#reverse_merge!`
+    # Duplicate specs found in `other` are stored in `@duplicates`.
+    def use(other)
+      return unless other
+      other.each do |spec|
+        exist?(spec) ? add_duplicate(spec) : add(spec)
+      end
+      self
+    end
+
+    # Combines indexes proritizing specs from `other`, like `Hash#merge!`
+    # Duplicate specs found in `self` are saved in `@duplicates`.
+    def merge!(other)
+      return unless other
+      other.each do |spec|
+        if existing = find_by_spec(spec)
+          unless dependencies_eql?(existing, spec)
+            Bundler.ui.warn "Local specification for #{spec.full_name} has different dependencies than the remote gem, ignoring it"
+            next
+          end
+
+          add_duplicate(existing)
+        end
+        add spec
+      end
+      self
+    end
+
+    def size
+      @sources.inject(@specs.size) do |size, source|
+        size += source.size
+      end
+    end
+
+    # Whether all the specs in self are in other
+    def subset?(other)
+      all? do |spec|
+        other_spec = other[spec].first
+        other_spec && dependencies_eql?(spec, other_spec) && spec.source == other_spec.source
+      end
+    end
+
+    def dependencies_eql?(spec, other_spec)
+      deps       = spec.runtime_dependencies
+      other_deps = other_spec.runtime_dependencies
+      deps.sort == other_deps.sort
+    end
+
+    def add_source(index)
+      raise ArgumentError, "Source must be an index, not #{index.class}" unless index.is_a?(Index)
+      @sources << index
+      @sources.uniq! # need to use uniq! here instead of checking for the item before adding
+    end
+
+    private
+
+    def safe_concat(a, b)
+      return a if b.empty?
+      return b if a.empty?
+      a.concat(b)
+    end
+
+    def add_duplicate(spec)
+      (@duplicates[spec.name] ||= []) << spec
+    end
+
+    def specs_by_name_and_version(name, version)
+      results = @specs[name]&.values
+      return EMPTY_SEARCH unless results
+      results.select! {|spec| spec.version == version }
+      results
+    end
+
+    def specs_by_name(name)
+      @specs[name]&.values || EMPTY_SEARCH
+    end
+
+    EMPTY_SEARCH = [].freeze
+
+    def search_by_spec(spec)
+      spec = find_by_spec(spec)
+      spec ? [spec] : EMPTY_SEARCH
+    end
+
+    def find_by_spec(spec)
+      @specs[spec.name]&.fetch(spec.full_name, nil)
+    end
+
+    def exist?(spec)
+      @specs[spec.name]&.key?(spec.full_name)
+    end
+  end
+end