# class Gem::SpecFetcher

`SpecFetcher` handles metadata updates from remote gem repositories.

### Public Class Methods

fetcher ()
Source

    # File lib/rubygems/spec_fetcher.rb, line 42
    def self.fetcher
      @fetcher ||= new
    end

Default fetcher instance. Use this instead of `::new` to reduce object allocation.

new (sources = nil)
Source

    # File lib/rubygems/spec_fetcher.rb, line 57
    def initialize(sources = nil)
      @sources = sources || Gem.sources

      @update_cache =
        begin
          File.stat(Gem.user_home).uid == Process.uid
        rescue Errno::EACCES, Errno::ENOENT
          false
        end

      @specs = {}
      @latest_specs = {}
      @prerelease_specs = {}

      @caches = {
        latest: @latest_specs,
        prerelease: @prerelease_specs,
        released: @specs,
      }

      @fetcher = Gem::RemoteFetcher.fetcher
    end

Creates a new `SpecFetcher`. Ordinarily you want to use the default fetcher from `Gem::SpecFetcher::fetcher` which uses the `Gem.sources`.

If you need to retrieve specifications from a different `source`, you can send it as an argument.

### Public Instance Methods

available_specs (type)
Source

    # File lib/rubygems/spec_fetcher.rb, line 243
    def available_specs(type)
      errors = []
      list = {}

      @sources.each_source do |source|
        names = case type
                when :latest
                  tuples_for source, :latest
                when :released
                  tuples_for source, :released
                when :complete
                  names =
                    tuples_for(source, :prerelease, true) +
                    tuples_for(source, :released)

                  names.sort
                when :abs_latest
                  names =
                    tuples_for(source, :prerelease, true) +
                    tuples_for(source, :latest)

                  names.sort
                when :prerelease
                  tuples_for(source, :prerelease)
                else
                  raise Gem::Exception, "Unknown type - :#{type}"
        end
      rescue Gem::RemoteFetcher::FetchError => e
        errors << Gem::SourceFetchProblem.new(source, e)
      else
        list[source] = names
      end

      [list, errors]
    end

Returns a list of gems available for each source in `Gem::sources`.

`type` can be one of 3 values: :released => Return the list of all released specs :complete => Return the list of all specs :latest => Return the list of only the highest version of each gem :prerelease => Return the list of all prerelease only specs

detect (type=:complete) { |tup| ... }
Source

    # File lib/rubygems/spec_fetcher.rb, line 133
    def detect(type=:complete)
      tuples = []

      list, _ = available_specs(type)
      list.each do |source, specs|
        specs.each do |tup|
          if yield(tup)
            tuples << [tup, source]
          end
        end
      end

      tuples
    end

Return all gem name tuples who’s names match `obj`

search_for_dependency (dependency, matching_platform=true)
Source

    # File lib/rubygems/spec_fetcher.rb, line 86
    def search_for_dependency(dependency, matching_platform=true)
      found = {}

      rejected_specs = {}

      list, errors = available_specs(dependency.identity)

      list.each do |source, specs|
        if dependency.name.is_a?(String) && specs.respond_to?(:bsearch)
          start_index = (0...specs.length).bsearch {|i| specs[i].name >= dependency.name }
          end_index   = (0...specs.length).bsearch {|i| specs[i].name > dependency.name }
          specs = specs[start_index...end_index] if start_index && end_index
        end

        found[source] = specs.select do |tup|
          if dependency.match?(tup)
            if matching_platform && !Gem::Platform.match_gem?(tup.platform, tup.name)
              pm = (
                rejected_specs[dependency] ||= \
                  Gem::PlatformMismatch.new(tup.name, tup.version))
              pm.add_platform tup.platform
              false
            else
              true
            end
          end
        end
      end

      errors += rejected_specs.values

      tuples = []

      found.each do |source, specs|
        specs.each do |s|
          tuples << [s, source]
        end
      end

      tuples = tuples.sort_by {|x| x[0].version }

      [tuples, errors]
    end

`Find` and fetch gem name tuples that match `dependency`.

If `matching_platform` is false, gems for all platforms are returned.

spec_for_dependency (dependency, matching_platform=true)
Source

    # File lib/rubygems/spec_fetcher.rb, line 153
    def spec_for_dependency(dependency, matching_platform=true)
      tuples, errors = search_for_dependency(dependency, matching_platform)

      specs = []
      tuples.each do |tup, source|
        spec = source.fetch_spec(tup)
      rescue Gem::RemoteFetcher::FetchError => e
        errors << Gem::SourceFetchProblem.new(source, e)
      else
        specs << [spec, source]
      end

      [specs, errors]
    end

`Find` and fetch specs that match `dependency`.

If `matching_platform` is false, gems for all platforms are returned.

suggest_gems_from_name (gem_name, type = :latest, num_results = 5)
Source

    # File lib/rubygems/spec_fetcher.rb, line 172
    def suggest_gems_from_name(gem_name, type = :latest, num_results = 5)
      gem_name = gem_name.downcase.tr("_-", "")

      # All results for 3-character-or-shorter (minus hyphens/underscores) gem
      # names get rejected, so we just return an empty array immediately instead.
      return [] if gem_name.length <= 3

      max   = gem_name.size / 2
      names = available_specs(type).first.values.flatten(1)

      min_length = gem_name.length - max
      max_length = gem_name.length + max

      gem_name_with_postfix = "#{gem_name}ruby"
      gem_name_with_prefix = "ruby#{gem_name}"

      matches = names.filter_map do |n|
        len = n.name.length
        # If the gem doesn't support the current platform, bail early.
        next unless n.match_platform?

        # If the length is min_length or shorter, we've done `max` deletions.
        # This would be rejected later, so we skip it for performance.
        next if len <= min_length

        # The candidate name, normalized the same as gem_name.
        normalized_name = n.name.downcase
        normalized_name.tr!("_-", "")

        # If the gem is "{NAME}-ruby" and "ruby-{NAME}", we want to return it.
        # But we already removed hyphens, so we check "{NAME}ruby" and "ruby{NAME}".
        next [n.name, 0] if normalized_name == gem_name_with_postfix
        next [n.name, 0] if normalized_name == gem_name_with_prefix

        # If the length is max_length or longer, we've done `max` insertions.
        # This would be rejected later, so we skip it for performance.
        next if len >= max_length

        # If we found an exact match (after stripping underscores and hyphens),
        # that's our most likely candidate.
        # Return it immediately, and skip the rest of the loop.
        return [n.name] if normalized_name == gem_name

        distance = levenshtein_distance gem_name, normalized_name

        # Skip current candidate, if the edit distance is greater than allowed.
        next if distance >= max

        # If all else fails, return the name and the calculated distance.
        [n.name, distance]
      end

      matches = if matches.empty? && type != :prerelease
        suggest_gems_from_name gem_name, :prerelease
      else
        matches.uniq.sort_by {|_name, dist| dist }
      end

      matches.map {|name, _dist| name }.uniq.first(num_results)
    end

Suggests gems based on the supplied `gem_name`. Returns an array of alternative gem names.