add a cached Wiki#tree_map_for method

lib/gollum/wiki.rb

@@ -63,6 +63,7 @@ module Gollum
       @base_path  = options[:base_path]  || "/"
       @page_class = options[:page_class] || self.class.page_class
       @file_class = options[:file_class] || self.class.file_class
+      clear_cache
     end
 
     # Public: check whether the wiki's git repo exists on the filesystem.
@@ -235,6 +236,20 @@ module Gollum
     # Returns the String path.
     attr_reader :path
 
+    # Gets a Hash cache of refs to commit SHAs.
+    #
+    #   {"master" => "abc123", ...}
+    #
+    # Returns the Hash cache.
+    attr_reader :ref_map
+
+    # Gets a Hash cache of commit SHAs to a recursive tree of blobs.
+    #
+    #   {"abc123" => [["lib/foo.rb", "blob-sha"], [file, sha], ...], ...}
+    #
+    # Returns the Hash cache.
+    attr_reader :tree_map
+
     # Normalize the data.
     #
     # data - The String data to be normalized.
@@ -348,5 +363,69 @@ module Gollum
       commit[:email]  = self.class.default_committer_email if commit[:email].to_s.empty?
       commit
     end
+
+    # Finds a full listing of files and their blob SHA for a given ref.  Each
+    # listing is cached based on its actual commit SHA.
+    #
+    # ref - A String ref that is either a commit SHA or references one.
+    #
+    # Returns an Array of [filename, sha] Arrays.
+    def tree_map_for(ref)
+      sha = @ref_map[ref] || ref
+      @tree_map[sha] || begin
+        real_sha              = @repo.git.rev_list({:max_count=>1}, ref)
+        @ref_map[ref]         = real_sha if real_sha != ref
+        @tree_map[real_sha] ||= parse_tree_for(real_sha)
+      end
+    end
+
+    # Finds the full listing of files and their blob SHA for a given commit
+    # SHA.  No caching or ref lookups are performed.
+    #
+    # sha - String commit SHA.
+    #
+    # Returns an Array of [filename, sha] Arrays.
+    def parse_tree_for(sha)
+      tree  = @repo.git.native(:ls_tree, {:r => true, :z => true}, sha)
+      items = []
+      tree.split("\0").each do |line|
+        items << parse_tree_line(line)
+      end
+      items
+    end
+
+    # Parses a line of output from the `ls-tree` command.
+    #
+    # line - A String line of output:
+    #          "100644 blob 839c2291b30495b9a882c17d08254d3c90d8fb53	Home.md"
+    #
+    # Returns an Array of [filename, sha].
+    def parse_tree_line(line)
+      data, name = line.split("\t")
+      mode, type, sha = data.split(' ')
+      name = decode_git_path(name)
+      [name, sha]
+    end
+
+    # Decode octal sequences (\NNN) in tree path names.
+    #
+    # path - String path name.
+    #
+    # Returns a decoded String.
+    def decode_git_path(path)
+      if path[0] == ?" && path[-1] == ?"
+        path = path[1...-1]
+        path.gsub!(/\\\d{3}/)   { |m| m[1..-1].to_i(8).chr }
+      end
+      path.gsub!(/\\[rn"\\]/) { |m| eval(%("#{m.to_s}")) }
+      path.downcase!
+      path
+    end
+
+    # Resets the ref and tree caches for this wiki.
+    def clear_cache
+      @ref_map  = {}
+      @tree_map = {}
+    end
   end
 end

test/test_wiki.rb

@@ -53,6 +53,21 @@ context "Wiki" do
     assert_equal({:message => 'abc', :name => 'bob', :email => 'foo@bar.com'},
       @wiki.normalize_commit(commit.dup))
   end
+
+  test "#tree_map_for caches ref and tree" do
+    assert @wiki.ref_map.empty?
+    assert @wiki.tree_map.empty?
+    @wiki.tree_map_for 'master'
+    assert_equal({"master"=>"60f12f4254f58801b9ee7db7bca5fa8aeefaa56b"}, @wiki.ref_map)
+    assert_equal 'bilbo-baggins.md', @wiki.tree_map['60f12f4254f58801b9ee7db7bca5fa8aeefaa56b'][0][0]
+  end
+
+  test "#tree_map_for only caches tree for commit" do
+    assert @wiki.tree_map.empty?
+    @wiki.tree_map_for '60f12f4254f58801b9ee7db7bca5fa8aeefaa56b'
+    assert @wiki.ref_map.empty?
+    assert_equal 'bilbo-baggins.md', @wiki.tree_map['60f12f4254f58801b9ee7db7bca5fa8aeefaa56b'][0][0]
+  end
 end
 
 context "Wiki page previewing" do