Absorb gitlab_git

1 files changed, 131 insertions, 0 deletions

diff --git a/lib/gitlab/git/attributes.rb b/lib/gitlab/git/attributes.rb
new file mode 100644
index 00000000000..42140ecc993
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+++ b/lib/gitlab/git/attributes.rb
@@ -0,0 +1,131 @@
+module Gitlab
+  module Git
+    # Class for parsing Git attribute files and extracting the attributes for
+    # file patterns.
+    #
+    # Unlike Rugged this parser only needs a single IO call (a call to `open`),
+    # vastly reducing the time spent in extracting attributes.
+    #
+    # This class _only_ supports parsing the attributes file located at
+    # `$GIT_DIR/info/attributes` as GitLab doesn't use any other files
+    # (`.gitattributes` is copied to this particular path).
+    #
+    # Basic usage:
+    #
+    #     attributes = Gitlab::Git::Attributes.new(some_repo.path)
+    #
+    #     attributes.attributes('README.md') # => { "eol" => "lf }
+    class Attributes
+      # path - The path to the Git repository.
+      def initialize(path)
+        @path = File.expand_path(path)
+        @patterns = nil
+      end
+
+      # Returns all the Git attributes for the given path.
+      #
+      # path - A path to a file for which to get the attributes.
+      #
+      # Returns a Hash.
+      def attributes(path)
+        full_path = File.join(@path, path)
+
+        patterns.each do |pattern, attrs|
+          return attrs if File.fnmatch?(pattern, full_path)
+        end
+
+        {}
+      end
+
+      # Returns a Hash containing the file patterns and their attributes.
+      def patterns
+        @patterns ||= parse_file
+      end
+
+      # Parses an attribute string.
+      #
+      # These strings can be in the following formats:
+      #
+      #     text      # => { "text" => true }
+      #     -text     # => { "text" => false }
+      #     key=value # => { "key" => "value" }
+      #
+      # string - The string to parse.
+      #
+      # Returns a Hash containing the attributes and their values.
+      def parse_attributes(string)
+        values = {}
+        dash = '-'
+        equal = '='
+        binary = 'binary'
+
+        string.split(/\s+/).each do |chunk|
+          # Data such as "foo = bar" should be treated as "foo" and "bar" being
+          # separate boolean attributes.
+          next if chunk == equal
+
+          key = chunk
+
+          # Input: "-foo"
+          if chunk.start_with?(dash)
+            key = chunk.byteslice(1, chunk.length - 1)
+            value = false
+
+          # Input: "foo=bar"
+          elsif chunk.include?(equal)
+            key, value = chunk.split(equal, 2)
+
+          # Input: "foo"
+          else
+            value = true
+          end
+
+          values[key] = value
+
+          # When the "binary" option is set the "diff" option should be set to
+          # the inverse. If "diff" is later set it should overwrite the
+          # automatically set value.
+          values['diff'] = false if key == binary && value
+        end
+
+        values
+      end
+
+      # Iterates over every line in the attributes file.
+      def each_line
+        full_path = File.join(@path, 'info/attributes')
+
+        return unless File.exist?(full_path)
+
+        File.open(full_path, 'r') do |handle|
+          handle.each_line do |line|
+            break unless line.valid_encoding?
+
+            yield line.strip
+          end
+        end
+      end
+
+      private
+
+      # Parses the Git attributes file.
+      def parse_file
+        pairs = []
+        comment = '#'
+
+        each_line do |line|
+          next if line.start_with?(comment) || line.empty?
+
+          pattern, attrs = line.split(/\s+/, 2)
+
+          parsed = attrs ? parse_attributes(attrs) : {}
+
+          pairs << [File.join(@path, pattern), parsed]
+        end
+
+        # Newer entries take precedence over older entries.
+        pairs.reverse.to_h
+      end
+    end
+  end
+end