added files from the gitrb project, which seems abandoned, but which is great code

1 files changed, 44 insertions, 0 deletions

diff --git a/lib/git/raw/internal/mmap.rb b/lib/git/raw/internal/mmap.rb
new file mode 100644
index 0000000..d7390b1
--- /dev/null
+++ b/lib/git/raw/internal/mmap.rb
@@ -0,0 +1,44 @@
+begin
+  require 'mmap'
+rescue LoadError
+
+module Git module Raw module Internal
+  class Mmap
+    def initialize(file)
+      @file = file
+      @offset = nil
+    end
+
+    def unmap
+      @file = nil
+    end
+
+    def [](*idx)
+      idx = idx[0] if idx.length == 1
+      case idx
+      when Range
+        offset = idx.first
+        len = idx.last - idx.first + idx.exclude_end? ? 0 : 1
+      when Fixnum
+        offset = idx
+        len = nil
+      when Array
+        offset, len = idx
+      else
+        raise RuntimeError, "invalid index param: #{idx.class}"
+      end
+      if @offset != offset
+        @file.seek(offset)
+      end
+      @offset = offset + len ? len : 1
+      if not len
+        @file.read(1)[0]
+      else
+        @file.read(len)
+      end
+    end
+  end
+end end
+
+end     # rescue LoadError
+