cursor.rb in impala-0.1.3

- old
+ new

@@ -1,6 +1,9 @@
 module Impala
+  # Cursors are used to iterate over result sets without loading them all
+  # into memory at once. This can be useful if you're dealing with lots of
+  # rows. It implements Enumerable, so you can use each/select/map/etc.
   class Cursor
     include Enumerable
 
     def initialize(handle, service, buffer_length=1024)
       @handle = handle
@@ -9,21 +12,29 @@
 
       @buffer_length = buffer_length
       @row_buffer = []
 
       @done = false
-      @closed = false
+      @open = true
     end
 
+    def inspect
+      "#<#{self.class}#{open? ? '' : ' (CLOSED)'}>"
+    end
+
     def each
       while row = fetch_row
         yield row
       end
     end
 
+    # Returns the next available row as a hash, or nil if there are none left.
+    # @return [Hash, nil] the next available row, or nil if there are none
+    #    left
+    # @see #fetch_all
     def fetch_row
-      raise CursorError.new("Cursor has expired or been closed") if @closed
+      raise CursorError.new("Cursor has expired or been closed") unless @open
 
       if @row_buffer.empty?
         if @done
           return nil
         else
@@ -32,16 +43,31 @@
       end
 
       @row_buffer.shift
     end
 
+    # Returns all the remaining rows in the result set.
+    # @return [Array<Hash>] the remaining rows in the result set
+    # @see #fetch_one
     def fetch_all
       self.to_a
     end
 
+    # Close the cursor on the remote server. Once a cursor is closed, you
+    # can no longer fetch any rows from it.
     def close
-      @closed = true
+      @open = false
       @service.close(@handle)
+    end
+
+    # Returns true if the cursor is still open.
+    def open?
+      @open
+    end
+
+    # Returns true if there are any more rows to fetch.
+    def has_more?
+      !@done || !@row_buffer.empty?
     end
 
     private
 
     def fetch_more
\ No newline at end of file