From 9aaaf8b6c9832dcbebdf24fbf5720987a4ae80d2 Mon Sep 17 00:00:00 2001
From: Masatoshi SEKI <m_seki@mva.biglobe.ne.jp>
Date: Wed, 14 Sep 2011 01:06:56 +0900
Subject: [PATCH] head_tag

---
 lib/drip.rb   | 33 +++++++++++++++++++++++++++++++--
 test/basic.rb | 32 +++++++++++++++++++++++++-------
 2 files changed, 56 insertions(+), 9 deletions(-)

diff --git a/lib/drip.rb b/lib/drip.rb
index b5c1030..0be72e4 100644
--- a/lib/drip.rb
+++ b/lib/drip.rb
@@ -8,6 +8,26 @@ class Drip
   def inspect; to_s; end
 
   class ImmutableDrip
+    class Generator
+      def initialize(pool=[], tag=[])
+        @pool = pool
+        @tag = tag
+      end
+
+      def add(key, value, *tag)
+        @pool << [key, value]
+        tag.uniq.each do |t|
+          @tag << [[t, key], value]
+        end
+      end
+      
+      def generate
+        ImmutableDrip.new(@pool.sort, @tag.sort)
+      end
+    end
+
+    INF = 1.0/0
+
     def initialize(pool=[], tag=[])
       @pool = pool
       @tag = tag
@@ -35,6 +55,15 @@ def read_tag(key, tag, n=1)
       }
     end
 
+    def head_tag(n, tag)
+      lower = lower_boundary(@tag, [tag, 0])
+      upper = upper_boundary(@tag, [tag, INF])
+      lower = [lower, upper - n].max
+      @tag[lower ... upper].collect {|kv|
+        [kv[0][1], *kv[1].to_a]
+      }
+    end
+
     def head(n=1, tag=nil)
       return head_tag(n, tag) if tag
       n = @pool.size < n ? @pool.size : n
@@ -61,7 +90,7 @@ def lower_boundary(ary, key)
       upper = ary.size
       while lower + 1 != upper
         mid = (lower + upper).div(2)
-        if key > ary[mid][0]
+        if (ary[mid][0] <=> key) < 0
           lower = mid
         else
           upper = mid
@@ -75,7 +104,7 @@ def upper_boundary(ary, key)
       upper = ary.size
       while lower + 1 != upper
         mid = (lower + upper).div(2)
-        if key >= ary[mid][0]
+        if (ary[mid][0] <=> key) <= 0
           lower = mid
         else
           upper = mid
diff --git a/test/basic.rb b/test/basic.rb
index d410e4a..aabe8e0 100644
--- a/test/basic.rb
+++ b/test/basic.rb
@@ -201,14 +201,19 @@ def test_bsearch
     assert_equal(8, im.upper_boundary(ary, 'g'))
   end
 
+  def add_to_gen(gen, key, value, *tag)
+    gen.add(key, [value, *tag], *tag)
+  end
+
   def test_fetch_and_read_wo_tag
-    ary = []
-    ary << [21, ['a']]
-    ary << [39, ['b']]
-    ary << [60, ['c', 'tag']]
-    ary << [99, ['d', 'tag']]
-    
-    im = Drip::ImmutableDrip.new(ary, [])
+    gen = Drip::ImmutableDrip::Generator.new
+    add_to_gen(gen, 21, 'a')
+    add_to_gen(gen, 99, 'd', 'tag')
+    add_to_gen(gen, 39, 'b')
+    add_to_gen(gen, 60, 'c', 'tag')
+
+    im = gen.generate
+
     assert_equal(nil, im.fetch(20))
     assert_equal(['a'], im.fetch(21))
     assert_equal(nil, im.fetch(23))
@@ -242,4 +247,17 @@ def test_fetch_and_read_wo_tag
     assert_equal([99, 'd', 'tag'], im.newer(60))
     assert_equal(nil, im.newer(99))
   end
+
+  def test_read_w_tag
+    gen = Drip::ImmutableDrip::Generator.new
+    add_to_gen(gen, 21, 'a')
+    add_to_gen(gen, 39, 'b', 'b', 'tag')
+    add_to_gen(gen, 60, 'c', 'c', 'tag')
+    add_to_gen(gen, 99, 'd', 'tag', 'd')
+    add_to_gen(gen, 159, 'e', 'tag2', 'e')
+    im = gen.generate
+    
+    assert_equal([[99, 'd', 'tag', 'd']], im.head(1, 'tag'))
+    assert_equal([[99, 'd', 'tag', 'd']], im.head(1, 'd'))
+  end
 end