1 files changed, 79 insertions, 5 deletions
diff --git a/activerecord/lib/active_record/statement_cache.rb b/activerecord/lib/active_record/statement_cache.rb
index dd4ee0c4a0..aece446384 100644
--- a/activerecord/lib/active_record/statement_cache.rb
+++ b/activerecord/lib/active_record/statement_cache.rb
@@ -14,13 +14,87 @@ module ActiveRecord
   # The relation returned by the block is cached, and for each +execute+ call the cached relation gets duped.
   # Database is queried when +to_a+ is called on the relation.
   class StatementCache
-    def initialize
-      @relation = yield
-      raise ArgumentError.new("Statement cannot be nil") if @relation.nil?
+    class Substitute; end
+
+    class Query
+      def initialize(sql)
+        @sql = sql
+      end
+
+      def sql_for(binds, connection)
+        @sql
+      end
+    end
+
+    class PartialQuery < Query
+      def initialize values
+        @values = values
+        @indexes = values.each_with_index.find_all { |thing,i|
+          Arel::Nodes::BindParam === thing
+        }.map(&:last)
+      end
+
+      def sql_for(binds, connection)
+        val = @values.dup
+        binds = binds.dup
+        @indexes.each { |i| val[i] = connection.quote(*binds.shift.reverse) }
+        val.join
+      end
+    end
+
+    def self.query(visitor, ast)
+      Query.new visitor.accept(ast, Arel::Collectors::SQLString.new).value
+    end
+
+    def self.partial_query(visitor, ast, collector)
+      collected = visitor.accept(ast, collector).value
+      PartialQuery.new collected
+    end
+
+    class Params
+      def bind; Substitute.new; end
     end
 
-    def execute
-      @relation.dup.to_a
+    class BindMap
+      def initialize(bind_values)
+        @indexes   = []
+        @bind_values = bind_values
+
+        bind_values.each_with_index do |(_, value), i|
+          if Substitute === value
+            @indexes << i
+          end
+        end
+      end
+
+      def bind(values)
+        bvs = @bind_values.map { |pair| pair.dup }
+        @indexes.each_with_index { |offset,i| bvs[offset][1] = values[i] }
+        bvs
+      end
+    end
+
+    attr_reader :bind_map, :query_builder
+
+    def self.create(connection, block = Proc.new)
+      relation      = block.call Params.new
+      bind_map      = BindMap.new relation.bind_values
+      query_builder = connection.cacheable_query relation.arel
+      new query_builder, bind_map
+    end
+
+    def initialize(query_builder, bind_map)
+      @query_builder = query_builder
+      @bind_map      = bind_map
+    end
+
+    def execute(params, klass, connection)
+      bind_values = bind_map.bind params
+
+      sql = query_builder.sql_for bind_values, connection
+
+      klass.find_by_sql sql, bind_values
     end
+    alias :call :execute
   end
 end