1 files changed, 63 insertions, 0 deletions
diff --git a/lib/arel/predicates.rb b/lib/arel/predicates.rb
new file mode 100644
index 0000000000..ccaec1ad93
--- /dev/null
+++ b/lib/arel/predicates.rb
@@ -0,0 +1,63 @@
+module Arel
+  class Predicate
+    def ==(other)
+      self.class == other.class
+    end
+  end
+
+  class Binary < Predicate
+    attr_reader :operand1, :operand2
+
+    def initialize(operand1, operand2)
+      @operand1, @operand2 = operand1, operand2
+    end
+
+    def ==(other)
+      super and @operand1 == other.operand1 and @operand2 == other.operand2
+    end
+    
+    def bind(relation)
+      self.class.new(operand1.bind(relation), operand2.bind(relation))
+    end
+    
+    def to_sql(formatter = nil)
+      "#{operand1.to_sql} #{predicate_sql} #{operand1.format(operand2)}"
+    end
+  end
+
+  class Equality < Binary
+    def ==(other)
+      self.class == other.class and
+        ((operand1 == other.operand1 and operand2 == other.operand2) or
+         (operand1 == other.operand2 and operand2 == other.operand1))
+    end
+
+    def predicate_sql
+      operand2.equality_predicate_sql
+    end
+  end
+
+  class GreaterThanOrEqualTo < Binary
+    def predicate_sql; '>=' end
+  end
+
+  class GreaterThan < Binary
+    def predicate_sql; '>' end
+  end
+
+  class LessThanOrEqualTo < Binary
+    def predicate_sql; '<=' end
+  end
+
+  class LessThan < Binary
+    def predicate_sql; '<' end
+  end
+
+  class Match < Binary
+    alias_method :regexp, :operand2
+  end
+  
+  class In < Binary
+    def predicate_sql; operand2.inclusion_predicate_sql end
+  end
+end
+\ No newline at end of file