Adding specialization of Equals for positions, as they logically need to take...

Adding specialization of Equals for positions, as they logically need to take into account actual sentence context for full comparison.

libwccl/ops/equals.h

@@ -57,6 +57,115 @@ protected:
 	}
 };
 
+/**
+ * Predicate that checks for equality of Positions, given sentence context
+ */
+template <>
+class Equals<Position> : public Predicate {
+public:
+	typedef boost::shared_ptr<Function<Position> > ArgFunctionPtr;
+
+	Equals(const ArgFunctionPtr& arg1_expr, const ArgFunctionPtr& arg2_expr)
+		: arg1_expr_(arg1_expr), arg2_expr_(arg2_expr)
+	{
+		BOOST_ASSERT(arg1_expr_);
+		BOOST_ASSERT(arg2_expr_);
+	}
+
+	virtual std::string to_string(const Corpus2::Tagset& tagset) const {
+		return BinaryFunctionFormatter::to_string(tagset, *this, *arg1_expr_, *arg2_expr_);
+	}
+
+	virtual std::string to_raw_string() const {
+		return BinaryFunctionFormatter::to_raw_string(*this, *arg1_expr_, *arg2_expr_);
+	}
+
+	virtual const std::string raw_operator_name() const {
+		return "equals";
+	}
+
+protected:
+	const ArgFunctionPtr arg1_expr_;
+	const ArgFunctionPtr arg2_expr_;
+
+	typedef FunctionBase::BaseRetValPtr BaseRetValPtr;
+
+	/**
+	 * Take values of arguments from expressions and return True if they are equal,
+	 * False otherwise.
+	 */
+	virtual BaseRetValPtr apply_internal(const SentenceContext& context) const {
+		boost::shared_ptr<Position> arg1 = this->arg1_expr_->apply(context);
+		boost::shared_ptr<Position> arg2 = this->arg2_expr_->apply(context);
+		if(arg1->equals(*arg2)) {
+			return Predicate::True->apply(context);
+		} else {
+			//in the given context both positions can still point nowhere
+			//even if they have different underlying value
+			int abs_pos1 = context.get_abs_position(*arg1);
+			int abs_pos2 = context.get_abs_position(*arg2);
+			if(!context.is_inside(abs_pos1) && !context.is_inside(abs_pos2)) {
+				return Predicate::True->apply(context);
+			}
+		}
+		return Predicate::False->apply(context);
+	}
+};
+
+/**
+ * Predicate that checks for equality of PositionRefs, given sentence context
+ */
+template <>
+class Equals<PositionRef> : public Predicate {
+public:
+	typedef boost::shared_ptr<Function<PositionRef> > ArgFunctionPtr;
+
+	Equals(const ArgFunctionPtr& arg1_expr, const ArgFunctionPtr& arg2_expr)
+		: arg1_expr_(arg1_expr), arg2_expr_(arg2_expr)
+	{
+		BOOST_ASSERT(arg1_expr_);
+		BOOST_ASSERT(arg2_expr_);
+	}
+
+	virtual std::string to_string(const Corpus2::Tagset& tagset) const {
+		return BinaryFunctionFormatter::to_string(tagset, *this, *arg1_expr_, *arg2_expr_);
+	}
+
+	virtual std::string to_raw_string() const {
+		return BinaryFunctionFormatter::to_raw_string(*this, *arg1_expr_, *arg2_expr_);
+	}
+
+	virtual const std::string raw_operator_name() const {
+		return "equals";
+	}
+
+protected:
+	const ArgFunctionPtr arg1_expr_;
+	const ArgFunctionPtr arg2_expr_;
+
+	typedef FunctionBase::BaseRetValPtr BaseRetValPtr;
+
+	/**
+	 * Take values of arguments from expressions and return True if they are equal,
+	 * False otherwise.
+	 */
+	virtual BaseRetValPtr apply_internal(const SentenceContext& context) const {
+		boost::shared_ptr<PositionRef> arg1 = this->arg1_expr_->apply(context);
+		boost::shared_ptr<PositionRef> arg2 = this->arg2_expr_->apply(context);
+		if(arg1->equals(*arg2)) {
+			return Predicate::True->apply(context);
+		} else {
+			//in the given context both position refs can still point nowhere
+			//even if they have different underlying value
+			int abs_pos1 = context.get_abs_position(*arg1);
+			int abs_pos2 = context.get_abs_position(*arg2);
+			if(!context.is_inside(abs_pos1) && !context.is_inside(abs_pos2)) {
+				return Predicate::True->apply(context);
+			}
+		}
+		return Predicate::False->apply(context);
+	}
+};
 } /* end ns Wccl */
 
 #endif // EQUALS_H