Some checks for Position operating on sentence context.

Checks wether Position is_inside, is_outside, or equals to other Position given the SentenceContext.

libwccl/values/position.cpp

 #include <libwccl/values/position.h>
+#include <libwccl/sentencecontext.h>
 #include <boost/lexical_cast.hpp>
+
 namespace Wccl {
 
 const char* Position::type_name = "Position";
@@ -25,4 +27,10 @@ std::string Position::var_repr(const std::string &var_name)
 	return ss.str();
 }
 
+bool Position::is_inside(const SentenceContext& context) const
+{
+	int abs_position = context.get_abs_position(*this);
+	return context.is_inside(abs_position);
+}
+
 } /* end ns Wccl */

libwccl/values/position.h

@@ -7,6 +7,8 @@
 
 namespace Wccl {
 
+class SentenceContext;
+
 class Position : public Value
 {
 public:
@@ -32,10 +34,36 @@ public:
 	/// Value override
 	std::string to_raw_string() const;
 
-	bool equals(const Position& other) {
+	/**
+	 * @returns True if Position is within bounds of a sentence, false otherwise.
+	 */
+	bool is_inside(const SentenceContext& context) const;
+
+	/**
+	 * @returns True if Position is outside of bounds of a sentence, false otherwise.
+	 */
+	bool is_outside(const SentenceContext& context) const {
+		return !is_inside(context);
+	}
+	/**
+	 * @returns True if underlying position values are equal, false otherwise.
+	 * @note This version does not take into account sentence context, only
+	 * the raw value of position.
+	 */
+	bool equals(const Position& other) const {
 		return val_ == other.val_;
 	}
 
+	/**
+	 * @returns True if positions are equal in context of a sentence, false otherwise.
+	 * @note This version determines if position values point outside of a sentence,
+	 * and if both of them do, they are considered to be equal as well (both "nowhere").
+	 */
+	bool equals(const Position& other, const SentenceContext& context) const
+	{
+		return equals(other) || is_outside(context) && other.is_outside(context);
+	}
+
 private:
 	int val_;
 };