Tweak some code.

MatchResult - change constructor so when you provide Match it defaults to matched = true.
TokenCondition - be a bit defensive about possibility of inner predicates changing $_

libwccl/ops/match/conditions/tokencondition.cpp

@@ -3,10 +3,10 @@
 
 namespace Wccl {
 
-
 TokenCondition::TokenCondition(const boost::shared_ptr<Function<Bool> >& predicate)
 	: _predicate(predicate)
 {
+	BOOST_ASSERT(_predicate);
 }
 
 std::string TokenCondition::name() const
@@ -21,14 +21,15 @@ std::string TokenCondition::to_string(const Corpus2::Tagset& tagset) const
 
 MatchResult TokenCondition::apply(boost::shared_ptr<Position> iter_pos, const FunExecContext& context) const
 {
+	int orig_iter = iter_pos->get_value();
 	if (_predicate->apply(context)->get_value()) {
-		boost::shared_ptr<Match> match = boost::shared_ptr<Match>(new TokenMatch(
-				context.sentence_context().get_abs_position(*iter_pos)));
+		boost::shared_ptr<Match> match(new TokenMatch(context.sentence_context().get_abs_position(*iter_pos)));
 		// increase the $_ variable by one after successful token match
-		iter_pos->set_value(iter_pos->get_value() + 1);
-		return MatchResult(true, match);
+		iter_pos->set_value(orig_iter + 1);
+		return MatchResult(match);
 	}
 	else {
+		iter_pos->set_value(orig_iter);
 		return MatchResult();
 	}
 }

libwccl/ops/match/matchresult.h

@@ -12,7 +12,7 @@ namespace Wccl {
 class MatchResult
 {
 public:
-	MatchResult(bool matched, const boost::shared_ptr<Match>& match);
+	MatchResult(const boost::shared_ptr<Match>& match);
 	MatchResult();
 	boost::shared_ptr<Match> get_match() const;
 	bool matched() const;
@@ -30,8 +30,8 @@ MatchResult::MatchResult() : _matched(false), _match() {
 }
 
 inline
-MatchResult::MatchResult(bool matched, const boost::shared_ptr<Match>& match)
-	: _matched(matched),
+MatchResult::MatchResult(const boost::shared_ptr<Match>& match)
+	: _matched(true),
 	  _match(match) {
 }