weakagreement.h

#ifndef LIBWCCL_OPS_FUNCTIONS_BOOL_PREDICATE_WEAKAGREEMENT_H
#define LIBWCCL_OPS_FUNCTIONS_BOOL_PREDICATE_WEAKAGREEMENT_H

#include <libwccl/ops/functions/bool/predicate.h>
#include <libwccl/values/position.h>

namespace Wccl {

/**
 * Predicate checking weak agreement on a range of tokens.
 */
class WeakAgreement : public Predicate
{
public:
	typedef boost::shared_ptr<Function<Position> > PosFunctionPtr;
	typedef boost::shared_ptr<Function<TSet> > TSetFunctionPtr;

	WeakAgreement(
		const PosFunctionPtr& left_pos_expr,
		const PosFunctionPtr& right_pos_expr,
		const TSetFunctionPtr& attribs_expr,
		const Corpus2::Tagset& tagset)
		: left_pos_expr_(left_pos_expr),
		  right_pos_expr_(right_pos_expr),
		  attribs_expr_(attribs_expr),
		  tagset_(tagset)
	{
		BOOST_ASSERT(left_pos_expr_);
		BOOST_ASSERT(right_pos_expr_);
		BOOST_ASSERT(attribs_expr);
	}

	/**
	 * @returns Name of the function: "wagr"
	 */
	std::string raw_name() const {
		return "wagr";
	}

	/**
	 * @returns String reperesentation of the predicate in form of
	 * "wagr(pos1_expr, pos2_expr, attrib_expr)"
	 */
	std::string to_string(const Corpus2::Tagset& tagset) const;

protected:
	const PosFunctionPtr left_pos_expr_;
	const PosFunctionPtr right_pos_expr_;
	const TSetFunctionPtr attribs_expr_;
	const Corpus2::Tagset& tagset_;

	/**
	 * Gets start and end positions for range from arguments.
	 * Range is trimmed to sentence boundaries.
	 * If either of the positions is Nowhere, or range is empty, False
	 * is returned.
	 * Otherwise, weak agreement for given attributes is checked
	 * on the specified range of tokens and result of this test is returned.
	 * @returns True if the tokens in specified range are in weak
	 * agreement for specified attributes. False otherwise, including
	 * cases of empty range or either of the positions being Nowhere.
	 */
	BaseRetValPtr apply_internal(const FunExecContext& context) const;

	/**
	 * Writes raw string reperesentation of the predicate in form of
	 * "wagr(pos1_raw_expr, pos2_raw_expr, attribs_raw_expr)"
	 * @note This version doesn't require a Tagset, but will
	 * be incomplete and/or contain internal info.
	 * @returns Stream written to.
	 */
	std::ostream& write_to(std::ostream& ostream) const;

};

} /* end ns Wccl */

#endif // LIBWCCL_OPS_FUNCTIONS_BOOL_PREDICATE_WEAKAGREEMENT_H