/*
* opencog/atoms/free/Quotation.h
*
* Copyright (C) 2016 OpenCog Foundation
* All Rights Reserved
*
* Written by Nil Geisweiller
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License v3 as
* published by the Free Software Foundation and including the exceptions
* at http://opencog.org/wiki/Licenses
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program; if not, write to:
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef _OPENCOG_QUOTATION_H
#define _OPENCOG_QUOTATION_H
#include <string>
#include <opencog/util/empty_string.h>
#include <opencog/atoms/base/Handle.h>
namespace opencog
{
/** \addtogroup grp_atomspace
* @{
*/
/**
* Quotation data and methods. See http://wiki.opencog.org/w/QuoteLink.
*/
class Quotation
{
int _quotation_level;
bool _local_quote;
public:
explicit Quotation(int ql=0, bool lq=false);
int level() const;
bool is_locally_quoted() const;
bool is_quoted() const;
bool is_unquoted() const;
/**
* Return true iff the type is QUOTE_LINK, UNQUOTE_LINK or
* LOCAL_QUOTE_LINK.
*/
static bool is_quotation_type(Type t);
/**
* Check whether the current atom would be consumed as quotation
* operator or not. More specifically:
*
* 1. An unquoted QuoteLink would be consumed, turning the
* quotation state from unquoted to quoted.
*
* 2. An UnquoteLink with quotation level of 1 would be consumed,
* turning the quotation state from quoted to unquoted.
*
* 3. An unquoted LocalQuoteLink would be consumed, turning
* temporarily the quotation state from unquoted to quoted.
*
* Remark: you must call this function before calling update,
* otherwise the result will not be correct on the current atom.
*/
bool consumable(Type t) const;
/**
* Increment, decrement or change local quote given the type of
* the current atom before handing the quotation to the outgoing.
*/
void update(Type t);
/**
* Comparison
*/
bool operator<(const Quotation& quotation) const;
bool operator==(const Quotation& quotation) const;
std::string to_string(const std::string& indent) const;
};
/// Return true if there are unquotes below the given atom. From this,
/// we can infer that the Atom itself is quoted. Roughly speaking,
/// this performs the 'opposite' of `class Quotation` above.
bool unquoted_below(const Handle&);
bool unquoted_below(const HandleSeq&);
// Debugging helpers see
// http://wiki.opencog.org/w/Development_standards#Print_OpenCog_Objects
// The reason indent is not an optional argument with default is
// because gdb doesn't support that, see
// http://stackoverflow.com/questions/16734783 for more explanation.
std::string oc_to_string(const Quotation& quotation,
const std::string& indent=empty_string);
/** @}*/
} // namespace opencog
#endif // _OPENCOG_QUOTATION_H