harfbuzz/src/hb-iter.hh

109 lines
4.1 KiB
C++
Raw Normal View History

/*
* Copyright © 2018 Google, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
*/
#ifndef HB_ITER_HH
#define HB_ITER_HH
#include "hb.hh"
/* Unified iterator object.
*
* The goal of this template is to make the same iterator interface
* available to all types, and make it very easy and compact to use.
2018-12-21 06:54:55 +01:00
* hb_iter_tator objects are small, light-weight, objects that can be
* copied by value. If the collection / object being iterated on
2018-12-21 06:54:55 +01:00
* is writable, then the iterator returns lvalues, otherwise it
* returns rvalues.
*/
2018-12-21 06:54:55 +01:00
/* Base class for all iterators. */
template <typename Iter>
struct hb_iter_t
{
2018-12-21 06:54:55 +01:00
typedef Iter type_t;
typedef typename Iter::__type__ item_type_t;
/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
const type_t* thiz () const { return static_cast<const type_t *> (this); }
type_t* thiz () { return static_cast< type_t *> (this); }
/* Operators. */
operator type_t () { return iter(); }
explicit_operator bool () const { return more (); }
item_type_t& operator * () { return item (); }
item_type_t& operator [] (unsigned i) { return item (i); }
type_t& operator += (unsigned count) { forward (count); return thiz(); }
type_t& operator ++ () { next (); return thiz(); }
2018-12-21 07:17:35 +01:00
type_t& operator -= (unsigned count) { rewind (count); return thiz(); }
type_t& operator -- () { prev (); return thiz(); }
2018-12-21 06:54:55 +01:00
type_t operator + (unsigned count) { type_t c (*thiz()); c += count; return c; }
2018-12-21 07:17:35 +01:00
type_t operator ++ (int) { type_t c (*thiz()); ++*thiz(); return c; }
type_t operator - (unsigned count) { type_t c (*thiz()); c -= count; return c; }
type_t operator -- (int) { type_t c (*thiz()); --*thiz(); return c; }
2018-12-21 06:54:55 +01:00
/* Methods. */
type_t iter () const { return *thiz(); }
item_type_t item () const { return thiz()->__item__ (); }
item_type_t item (unsigned i) const { return thiz()->__item__ (i); }
bool more () const { return thiz()->__more__ (); }
2018-12-21 07:17:35 +01:00
void next () { thiz()->__next__ (); }
2018-12-21 06:54:55 +01:00
void forward (unsigned n) { thiz()->__forward__ (n); }
2018-12-21 07:17:35 +01:00
void prev () { thiz()->__prev__ (); }
void rewind (unsigned n) { thiz()->__rewind__ (n); }
2018-12-21 06:54:55 +01:00
unsigned len () const { return thiz()->__len__ (); }
/*
* Subclasses overrides:
*/
/* Item type. */
//typedef ... __type__;
/* Access: Implement __item__(), or __item__(n) if random-access. */
item_type_t __item__ () const { return thiz()->item (0); }
item_type_t __item__ (unsigned i) const { return *(thiz() + i); }
/* Termination: Implement __more__() or __end__(). */
bool __more__ () const { return item () != thiz()->__end__ (); }
const item_type_t& __end__ () const { return type_t::__sentinel__; }
/* Advancing: Implement __next__(), or __forward__() if random-access. */
void __next__ () { thiz()->forward (1); }
void __forward__ (unsigned n) { while (n--) next (); }
2018-12-21 07:17:35 +01:00
/* Rewinding: Implement __prev__() or __rewind__() if bidirectional. */
void __prev__ () { thiz()->rewind (1); }
void __rewind__ (unsigned n) { while (n--) prev (); }
2018-12-21 06:54:55 +01:00
/* Population: Implement __len__() if known. */
unsigned __len__ () const
{ type_t c (*thiz()); unsigned l = 0; while (c) { c++; l++; }; return l; }
};
#endif /* HB_ITER_HH */