Ichthyostega
20f3252892
Yet another chainsaw massacre. One of the most obnoxious annoyances with C++ metaprogramming is the need to insert `typename` and `template` qualifiers into most definitions, to help the compiler to cope with the syntax, which is not context-free. The recent standards adds several clarifications, so that most of these qualifiers are redundant now, at least at places where it is unambiguously clear that only a type can be given. GCC already supports most of these relaxing rules (Clang unfortunately lags way behind with support of newer language features...)
121 lines
2.9 KiB
C++
121 lines
2.9 KiB
C++
/*
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INDEX-TABLE.hpp - helper for lookup and membership check of sequence like data
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Copyright (C)
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2015, Hermann Vosseler <Ichthyostega@web.de>
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**Lumiera** is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2 of the License, or (at your
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option) any later version. See the file COPYING for further details.
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*/
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/** @file index-table.hpp
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** Generic lookup table for a sequence of unique values.
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** This helper facility for detecting differences in data sequences
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** takes a snapshot of the data at construction time and builds a lookup tree.
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** This allows to find the index position of a given key element, and to detect
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** membership.
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**
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** @see diff-index-table-test.cpp
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** @see diff-list-generation-test.cpp
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** @see DiffDetector
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**
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*/
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#ifndef LIB_DIFF_INDEX_TABLE_H
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#define LIB_DIFF_INDEX_TABLE_H
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#include "lib/error.hpp"
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#include "lib/util.hpp"
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#include "lib/format-string.hpp"
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#include <vector>
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#include <map>
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namespace lib {
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namespace diff{
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namespace error = lumiera::error;
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using util::_Fmt;
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/** data snapshot and lookup table */
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template<typename VAL>
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class IndexTable
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{
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std::vector<VAL> data_;
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std::map<VAL,size_t> idx_;
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public:
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template<class SEQ>
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IndexTable(SEQ const& seq)
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{
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size_t i = 0;
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for (auto const& elm : seq)
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{
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__rejectDuplicate(elm);
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data_.push_back (elm);
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idx_[elm] = i++;
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}
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}
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/* === forwarded sequence access === */
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using iterator = std::vector<VAL>::iterator;
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using const_iterator = std::vector<VAL>::const_iterator;
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iterator begin() { return data_.begin(); }
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iterator end() { return data_.end(); }
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const_iterator begin() const { return data_.begin(); }
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const_iterator end() const { return data_.end(); }
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size_t size() const { return data_.size(); }
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VAL const&
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getElement (size_t i) const
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{
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REQUIRE (i < size());
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return data_[i];
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}
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bool
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contains (VAL const& elm) const
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{
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return pos(elm) != size();
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}
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size_t
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pos (VAL const& elm) const
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{
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auto entry = idx_.find (elm);
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return entry==idx_.end()? size()
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: entry->second;
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}
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private:
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void
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__rejectDuplicate (VAL const& elm)
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{
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if (util::contains (idx_, elm))
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throw error::Logic(_Fmt("Attempt to add duplicate %s to index table") % elm);
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}
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};
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}} // namespace lib::diff
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#endif /*LIB_DIFF_INDEX_TABLE_H*/
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