138 lines
3.2 KiB
C++
138 lines
3.2 KiB
C++
/**
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* Copyright 2014 (c) Anna Schumaker.
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*/
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#ifndef OCARINA_CORE_INDEX_H
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#define OCARINA_CORE_INDEX_H
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#include <core/database.h>
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#include <set>
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#include <string>
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/**
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* The IndexEntry class is used to associate a specific key with a set of
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* integer identifiers. This lets us use a Database as an inverted index.
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*/
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class IndexEntry : public DatabaseEntry {
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private:
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std::string _key; /**< The term stored by this IndexEntry. */
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std::set<unsigned int> _values; /**< Integers representing strings that
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contain this term. */
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public:
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/** Iterator access for our backing std::set */
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typedef typename std::set<unsigned int>::iterator iterator;
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/** Const iterator access for our backing std::set */
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typedef typename std::set<unsigned int>::const_iterator const_iterator;
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IndexEntry(); /**< Create an empty IndexEntry. */
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/**
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* Create an IndexEntry with a specific key.
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*
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* @param key The key associated with this IndexEntry.
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*/
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IndexEntry(const std::string &);
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/**
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* Access the key stored by this IndexEntry.
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*
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* @return IndexEntry::_key.
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*/
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const std::string primary_key() const;
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/**
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* Add a new value to this IndexEntry.
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*
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* @param value The new value to add.
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*/
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void insert(unsigned int);
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/**
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* Remove a value from this IndexEntry.
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*
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* @param value The value to remove.
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*/
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void remove(unsigned int);
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/**
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* Called to find the number of values in our backing std::set.
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*
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* @return IndexEntry::_values.size()
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*/
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size_t size();
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/**
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* Called to check if a specific value is stored in this IndexEntry.
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*
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* @param value The value to find.
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* @return True if the value was found and false otherwise.
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*/
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bool has(unsigned int);
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/**
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* @return An iterator pointing to the first item in IndexEntry::_values
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*/
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iterator begin();
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/**
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* @return An iterator pointing past the last item in IndexEntry::_vaues
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*/
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iterator end();
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/**
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* Write an IndexEntry to file.
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*
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* @param file The file to use when writing data.
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*/
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void write(File &);
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/**
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* Read an IndexEntry from file.
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*
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* @param file The file read from.
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*/
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void read(File &);
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};
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/**
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* An Index is a special Database for mapping std::strings to a std::set of
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* integer identifiers.
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*/
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class Index : public Database<IndexEntry> {
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public:
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/**
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* Index constructor. This simply passes the filepath and autosave
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* parameters to the Database constructor.
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*
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* @param filepath Where to store the file on disk.
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* @param autosave True if changes should automatically be saved.
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*/
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Index(const std::string &, bool);
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/**
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* Check if we already have an IndexEntry for key, and create one if
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* we don't. Insert value into the found or created IndexEntry and
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* call autosave() to save the Index.
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*
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* @param key String to store in the index.
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* @param value Integer value associated with the key.
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*/
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void insert(const std::string &, unsigned int);
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/**
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* Remove value from the IndexEntry corresponding to key. The
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* IndexEntry will not be removed even if it has 0 values left.
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*
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* @param key Key associated with the value to be removed.
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* @param value Value to remove from the index.
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*/
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void remove(const std::string &, unsigned int);
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};
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#endif /* OCARINA_CORE_DATABASE_H */
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