Upstream | cc2ee17 | 1970-01-12 13:46:40 +0000 | [diff] [blame^] | 1 | /** |
| 2 | * @file unique_storage.h |
| 3 | * Unique storage of values |
| 4 | * |
| 5 | * @remark Copyright 2002 OProfile authors |
| 6 | * @remark Read the file COPYING |
| 7 | * |
| 8 | * @author Philippe Elie |
| 9 | * @author John Levon |
| 10 | */ |
| 11 | |
| 12 | #ifndef UNIQUE_STORAGE_H |
| 13 | #define UNIQUE_STORAGE_H |
| 14 | |
| 15 | #include <vector> |
| 16 | #include <map> |
| 17 | #include <stdexcept> |
| 18 | |
| 19 | /** |
| 20 | * Store values such that only one copy of the value |
| 21 | * is ever stored. |
| 22 | * |
| 23 | * I is an arbitrary typename that's never |
| 24 | * used. |
| 25 | * |
| 26 | * It is a required parameter in order to enforce |
| 27 | * type-safety for a collection. |
| 28 | * |
| 29 | * The value type "V" must be default-constructible, |
| 30 | * and this is the value returned by a stored id_value |
| 31 | * where .set() is false |
| 32 | */ |
| 33 | template <typename I, typename V> class unique_storage { |
| 34 | |
| 35 | public: |
| 36 | unique_storage() { |
| 37 | // id 0 |
| 38 | values.push_back(V()); |
| 39 | } |
| 40 | |
| 41 | virtual ~unique_storage() {} |
| 42 | |
| 43 | typedef std::vector<V> stored_values; |
| 44 | |
| 45 | /// the actual ID type |
| 46 | struct id_value { |
| 47 | /// id == 0 means "empty" / "undefined" |
| 48 | id_value() : id(0) {} |
| 49 | |
| 50 | /// does this ID map to a non-default value ? |
| 51 | bool set() const { |
| 52 | return id; |
| 53 | } |
| 54 | |
| 55 | bool operator<(id_value const & rhs) const { |
| 56 | return id < rhs.id; |
| 57 | } |
| 58 | |
| 59 | bool operator==(id_value const & rhs) const { |
| 60 | return id == rhs.id; |
| 61 | } |
| 62 | |
| 63 | bool operator!=(id_value const & rhs) const { |
| 64 | return !(id == rhs.id); |
| 65 | } |
| 66 | |
| 67 | private: |
| 68 | friend class unique_storage<I, V>; |
| 69 | |
| 70 | typedef typename stored_values::size_type size_type; |
| 71 | |
| 72 | explicit id_value(size_type s) : id(s) {} |
| 73 | |
| 74 | /// actual ID value |
| 75 | size_type id; |
| 76 | }; |
| 77 | |
| 78 | |
| 79 | /// ensure this value is available |
| 80 | id_value const create(V const & value) { |
| 81 | typename id_map::value_type val(value, id_value(values.size())); |
| 82 | std::pair<typename id_map::iterator, bool> |
| 83 | inserted = ids.insert(val); |
| 84 | if (inserted.second) { |
| 85 | values.push_back(value); |
| 86 | } |
| 87 | |
| 88 | return inserted.first->second; |
| 89 | } |
| 90 | |
| 91 | |
| 92 | /// return the stored value for the given ID |
| 93 | V const & get(id_value const & id) const { |
| 94 | // some stl lack at(), so we emulate it |
| 95 | if (id.id < values.size()) |
| 96 | return values[id.id]; |
| 97 | |
| 98 | throw std::out_of_range("unique_storage::get(): out of bounds"); |
| 99 | } |
| 100 | |
| 101 | private: |
| 102 | typedef std::map<V, id_value> id_map; |
| 103 | |
| 104 | /// the contained values |
| 105 | stored_values values; |
| 106 | |
| 107 | /// map from ID to value |
| 108 | id_map ids; |
| 109 | }; |
| 110 | |
| 111 | #endif /* !UNIQUE_STORAGE_H */ |