src/base/LookupTable.h

   1 /*
   2  * Copyright (C) 1996-2015 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_LOOKUPTABLE_H_
  10 #define SQUID_LOOKUPTABLE_H_
  11
  12 #include "SBuf.h"
  13
  14 #include <map>
  15
  16 /**
  17  * SBuf -> enum lookup table
  18  *
  19  * How to use:
  20  * enum enum_type { ... };
  21  * static const LookupTable<enum_type>::Record initializerTable[] {
  22  *   {"key1", ENUM_1}, {"key2", ENUM_2}, ... {nullptr, ENUM_INVALID_VALUE}
  23  * };
  24  * LookupTable<enum_type> lookupTableInstance(ENUM_INVALID_VALUE, initializerTable);
  25  *
  26  * then in the code:
  27  * SBuf s(string_to_lookup);
  28  * enum_type item = lookupTableInstance.lookup(s);
  29  * if (item != ENUM_INVALID_VALUE) { // do stuff }
  30  *
  31  */
  32 template<typename EnumType>
  33 class LookupTable
  34 {
  35 public:
  36     /// element of the lookup table initialization list
  37     typedef struct {
  38         const char *name;
  39         EnumType id;
  40     } Record;
  41
  42     LookupTable(const EnumType theInvalid, const Record data[]) :
  43         invalidValue(theInvalid)
  44     {
  45         for (auto i = 0; data[i].name != nullptr; ++i) {
  46             lookupTable[SBuf(data[i].name)] = data[i].id;
  47         }
  48     }
  49     EnumType lookup(const SBuf &key) const {
  50         auto r = lookupTable.find(key);
  51         if (r == lookupTable.end())
  52             return invalidValue;
  53         return r->second;
  54     }
  55
  56 private:
  57     typedef std::map<const SBuf, EnumType> lookupTable_t;
  58     lookupTable_t lookupTable;
  59     EnumType invalidValue;
  60 };
  61
  62 #endif /* SQUID_LOOKUPTABLE_H_ */