src/SBufAlgos.h

   1 #ifndef SQUID_SBUFALGOS_H_
   2 #define SQUID_SBUFALGOS_H_
   3
   4 #include "SBuf.h"
   5
   6 #include <algorithm>
   7 #include <numeric>
   8
   9 /// SBuf equality predicate for STL algorithms etc
  10 class SBufEqual
  11 {
  12 public:
  13     explicit SBufEqual(const SBuf &reference, SBufCaseSensitive sensitivity = caseSensitive) :
  14             reference_(reference), sensitivity_(sensitivity) {}
  15     bool operator() (const SBuf & checking) { return checking.compare(reference_,sensitivity_) == 0; }
  16 private:
  17     SBuf reference_;
  18     SBufCaseSensitive sensitivity_;
  19 };
  20
  21 /// SBuf "starts with" predicate for STL algorithms etc
  22 class SBufStartsWith
  23 {
  24 public:
  25     explicit SBufStartsWith(const SBuf &prefix, SBufCaseSensitive sensitivity = caseSensitive) :
  26             prefix_(prefix), sensitivity_(sensitivity) {}
  27     bool operator() (const SBuf & checking) { return checking.startsWith(prefix_,sensitivity_); }
  28 private:
  29     SBuf prefix_;
  30     SBufCaseSensitive sensitivity_;
  31 };
  32
  33 /** SBuf size addition accumulator for STL contaniners
  34  *
  35  * Equivalent to prefix_length +  SBuf.length() +  separator.length()
  36  */
  37 class SBufAddLength
  38 {
  39 public:
  40     explicit SBufAddLength(const SBuf &separator) :
  41             separatorLen_(separator.length()) {}
  42     SBuf::size_type operator()(const SBuf::size_type sz, const SBuf & item) {
  43         return sz + item.length() + separatorLen_;
  44     }
  45 private:
  46     SBuf::size_type separatorLen_;
  47 };
  48
  49 /// join all the SBuf in a container of SBuf into a single SBuf, separating with separator
  50 template <class Container>
  51 SBuf
  52 SBufContainerJoin(const Container &items, const SBuf& separator)
  53 {
  54     // optimization: pre-calculate needed storage
  55     const SBuf::size_type sz = std::accumulate(items.begin(), items.end(), 0, SBufAddLength(separator));
  56
  57     // sz can be zero in two cases: either items is empty, or all items
  58     //  are zero-length. In the former case, we must protect against
  59     //  dereferencing the iterator later on, and checking sz is more efficient
  60     //  than checking items.size(). This check also provides an optimization
  61     //  for the latter case without adding complexity.
  62     if (sz == 0)
  63         return SBuf();
  64
  65     SBuf rv;
  66     rv.reserveSpace(sz);
  67
  68     typename Container::const_iterator i(items.begin());
  69     rv.append(*i);
  70     ++i;
  71     for (; i != items.end(); ++i)
  72         rv.append(separator).append(*i);
  73     return rv;
  74 }
  75
  76 #endif /* SQUID_SBUFALGOS_H_ */