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      1 // Copyright (C) 2009-2010, International Business Machines
      2 // Corporation and others. All Rights Reserved.
      3 //
      4 // Copyright 2004 and onwards Google Inc.
      5 //
      6 // Author: wilsonh (at) google.com (Wilson Hsieh)
      7 //
      8 
      9 #include "unicode/utypes.h"
     10 #include "unicode/stringpiece.h"
     11 #include "cstring.h"
     12 #include "cmemory.h"
     13 
     14 U_NAMESPACE_BEGIN
     15 
     16 StringPiece::StringPiece(const char* str)
     17     : ptr_(str), length_((str == NULL) ? 0 : static_cast<int32_t>(uprv_strlen(str))) { }
     18 
     19 StringPiece::StringPiece(const StringPiece& x, int32_t pos) {
     20   if (pos < 0) {
     21     pos = 0;
     22   } else if (pos > x.length_) {
     23     pos = x.length_;
     24   }
     25   ptr_ = x.ptr_ + pos;
     26   length_ = x.length_ - pos;
     27 }
     28 
     29 StringPiece::StringPiece(const StringPiece& x, int32_t pos, int32_t len) {
     30   if (pos < 0) {
     31     pos = 0;
     32   } else if (pos > x.length_) {
     33     pos = x.length_;
     34   }
     35   if (len < 0) {
     36     len = 0;
     37   } else if (len > x.length_ - pos) {
     38     len = x.length_ - pos;
     39   }
     40   ptr_ = x.ptr_ + pos;
     41   length_ = len;
     42 }
     43 
     44 void StringPiece::set(const char* str) {
     45   ptr_ = str;
     46   if (str != NULL)
     47     length_ = static_cast<int32_t>(uprv_strlen(str));
     48   else
     49     length_ = 0;
     50 }
     51 
     52 U_EXPORT UBool U_EXPORT2
     53 operator==(const StringPiece& x, const StringPiece& y) {
     54   int32_t len = x.size();
     55   if (len != y.size()) {
     56     return false;
     57   }
     58   if (len == 0) {
     59     return true;
     60   }
     61   const char* p = x.data();
     62   const char* p2 = y.data();
     63   // Test last byte in case strings share large common prefix
     64   --len;
     65   if (p[len] != p2[len]) return false;
     66   // At this point we can, but don't have to, ignore the last byte.
     67   return uprv_memcmp(p, p2, len) == 0;
     68 }
     69 
     70 
     71 /* Microsft Visual Studios <= 8.0 complains about redefinition of this
     72  * static const class variable. However, the C++ standard states that this
     73  * definition is correct. Perhaps there is a bug in the Microsoft compiler.
     74  * This is not an issue on any other compilers (that we know of) including
     75  * Visual Studios 9.0.
     76  * Cygwin with MSVC 9.0 also complains here about redefinition.
     77  */
     78 #if (!defined(_MSC_VER) || (_MSC_VER > 1500)) && !defined(CYGWINMSVC)
     79 const int32_t StringPiece::npos;
     80 #endif
     81 
     82 U_NAMESPACE_END
     83