intl/icu/source/common/stringpiece.cpp

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 // Copyright (C) 2009-2013, International Business Machines
   4 // Corporation and others. All Rights Reserved.
   5 //
   6 // Copyright 2004 and onwards Google Inc.
   7 //
   8 // Author: wilsonh@google.com (Wilson Hsieh)
   9 //
  10
  11 #include "unicode/utypes.h"
  12 #include "unicode/stringpiece.h"
  13 #include "cstring.h"
  14 #include "cmemory.h"
  15
  16 U_NAMESPACE_BEGIN
  17
  18 StringPiece::StringPiece(const char* str)
  19     : ptr_(str), length_((str == nullptr) ? 0 : static_cast<int32_t>(uprv_strlen(str))) { }
  20
  21 StringPiece::StringPiece(const StringPiece& x, int32_t pos) {
  22   if (pos < 0) {
  23     pos = 0;
  24   } else if (pos > x.length_) {
  25     pos = x.length_;
  26   }
  27   ptr_ = x.ptr_ + pos;
  28   length_ = x.length_ - pos;
  29 }
  30
  31 StringPiece::StringPiece(const StringPiece& x, int32_t pos, int32_t len) {
  32   if (pos < 0) {
  33     pos = 0;
  34   } else if (pos > x.length_) {
  35     pos = x.length_;
  36   }
  37   if (len < 0) {
  38     len = 0;
  39   } else if (len > x.length_ - pos) {
  40     len = x.length_ - pos;
  41   }
  42   ptr_ = x.ptr_ + pos;
  43   length_ = len;
  44 }
  45
  46 void StringPiece::set(const char* str) {
  47   ptr_ = str;
  48   if (str != nullptr)
  49     length_ = static_cast<int32_t>(uprv_strlen(str));
  50   else
  51     length_ = 0;
  52 }
  53
  54 int32_t StringPiece::find(StringPiece needle, int32_t offset) {
  55   if (length() == 0 && needle.length() == 0) {
  56     return 0;
  57   }
  58   // TODO: Improve to be better than O(N^2)?
  59   for (int32_t i = offset; i < length(); i++) {
  60     int32_t j = 0;
  61     for (; j < needle.length(); i++, j++) {
  62       if (data()[i] != needle.data()[j]) {
  63         i -= j;
  64         goto outer_end;
  65       }
  66     }
  67     return i - j;
  68     outer_end: void();
  69   }
  70   return -1;
  71 }
  72
  73 int32_t StringPiece::compare(StringPiece other) {
  74   int32_t i = 0;
  75   for (; i < length(); i++) {
  76     if (i == other.length()) {
  77       // this is longer
  78       return 1;
  79     }
  80     char a = data()[i];
  81     char b = other.data()[i];
  82     if (a < b) {
  83       return -1;
  84     } else if (a > b) {
  85       return 1;
  86     }
  87   }
  88   if (i < other.length()) {
  89     // other is longer
  90     return -1;
  91   }
  92   return 0;
  93 }
  94
  95 U_EXPORT UBool U_EXPORT2
  96 operator==(const StringPiece& x, const StringPiece& y) {
  97   int32_t len = x.size();
  98   if (len != y.size()) {
  99     return false;
 100   }
 101   if (len == 0) {
 102     return true;
 103   }
 104   const char* p = x.data();
 105   const char* p2 = y.data();
 106   // Test last byte in case strings share large common prefix
 107   --len;
 108   if (p[len] != p2[len]) return false;
 109   // At this point we can, but don't have to, ignore the last byte.
 110   return uprv_memcmp(p, p2, len) == 0;
 111 }
 112
 113
 114 const int32_t StringPiece::npos = 0x7fffffff;
 115
 116 U_NAMESPACE_END