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[apt.git] / apt-pkg / contrib / string_view.h

diff --git a/apt-pkg/contrib/string_view.h b/apt-pkg/contrib/string_view.h
index b4ce0431ccb28dcb63e64c4ed343e406d2261db9..c504edd27717178920875a34c421399d03601d6c 100644 (file)
--- a/apt-pkg/contrib/string_view.h
+++ b/apt-pkg/contrib/string_view.h
@@ -13,6 +13,7 @@
 #define APT_STRINGVIEW_H
 #include <string.h>
 #include <string>
+#include <apt-pkg/macros.h>
 
 namespace APT {
 
@@ -23,12 +24,13 @@ namespace APT {
  * used by APT. It is not meant to be used in programs, only inside the
  * library for performance critical paths.
  */
-class StringView {
+class APT_HIDDEN StringView {
     const char *data_;
     size_t size_;
 
 public:
     static constexpr size_t npos = static_cast<size_t>(-1);
+    static_assert(APT::StringView::npos == std::string::npos, "npos values are different");
 
     /* Constructors */
     constexpr StringView() : data_(""), size_(0) {}
@@ -43,10 +45,15 @@ public:
         return StringView(data_ + pos, n > (size_ - pos) ? (size_ - pos) : n);
     }
 
-    size_t find(int c, size_t pos=0) const {
-        if (pos != 0)
-            return substr(pos).find(c);
-
+    size_t find(int c, size_t pos) const {
+       if (pos == 0)
+         return find(c);
+       size_t const found = substr(pos).find(c);
+       if (found == npos)
+         return npos;
+       return pos + found;
+    }
+    size_t find(int c) const {
         const char *found = static_cast<const char*>(memchr(data_, c, size_));
 
         if (found == NULL)
@@ -55,10 +62,12 @@ public:
         return found - data_;
     }
 
-    size_t rfind(int c, size_t pos=0) const {
-        if (pos != 0)
-            return substr(pos).find(c);
-
+    size_t rfind(int c, size_t pos) const {
+       if (pos == npos)
+         return rfind(c);
+       return APT::StringView(data_, pos).rfind(c);
+    }
+    size_t rfind(int c) const {
         const char *found = static_cast<const char*>(memrchr(data_, c, size_));
 
         if (found == NULL)
@@ -103,10 +112,21 @@ public:
     constexpr size_t length() const { return size_; }
 };
 
+/**
+ * \brief Faster comparison for string views (compare size before data)
+ *
+ * Still stable, but faster than the normal ordering. */
+static inline int StringViewCompareFast(StringView a, StringView b) {
+    if (a.size() != b.size())
+        return a.size() - b.size();
+
+    return memcmp(a.data(), b.data(), a.size());
+}
+
 
 }
 
 inline bool operator ==(const char *other, APT::StringView that);
-inline bool operator ==(const char *other, APT::StringView that) { return that.compare(other) == 0; }
+inline bool operator ==(const char *other, APT::StringView that) { return that.operator==(other); }
 
 #endif