Squashed 'src/rocksdb/' content from commit 224932d

git-subtree-dir: src/rocksdb
git-subtree-split: 224932d4d0b561712107d747c662df181c39644d

include/rocksdb/slice.h

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+// Copyright (c) 2013, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// Slice is a simple structure containing a pointer into some external
+// storage and a size.  The user of a Slice must ensure that the slice
+// is not used after the corresponding external storage has been
+// deallocated.
+//
+// Multiple threads can invoke const methods on a Slice without
+// external synchronization, but if any of the threads may call a
+// non-const method, all threads accessing the same Slice must use
+// external synchronization.
+
+#ifndef STORAGE_ROCKSDB_INCLUDE_SLICE_H_
+#define STORAGE_ROCKSDB_INCLUDE_SLICE_H_
+
+#include <assert.h>
+#include <stddef.h>
+#include <string.h>
+#include <string>
+
+namespace rocksdb {
+
+class Slice {
+ public:
+  // Create an empty slice.
+  Slice() : data_(""), size_(0) { }
+
+  // Create a slice that refers to d[0,n-1].
+  Slice(const char* d, size_t n) : data_(d), size_(n) { }
+
+  // Create a slice that refers to the contents of "s"
+  /* implicit */
+  Slice(const std::string& s) : data_(s.data()), size_(s.size()) { }
+
+  // Create a slice that refers to s[0,strlen(s)-1]
+  /* implicit */
+  Slice(const char* s) : data_(s), size_(strlen(s)) { }
+
+  // Return a pointer to the beginning of the referenced data
+  const char* data() const { return data_; }
+
+  // Return the length (in bytes) of the referenced data
+  size_t size() const { return size_; }
+
+  // Return true iff the length of the referenced data is zero
+  bool empty() const { return size_ == 0; }
+
+  // Return the ith byte in the referenced data.
+  // REQUIRES: n < size()
+  char operator[](size_t n) const {
+    assert(n < size());
+    return data_[n];
+  }
+
+  // Change this slice to refer to an empty array
+  void clear() { data_ = ""; size_ = 0; }
+
+  // Drop the first "n" bytes from this slice.
+  void remove_prefix(size_t n) {
+    assert(n <= size());
+    data_ += n;
+    size_ -= n;
+  }
+
+  // Return a string that contains the copy of the referenced data.
+  std::string ToString(bool hex = false) const {
+    if (hex) {
+      std::string result;
+      char buf[10];
+      for (size_t i = 0; i < size_; i++) {
+        snprintf(buf, 10, "%02X", (unsigned char)data_[i]);
+        result += buf;
+      }
+      return result;
+    } else {
+      return std::string(data_, size_);
+    }
+  }
+
+  // Three-way comparison.  Returns value:
+  //   <  0 iff "*this" <  "b",
+  //   == 0 iff "*this" == "b",
+  //   >  0 iff "*this" >  "b"
+  int compare(const Slice& b) const;
+
+  // Return true iff "x" is a prefix of "*this"
+  bool starts_with(const Slice& x) const {
+    return ((size_ >= x.size_) &&
+            (memcmp(data_, x.data_, x.size_) == 0));
+  }
+
+ // private: make these public for rocksdbjni access
+  const char* data_;
+  size_t size_;
+
+  // Intentionally copyable
+};
+
+// A set of Slices that are virtually concatenated together.  'parts' points
+// to an array of Slices.  The number of elements in the array is 'num_parts'.
+struct SliceParts {
+  SliceParts(const Slice* _parts, int _num_parts) :
+      parts(_parts), num_parts(_num_parts) { }
+  SliceParts() : parts(nullptr), num_parts(0) {}
+
+  const Slice* parts;
+  int num_parts;
+};
+
+inline bool operator==(const Slice& x, const Slice& y) {
+  return ((x.size() == y.size()) &&
+          (memcmp(x.data(), y.data(), x.size()) == 0));
+}
+
+inline bool operator!=(const Slice& x, const Slice& y) {
+  return !(x == y);
+}
+
+inline int Slice::compare(const Slice& b) const {
+  const int min_len = (size_ < b.size_) ? size_ : b.size_;
+  int r = memcmp(data_, b.data_, min_len);
+  if (r == 0) {
+    if (size_ < b.size_) r = -1;
+    else if (size_ > b.size_) r = +1;
+  }
+  return r;
+}
+
+}  // namespace rocksdb
+
+#endif  // STORAGE_ROCKSDB_INCLUDE_SLICE_H_