Squashed 'src/leveldb/' content from commit aca1ffc

git-subtree-dir: src/leveldb
git-subtree-split: aca1ffc4b65be5e099b2088c6e6a308d69e1ad73

include/leveldb/status.h

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+// 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.
+//
+// A Status encapsulates the result of an operation.  It may indicate success,
+// or it may indicate an error with an associated error message.
+//
+// Multiple threads can invoke const methods on a Status without
+// external synchronization, but if any of the threads may call a
+// non-const method, all threads accessing the same Status must use
+// external synchronization.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_STATUS_H_
+#define STORAGE_LEVELDB_INCLUDE_STATUS_H_
+
+#include <string>
+#include "leveldb/slice.h"
+
+namespace leveldb {
+
+class Status {
+ public:
+  // Create a success status.
+  Status() : state_(NULL) { }
+  ~Status() { delete[] state_; }
+
+  // Copy the specified status.
+  Status(const Status& s);
+  void operator=(const Status& s);
+
+  // Return a success status.
+  static Status OK() { return Status(); }
+
+  // Return error status of an appropriate type.
+  static Status NotFound(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kNotFound, msg, msg2);
+  }
+  static Status Corruption(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kCorruption, msg, msg2);
+  }
+  static Status NotSupported(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kNotSupported, msg, msg2);
+  }
+  static Status InvalidArgument(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kInvalidArgument, msg, msg2);
+  }
+  static Status IOError(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kIOError, msg, msg2);
+  }
+
+  // Returns true iff the status indicates success.
+  bool ok() const { return (state_ == NULL); }
+
+  // Returns true iff the status indicates a NotFound error.
+  bool IsNotFound() const { return code() == kNotFound; }
+
+  // Returns true iff the status indicates a Corruption error.
+  bool IsCorruption() const { return code() == kCorruption; }
+
+  // Returns true iff the status indicates an IOError.
+  bool IsIOError() const { return code() == kIOError; }
+
+  // Return a string representation of this status suitable for printing.
+  // Returns the string "OK" for success.
+  std::string ToString() const;
+
+ private:
+  // OK status has a NULL state_.  Otherwise, state_ is a new[] array
+  // of the following form:
+  //    state_[0..3] == length of message
+  //    state_[4]    == code
+  //    state_[5..]  == message
+  const char* state_;
+
+  enum Code {
+    kOk = 0,
+    kNotFound = 1,
+    kCorruption = 2,
+    kNotSupported = 3,
+    kInvalidArgument = 4,
+    kIOError = 5
+  };
+
+  Code code() const {
+    return (state_ == NULL) ? kOk : static_cast<Code>(state_[4]);
+  }
+
+  Status(Code code, const Slice& msg, const Slice& msg2);
+  static const char* CopyState(const char* s);
+};
+
+inline Status::Status(const Status& s) {
+  state_ = (s.state_ == NULL) ? NULL : CopyState(s.state_);
+}
+inline void Status::operator=(const Status& s) {
+  // The following condition catches both aliasing (when this == &s),
+  // and the common case where both s and *this are ok.
+  if (state_ != s.state_) {
+    delete[] state_;
+    state_ = (s.state_ == NULL) ? NULL : CopyState(s.state_);
+  }
+}
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_STATUS_H_