Adding grpc::string_ref class.

- Strict subset of
  http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3442.html
- Useful to avoid unnecessary string copies.

1 files changed, 119 insertions, 0 deletions

diff --git a/include/grpc++/string_ref.h b/include/grpc++/string_ref.h
new file mode 100644
index 0000000000..dd33ab73c0
--- /dev/null
+++ b/include/grpc++/string_ref.h
@@ -0,0 +1,119 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPCXX_STRING_REF_H
+#define GRPCXX_STRING_REF_H
+
+#include <iterator>
+
+#include <grpc++/config.h>
+
+namespace grpc {
+
+// This class is a non owning reference to a string.
+// It should be a strict subset of the upcoming std::string_ref. See:
+// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3442.html
+class string_ref {
+ public:
+  // types
+  typedef const char* const_iterator;
+  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+
+  // constants
+  static constexpr size_t npos = size_t(-1);
+
+  // construct/copy.
+  constexpr string_ref() : data_(nullptr), length_(0) {}
+  constexpr string_ref(const string_ref& other)
+      : data_(other.data_), length_(other.length_) {}
+  string_ref& operator=(const string_ref& rhs);
+  string_ref(const char* s);
+  constexpr string_ref(const char* s, size_t l) : data_(s), length_(l) {}
+  string_ref(const grpc::string& s) : data_(s.data()), length_(s.length()) {}
+
+  // iterators
+  constexpr const_iterator begin() const { return data_; }
+  constexpr const_iterator end() const { return data_ + length_; }
+  constexpr const_iterator cbegin() const { return data_; }
+  constexpr const_iterator cend() const { return data_ + length_; }
+  const_reverse_iterator rbegin() const {
+    return const_reverse_iterator(end());
+  }
+  const_reverse_iterator rend() const {
+    return const_reverse_iterator(begin());
+  }
+  const_reverse_iterator crbegin() const {
+    return const_reverse_iterator(end());
+  }
+  const_reverse_iterator crend() const {
+    return const_reverse_iterator(begin());
+  }
+
+  // capacity
+  constexpr size_t size() const { return length_; }
+  constexpr size_t length() const { return length_; }
+  constexpr size_t max_size() const { return length_; }
+  constexpr bool empty() const { return length_ == 0; }
+
+  // element access
+  const char* data() const { return data_; }
+
+  // string operations
+  int compare(string_ref x) const;
+  bool starts_with(string_ref x) const;
+  bool ends_with(string_ref x) const;
+  size_t find(string_ref s) const;
+  size_t find(char c) const;
+
+  // Defined as constexpr in n3442 but C++11 constexpr semantics do not allow
+  // the implementation of this function to comply.
+  /* constrexpr */ string_ref substr(size_t pos, size_t n = npos) const;
+
+ private:
+  const char* data_;
+  size_t length_;
+};
+
+// Comparison operators
+bool operator==(string_ref x, string_ref y);
+bool operator!=(string_ref x, string_ref y);
+bool operator<(string_ref x, string_ref y);
+bool operator>(string_ref x, string_ref y);
+bool operator<=(string_ref x, string_ref y);
+bool operator>=(string_ref x, string_ref y);
+
+}  // namespace grpc
+
+#endif  // GRPCXX_STRING_REF_H
+
+