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+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.
+// http://code.google.com/p/protobuf/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Author: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+//
+// Utility class for writing text to a ZeroCopyOutputStream.
+
+#ifndef GOOGLE_PROTOBUF_IO_PRINTER_H__
+#define GOOGLE_PROTOBUF_IO_PRINTER_H__
+
+#include <string>
+#include <map>
+#include <google/protobuf/stubs/common.h>
+
+namespace google {
+namespace protobuf {
+namespace io {
+
+class ZeroCopyOutputStream;     // zero_copy_stream.h
+
+// This simple utility class assists in code generation.  It basically
+// allows the caller to define a set of variables and then output some
+// text with variable substitutions.  Example usage:
+//
+//   Printer printer(output, '$');
+//   map<string, string> vars;
+//   vars["name"] = "Bob";
+//   printer.Print(vars, "My name is $name$.");
+//
+// The above writes "My name is Bob." to the output stream.
+//
+// Printer aggressively enforces correct usage, crashing (with assert failures)
+// in the case of undefined variables.  This helps greatly in debugging code
+// which uses it.  This class is not intended to be used by production servers.
+class LIBPROTOBUF_EXPORT Printer {
+ public:
+  // Create a printer that writes text to the given output stream.  Use the
+  // given character as the delimiter for variables.
+  Printer(ZeroCopyOutputStream* output, char variable_delimiter);
+  ~Printer();
+
+  // Print some text after applying variable substitutions.  If a particular
+  // variable in the text is not defined, this will crash.  Variables to be
+  // substituted are identified by their names surrounded by delimiter
+  // characters (as given to the constructor).  The variable bindings are
+  // defined by the given map.
+  void Print(const map<string, string>& variables, const char* text);
+
+  // Like the first Print(), except the substitutions are given as parameters.
+  void Print(const char* text);
+  // Like the first Print(), except the substitutions are given as parameters.
+  void Print(const char* text, const char* variable, const string& value);
+  // Like the first Print(), except the substitutions are given as parameters.
+  void Print(const char* text, const char* variable1, const string& value1,
+                               const char* variable2, const string& value2);
+  // TODO(kenton):  Overloaded versions with more variables?  Two seems
+  //   to be enough.
+
+  // Indent text by two spaces.  After calling Indent(), two spaces will be
+  // inserted at the beginning of each line of text.  Indent() may be called
+  // multiple times to produce deeper indents.
+  void Indent();
+
+  // Reduces the current indent level by two spaces, or crashes if the indent
+  // level is zero.
+  void Outdent();
+
+  // True if any write to the underlying stream failed.  (We don't just
+  // crash in this case because this is an I/O failure, not a programming
+  // error.)
+  bool failed() const { return failed_; }
+
+ private:
+  // Write some text to the output buffer.
+  void Write(const char* data, int size);
+
+  const char variable_delimiter_;
+
+  ZeroCopyOutputStream* const output_;
+  char* buffer_;
+  int buffer_size_;
+
+  string indent_;
+  bool at_start_of_line_;
+  bool failed_;
+
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Printer);
+};
+
+}  // namespace io
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_IO_PRINTER_H__