printer.h

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// Protocol Buffers - Google's data interchange format
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// Author: [email protected] (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 in debug builds. This helps greatly in
// debugging code which uses it.
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);
 // 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,
 const char* variable3, const string& value3);
 // TODO(kenton): Overloaded versions with more variables? Three 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();

 // Write a string to the output buffer.
 // This method does not look for newlines to add indentation.
 void PrintRaw(const string& data);

 // Write a zero-delimited string to output buffer.
 // This method does not look for newlines to add indentation.
 void PrintRaw(const char* data);

 // Write some bytes to the output buffer.
 // This method does not look for newlines to add indentation.
 void WriteRaw(const char* data, int size);

 // 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:
 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__