chromium/third_party/protobuf/src/google/protobuf/io/printer.h

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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//
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// in the documentation and/or other materials provided with the
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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 <map>
#include <string>
#include <vector>

#include <google/protobuf/stubs/common.h>

// Must be included last.
#include <google/protobuf/port_def.inc>

namespace google {
namespace protobuf {
namespace io {

class ZeroCopyOutputStream;  // zero_copy_stream.h

// Records annotations about a Printer's output.
class PROTOBUF_EXPORT AnnotationCollector { … };

// Records annotations about a Printer's output to the given protocol buffer,
// assuming that the buffer has an ::Annotation message exposing path,
// source_file, begin and end fields.
template <typename AnnotationProto>
class AnnotationProtoCollector : public AnnotationCollector { … };

// 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.
//
// If a Printer is constructed with an AnnotationCollector, it will provide it
// with annotations that connect the Printer's output to paths that can identify
// various descriptors.  In the above example, if person_ is a descriptor that
// identifies Bob, we can associate the output string "My name is Bob." with
// a source path pointing to that descriptor with:
//
//   printer.Annotate("name", person_);
//
// The AnnotationCollector will be sent an annotation linking the output range
// covering "Bob" to the logical path provided by person_.  Tools may use
// this association to (for example) link "Bob" in the output back to the
// source file that defined the person_ descriptor identifying Bob.
//
// Annotate can only examine variables substituted during the last call to
// Print.  It is invalid to refer to a variable that was used multiple times
// in a single Print call.
//
// In full generality, one may specify a range of output text using a beginning
// substitution variable and an ending variable.  The resulting annotation will
// span from the first character of the substituted value for the beginning
// variable to the last character of the substituted value for the ending
// variable.  For example, the Annotate call above is equivalent to this one:
//
//   printer.Annotate("name", "name", person_);
//
// This is useful if multiple variables combine to form a single span of output
// that should be annotated with the same source path.  For example:
//
//   Printer printer(output, '$');
//   map<string, string> vars;
//   vars["first"] = "Alice";
//   vars["last"] = "Smith";
//   printer.Print(vars, "My name is $first$ $last$.");
//   printer.Annotate("first", "last", person_);
//
// This code would associate the span covering "Alice Smith" in the output with
// the person_ descriptor.
//
// Note that the beginning variable must come before (or overlap with, in the
// case of zero-sized substitution values) the ending variable.
//
// It is also sometimes useful to use variables with zero-sized values as
// markers.  This avoids issues with multiple references to the same variable
// and also allows annotation ranges to span literal text from the Print
// templates:
//
//   Printer printer(output, '$');
//   map<string, string> vars;
//   vars["foo"] = "bar";
//   vars["function"] = "call";
//   vars["mark"] = "";
//   printer.Print(vars, "$function$($foo$,$foo$)$mark$");
//   printer.Annotate("function", "mark", call_);
//
// This code associates the span covering "call(bar,bar)" in the output with the
// call_ descriptor.

class PROTOBUF_EXPORT Printer { … };

}  // namespace io
}  // namespace protobuf
}  // namespace google

#include <google/protobuf/port_undef.inc>

#endif  // GOOGLE_PROTOBUF_IO_PRINTER_H__