substitute.h

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// Protocol Buffers - Google's data interchange format
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// Author: [email protected] (Kenton Varda)
// from google3/strings/substitute.h

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

#ifndef GOOGLE_PROTOBUF_STUBS_SUBSTITUTE_H_
#define GOOGLE_PROTOBUF_STUBS_SUBSTITUTE_H_

namespace google {
namespace protobuf {
namespace strings {

// ----------------------------------------------------------------------
// strings::Substitute()
// strings::SubstituteAndAppend()
// Kind of like StringPrintf, but different.
//
// Example:
// string GetMessage(string first_name, string last_name, int age) {
// return strings::Substitute("My name is $0 $1 and I am $2 years old.",
// first_name, last_name, age);
// }
//
// Differences from StringPrintf:
// * The format string does not identify the types of arguments.
// Instead, the magic of C++ deals with this for us. See below
// for a list of accepted types.
// * Substitutions in the format string are identified by a '$'
// followed by a digit. So, you can use arguments out-of-order and
// use the same argument multiple times.
// * It's much faster than StringPrintf.
//
// Supported types:
// * Strings (const char*, const string&)
// * Note that this means you do not have to add .c_str() to all of
// your strings. In fact, you shouldn't; it will be slower.
// * int32, int64, uint32, uint64: Formatted using SimpleItoa().
// * float, double: Formatted using SimpleFtoa() and SimpleDtoa().
// * bool: Printed as "true" or "false".
//
// SubstituteAndAppend() is like Substitute() but appends the result to
// *output. Example:
//
// string str;
// strings::SubstituteAndAppend(&str,
// "My name is $0 $1 and I am $2 years old.",
// first_name, last_name, age);
//
// Substitute() is significantly faster than StringPrintf(). For very
// large strings, it may be orders of magnitude faster.
// ----------------------------------------------------------------------

namespace internal { // Implementation details.

class SubstituteArg {
 public:
 inline SubstituteArg(const char* value)
 : text_(value), size_(strlen(text_)) {}
 inline SubstituteArg(const string& value)
 : text_(value.data()), size_(value.size()) {}

 // Indicates that no argument was given.
 inline explicit SubstituteArg()
 : text_(NULL), size_(-1) {}

 // Primitives
 // We don't overload for signed and unsigned char because if people are
 // explicitly declaring their chars as signed or unsigned then they are
 // probably actually using them as 8-bit integers and would probably
 // prefer an integer representation. But, we don't really know. So, we
 // make the caller decide what to do.
 inline SubstituteArg(char value)
 : text_(scratch_), size_(1) { scratch_[0] = value; }
 inline SubstituteArg(short value)
 : text_(FastInt32ToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(unsigned short value)
 : text_(FastUInt32ToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(int value)
 : text_(FastInt32ToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(unsigned int value)
 : text_(FastUInt32ToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(long value)
 : text_(FastLongToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(unsigned long value)
 : text_(FastULongToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(long long value)
 : text_(FastInt64ToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(unsigned long long value)
 : text_(FastUInt64ToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(float value)
 : text_(FloatToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(double value)
 : text_(DoubleToBuffer(value, scratch_)), size_(strlen(text_)) {}
 inline SubstituteArg(bool value)
 : text_(value ? "true" : "false"), size_(strlen(text_)) {}

 inline const char* data() const { return text_; }
 inline int size() const { return size_; }

 private:
 const char* text_;
 int size_;
 char scratch_[kFastToBufferSize];
};

} // namespace internal

LIBPROTOBUF_EXPORT string Substitute(
 const char* format,
 const internal::SubstituteArg& arg0 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg1 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg2 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg3 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg4 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg5 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg6 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg7 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg8 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg9 = internal::SubstituteArg());

LIBPROTOBUF_EXPORT void SubstituteAndAppend(
 string* output, const char* format,
 const internal::SubstituteArg& arg0 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg1 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg2 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg3 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg4 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg5 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg6 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg7 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg8 = internal::SubstituteArg(),
 const internal::SubstituteArg& arg9 = internal::SubstituteArg());

} // namespace strings
} // namespace protobuf
} // namespace google

#endif // GOOGLE_PROTOBUF_STUBS_SUBSTITUTE_H_