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// ---
// Author: Sanjay Ghemawat
//
// A printf() wrapper that writes into a fixed length buffer.
// Useful in low-level code that does not want to use allocating
// routines like StringPrintf().
//
// The implementation currently uses vsnprintf(). This seems to
// be fine for use in many low-level contexts, but we may need to
// rethink this decision if we hit a problem with it calling
// down into malloc() etc.
#ifndef BASE_RAW_PRINTER_H_
#define BASE_RAW_PRINTER_H_
#include <config.h>
#include "base/basictypes.h"
namespace base {
class RawPrinter {
public:
// REQUIRES: "length > 0"
// Will printf any data added to this into "buf[0,length-1]" and
// will arrange to always keep buf[] null-terminated.
RawPrinter(char* buf, int length);
// Return the number of bytes that have been appended to the string
// so far. Does not count any bytes that were dropped due to overflow.
int length() const { return (ptr_ - base_); }
// Return the number of bytes that can be added to this.
int space_left() const { return (limit_ - ptr_); }
// Format the supplied arguments according to the "format" string
// and append to this. Will silently truncate the output if it does
// not fit.
void Printf(const char* format, ...)
#ifdef HAVE___ATTRIBUTE__
__attribute__ ((__format__ (__printf__, 2, 3)))
#endif
;
private:
// We can write into [ptr_ .. limit_-1].
// *limit_ is also writable, but reserved for a terminating \0
// in case we overflow.
//
// Invariants: *ptr_ == \0
// Invariants: *limit_ == \0
char* base_; // Initial pointer
char* ptr_; // Where should we write next
char* limit_; // One past last non-\0 char we can write
DISALLOW_COPY_AND_ASSIGN(RawPrinter);
};
}
#endif // BASE_RAW_PRINTER_H_