third_party/tcmalloc/chromium/src/raw_printer.h

   1 // Copyright (c) 2008, Google Inc.
   2 // All rights reserved.
   3 //
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   9 // notice, this list of conditions and the following disclaimer.
  10 //     * Redistributions in binary form must reproduce the above
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  29
  30 // ---
  31 // Author: Sanjay Ghemawat
  32 //
  33 // A printf() wrapper that writes into a fixed length buffer.
  34 // Useful in low-level code that does not want to use allocating
  35 // routines like StringPrintf().
  36 //
  37 // The implementation currently uses vsnprintf().  This seems to
  38 // be fine for use in many low-level contexts, but we may need to
  39 // rethink this decision if we hit a problem with it calling
  40 // down into malloc() etc.
  41
  42 #ifndef BASE_RAW_PRINTER_H_
  43 #define BASE_RAW_PRINTER_H_
  44
  45 #include <config.h>
  46 #include "base/basictypes.h"
  47
  48 namespace base {
  49
  50 class RawPrinter {
  51  public:
  52   // REQUIRES: "length > 0"
  53   // Will printf any data added to this into "buf[0,length-1]" and
  54   // will arrange to always keep buf[] null-terminated.
  55   RawPrinter(char* buf, int length);
  56
  57   // Return the number of bytes that have been appended to the string
  58   // so far.  Does not count any bytes that were dropped due to overflow.
  59   int length() const { return (ptr_ - base_); }
  60
  61   // Return the number of bytes that can be added to this.
  62   int space_left() const { return (limit_ - ptr_); }
  63
  64   // Format the supplied arguments according to the "format" string
  65   // and append to this.  Will silently truncate the output if it does
  66   // not fit.
  67   void Printf(const char* format, ...)
  68 #ifdef HAVE___ATTRIBUTE__
  69   __attribute__ ((__format__ (__printf__, 2, 3)))
  70 #endif
  71 ;
  72
  73  private:
  74   // We can write into [ptr_ .. limit_-1].
  75   // *limit_ is also writable, but reserved for a terminating \0
  76   // in case we overflow.
  77   //
  78   // Invariants: *ptr_ == \0
  79   // Invariants: *limit_ == \0
  80   char* base_;          // Initial pointer
  81   char* ptr_;           // Where should we write next
  82   char* limit_;         // One past last non-\0 char we can write
  83
  84   DISALLOW_COPY_AND_ASSIGN(RawPrinter);
  85 };
  86
  87 }
  88
  89 #endif  // BASE_RAW_PRINTER_H_