include/wvbackslash.h

   1 /* -*- Mode: C++ -*-
   2  * Worldvisions Weaver Software:
   3  *   Copyright (C) 2002 Net Integration Technologies, Inc.
   4  *
   5  * C-style backslash escaping and unescaping of strings.
   6  */
   7 #ifndef __WVBACKSLASH_H
   8 #define __WVBACKSLASH_H
   9
  10 #include "wvencoder.h"
  11
  12 /**
  13  * An encoder that performs C-style backslash escaping of strings.
  14  *
  15  * Use this to escape control characters, unprintable characters,
  16  * and optionally quotes or any other special printable characters
  17  * into sequences of the form \\n, \\xFF, \\", etc...
  18  *
  19  * Supports reset().
  20  *
  21  */
  22 class WvBackslashEncoder : public WvEncoder
  23 {
  24     WvString nasties;
  25
  26 public:
  27     /**
  28      * Creates a C-style backslash encoder.
  29      *   nasties - the set of printable characters to escape
  30      *             in addition to the non-printable ones
  31      *             (should always contain at least backslash)
  32      */
  33     WvBackslashEncoder(WvStringParm _nasties = "\\\"");
  34     virtual ~WvBackslashEncoder() { }
  35
  36 protected:
  37     virtual bool _encode(WvBuf &inbuf, WvBuf &outbuf, bool flush);
  38     virtual bool _reset();
  39 };
  40
  41
  42 /**
  43  * An encoder that performs C-style backslash unescaping of strings.
  44  *
  45  * Recognizes the following sequences preceeded by backslash:
  46  *
  47  *  - a: substitutes alarm bell (ascii 7)
  48  *  - b: substitutes backspace (ascii 8)
  49  *  - f: substitutes formfeed (ascii 12)
  50  *  - n: substitutes newline (ascii 10)
  51  *  - r: substitutes carriage return (ascii 13)
  52  *  - t: substitutes tab (ascii 9)
  53  *  - v: substitutes vertical tab (ascii 11)
  54  *  - 0: substitutes null (ascii 0)
  55  *  - 0xyz: substitutes character with octal encoding xyz
  56  *  - xxy: substitutes character with hex encoding xy
  57  *  - newline: substitutes space (line continuation sequence)
  58  *  - \\: substitutes backslash
  59  *  - otherwise substitutes the next character (strips the backslash)
  60  *
  61  *
  62  * Supports reset().
  63  *
  64  */
  65 class WvBackslashDecoder : public WvEncoder
  66 {
  67     enum State
  68         { Initial, Escape, Hex1, Hex2, Octal1, Octal2, Octal3 };
  69     State state;
  70     WvInPlaceBuf tmpbuf;
  71     int value;
  72
  73 public:
  74     /** Creates a C-style backslash decoder. */
  75     WvBackslashDecoder();
  76     virtual ~WvBackslashDecoder() { }
  77
  78 protected:
  79     virtual bool _encode(WvBuf &inbuf, WvBuf &outbuf, bool flush);
  80     virtual bool _reset();
  81
  82 private:
  83     bool flushtmpbuf(WvBuf &outbuf);
  84 };
  85
  86 #endif // __WVBACKSLASH_H