lib/Support/StringExtras.cpp

   1 //===-- StringExtras.cpp - Implement the StringExtras header --------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the StringExtras.h header
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/ADT/StringExtras.h"
  15 #include <cstring>
  16 using namespace llvm;
  17
  18 /// getToken - This function extracts one token from source, ignoring any
  19 /// leading characters that appear in the Delimiters string, and ending the
  20 /// token at any of the characters that appear in the Delimiters string.  If
  21 /// there are no tokens in the source string, an empty string is returned.
  22 /// The Source source string is updated in place to remove the returned string
  23 /// and any delimiter prefix from it.
  24 std::string llvm::getToken(std::string &Source, const char *Delimiters) {
  25   size_t NumDelimiters = std::strlen(Delimiters);
  26
  27   // Figure out where the token starts.
  28   std::string::size_type Start =
  29     Source.find_first_not_of(Delimiters, 0, NumDelimiters);
  30   if (Start == std::string::npos) Start = Source.size();
  31
  32   // Find the next occurance of the delimiter.
  33   std::string::size_type End =
  34     Source.find_first_of(Delimiters, Start, NumDelimiters);
  35   if (End == std::string::npos) End = Source.size();
  36
  37   // Create the return token.
  38   std::string Result = std::string(Source.begin()+Start, Source.begin()+End);
  39
  40   // Erase the token that we read in.
  41   Source.erase(Source.begin(), Source.begin()+End);
  42
  43   return Result;
  44 }
  45
  46 /// SplitString - Split up the specified string according to the specified
  47 /// delimiters, appending the result fragments to the output list.
  48 void llvm::SplitString(const std::string &Source,
  49                        std::vector<std::string> &OutFragments,
  50                        const char *Delimiters) {
  51   std::string S = Source;
  52
  53   std::string S2 = getToken(S, Delimiters);
  54   while (!S2.empty()) {
  55     OutFragments.push_back(S2);
  56     S2 = getToken(S, Delimiters);
  57   }
  58 }
  59
  60
  61
  62 /// UnescapeString - Modify the argument string, turning two character sequences
  63 /// @verbatim
  64 /// like '\\' 'n' into '\n'.  This handles: \e \a \b \f \n \r \t \v \' \ and
  65 /// \num (where num is a 1-3 byte octal value).
  66 /// @endverbatim
  67 void llvm::UnescapeString(std::string &Str) {
  68   for (unsigned i = 0; i != Str.size(); ++i) {
  69     if (Str[i] == '\\' && i != Str.size()-1) {
  70       switch (Str[i+1]) {
  71       default: continue;  // Don't execute the code after the switch.
  72       case 'a': Str[i] = '\a'; break;
  73       case 'b': Str[i] = '\b'; break;
  74       case 'e': Str[i] = 27; break;
  75       case 'f': Str[i] = '\f'; break;
  76       case 'n': Str[i] = '\n'; break;
  77       case 'r': Str[i] = '\r'; break;
  78       case 't': Str[i] = '\t'; break;
  79       case 'v': Str[i] = '\v'; break;
  80       case '"': Str[i] = '\"'; break;
  81       case '\'': Str[i] = '\''; break;
  82       case '\\': Str[i] = '\\'; break;
  83       }
  84       // Nuke the second character.
  85       Str.erase(Str.begin()+i+1);
  86     }
  87   }
  88 }
  89
  90 /// EscapeString - Modify the argument string, turning '\\' and anything that
  91 /// doesn't satisfy std::isprint into an escape sequence.
  92 void llvm::EscapeString(std::string &Str) {
  93   for (unsigned i = 0; i != Str.size(); ++i) {
  94     if (Str[i] == '\\') {
  95       ++i;
  96       Str.insert(Str.begin()+i, '\\');
  97     } else if (Str[i] == '\t') {
  98       Str[i++] = '\\';
  99       Str.insert(Str.begin()+i, 't');
 100     } else if (Str[i] == '"') {
 101       Str.insert(Str.begin()+i++, '\\');
 102     } else if (Str[i] == '\n') {
 103       Str[i++] = '\\';
 104       Str.insert(Str.begin()+i, 'n');
 105     } else if (!std::isprint(Str[i])) {
 106       // Always expand to a 3-digit octal escape.
 107       unsigned Char = Str[i];
 108       Str[i++] = '\\';
 109       Str.insert(Str.begin()+i++, '0'+((Char/64) & 7));
 110       Str.insert(Str.begin()+i++, '0'+((Char/8)  & 7));
 111       Str.insert(Str.begin()+i  , '0'+( Char     & 7));
 112     }
 113   }
 114 }