LLVM API Documentation

StringExtras.cpp

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00001 //===-- StringExtras.cpp - Implement the StringExtras header --------------===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file implements the StringExtras.h header
00011 //
00012 //===----------------------------------------------------------------------===//
00013 
00014 #include "llvm/ADT/StringExtras.h"
00015 using namespace llvm;
00016 
00017 /// getToken - This function extracts one token from source, ignoring any
00018 /// leading characters that appear in the Delimiters string, and ending the
00019 /// token at any of the characters that appear in the Delimiters string.  If
00020 /// there are no tokens in the source string, an empty string is returned.
00021 /// The Source source string is updated in place to remove the returned string
00022 /// and any delimiter prefix from it.
00023 std::string llvm::getToken(std::string &Source, const char *Delimiters) {
00024   unsigned NumDelimiters = std::strlen(Delimiters);
00025 
00026   // Figure out where the token starts.
00027   std::string::size_type Start =
00028     Source.find_first_not_of(Delimiters, 0, NumDelimiters);
00029   if (Start == std::string::npos) Start = Source.size();
00030 
00031   // Find the next occurance of the delimiter.
00032   std::string::size_type End =
00033     Source.find_first_of(Delimiters, Start, NumDelimiters);
00034   if (End == std::string::npos) End = Source.size();
00035 
00036   // Create the return token.
00037   std::string Result = std::string(Source.begin()+Start, Source.begin()+End);
00038 
00039   // Erase the token that we read in.
00040   Source.erase(Source.begin(), Source.begin()+End);
00041 
00042   return Result;
00043 }
00044 
00045 
00046 /// UnescapeString - Modify the argument string, turning two character sequences
00047 /// like '\\' 'n' into '\n'.  This handles: \e \a \b \f \n \r \t \v \' \\ and
00048 /// \num (where num is a 1-3 byte octal value).
00049 void llvm::UnescapeString(std::string &Str) {
00050   for (unsigned i = 0; i != Str.size(); ++i) {
00051     if (Str[i] == '\\' && i != Str.size()-1) {
00052       switch (Str[i+1]) {
00053       default: continue;  // Don't execute the code after the switch.
00054       case 'a': Str[i] = '\a'; break;
00055       case 'b': Str[i] = '\b'; break;
00056       case 'e': Str[i] = 27; break;
00057       case 'f': Str[i] = '\f'; break;
00058       case 'n': Str[i] = '\n'; break;
00059       case 'r': Str[i] = '\r'; break;
00060       case 't': Str[i] = '\t'; break;
00061       case 'v': Str[i] = '\v'; break;
00062       case '\'': Str[i] = '\''; break;
00063       case '\\': Str[i] = '\\'; break;
00064       }
00065       // Nuke the second character.
00066       Str.erase(Str.begin()+i+1);
00067     }
00068   }
00069 }
00070 
00071 /// EscapeString - Modify the argument string, turning '\\' and anything that
00072 /// doesn't satisfy std::isprint into an escape sequence.
00073 void llvm::EscapeString(std::string &Str) {
00074   for (unsigned i = 0; i != Str.size(); ++i) {
00075     if (Str[i] == '\\') {
00076       ++i;
00077       Str.insert(Str.begin()+i, '\\');
00078     } else if (Str[i] == '\t') {
00079       Str[i++] = '\\';
00080       Str.insert(Str.begin()+i, 't');
00081     } else if (Str[i] == '\n') {
00082       Str[i++] = '\\';
00083       Str.insert(Str.begin()+i, 'n');
00084     } else if (!std::isprint(Str[i])) {
00085       // Always expand to a 3-digit octal escape.
00086       unsigned Char = Str[i];
00087       Str[i++] = '\\';
00088       Str.insert(Str.begin()+i++, '0'+((Char/64) & 7));
00089       Str.insert(Str.begin()+i++, '0'+((Char/8)  & 7));
00090       Str.insert(Str.begin()+i  , '0'+( Char     & 7));
00091     }
00092   }
00093 }