StringExtras.cpp revision 4ee451de366474b9c228b4e5fa573795a715216d 
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"
15using namespace llvm;
16
17/// getToken - This function extracts one token from source, ignoring any
18/// leading characters that appear in the Delimiters string, and ending the
19/// token at any of the characters that appear in the Delimiters string.  If
20/// there are no tokens in the source string, an empty string is returned.
21/// The Source source string is updated in place to remove the returned string
22/// and any delimiter prefix from it.
23std::string llvm::getToken(std::string &Source, const char *Delimiters) {
24  unsigned NumDelimiters = std::strlen(Delimiters);
25
26  // Figure out where the token starts.
27  std::string::size_type Start =
28    Source.find_first_not_of(Delimiters, 0, NumDelimiters);
29  if (Start == std::string::npos) Start = Source.size();
30
31  // Find the next occurance of the delimiter.
32  std::string::size_type End =
33    Source.find_first_of(Delimiters, Start, NumDelimiters);
34  if (End == std::string::npos) End = Source.size();
35
36  // Create the return token.
37  std::string Result = std::string(Source.begin()+Start, Source.begin()+End);
38
39  // Erase the token that we read in.
40  Source.erase(Source.begin(), Source.begin()+End);
41
42  return Result;
43}
44
45/// SplitString - Split up the specified string according to the specified
46/// delimiters, appending the result fragments to the output list.
47void llvm::SplitString(const std::string &Source,
48                       std::vector<std::string> &OutFragments,
49                       const char *Delimiters) {
50  std::string S = Source;
51
52  std::string S2 = getToken(S, Delimiters);
53  while (!S2.empty()) {
54    OutFragments.push_back(S2);
55    S2 = getToken(S, Delimiters);
56  }
57}
58
59
60
61/// UnescapeString - Modify the argument string, turning two character sequences
62/// @verbatim
63/// like '\\' 'n' into '\n'.  This handles: \e \a \b \f \n \r \t \v \' \ and
64/// \num (where num is a 1-3 byte octal value).
65/// @endverbatim
66void llvm::UnescapeString(std::string &Str) {
67  for (unsigned i = 0; i != Str.size(); ++i) {
68    if (Str[i] == '\\' && i != Str.size()-1) {
69      switch (Str[i+1]) {
70      default: continue;  // Don't execute the code after the switch.
71      case 'a': Str[i] = '\a'; break;
72      case 'b': Str[i] = '\b'; break;
73      case 'e': Str[i] = 27; break;
74      case 'f': Str[i] = '\f'; break;
75      case 'n': Str[i] = '\n'; break;
76      case 'r': Str[i] = '\r'; break;
77      case 't': Str[i] = '\t'; break;
78      case 'v': Str[i] = '\v'; break;
79      case '\'': Str[i] = '\''; break;
80      case '\\': Str[i] = '\\'; break;
81      }
82      // Nuke the second character.
83      Str.erase(Str.begin()+i+1);
84    }
85  }
86}
87
88/// EscapeString - Modify the argument string, turning '\\' and anything that
89/// doesn't satisfy std::isprint into an escape sequence.
90void llvm::EscapeString(std::string &Str) {
91  for (unsigned i = 0; i != Str.size(); ++i) {
92    if (Str[i] == '\\') {
93      ++i;
94      Str.insert(Str.begin()+i, '\\');
95    } else if (Str[i] == '\t') {
96      Str[i++] = '\\';
97      Str.insert(Str.begin()+i, 't');
98    } else if (Str[i] == '\n') {
99      Str[i++] = '\\';
100      Str.insert(Str.begin()+i, 'n');
101    } else if (!std::isprint(Str[i])) {
102      // Always expand to a 3-digit octal escape.
103      unsigned Char = Str[i];
104      Str[i++] = '\\';
105      Str.insert(Str.begin()+i++, '0'+((Char/64) & 7));
106      Str.insert(Str.begin()+i++, '0'+((Char/8)  & 7));
107      Str.insert(Str.begin()+i  , '0'+( Char     & 7));
108    }
109  }
110}
111