1 //===--- StringRef.h - Constant String Reference Wrapper --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_ADT_STRINGREF_H
11 #define LLVM_ADT_STRINGREF_H
20 /// StringRef - Represent a constant reference to a string, i.e. a character
21 /// array and a length, which need not be null terminated.
23 /// This class does not own the string data, it is expected to be used in
24 /// situations where the character data resides in some other buffer, whose
25 /// lifetime extends past that of the StringRef. For this reason, it is not in
26 /// general safe to store a StringRef.
29 typedef const char *iterator;
30 static const size_t npos = ~size_t(0);
33 /// The start of the string, in an external buffer.
36 /// The length of the string.
40 /// @name Constructors
43 /// Construct an empty string ref.
44 /*implicit*/ StringRef() : Data(0), Length(0) {}
46 /// Construct a string ref from a cstring.
47 /*implicit*/ StringRef(const char *Str)
48 : Data(Str), Length(::strlen(Str)) {}
50 /// Construct a string ref from a pointer and length.
51 /*implicit*/ StringRef(const char *_Data, unsigned _Length)
52 : Data(_Data), Length(_Length) {}
54 /// Construct a string ref from an std::string.
55 /*implicit*/ StringRef(const std::string &Str)
56 : Data(Str.c_str()), Length(Str.length()) {}
62 iterator begin() const { return Data; }
64 iterator end() const { return Data + Length; }
67 /// @name String Operations
70 /// data - Get a pointer to the start of the string (which may not be null
72 const char *data() const { return Data; }
74 /// empty - Check if the string is empty.
75 bool empty() const { return Length == 0; }
77 /// size - Get the string size.
78 size_t size() const { return Length; }
80 /// front - Get the first character in the string.
86 /// back - Get the last character in the string.
89 return Data[Length-1];
92 /// equals - Check for string equality, this is more efficient than
93 /// compare() when the relative ordering of inequal strings isn't needed.
94 bool equals(const StringRef &RHS) const {
95 return (Length == RHS.Length &&
96 memcmp(Data, RHS.Data, RHS.Length) == 0);
99 /// compare - Compare two strings; the result is -1, 0, or 1 if this string
100 /// is lexicographically less than, equal to, or greater than the \arg RHS.
101 int compare(const StringRef &RHS) const {
102 // Check the prefix for a mismatch.
103 if (int Res = memcmp(Data, RHS.Data, std::min(Length, RHS.Length)))
104 return Res < 0 ? -1 : 1;
106 // Otherwise the prefixes match, so we only need to check the lengths.
107 if (Length == RHS.Length)
109 return Length < RHS.Length ? -1 : 1;
112 /// str - Get the contents as an std::string.
113 std::string str() const { return std::string(Data, Length); }
116 /// @name Operator Overloads
119 char operator[](size_t Index) const {
120 assert(Index < Length && "Invalid index!");
125 /// @name Type Conversions
128 operator std::string() const {
133 /// @name String Predicates
136 /// startswith - Check if this string starts with the given \arg Prefix.
137 bool startswith(const StringRef &Prefix) const {
138 return substr(0, Prefix.Length).equals(Prefix);
141 /// endswith - Check if this string ends with the given \arg Suffix.
142 bool endswith(const StringRef &Suffix) const {
143 return slice(size() - Suffix.Length, size()).equals(Suffix);
147 /// @name String Searching
150 /// find - Search for the character \arg C in the string.
152 /// \return - The index of the first occurence of \arg C, or npos if not
154 size_t find(char C) const {
155 for (size_t i = 0, e = Length; i != e; ++i)
161 /// find - Search for the string \arg Str in the string.
163 /// \return - The index of the first occurence of \arg Str, or npos if not
165 size_t find(const StringRef &Str) const {
166 size_t N = Str.size();
169 for (size_t i = 0, e = Length - N + 1; i != e; ++i)
170 if (substr(i, N).equals(Str))
175 /// count - Return the number of occurrences of \arg C in the string.
176 size_t count(char C) const {
178 for (size_t i = 0, e = Length; i != e; ++i)
184 /// count - Return the number of non-overlapped occurrences of \arg Str in
186 size_t count(const StringRef &Str) const {
188 size_t N = Str.size();
191 for (size_t i = 0, e = Length - N + 1; i != e; ++i)
192 if (substr(i, N).equals(Str))
198 /// @name Substring Operations
201 /// substr - Return a reference to the substring from [Start, Start + N).
203 /// \param Start - The index of the starting character in the substring; if
204 /// the index is npos or greater than the length of the string then the
205 /// empty substring will be returned.
207 /// \param N - The number of characters to included in the substring. If N
208 /// exceeds the number of characters remaining in the string, the string
209 /// suffix (starting with \arg Start) will be returned.
210 StringRef substr(size_t Start, size_t N = npos) const {
211 Start = std::min(Start, Length);
212 return StringRef(Data + Start, std::min(N, Length - Start));
215 /// slice - Return a reference to the substring from [Start, End).
217 /// \param Start - The index of the starting character in the substring; if
218 /// the index is npos or greater than the length of the string then the
219 /// empty substring will be returned.
221 /// \param End - The index following the last character to include in the
222 /// substring. If this is npos, or less than \arg Start, or exceeds the
223 /// number of characters remaining in the string, the string suffix
224 /// (starting with \arg Start) will be returned.
225 StringRef slice(size_t Start, size_t End) const {
226 Start = std::min(Start, Length);
227 End = std::min(std::max(Start, End), Length);
228 return StringRef(Data + Start, End - Start);
231 /// split - Split into two substrings around the first occurence of a
232 /// separator character.
234 /// If \arg Separator is in the string, then the result is a pair (LHS, RHS)
235 /// such that (*this == LHS + Separator + RHS) is true and RHS is
236 /// maximal. If \arg Separator is not in the string, then the result is a
237 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
239 /// \param Separator - The character to split on.
240 /// \return - The split substrings.
241 std::pair<StringRef, StringRef> split(char Separator) const {
242 size_t Idx = find(Separator);
244 return std::make_pair(*this, StringRef());
245 return std::make_pair(slice(0, Idx), slice(Idx+1, npos));
251 /// @name StringRef Comparison Operators
254 inline bool operator==(const StringRef &LHS, const StringRef &RHS) {
255 return LHS.equals(RHS);
258 inline bool operator!=(const StringRef &LHS, const StringRef &RHS) {
259 return !(LHS == RHS);
262 inline bool operator<(const StringRef &LHS, const StringRef &RHS) {
263 return LHS.compare(RHS) == -1;
266 inline bool operator<=(const StringRef &LHS, const StringRef &RHS) {
267 return LHS.compare(RHS) != 1;
270 inline bool operator>(const StringRef &LHS, const StringRef &RHS) {
271 return LHS.compare(RHS) == 1;
274 inline bool operator>=(const StringRef &LHS, const StringRef &RHS) {
275 return LHS.compare(RHS) != -1;