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 /// equals - Check for string equality, this is more efficient than
81 /// compare() in when the relative ordering of inequal strings isn't needed.
82 bool equals(const StringRef &RHS) const {
83 return (Length == RHS.Length &&
84 memcmp(Data, RHS.Data, RHS.Length) == 0);
87 /// compare - Compare two strings; the result is -1, 0, or 1 if this string
88 /// is lexicographically less than, equal to, or greater than the \arg RHS.
89 int compare(const StringRef &RHS) const {
90 // Check the prefix for a mismatch.
91 if (int Res = memcmp(Data, RHS.Data, std::min(Length, RHS.Length)))
92 return Res < 0 ? -1 : 1;
94 // Otherwise the prefixes match, so we only need to check the lengths.
95 if (Length == RHS.Length)
97 return Length < RHS.Length ? -1 : 1;
100 /// str - Get the contents as an std::string.
101 std::string str() const { return std::string(Data, Length); }
104 /// @name Operator Overloads
107 char operator[](size_t Index) const {
108 assert(Index < Length && "Invalid index!");
113 /// @name Type Conversions
116 operator std::string() const {
121 /// @name Utility Functions
124 /// substr - Return a reference to the substring from [Start, Start + N).
126 /// \param Start - The index of the starting character in the substring; if
127 /// the index is npos or greater than the length of the string then the
128 /// empty substring will be returned.
130 /// \param N - The number of characters to included in the substring. If N
131 /// exceeds the number of characters remaining in the string, the string
132 /// suffix (starting with \arg Start) will be returned.
133 StringRef substr(size_t Start, size_t N = npos) const {
134 Start = std::min(Start, Length);
135 return StringRef(Data + Start, std::min(N, Length - Start));
138 /// slice - Return a reference to the substring from [Start, End).
140 /// \param Start - The index of the starting character in the substring; if
141 /// the index is npos or greater than the length of the string then the
142 /// empty substring will be returned.
144 /// \param End - The index following the last character to include in the
145 /// substring. If this is npos, or less than \arg Start, or exceeds the
146 /// number of characters remaining in the string, the string suffix
147 /// (starting with \arg Start) will be returned.
148 StringRef slice(size_t Start, size_t End) const {
149 Start = std::min(Start, Length);
150 End = std::min(std::max(Start, End), Length);
151 return StringRef(Data + Start, End - Start);
154 /// split - Split into two substrings around the first occurence of a
155 /// separator character.
157 /// If \arg Separator is in the string, then the result is a pair (LHS, RHS)
158 /// such that (*this == LHS + Separator + RHS) is true and RHS is
159 /// maximal. If \arg Separator is not in the string, then the result is a
160 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
162 /// \param Separator - The character to split on.
163 /// \return - The split substrings.
164 std::pair<StringRef, StringRef> split(char Separator) const {
165 iterator it = std::find(begin(), end(), Separator);
167 return std::make_pair(*this, StringRef());
168 return std::make_pair(StringRef(begin(), it - begin()),
169 StringRef(it + 1, end() - (it + 1)));
172 /// startswith - Check if this string starts with the given \arg Prefix.
173 bool startswith(const StringRef &Prefix) const {
174 return substr(0, Prefix.Length).equals(Prefix);
180 /// @name StringRef Comparison Operators
183 inline bool operator==(const StringRef &LHS, const StringRef &RHS) {
184 return LHS.equals(RHS);
187 inline bool operator!=(const StringRef &LHS, const StringRef &RHS) {
188 return !(LHS == RHS);
191 inline bool operator<(const StringRef &LHS, const StringRef &RHS) {
192 return LHS.compare(RHS) == -1;
195 inline bool operator<=(const StringRef &LHS, const StringRef &RHS) {
196 return LHS.compare(RHS) != 1;
199 inline bool operator>(const StringRef &LHS, const StringRef &RHS) {
200 return LHS.compare(RHS) == 1;
203 inline bool operator>=(const StringRef &LHS, const StringRef &RHS) {
204 return LHS.compare(RHS) != -1;