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
13 #include "llvm/Support/type_traits.h"
14 #include "llvm/Support/Allocator.h"
24 class SmallVectorImpl;
29 /// Helper functions for StringRef::getAsInteger.
30 bool getAsUnsignedInteger(StringRef Str, unsigned Radix,
31 unsigned long long &Result);
33 bool getAsSignedInteger(StringRef Str, unsigned Radix, long long &Result);
35 /// StringRef - Represent a constant reference to a string, i.e. a character
36 /// array and a length, which need not be null terminated.
38 /// This class does not own the string data, it is expected to be used in
39 /// situations where the character data resides in some other buffer, whose
40 /// lifetime extends past that of the StringRef. For this reason, it is not in
41 /// general safe to store a StringRef.
44 typedef const char *iterator;
45 typedef const char *const_iterator;
46 static const size_t npos = ~size_t(0);
47 typedef size_t size_type;
50 /// The start of the string, in an external buffer.
53 /// The length of the string.
56 // Workaround PR5482: nearly all gcc 4.x miscompile StringRef and std::min()
57 // Changing the arg of min to be an integer, instead of a reference to an
58 // integer works around this bug.
59 static size_t min(size_t a, size_t b) { return a < b ? a : b; }
60 static size_t max(size_t a, size_t b) { return a > b ? a : b; }
62 // Workaround memcmp issue with null pointers (undefined behavior)
63 // by providing a specialized version
64 static int compareMemory(const char *Lhs, const char *Rhs, size_t Length) {
65 if (Length == 0) { return 0; }
66 return ::memcmp(Lhs,Rhs,Length);
70 /// @name Constructors
73 /// Construct an empty string ref.
74 /*implicit*/ StringRef() : Data(0), Length(0) {}
76 /// Construct a string ref from a cstring.
77 /*implicit*/ StringRef(const char *Str)
79 assert(Str && "StringRef cannot be built from a NULL argument");
80 Length = ::strlen(Str); // invoking strlen(NULL) is undefined behavior
83 /// Construct a string ref from a pointer and length.
84 /*implicit*/ StringRef(const char *data, size_t length)
85 : Data(data), Length(length) {
86 assert((data || length == 0) &&
87 "StringRef cannot be built from a NULL argument with non-null length");
90 /// Construct a string ref from an std::string.
91 /*implicit*/ StringRef(const std::string &Str)
92 : Data(Str.data()), Length(Str.length()) {}
98 iterator begin() const { return Data; }
100 iterator end() const { return Data + Length; }
103 /// @name String Operations
106 /// data - Get a pointer to the start of the string (which may not be null
108 const char *data() const { return Data; }
110 /// empty - Check if the string is empty.
111 bool empty() const { return Length == 0; }
113 /// size - Get the string size.
114 size_t size() const { return Length; }
116 /// front - Get the first character in the string.
122 /// back - Get the last character in the string.
125 return Data[Length-1];
128 // copy - Allocate copy in BumpPtrAllocator and return StringRef to it.
129 StringRef copy(BumpPtrAllocator &Allocator) {
130 char *S = Allocator.Allocate<char>(Length);
131 std::copy(begin(), end(), S);
132 return StringRef(S, Length);
135 /// equals - Check for string equality, this is more efficient than
136 /// compare() when the relative ordering of inequal strings isn't needed.
137 bool equals(StringRef RHS) const {
138 return (Length == RHS.Length &&
139 compareMemory(Data, RHS.Data, RHS.Length) == 0);
142 /// equals_lower - Check for string equality, ignoring case.
143 bool equals_lower(StringRef RHS) const {
144 return Length == RHS.Length && compare_lower(RHS) == 0;
147 /// compare - Compare two strings; the result is -1, 0, or 1 if this string
148 /// is lexicographically less than, equal to, or greater than the \p RHS.
149 int compare(StringRef RHS) const {
150 // Check the prefix for a mismatch.
151 if (int Res = compareMemory(Data, RHS.Data, min(Length, RHS.Length)))
152 return Res < 0 ? -1 : 1;
154 // Otherwise the prefixes match, so we only need to check the lengths.
155 if (Length == RHS.Length)
157 return Length < RHS.Length ? -1 : 1;
160 /// compare_lower - Compare two strings, ignoring case.
161 int compare_lower(StringRef RHS) const;
163 /// compare_numeric - Compare two strings, treating sequences of digits as
165 int compare_numeric(StringRef RHS) const;
167 /// \brief Determine the edit distance between this string and another
170 /// \param Other the string to compare this string against.
172 /// \param AllowReplacements whether to allow character
173 /// replacements (change one character into another) as a single
174 /// operation, rather than as two operations (an insertion and a
177 /// \param MaxEditDistance If non-zero, the maximum edit distance that
178 /// this routine is allowed to compute. If the edit distance will exceed
179 /// that maximum, returns \c MaxEditDistance+1.
181 /// \returns the minimum number of character insertions, removals,
182 /// or (if \p AllowReplacements is \c true) replacements needed to
183 /// transform one of the given strings into the other. If zero,
184 /// the strings are identical.
185 unsigned edit_distance(StringRef Other, bool AllowReplacements = true,
186 unsigned MaxEditDistance = 0) const;
188 /// str - Get the contents as an std::string.
189 std::string str() const {
190 if (Data == 0) return std::string();
191 return std::string(Data, Length);
195 /// @name Operator Overloads
198 char operator[](size_t Index) const {
199 assert(Index < Length && "Invalid index!");
204 /// @name Type Conversions
207 operator std::string() const {
212 /// @name String Predicates
215 /// Check if this string starts with the given \p Prefix.
216 bool startswith(StringRef Prefix) const {
217 return Length >= Prefix.Length &&
218 compareMemory(Data, Prefix.Data, Prefix.Length) == 0;
221 /// Check if this string starts with the given \p Prefix, ignoring case.
222 bool startswith_lower(StringRef Prefix) const;
224 /// Check if this string ends with the given \p Suffix.
225 bool endswith(StringRef Suffix) const {
226 return Length >= Suffix.Length &&
227 compareMemory(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
230 /// Check if this string ends with the given \p Suffix, ignoring case.
231 bool endswith_lower(StringRef Suffix) const;
234 /// @name String Searching
237 /// Search for the first character \p C in the string.
239 /// \returns The index of the first occurrence of \p C, or npos if not
241 size_t find(char C, size_t From = 0) const {
242 for (size_t i = min(From, Length), e = Length; i != e; ++i)
248 /// Search for the first string \p Str in the string.
250 /// \returns The index of the first occurrence of \p Str, or npos if not
252 size_t find(StringRef Str, size_t From = 0) const;
254 /// Search for the last character \p C in the string.
256 /// \returns The index of the last occurrence of \p C, or npos if not
258 size_t rfind(char C, size_t From = npos) const {
259 From = min(From, Length);
269 /// Search for the last string \p Str in the string.
271 /// \returns The index of the last occurrence of \p Str, or npos if not
273 size_t rfind(StringRef Str) const;
275 /// Find the first character in the string that is \p C, or npos if not
276 /// found. Same as find.
277 size_t find_first_of(char C, size_t From = 0) const {
278 return find(C, From);
281 /// Find the first character in the string that is in \p Chars, or npos if
284 /// Complexity: O(size() + Chars.size())
285 size_t find_first_of(StringRef Chars, size_t From = 0) const;
287 /// Find the first character in the string that is not \p C or npos if not
289 size_t find_first_not_of(char C, size_t From = 0) const;
291 /// Find the first character in the string that is not in the string
292 /// \p Chars, or npos if not found.
294 /// Complexity: O(size() + Chars.size())
295 size_t find_first_not_of(StringRef Chars, size_t From = 0) const;
297 /// Find the last character in the string that is \p C, or npos if not
299 size_t find_last_of(char C, size_t From = npos) const {
300 return rfind(C, From);
303 /// Find the last character in the string that is in \p C, or npos if not
306 /// Complexity: O(size() + Chars.size())
307 size_t find_last_of(StringRef Chars, size_t From = npos) const;
309 /// Find the last character in the string that is not \p C, or npos if not
311 size_t find_last_not_of(char C, size_t From = npos) const;
313 /// Find the last character in the string that is not in \p Chars, or
314 /// npos if not found.
316 /// Complexity: O(size() + Chars.size())
317 size_t find_last_not_of(StringRef Chars, size_t From = npos) const;
320 /// @name Helpful Algorithms
323 /// Return the number of occurrences of \p C in the string.
324 size_t count(char C) const {
326 for (size_t i = 0, e = Length; i != e; ++i)
332 /// Return the number of non-overlapped occurrences of \p Str in
334 size_t count(StringRef Str) const;
336 /// Parse the current string as an integer of the specified radix. If
337 /// \p Radix is specified as zero, this does radix autosensing using
338 /// extended C rules: 0 is octal, 0x is hex, 0b is binary.
340 /// If the string is invalid or if only a subset of the string is valid,
341 /// this returns true to signify the error. The string is considered
342 /// erroneous if empty or if it overflows T.
343 template <typename T>
344 typename enable_if_c<std::numeric_limits<T>::is_signed, bool>::type
345 getAsInteger(unsigned Radix, T &Result) const {
347 if (getAsSignedInteger(*this, Radix, LLVal) ||
348 static_cast<T>(LLVal) != LLVal)
354 template <typename T>
355 typename enable_if_c<!std::numeric_limits<T>::is_signed, bool>::type
356 getAsInteger(unsigned Radix, T &Result) const {
357 unsigned long long ULLVal;
358 if (getAsUnsignedInteger(*this, Radix, ULLVal) ||
359 static_cast<T>(ULLVal) != ULLVal)
365 /// Parse the current string as an integer of the specified \p Radix, or of
366 /// an autosensed radix if the \p Radix given is 0. The current value in
367 /// \p Result is discarded, and the storage is changed to be wide enough to
368 /// store the parsed integer.
370 /// \returns true if the string does not solely consist of a valid
371 /// non-empty number in the appropriate base.
373 /// APInt::fromString is superficially similar but assumes the
374 /// string is well-formed in the given radix.
375 bool getAsInteger(unsigned Radix, APInt &Result) const;
378 /// @name String Operations
381 // Convert the given ASCII string to lowercase.
382 std::string lower() const;
384 /// Convert the given ASCII string to uppercase.
385 std::string upper() const;
388 /// @name Substring Operations
391 /// Return a reference to the substring from [Start, Start + N).
393 /// \param Start The index of the starting character in the substring; if
394 /// the index is npos or greater than the length of the string then the
395 /// empty substring will be returned.
397 /// \param N The number of characters to included in the substring. If N
398 /// exceeds the number of characters remaining in the string, the string
399 /// suffix (starting with \p Start) will be returned.
400 StringRef substr(size_t Start, size_t N = npos) const {
401 Start = min(Start, Length);
402 return StringRef(Data + Start, min(N, Length - Start));
405 /// Return a StringRef equal to 'this' but with the first \p N elements
407 StringRef drop_front(size_t N = 1) const {
408 assert(size() >= N && "Dropping more elements than exist");
412 /// Return a StringRef equal to 'this' but with the last \p N elements
414 StringRef drop_back(size_t N = 1) const {
415 assert(size() >= N && "Dropping more elements than exist");
416 return substr(0, size()-N);
419 /// Return a reference to the substring from [Start, End).
421 /// \param Start The index of the starting character in the substring; if
422 /// the index is npos or greater than the length of the string then the
423 /// empty substring will be returned.
425 /// \param End The index following the last character to include in the
426 /// substring. If this is npos, or less than \p Start, or exceeds the
427 /// number of characters remaining in the string, the string suffix
428 /// (starting with \p Start) will be returned.
429 StringRef slice(size_t Start, size_t End) const {
430 Start = min(Start, Length);
431 End = min(max(Start, End), Length);
432 return StringRef(Data + Start, End - Start);
435 /// Split into two substrings around the first occurrence of a separator
438 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
439 /// such that (*this == LHS + Separator + RHS) is true and RHS is
440 /// maximal. If \p Separator is not in the string, then the result is a
441 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
443 /// \param Separator The character to split on.
444 /// \returns The split substrings.
445 std::pair<StringRef, StringRef> split(char Separator) const {
446 size_t Idx = find(Separator);
448 return std::make_pair(*this, StringRef());
449 return std::make_pair(slice(0, Idx), slice(Idx+1, npos));
452 /// Split into two substrings around the first occurrence of a separator
455 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
456 /// such that (*this == LHS + Separator + RHS) is true and RHS is
457 /// maximal. If \p Separator is not in the string, then the result is a
458 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
460 /// \param Separator - The string to split on.
461 /// \return - The split substrings.
462 std::pair<StringRef, StringRef> split(StringRef Separator) const {
463 size_t Idx = find(Separator);
465 return std::make_pair(*this, StringRef());
466 return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos));
469 /// Split into substrings around the occurrences of a separator string.
471 /// Each substring is stored in \p A. If \p MaxSplit is >= 0, at most
472 /// \p MaxSplit splits are done and consequently <= \p MaxSplit
473 /// elements are added to A.
474 /// If \p KeepEmpty is false, empty strings are not added to \p A. They
475 /// still count when considering \p MaxSplit
476 /// An useful invariant is that
477 /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true
479 /// \param A - Where to put the substrings.
480 /// \param Separator - The string to split on.
481 /// \param MaxSplit - The maximum number of times the string is split.
482 /// \param KeepEmpty - True if empty substring should be added.
483 void split(SmallVectorImpl<StringRef> &A,
484 StringRef Separator, int MaxSplit = -1,
485 bool KeepEmpty = true) const;
487 /// Split into two substrings around the last occurrence of a separator
490 /// If \p Separator is in the string, then the result is a pair (LHS, RHS)
491 /// such that (*this == LHS + Separator + RHS) is true and RHS is
492 /// minimal. If \p Separator is not in the string, then the result is a
493 /// pair (LHS, RHS) where (*this == LHS) and (RHS == "").
495 /// \param Separator - The character to split on.
496 /// \return - The split substrings.
497 std::pair<StringRef, StringRef> rsplit(char Separator) const {
498 size_t Idx = rfind(Separator);
500 return std::make_pair(*this, StringRef());
501 return std::make_pair(slice(0, Idx), slice(Idx+1, npos));
504 /// Return string with consecutive characters in \p Chars starting from
505 /// the left removed.
506 StringRef ltrim(StringRef Chars = " \t\n\v\f\r") const {
507 return drop_front(std::min(Length, find_first_not_of(Chars)));
510 /// Return string with consecutive characters in \p Chars starting from
511 /// the right removed.
512 StringRef rtrim(StringRef Chars = " \t\n\v\f\r") const {
513 return drop_back(Length - std::min(Length, find_last_not_of(Chars) + 1));
516 /// Return string with consecutive characters in \p Chars starting from
517 /// the left and right removed.
518 StringRef trim(StringRef Chars = " \t\n\v\f\r") const {
519 return ltrim(Chars).rtrim(Chars);
525 /// @name StringRef Comparison Operators
528 inline bool operator==(StringRef LHS, StringRef RHS) {
529 return LHS.equals(RHS);
532 inline bool operator!=(StringRef LHS, StringRef RHS) {
533 return !(LHS == RHS);
536 inline bool operator<(StringRef LHS, StringRef RHS) {
537 return LHS.compare(RHS) == -1;
540 inline bool operator<=(StringRef LHS, StringRef RHS) {
541 return LHS.compare(RHS) != 1;
544 inline bool operator>(StringRef LHS, StringRef RHS) {
545 return LHS.compare(RHS) == 1;
548 inline bool operator>=(StringRef LHS, StringRef RHS) {
549 return LHS.compare(RHS) != -1;
552 inline std::string &operator+=(std::string &buffer, StringRef string) {
553 return buffer.append(string.data(), string.size());
558 /// \brief Compute a hash_code for a StringRef.
559 hash_code hash_value(StringRef S);
561 // StringRefs can be treated like a POD type.
562 template <typename T> struct isPodLike;
563 template <> struct isPodLike<StringRef> { static const bool value = true; };