1 //===-- StringRef.cpp - Lightweight String References ---------------------===//
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 #include "llvm/ADT/StringRef.h"
11 #include "llvm/ADT/APInt.h"
15 // MSVC emits references to this into the translation units which reference it.
17 const size_t StringRef::npos;
20 static char ascii_tolower(char x) {
21 if (x >= 'A' && x <= 'Z')
26 /// compare_lower - Compare strings, ignoring case.
27 int StringRef::compare_lower(StringRef RHS) const {
28 for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {
29 char LHC = ascii_tolower(Data[I]);
30 char RHC = ascii_tolower(RHS.Data[I]);
32 return LHC < RHC ? -1 : 1;
35 if (Length == RHS.Length)
37 return Length < RHS.Length ? -1 : 1;
40 // Compute the edit distance between the two given strings.
41 unsigned StringRef::edit_distance(llvm::StringRef Other,
42 bool AllowReplacements) {
43 // The algorithm implemented below is the "classic"
44 // dynamic-programming algorithm for computing the Levenshtein
45 // distance, which is described here:
47 // http://en.wikipedia.org/wiki/Levenshtein_distance
49 // Although the algorithm is typically described using an m x n
50 // array, only two rows are used at a time, so this implemenation
51 // just keeps two separate vectors for those two rows.
53 size_type n = Other.size();
55 const unsigned SmallBufferSize = 64;
56 unsigned SmallBuffer[SmallBufferSize];
57 unsigned *Allocated = 0;
58 unsigned *previous = SmallBuffer;
59 if (2*(n + 1) > SmallBufferSize)
60 Allocated = previous = new unsigned [2*(n+1)];
61 unsigned *current = previous + (n + 1);
63 for (unsigned i = 0; i <= n; ++i)
66 for (size_type y = 1; y <= m; ++y) {
68 for (size_type x = 1; x <= n; ++x) {
69 if (AllowReplacements) {
70 current[x] = min(previous[x-1] + ((*this)[y-1] == Other[x-1]? 0u:1u),
71 min(current[x-1], previous[x])+1);
74 if ((*this)[y-1] == Other[x-1]) current[x] = previous[x-1];
75 else current[x] = min(current[x-1], previous[x]) + 1;
79 unsigned *tmp = current;
84 unsigned Result = previous[n];
90 //===----------------------------------------------------------------------===//
92 //===----------------------------------------------------------------------===//
95 /// find - Search for the first string \arg Str in the string.
97 /// \return - The index of the first occurence of \arg Str, or npos if not
99 size_t StringRef::find(StringRef Str, size_t From) const {
100 size_t N = Str.size();
103 for (size_t e = Length - N + 1, i = min(From, e); i != e; ++i)
104 if (substr(i, N).equals(Str))
109 /// rfind - Search for the last string \arg Str in the string.
111 /// \return - The index of the last occurence of \arg Str, or npos if not
113 size_t StringRef::rfind(StringRef Str) const {
114 size_t N = Str.size();
117 for (size_t i = Length - N + 1, e = 0; i != e;) {
119 if (substr(i, N).equals(Str))
125 /// find_first_of - Find the first character in the string that is in \arg
126 /// Chars, or npos if not found.
128 /// Note: O(size() * Chars.size())
129 StringRef::size_type StringRef::find_first_of(StringRef Chars,
131 for (size_type i = min(From, Length), e = Length; i != e; ++i)
132 if (Chars.find(Data[i]) != npos)
137 /// find_first_not_of - Find the first character in the string that is not
138 /// \arg C or npos if not found.
139 StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
140 for (size_type i = min(From, Length), e = Length; i != e; ++i)
146 /// find_first_not_of - Find the first character in the string that is not
147 /// in the string \arg Chars, or npos if not found.
149 /// Note: O(size() * Chars.size())
150 StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
152 for (size_type i = min(From, Length), e = Length; i != e; ++i)
153 if (Chars.find(Data[i]) == npos)
159 //===----------------------------------------------------------------------===//
160 // Helpful Algorithms
161 //===----------------------------------------------------------------------===//
163 /// count - Return the number of non-overlapped occurrences of \arg Str in
165 size_t StringRef::count(StringRef Str) const {
167 size_t N = Str.size();
170 for (size_t i = 0, e = Length - N + 1; i != e; ++i)
171 if (substr(i, N).equals(Str))
176 static unsigned GetAutoSenseRadix(StringRef &Str) {
177 if (Str.startswith("0x")) {
180 } else if (Str.startswith("0b")) {
183 } else if (Str.startswith("0")) {
191 /// GetAsUnsignedInteger - Workhorse method that converts a integer character
192 /// sequence of radix up to 36 to an unsigned long long value.
193 static bool GetAsUnsignedInteger(StringRef Str, unsigned Radix,
194 unsigned long long &Result) {
195 // Autosense radix if not specified.
197 Radix = GetAutoSenseRadix(Str);
199 // Empty strings (after the radix autosense) are invalid.
200 if (Str.empty()) return true;
202 // Parse all the bytes of the string given this radix. Watch for overflow.
204 while (!Str.empty()) {
206 if (Str[0] >= '0' && Str[0] <= '9')
207 CharVal = Str[0]-'0';
208 else if (Str[0] >= 'a' && Str[0] <= 'z')
209 CharVal = Str[0]-'a'+10;
210 else if (Str[0] >= 'A' && Str[0] <= 'Z')
211 CharVal = Str[0]-'A'+10;
215 // If the parsed value is larger than the integer radix, the string is
217 if (CharVal >= Radix)
220 // Add in this character.
221 unsigned long long PrevResult = Result;
222 Result = Result*Radix+CharVal;
224 // Check for overflow.
225 if (Result < PrevResult)
234 bool StringRef::getAsInteger(unsigned Radix, unsigned long long &Result) const {
235 return GetAsUnsignedInteger(*this, Radix, Result);
239 bool StringRef::getAsInteger(unsigned Radix, long long &Result) const {
240 unsigned long long ULLVal;
242 // Handle positive strings first.
243 if (empty() || front() != '-') {
244 if (GetAsUnsignedInteger(*this, Radix, ULLVal) ||
245 // Check for value so large it overflows a signed value.
246 (long long)ULLVal < 0)
252 // Get the positive part of the value.
253 if (GetAsUnsignedInteger(substr(1), Radix, ULLVal) ||
254 // Reject values so large they'd overflow as negative signed, but allow
255 // "-0". This negates the unsigned so that the negative isn't undefined
256 // on signed overflow.
257 (long long)-ULLVal > 0)
264 bool StringRef::getAsInteger(unsigned Radix, int &Result) const {
266 if (getAsInteger(Radix, Val) ||
273 bool StringRef::getAsInteger(unsigned Radix, unsigned &Result) const {
274 unsigned long long Val;
275 if (getAsInteger(Radix, Val) ||
276 (unsigned)Val != Val)
282 bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
283 StringRef Str = *this;
285 // Autosense radix if not specified.
287 Radix = GetAutoSenseRadix(Str);
289 assert(Radix > 1 && Radix <= 36);
291 // Empty strings (after the radix autosense) are invalid.
292 if (Str.empty()) return true;
294 // Skip leading zeroes. This can be a significant improvement if
295 // it means we don't need > 64 bits.
296 while (!Str.empty() && Str.front() == '0')
299 // If it was nothing but zeroes....
301 Result = APInt(64, 0);
305 // (Over-)estimate the required number of bits.
306 unsigned Log2Radix = 0;
307 while ((1U << Log2Radix) < Radix) Log2Radix++;
308 bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix);
310 unsigned BitWidth = Log2Radix * Str.size();
311 if (BitWidth < Result.getBitWidth())
312 BitWidth = Result.getBitWidth(); // don't shrink the result
314 Result.zext(BitWidth);
316 APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix
317 if (!IsPowerOf2Radix) {
318 // These must have the same bit-width as Result.
319 RadixAP = APInt(BitWidth, Radix);
320 CharAP = APInt(BitWidth, 0);
323 // Parse all the bytes of the string given this radix.
325 while (!Str.empty()) {
327 if (Str[0] >= '0' && Str[0] <= '9')
328 CharVal = Str[0]-'0';
329 else if (Str[0] >= 'a' && Str[0] <= 'z')
330 CharVal = Str[0]-'a'+10;
331 else if (Str[0] >= 'A' && Str[0] <= 'Z')
332 CharVal = Str[0]-'A'+10;
336 // If the parsed value is larger than the integer radix, the string is
338 if (CharVal >= Radix)
341 // Add in this character.
342 if (IsPowerOf2Radix) {
343 Result <<= Log2Radix;