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      1 //===-- llvm/ADT/StringExtras.h - Useful string functions -------*- C++ -*-===//
      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 contains some functions that are useful when dealing with strings.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_ADT_STRINGEXTRAS_H
     15 #define LLVM_ADT_STRINGEXTRAS_H
     16 
     17 #include "llvm/ADT/StringRef.h"
     18 #include "llvm/Support/DataTypes.h"
     19 #include <iterator>
     20 
     21 namespace llvm {
     22 template<typename T> class SmallVectorImpl;
     23 
     24 /// hexdigit - Return the hexadecimal character for the
     25 /// given number \p X (which should be less than 16).
     26 static inline char hexdigit(unsigned X, bool LowerCase = false) {
     27   const char HexChar = LowerCase ? 'a' : 'A';
     28   return X < 10 ? '0' + X : HexChar + X - 10;
     29 }
     30 
     31 /// Construct a string ref from a boolean.
     32 static inline StringRef toStringRef(bool B) {
     33   return StringRef(B ? "true" : "false");
     34 }
     35 
     36 /// Interpret the given character \p C as a hexadecimal digit and return its
     37 /// value.
     38 ///
     39 /// If \p C is not a valid hex digit, -1U is returned.
     40 static inline unsigned hexDigitValue(char C) {
     41   if (C >= '0' && C <= '9') return C-'0';
     42   if (C >= 'a' && C <= 'f') return C-'a'+10U;
     43   if (C >= 'A' && C <= 'F') return C-'A'+10U;
     44   return -1U;
     45 }
     46 
     47 /// utohex_buffer - Emit the specified number into the buffer specified by
     48 /// BufferEnd, returning a pointer to the start of the string.  This can be used
     49 /// like this: (note that the buffer must be large enough to handle any number):
     50 ///    char Buffer[40];
     51 ///    printf("0x%s", utohex_buffer(X, Buffer+40));
     52 ///
     53 /// This should only be used with unsigned types.
     54 ///
     55 template<typename IntTy>
     56 static inline char *utohex_buffer(IntTy X, char *BufferEnd) {
     57   char *BufPtr = BufferEnd;
     58   *--BufPtr = 0;      // Null terminate buffer.
     59   if (X == 0) {
     60     *--BufPtr = '0';  // Handle special case.
     61     return BufPtr;
     62   }
     63 
     64   while (X) {
     65     unsigned char Mod = static_cast<unsigned char>(X) & 15;
     66     *--BufPtr = hexdigit(Mod);
     67     X >>= 4;
     68   }
     69   return BufPtr;
     70 }
     71 
     72 static inline std::string utohexstr(uint64_t X) {
     73   char Buffer[17];
     74   return utohex_buffer(X, Buffer+17);
     75 }
     76 
     77 static inline std::string utostr_32(uint32_t X, bool isNeg = false) {
     78   char Buffer[11];
     79   char *BufPtr = Buffer+11;
     80 
     81   if (X == 0) *--BufPtr = '0';  // Handle special case...
     82 
     83   while (X) {
     84     *--BufPtr = '0' + char(X % 10);
     85     X /= 10;
     86   }
     87 
     88   if (isNeg) *--BufPtr = '-';   // Add negative sign...
     89 
     90   return std::string(BufPtr, Buffer+11);
     91 }
     92 
     93 static inline std::string utostr(uint64_t X, bool isNeg = false) {
     94   char Buffer[21];
     95   char *BufPtr = Buffer+21;
     96 
     97   if (X == 0) *--BufPtr = '0';  // Handle special case...
     98 
     99   while (X) {
    100     *--BufPtr = '0' + char(X % 10);
    101     X /= 10;
    102   }
    103 
    104   if (isNeg) *--BufPtr = '-';   // Add negative sign...
    105   return std::string(BufPtr, Buffer+21);
    106 }
    107 
    108 
    109 static inline std::string itostr(int64_t X) {
    110   if (X < 0)
    111     return utostr(static_cast<uint64_t>(-X), true);
    112   else
    113     return utostr(static_cast<uint64_t>(X));
    114 }
    115 
    116 /// StrInStrNoCase - Portable version of strcasestr.  Locates the first
    117 /// occurrence of string 's1' in string 's2', ignoring case.  Returns
    118 /// the offset of s2 in s1 or npos if s2 cannot be found.
    119 StringRef::size_type StrInStrNoCase(StringRef s1, StringRef s2);
    120 
    121 /// getToken - This function extracts one token from source, ignoring any
    122 /// leading characters that appear in the Delimiters string, and ending the
    123 /// token at any of the characters that appear in the Delimiters string.  If
    124 /// there are no tokens in the source string, an empty string is returned.
    125 /// The function returns a pair containing the extracted token and the
    126 /// remaining tail string.
    127 std::pair<StringRef, StringRef> getToken(StringRef Source,
    128                                          StringRef Delimiters = " \t\n\v\f\r");
    129 
    130 /// SplitString - Split up the specified string according to the specified
    131 /// delimiters, appending the result fragments to the output list.
    132 void SplitString(StringRef Source,
    133                  SmallVectorImpl<StringRef> &OutFragments,
    134                  StringRef Delimiters = " \t\n\v\f\r");
    135 
    136 /// HashString - Hash function for strings.
    137 ///
    138 /// This is the Bernstein hash function.
    139 //
    140 // FIXME: Investigate whether a modified bernstein hash function performs
    141 // better: http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx
    142 //   X*33+c -> X*33^c
    143 static inline unsigned HashString(StringRef Str, unsigned Result = 0) {
    144   for (StringRef::size_type i = 0, e = Str.size(); i != e; ++i)
    145     Result = Result * 33 + (unsigned char)Str[i];
    146   return Result;
    147 }
    148 
    149 /// Returns the English suffix for an ordinal integer (-st, -nd, -rd, -th).
    150 static inline StringRef getOrdinalSuffix(unsigned Val) {
    151   // It is critically important that we do this perfectly for
    152   // user-written sequences with over 100 elements.
    153   switch (Val % 100) {
    154   case 11:
    155   case 12:
    156   case 13:
    157     return "th";
    158   default:
    159     switch (Val % 10) {
    160       case 1: return "st";
    161       case 2: return "nd";
    162       case 3: return "rd";
    163       default: return "th";
    164     }
    165   }
    166 }
    167 
    168 template <typename IteratorT>
    169 inline std::string join_impl(IteratorT Begin, IteratorT End,
    170                              StringRef Separator, std::input_iterator_tag) {
    171   std::string S;
    172   if (Begin == End)
    173     return S;
    174 
    175   S += (*Begin);
    176   while (++Begin != End) {
    177     S += Separator;
    178     S += (*Begin);
    179   }
    180   return S;
    181 }
    182 
    183 template <typename IteratorT>
    184 inline std::string join_impl(IteratorT Begin, IteratorT End,
    185                              StringRef Separator, std::forward_iterator_tag) {
    186   std::string S;
    187   if (Begin == End)
    188     return S;
    189 
    190   size_t Len = (std::distance(Begin, End) - 1) * Separator.size();
    191   for (IteratorT I = Begin; I != End; ++I)
    192     Len += (*Begin).size();
    193   S.reserve(Len);
    194   S += (*Begin);
    195   while (++Begin != End) {
    196     S += Separator;
    197     S += (*Begin);
    198   }
    199   return S;
    200 }
    201 
    202 /// Joins the strings in the range [Begin, End), adding Separator between
    203 /// the elements.
    204 template <typename IteratorT>
    205 inline std::string join(IteratorT Begin, IteratorT End, StringRef Separator) {
    206   typedef typename std::iterator_traits<IteratorT>::iterator_category tag;
    207   return join_impl(Begin, End, Separator, tag());
    208 }
    209 
    210 } // End llvm namespace
    211 
    212 #endif
    213