include/llvm/Support/UnicodeCharRanges.h

   1 //===--- UnicodeCharRanges.h - Types and functions for character ranges ---===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 #ifndef LLVM_SUPPORT_UNICODECHARRANGES_H
   9 #define LLVM_SUPPORT_UNICODECHARRANGES_H
  10
  11 #include "llvm/ADT/ArrayRef.h"
  12 #include "llvm/Support/Compiler.h"
  13 #include "llvm/Support/Debug.h"
  14 #include "llvm/Support/raw_ostream.h"
  15 #include <algorithm>
  16
  17 #define DEBUG_TYPE "unicode"
  18
  19 namespace llvm {
  20 namespace sys {
  21
  22 /// Represents a closed range of Unicode code points [Lower, Upper].
  23 struct UnicodeCharRange {
  24   uint32_t Lower;
  25   uint32_t Upper;
  26 };
  27
  28 inline bool operator<(uint32_t Value, UnicodeCharRange Range) {
  29   return Value < Range.Lower;
  30 }
  31 inline bool operator<(UnicodeCharRange Range, uint32_t Value) {
  32   return Range.Upper < Value;
  33 }
  34
  35 /// Holds a reference to an ordered array of UnicodeCharRange and allows
  36 /// to quickly check if a code point is contained in the set represented by this
  37 /// array.
  38 class UnicodeCharSet {
  39 public:
  40   typedef ArrayRef<UnicodeCharRange> CharRanges;
  41
  42   /// Constructs a UnicodeCharSet instance from an array of
  43   /// UnicodeCharRanges.
  44   ///
  45   /// Array pointed by \p Ranges should have the lifetime at least as long as
  46   /// the UnicodeCharSet instance, and should not change. Array is validated by
  47   /// the constructor, so it makes sense to create as few UnicodeCharSet
  48   /// instances per each array of ranges, as possible.
  49 #ifdef NDEBUG
  50
  51   // FIXME: This could use constexpr + static_assert. This way we
  52   // may get rid of NDEBUG in this header. Unfortunately there are some
  53   // problems to get this working with MSVC 2013. Change this when
  54   // the support for MSVC 2013 is dropped.
  55   constexpr UnicodeCharSet(CharRanges Ranges) : Ranges(Ranges) {}
  56 #else
  57   UnicodeCharSet(CharRanges Ranges) : Ranges(Ranges) {
  58     assert(rangesAreValid());
  59   }
  60 #endif
  61
  62   /// Returns true if the character set contains the Unicode code point
  63   /// \p C.
  64   bool contains(uint32_t C) const {
  65     return std::binary_search(Ranges.begin(), Ranges.end(), C);
  66   }
  67
  68 private:
  69   /// Returns true if each of the ranges is a proper closed range
  70   /// [min, max], and if the ranges themselves are ordered and non-overlapping.
  71   bool rangesAreValid() const {
  72     uint32_t Prev = 0;
  73     for (CharRanges::const_iterator I = Ranges.begin(), E = Ranges.end();
  74          I != E; ++I) {
  75       if (I != Ranges.begin() && Prev >= I->Lower) {
  76         LLVM_DEBUG(dbgs() << "Upper bound 0x");
  77         LLVM_DEBUG(dbgs().write_hex(Prev));
  78         LLVM_DEBUG(dbgs() << " should be less than succeeding lower bound 0x");
  79         LLVM_DEBUG(dbgs().write_hex(I->Lower) << "\n");
  80         return false;
  81       }
  82       if (I->Upper < I->Lower) {
  83         LLVM_DEBUG(dbgs() << "Upper bound 0x");
  84         LLVM_DEBUG(dbgs().write_hex(I->Lower));
  85         LLVM_DEBUG(dbgs() << " should not be less than lower bound 0x");
  86         LLVM_DEBUG(dbgs().write_hex(I->Upper) << "\n");
  87         return false;
  88       }
  89       Prev = I->Upper;
  90     }
  91
  92     return true;
  93   }
  94
  95   const CharRanges Ranges;
  96 };
  97
  98 } // namespace sys
  99 } // namespace llvm
 100
 101 #undef DEBUG_TYPE // "unicode"
 102
 103 #endif // LLVM_SUPPORT_UNICODECHARRANGES_H