flang/lib/Evaluate/character.h

   1 //===-- lib/Evaluate/character.h --------------------------------*- C++ -*-===//
   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
   9 #ifndef FORTRAN_EVALUATE_CHARACTER_H_
  10 #define FORTRAN_EVALUATE_CHARACTER_H_
  11
  12 #include "flang/Evaluate/type.h"
  13 #include <string>
  14
  15 // Provides implementations of intrinsic functions operating on character
  16 // scalars.
  17
  18 namespace Fortran::evaluate {
  19
  20 template <int KIND> class CharacterUtils {
  21   using Character = Scalar<Type<TypeCategory::Character, KIND>>;
  22   using CharT = typename Character::value_type;
  23
  24 public:
  25   // CHAR also implements ACHAR under assumption that character encodings
  26   // contain ASCII
  27   static Character CHAR(std::uint64_t code) {
  28     return Character{{static_cast<CharT>(code)}};
  29   }
  30
  31   // ICHAR also implements IACHAR under assumption that character encodings
  32   // contain ASCII
  33   static std::int64_t ICHAR(const Character &c) {
  34     CHECK(c.length() == 1);
  35     // Convert first to an unsigned integer type to avoid sign extension
  36     return static_cast<common::HostUnsignedIntType<(8 * KIND)>>(c[0]);
  37   }
  38
  39   static Character NEW_LINE() { return Character{{NewLine()}}; }
  40
  41   static Character ADJUSTL(const Character &str) {
  42     auto pos{str.find_first_not_of(Space())};
  43     if (pos != Character::npos && pos != 0) {
  44       return Character{str.substr(pos) + Character(pos, Space())};
  45     }
  46     // else empty or only spaces, or no leading spaces
  47     return str;
  48   }
  49
  50   static Character ADJUSTR(const Character &str) {
  51     auto pos{str.find_last_not_of(Space())};
  52     if (pos != Character::npos && pos != str.length() - 1) {
  53       auto delta{str.length() - 1 - pos};
  54       return Character{Character(delta, Space()) + str.substr(0, pos + 1)};
  55     }
  56     // else empty or only spaces, or no trailing spaces
  57     return str;
  58   }
  59
  60   static ConstantSubscript INDEX(
  61       const Character &str, const Character &substr, bool back = false) {
  62     auto pos{back ? str.rfind(substr) : str.find(substr)};
  63     return static_cast<ConstantSubscript>(pos == str.npos ? 0 : pos + 1);
  64   }
  65
  66   static ConstantSubscript SCAN(
  67       const Character &str, const Character &set, bool back = false) {
  68     auto pos{back ? str.find_last_of(set) : str.find_first_of(set)};
  69     return static_cast<ConstantSubscript>(pos == str.npos ? 0 : pos + 1);
  70   }
  71
  72   static ConstantSubscript VERIFY(
  73       const Character &str, const Character &set, bool back = false) {
  74     auto pos{back ? str.find_last_not_of(set) : str.find_first_not_of(set)};
  75     return static_cast<ConstantSubscript>(pos == str.npos ? 0 : pos + 1);
  76   }
  77
  78   // Resize adds spaces on the right if the new size is bigger than the
  79   // original, or by trimming the rightmost characters otherwise.
  80   static Character Resize(const Character &str, std::size_t newLength) {
  81     auto oldLength{str.length()};
  82     if (newLength > oldLength) {
  83       return str + Character(newLength - oldLength, Space());
  84     } else {
  85       return str.substr(0, newLength);
  86     }
  87   }
  88
  89   static ConstantSubscript LEN_TRIM(const Character &str) {
  90     auto j{str.length()};
  91     for (; j >= 1; --j) {
  92       if (str[j - 1] != ' ') {
  93         break;
  94       }
  95     }
  96     return static_cast<ConstantSubscript>(j);
  97   }
  98
  99   static Character REPEAT(const Character &str, ConstantSubscript ncopies) {
 100     Character result;
 101     if (!str.empty() && ncopies > 0) {
 102       result.reserve(ncopies * str.size());
 103       while (ncopies-- > 0) {
 104         result += str;
 105       }
 106     }
 107     return result;
 108   }
 109
 110   static Character TRIM(const Character &str) {
 111     return str.substr(0, LEN_TRIM(str));
 112   }
 113
 114 private:
 115   // Following helpers assume that character encodings contain ASCII
 116   static constexpr CharT Space() { return 0x20; }
 117   static constexpr CharT NewLine() { return 0x0a; }
 118 };
 119
 120 } // namespace Fortran::evaluate
 121
 122 #endif // FORTRAN_EVALUATE_CHARACTER_H_