107aa28930
Original-commit: flang-compiler/f18@55f4f0505e Reviewed-on: https://github.com/flang-compiler/f18/pull/61 Tree-same-pre-rewrite: false
50 lines
1.6 KiB
C++
50 lines
1.6 KiB
C++
#ifndef FORTRAN_PARSER_CHAR_SET_H_
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#define FORTRAN_PARSER_CHAR_SET_H_
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// Sets of distinct characters that are valid in Fortran programs outside
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// character literals are encoded as 64-bit integers by mapping them to a 6-bit
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// character set encoding in which the case of letters is lost. These sets
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// need to be suitable for constexprs, so std::bitset<> was not eligible.
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#include <cinttypes>
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#include <string>
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namespace Fortran {
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namespace parser {
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struct SetOfChars {
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constexpr SetOfChars() {}
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constexpr SetOfChars(char c) {
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if (c <= 32 /*space*/) {
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// map control characters, incl. LF (newline), to '?'
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c = '?';
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} else if (c >= 127) {
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// map DEL and 8-bit characters to '^'
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c = '^';
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} else if (c >= 96) {
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// map lower-case letters to upper-case
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c -= 32;
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}
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// range is now [32..95]; reduce to [0..63] and use as a shift count
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bits_ = static_cast<std::uint64_t>(1) << (c - 32);
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}
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constexpr SetOfChars(const char str[], std::size_t n = 256) {
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for (std::size_t j{0}; j < n; ++j) {
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bits_ |= SetOfChars{str[j]}.bits_;
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}
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}
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constexpr SetOfChars(std::uint64_t b) : bits_{b} {}
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constexpr SetOfChars(const SetOfChars &) = default;
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constexpr SetOfChars(SetOfChars &&) = default;
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constexpr SetOfChars &operator=(const SetOfChars &) = default;
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constexpr SetOfChars &operator=(SetOfChars &&) = default;
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std::string ToString() const;
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std::uint64_t bits_{0};
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};
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static inline constexpr bool IsCharInSet(SetOfChars set, char c) {
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return (set.bits_ & SetOfChars{c}.bits_) != 0;
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}
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} // namespace parser
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} // namespace Fortran
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#endif // FORTRAN_PARSER_CHAR_SET_H_
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