inner_literal_reverse.hpp

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#ifndef REAL_FRONTEND_INNER_LITERAL_REVERSE_HPP
#define REAL_FRONTEND_INNER_LITERAL_REVERSE_HPP
 
#include <real/version.hpp>
 
#include <cstddef>
#include <cstdint>
#include <string_view>
 
#include <real/automata/lazy_dfa.hpp> // build_byte_program, reverse_dfa
#include <real/frontend/ast.hpp>
#include <real/frontend/compiler.hpp> // compile
#include <real/frontend/inner_literal.hpp>
 
namespace real::detail {
 
  inline std::size_t prefix_reverse_start(const ast&       tree,
                                          std::int32_t     count,
                                          flags            compile_flags,
                                          std::string_view text,
                                          std::size_t      h,
                                          std::size_t      min_start)
  {
    if (count == 0) {
      return h; // literal at the head: start == candidate
    }
    const ast             prefix {build_prefix_ast(tree, count)};
    const dynamic_program prog   {compile(prefix, compile_flags | prefix.inline_flags)};
    const byte_program    bp     {build_byte_program(prog.view())};
    if (!bp.eligible) {
      return npos; // an assertion/lookaround in the prefix — unreachable for an extracted pattern
    }
    reverse_dfa rev {bp.code, bp.classes};
    return rev.reverse_start(text, h, min_start);
  }
} // namespace real::detail
 
#endif // REAL_FRONTEND_INNER_LITERAL_REVERSE_HPP