flang/runtime/connection.h

   1 //===-- runtime/connection.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 // Fortran I/O connection state (abstracted over internal & external units)
  10
  11 #ifndef FORTRAN_RUNTIME_IO_CONNECTION_H_
  12 #define FORTRAN_RUNTIME_IO_CONNECTION_H_
  13
  14 #include "format.h"
  15 #include <cinttypes>
  16 #include <optional>
  17
  18 namespace Fortran::runtime::io {
  19
  20 enum class Direction { Output, Input };
  21 enum class Access { Sequential, Direct, Stream };
  22
  23 inline bool IsRecordFile(Access a) { return a != Access::Stream; }
  24
  25 // These characteristics of a connection are immutable after being
  26 // established in an OPEN statement.
  27 struct ConnectionAttributes {
  28   Access access{Access::Sequential}; // ACCESS='SEQUENTIAL', 'DIRECT', 'STREAM'
  29   bool isUnformatted{false}; // FORM='UNFORMATTED'
  30   bool isUTF8{false}; // ENCODING='UTF-8'
  31   bool isFixedRecordLength{false}; // RECL= on OPEN
  32   std::optional<std::int64_t> recordLength; // RECL= or current record
  33 };
  34
  35 struct ConnectionState : public ConnectionAttributes {
  36   bool IsAtEOF() const; // true when read has hit EOF or endfile record
  37   std::size_t RemainingSpaceInRecord() const;
  38   void HandleAbsolutePosition(std::int64_t);
  39   void HandleRelativePosition(std::int64_t);
  40
  41   void BeginRecord() {
  42     positionInRecord = 0;
  43     furthestPositionInRecord = 0;
  44     leftTabLimit.reset();
  45   }
  46
  47   // Positions in a record file (sequential or direct, not stream)
  48   std::int64_t currentRecordNumber{1}; // 1 is first
  49   std::int64_t positionInRecord{0}; // offset in current record
  50   std::int64_t furthestPositionInRecord{0}; // max(position+bytes)
  51   bool nonAdvancing{false}; // ADVANCE='NO'
  52
  53   // Set at end of non-advancing I/O data transfer
  54   std::optional<std::int64_t> leftTabLimit; // offset in current record
  55
  56   // currentRecordNumber value captured after ENDFILE/REWIND/BACKSPACE statement
  57   // or an end-of-file READ condition on a sequential access file
  58   std::optional<std::int64_t> endfileRecordNumber;
  59
  60   // Mutable modes set at OPEN() that can be overridden in READ/WRITE & FORMAT
  61   MutableModes modes; // BLANK=, DECIMAL=, SIGN=, ROUND=, PAD=, DELIM=, kP
  62 };
  63 } // namespace Fortran::runtime::io
  64 #endif // FORTRAN_RUNTIME_IO_CONNECTION_H_