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//===-- runtime/connection.h ------------------------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Fortran I/O connection state (abstracted over internal & external units)
#include "format.h"
#include <cinttypes>
#include <optional>
namespace Fortran::runtime::io {
class IoStatementState;
enum class Direction { Output, Input };
enum class Access { Sequential, Direct, Stream };
inline bool IsRecordFile(Access a) { return a != Access::Stream; }
// These characteristics of a connection are immutable after being
// established in an OPEN statement, except for recordLength,
// which is immutable only when isFixedRecordLength is true.
struct ConnectionAttributes {
Access access{Access::Sequential}; // ACCESS='SEQUENTIAL', 'DIRECT', 'STREAM'
std::optional<bool> isUnformatted; // FORM='UNFORMATTED' if true
bool isUTF8{false}; // ENCODING='UTF-8'
bool isFixedRecordLength{false}; // RECL= on OPEN
std::optional<std::int64_t> recordLength; // RECL= or current record
struct ConnectionState : public ConnectionAttributes {
bool IsAtEOF() const; // true when read has hit EOF or endfile record
std::size_t RemainingSpaceInRecord() const;
bool NeedAdvance(std::size_t) const;
void HandleAbsolutePosition(std::int64_t);
void HandleRelativePosition(std::int64_t);
void BeginRecord() {
positionInRecord = 0;
furthestPositionInRecord = 0;
// Positions in a record file (sequential or direct, not stream)
std::int64_t currentRecordNumber{1}; // 1 is first
std::int64_t positionInRecord{0}; // offset in current record
std::int64_t furthestPositionInRecord{0}; // max(position+bytes)
// Set at end of non-advancing I/O data transfer
std::optional<std::int64_t> leftTabLimit; // offset in current record
// currentRecordNumber value captured after ENDFILE/REWIND/BACKSPACE statement
// or an end-of-file READ condition on a sequential access file
std::optional<std::int64_t> endfileRecordNumber;
// Mutable modes set at OPEN() that can be overridden in READ/WRITE & FORMAT
MutableModes modes; // BLANK=, DECIMAL=, SIGN=, ROUND=, PAD=, DELIM=, kP
// Set when processing repeated items during list-directed & NAMELIST input
// in order to keep a span of records in frame on a non-positionable file,
// so that backspacing to the beginning of the repeated item doesn't require
// repositioning the external storage medium when that's impossible.
bool pinnedFrame{false};
// Utility class for capturing and restoring a position in an input stream.
class SavedPosition {
explicit SavedPosition(IoStatementState &);
IoStatementState &io_;
ConnectionState saved_;
} // namespace Fortran::runtime::io